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Accurate and low-power decoding of brain signals such as electroencephalography (EEG) is key to constructing brain-computer interface (BCI) based wearable devices. While deep learning approaches have progressed substantially in terms of decoding accuracy, their power consumption is relatively high for mobile applications. Neuromorphic hardware arises as a promising solution to tackle this problem since it can run massive spiking neural networks with energy consumption orders of magnitude lower than traditional hardware. Herein, we show the viability of directly mapping a continuous-valued convolutional neural network for motor imagery EEG classification to a spiking neural network. The converted network, able to run on the SpiNNaker neuromorphic chip, only shows a 1.91% decrease in accuracy after conversion. Thus, we take full advantage of the benefits of both deep learning accuracies and low-power neuro-inspired hardware, properties that are key for the development of wearable BCI devices.

Acute appendicitis is one of the most common causes of acute abdominal pain seen in the emergency room. Common etiologies include obstructing appendicolith and lymphoid adenopathy. Appendiceal endometriosis is rare and typically involves the serosal layer. This case report describes an unusual case of appendicitis secondary to endometriosis in the musclularis mucosa of the appendix in the 36-year-old lady with no prior history of endometriosis.

Idiopathic spontaneous intraperitoneal hemorrhage (ISIH) is a rare event associated with high mortality. There have been multiple case reports of spontaneous rupture of middle colic pseudoaneurysms in the literature. Herein, we present a case of a 51-year-old female that presented with spontaneous rupture of the middle colic artery and associated massive intraabdominal hematoma without findings of a pseudoaneurysm. The patient underwent a computed tomography (CT) scan as an outpatient 24 hours prior to the onset of the bleeding due to abdominal pain without findings of hematoma or aneurysm of the mesenteric vessels. Subsequently, the patient underwent emergent exploratory laparotomy with findings of a massive hematoma in the lesser sac and spontaneous bleeding from the middle colic artery that was ligated. The patient had an uneventful postoperative course and fully recovered. To our knowledge, this is the second reported case of idiopathic bleeding from the middle colic artery without evidence of a pseudoaneurysm based on a current review of the literature.

Trabajo Final Integrador Especialista en Planeamiento y Gestión de Recursos Materiales de Organizaciones Militares Terrestres Fil: Belizon, Leonardo Anibal Belizon, L. A. (2015). Herramienta informática de empleo en la logística de material del componente ejército del teatro de operaciones para el registro integral de los efectos de arsenales e intendencia. (Trabajo final integrador). Escuela Superior de Guerra Tte Grl Luis María Campos : Ciudad Autónoma de Buenos Aires.

Surgical resection remains the mainstay of treatment for the vast majority of patients with primary solid tumors. However, there is evidence that the physiologic response to surgery may be a particularly dangerous one for cancer patients. In both the experimental and the human arena, several potential mechanisms by which surgical trauma might impact tumor growth have been discovered. Clinical studies have demonstrated that surgery is associated with alterations in immune function as well as plasma composition that may make the patient more susceptible to the development of tumor recurrences. It is logical to assume that the body should be primed for angiogenesis postoperatively because of the surgical wounds. This may be problematic for cancer patients since the conditions conducive to wound healing may also promote tumor growth. This article reviews the experimental evidence that suggests there is a significant increase in angiogenesis following surgical trauma and that this increase may impact long-term cancer-free survival.

Experimentally, laparotomy is associated with increased tumor growth. In humans, abdominal surgery is associated with immunosuppression and elevated plasma VEGF levels that might stimulate tumor growth early after surgery. Avoidance of these surgery-related changes and their consequences may be advantageous. Granulocyte-macrophage colony stimulating factor (GMCSF) is a non-specific immune system up-regulator that has also been associated, experimentally, with increased release of soluble VEGF Receptor 1 (sVEGFR1) which is an endogenous inhibitor of VEGF. This study's purpose was to determine the impact of perioperatively administered recombinant human GMCSF (rhu-GMCSF) on both immune function and plasma sVEGFR1 levels in colorectal cancer patients.This randomized placebo-controlled study included 36 colorectal cancer patients who underwent minimally invasive resection (17 GMCSF, 19 Placebo). Patients received 7 subcutaneous injections of either rhu-GMCSF, 125 microg/m2, or saline on preoperative days 3, 2 and 1 and on postoperative days (POD) 1, 2, 3 and 4. A number of immune parameters were followed and plasma levels of soluble VEGF Receptor 1 (sVEGFR1) and VEGF were determined.The total WBC, neutrophil, eosinophil, and monocyte counts were significantly higher after surgery in the GMCSF group; no differences were noted for the other immune parameters. In the GMCSF group, median plasma sVEGFR1 levels were significantly elevated on POD 1 (188.1 pg/ml), and on POD 5 (142.8 pg/ml) when compared to pre-GMCSF levels (0 pg/ml) (p-value0.05 for all comparisons). In the placebo group, the POD5 median sVEGFR1 level (116.3 pg/ml) was elevated and of borderline significance (p=0.05) vs the pre-treatment result (0 pg/ml). Of note, both groups had significantly elevated median plasma VEGF levels on POD 5 (Control 435.7 pg/ml; GMCSF 385.3 pg/ml) when compared to their preoperative results (Control 183.3 pg/ml, p=0.0013; GMCSF 171.5 pg/ml, p=0.0055).Perioperative GMCSF was not associated with an immune function benefit in this study, however, such treatment leads to increased plasma sVEGFR1 levels. Colorectal resection, with or without GMCSF, was also associated with increased VEGF levels postoperatively. Increased plasma levels of sVEGFR1 after surgery might limit the pro-angiogenic tumor stimulatory effects of VEGF. Further study of GMCSF's impact on angiogenesis appears warranted.

Chronic inflammation in the setting of inflammatory bowel disease is thought to result in altered epithelial cell growth regulation and ultimately carcinogenesis. This loss in cell growth regulation may be partially caused by a decrease in circulating intact insulin-like growth factor binding protein-3 (IFGB-3) as a result of chronic inflammation. This study evaluates the effect of IFGB-3 on carcinogenesis in the setting of colitis.A previously described animal model for colitis-induced carcinogenesis was used. Colitis was induced in both wild-type and IFGB-3 transgenic CD1 mice with a one-week oral exposure to dextran sodium sulfate (2 percent in drinking water). All mice received a single intraperitoneal administration (10 mg/kg body weight) of a genotoxic colonic carcinogen, azoxymethane. At Week 20, the animals were killed and their colons were excised. The colons were examined by a pathologist under blinded conditions. Criteria assessed included the severity of colitis, number of aberrant crypt foci per mouse colon, incidence of colonic adenomas, and mean size of colonic adenomas.A total of 20 mice (10 in each group) were included in the study. The severity of colitis was not significantly different between the two groups (mean colitis score wild-type = 13.2; IFGB-3 transgenic = 11; P = not significant). The average number of aberrant crypt foci per colon was significantly lower in the IFGB-3 transgenic mice compared with the wild-type mice (1.5 +/- 1.4 vs. 4.5 +/- 2.7, respectively; P0.0001). The number of adenomas per colon was significantly lower in IFGB-3 transgenic group (1.2 +/- 1.8) compared with the wild-type mice (3.7 +/- 2.7; P = 0.005). In addition the average size of adenomas was significantly smaller in IFGB-3 transgenic mice (1.4 +/- 1.3 mm) compared with the wild-type mice (2.6 +/- 2 mm; P = 0.013).IFGB-3 significantly reduces the development of colonic tumors and precursor lesions in the setting of induced murine colitis. It is possible that the loss of IFGB-3 as a result of chronic inflammation may be associated with an increased rate of carcinogenesis in the inflammatory bowel disease setting. Although further studies are necessary, in theory, inhibiting the depletion of IFGB-3 or replacement of IFGB-3 may serve as a novel treatment strategy to prevent the development of colitis-induced carcinogenesis.

The authors previously demonstrated a significant decrease in plasma levels of intact insulin-like growth factor binding protein-3 (IGFBP-3) after major open but not after laparoscopic-assisted surgery in humans. They postulated that this decrease may have an effect on postoperative tumor growth. It also has been shown that plasma levels of matrix metalloproteinase-9 (MMP-9), a protease capable of degrading IGFBP-3, are transiently increased after open colectomy in humans. The authors aimed to develop an animal model that would allow further study of the effect that surgical trauma has on plasma levels IGFBP-3 and MMP-9. In addition, they set out to assess the concentration of MMP-9 in circulating monocytes before and after surgery.The 30 mice included in this study were divided into three groups: sham laparotomy, carbon dioxide (CO2) pneumoperitoneum, and anesthesia control. All mice were IGFBP-3 transgenics (overexpressing human IGFBP-3) on a CD1 background. The mice were anesthetized using ketamine and xylazine. Blood was drawn retroorbitally 48 h before the procedure. The duration of the procedure was 30 min. The animals were killed 24 h postoperatively and blood was drawn. Intact IGFBP-3 levels were measured using a combination of Western blot analysis and enzyme-linked immunoassay (ELISA) at the two time points: before and after the operation. Plasma and peripheral blood mononuclear cell levels of MMP-9 were measured at each time point using zymography. Mononuclear cell lysates were used to determine intracellular MMP-9 levels.Plasma levels of intact IGFBP-3 were significantly lower than preoperative levels after sham laparotomy. A mean decrease of 76.6% was noted (p0.05). Zymography demonstrated significantly higher plasma MMP-9-related proteolytic activity than observed preoperatively after sham laparotomy (78.5 vs 42.3 Relative Units [RU]; p0.05). In the pneumoperitoneum group, no significant decrease was found between the pre- and postoperative levels of intact IGFBP-3. A nonsignificant increase in MMP-9 was noted after CO2 pneumoperitoneum (38 RU preoperatively vs. 46.4 RU postoperatively; p0.05). The anesthesia control group did not demonstrate a significant change in either circulating intact IGFBP-3 levels or MMP-9 levels. Mononuclear intracellular levels of MMP-9 were significantly lower after laparotomy than the preoperative levels (3 vs 37 RU). The postprocedure intracellular levels of MMP-9 were not significantly decreased in the pneumoperitoneum or anesthesia control group.Plasma levels of intact IGFBP-3, a cell growth regulating factor, were found to be decreased significantly after laparotomy. This decrease was not seen after pneumoperitoneum. Depletion of intact IGFBP-3 after laparotomy correlated with a rapid release of MMP-9 from mononuclear cells and an increase in circulating plasma MMP-9 levels. Matrix metalloproteinase-9 may play an important role in IGFBP-3 proteolysis after surgical trauma. Furthermore, circulating mononuclear cells are one source of MMP-9 after surgery. Finally, the model used reproduces events in humans after surgery, and thus should permit further study on the mechanism of IGFBP-3 proteolysis after surgical trauma.

Background The authors have previously demonstrated that insulin-like growth factor binding protein-3 (IGFBP-3) is depleted in plasma for 1 to 3 days after major open surgery (OS), but not after laparoscopic surgery (LS). After surgery, IGFP-3 cleavage occurs rapidly and is likely attributable to altered plasma proteolytic activity. This study aimed to assess plasma proteolysis after both open and closed colorectal resection and, if possible, to identify a protease/protease inhibitor system affected by surgery.

We have previously demonstrated a significant decrease in the serum concentration of intact insulin-like growth factor-binding protein (IGFBP-3) after laparotomy. IGFBP-3, a major IGF binding protein, inhibits the growth of tumor cells via several mechanisms. Our goal was to determine, in a murine model, whether matrix metalloproteinase-9 (MMP-9), a known protease of IGFBP-3, is responsible for the postoperative decrease in serum IGFBP-3 levels. Six IGFBP-3 transgenic mice on a CD-1 background were used in this study. These mice over-express human IGFBP-3. Sham laparotomy, in the form of a midline abdominal incision, was the test procedure. General anesthesia was established using ketamine and xylazine immediately before a 30-minute sham laparotomy and before preoperative blood sampling, done via retro-orbital venipuncture, 48 hours before surgery. The animals were sacrificed and blood was drawn 24 hours postoperatively. Plasma MMP-9 activity was measured using zymography at each time point (48 hours before and 24 hours after operation). MMP-9 activity was also measured in mononuclear cell lysates at both time points. Zymography analysis demonstrated significantly higher plasma levels of MMP-9 postoperatively compared with preoperative levels (81 RU vs 40 RU; P < .05). In contrast, mononuclear cell levels of MMP-9 were significantly higher preoperatively compared with postoperative levels (37.5 RU vs. 0.75 RU, P < .05). Plasma levels of MMP-9, a known protease of IGFBP-3, are significantly elevated postoperatively. In addition, mononuclear cells that store MMP-9 are depleted of it postoperatively. This suggests that rapid MMP-9 release by mononuclear cells leads to an increase in serum levels of this protease postoperatively. Further studies will elucidate mechanisms of MMP-9–related IGFBP-3 depletion.

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Complex fistula-in-ano is a frequent source of concern for both patients and surgeons because of its high rate of recurrence and potential for postoperative anal incontinence. There remains a balance between total sphincter-preserving surgery that may result in a high rate of fecal continence and the more radical approaches.

PURPOSE: Platelet-derived growth factor-BB plays a role in the development of vascular and lymphatic vessels in tumors. In this study plasma levels of platelet-derived growth factor-BB were assessed preoperatively in patients with adenomas and colorectal cancer to determine whether platelet-derived growth factor-BB is a useful marker or prognostic indicator. METHODS: Patients with adenomas and colorectal cancer undergoing resection were assessed. Clinical and pathologic data and preoperative blood samples were collected. Plasma platelet-derived growth factor-BB levels (median, 95 percent confidence interval for median) were determined and the Kruskal-Wallis test and Mann-Whitney U test were used for analysis. RESULTS: One hundred seventy-nine patients were studied (91 with colorectal cancer, 88 with adenomas). Preoperative colorectal cancer platelet-derived growth factor-BB levels were higher (1,771.1 pg/ml; confidence intervals, 1,429-2,065) than in the benign neoplasm group (1083 pg/ml; confidence intervals, 933―1,192, P < 0.001). In patients with colorectal cancer, a direct relationship was noted between platelet-derived growth factor-BB levels and disease severity. Despite the increase in platelet-derived growth factor-BB noted with increasing stage, the differences between the Stages 1, 2, 3, and 4 groups were not significant. CONCLUSION. Platelet-derived growth factor-BB levels were greater in patients with colorectal cancer (vs. patients with adenoma) and rose with increasing disease severity. Unfortunately, however, the modest differences between categories do not permit accurate stage determination.

Restorative proctocolectomy and ileal pouch-anal anastomosis is the current surgical treatment of choice for most patients with ulcerative colitis. Complications of the ileal pouch may necessitate additional operations to salvage the pouch. The aims of this study were to review the outcomes of reoperative restorative proctocolectomy and ileal pouch-anal anastomosis surgery and to define any predictors of successful pouch salvage surgery.The medical records of all patients who underwent reoperative ileoanal pouch surgery for either pouch salvage or pouch excision between 1988 and 2007 were reviewed. Successful ileoanal pouch salvage was considered to be an intact functioning pouch, after resolution of problem, with a follow-up of at least six months and good to excellent patient satisfaction and continence.Fifty-one patients underwent reoperation for pouch-related complications (44 mucosal ulcerative colitis, 6 familial adenomatous polyposis, and 1 indeterminate colitis), in addition to 8 patients with Crohn's disease. An additional 17 patients had primary pouch excision. Thirty-eight (74.4 percent) of the 51 patients who underwent pouch salvage had a successful outcome. Twenty-three patients had pouch reconstruction or revision via an abdominal approach with a 69.5 percent success rate. The remainder of patients had local perineal procedures for control of perianal sepsis, with 75 percent success rate. Patients required a mean of 2.1 procedures to achieve pouch salvage; there was no correlation between the number of ileoanal pouch salvage procedures and failure. Crohn's disease was ultimately diagnosed in more than half of the patients who underwent primary pouch excision. Among the patients with Crohn's disease who underwent pouch salvage only three retained their pouches, for a success rate of only 37 percent.Ileal pouch-anal anastomosis salvage surgery can save a considerable number of patients from pouch excision and permanent ileostomy. Both local perineal and abdominal approaches yield acceptable results. The choice of procedure is based on the etiology and anatomy of the problem and the surgeon's preference and patient-related factors such as diagnosis.

En este documento se lleva a cabo un estudio de tipo cuantitativo, con el objetivo de conocer, a través de la percepción de sus altos directivos, los distintos aspectos y factores que conforman la reputación del CEO, y analizar las diferencias que existen entre los diferentes sectores. El análisis empírico se basa en un estudio cuantitativo de los datos obtenidos en una encuesta realizada en marzo de 2007 en España. El documento concluye que las tres características más relevantes del perfil reputacional del CEO son: la credibilidad, la visión estratégica y la comunicación externa, constituyendo la mayor aportación de este trabajo, las características diferenciadoras y comunes entre unos sectores y otros.

Elevations of plasma vascular endothelial growth factor (VEGF) have been noted early after colorectal resection. The duration of this increase is unknown. Because VEGF is a potent promoter of angiogenesis, which is critical to tumor growth, a sustained increase in blood VEGF levels after surgery may stimulate the growth of residual metastases early after surgery. This preliminary study aimed to determine VEGF levels during the first month after colorectal resection.Patients from three prospective studies that had late postoperative blood samples available comprised the study population. Demographic, perioperative, pathologic, and complication data were collected. Plasma samples were obtained preoperatively for all patients: on postoperative day (POD) 1 for most patients and at varying time points thereafter during the first month after surgery and beyond. Levels of VEGF were determined via enzyme-linked immunoassay (ELISA) and compared using Wilcoxon's matched pairs test. Because the numbers of specimens beyond POD 5 were limited, samples from 7-day time blocks were bundled and averaged to permit statistical analysis.A total of 49 patients with cancer and 30 patients with benign indications, all of whom underwent minimally invasive colorectal resection, were assessed separately. With regard to the patients with cancer, the median preoperative plasma value was 150 pg/ml, and the peak postoperative median value for the POD 14 to 20 time block was 611.1 pg/ml. Furthermore, compared with the preoperative results, significant VEGF elevations were noted on POD 3 as well as during week 2 (POD 7-13), week 3 (POD 14-20), and week 4 (POD 21-27) (p0.05 for each). With regard to the benign patients, the median preoperative VEGF level was 112 pg/ml, and the peak postoperative value, 286 pg/ml, was noted during postoperative week 2. Significant elevations were noted on POD 3, and for weeks 2 and 3 as well as for POD 28 and later. Between 63% and 89% of the patients at each time point beyond POD 5 had elevated VEGF levels.This preliminary study demonstrates that after minimally invasive colorectal resection for cancer, median VEGF levels are significantly elevated on POD 3 and remain increased for as long as 4 weeks. Significant elevations in a similar pattern also were noted for the benign patients. However, the baseline and postoperative median values were lower. The clinical impact from increased blood levels of VEGF is uncertain. It is possible that the growth of residual tumor deposits may be stimulated early after surgery. These results warrant a larger study as well as endothelial cell in vitro assays to determine whether postoperative plasma stimulates proliferation and invasion.

The safety and benefits of laparoscopic colon resection are well documented. However, few reports have addressed the safety and comparative outcome of laparoscopic colon operations that necessitated conversion. All consecutive laparoscopic colon resections performed by a single surgeon from July 1996 to October 2003 were assessed. Data obtained from a prospective computerized database included demographics, diagnosis, reason and time to conversion, length of stay, morbidity, and mortality. Additionally, all laparoscopic-converted colectomies were then matched with open colectomies by diagnosis and severity of disease and analyzed with respect to morbidity, mortality, and clinical outcome. A total of 143 laparoscopic colon resections were analyzed, 78 of which were left colon resections and 65 were right colon resections. The overall conversion rate was 19.6% (28 patients). The disease entities of the 28 converted patients were diverticulitis (16), polyps (four), Crohn’s disease (three), metastatic cancer (three), and others (two). Conversion was higher in the left-sided (24 patients, 30.8%) versus right-sided (four patients, 6.1%) procedures. There were no differences regarding age, gender, and comorbidities among the laparoscopic, open, and converted groups; the median follow-up was 39 months. The median length of stay was 6, 8, and 12 days for the laparoscopic, open, and converted groups, respectively. Right-sided conversions were due to the size of the inflammatory mass in three patients and intraoperative bleeding in one patient. Left-sided conversions were due to the inflammatory process extending beyond the sigmoid colon in 12 patients, adhesions in five, obesity in four, pericolonic abscess in two, and fixed mass in one patient. Postoperative morbidity was significantly higher for laparoscopic procedures that were converted to open procedures more than 30 min into the operation. Preoperative predictors of conversion were extent of inflammatory process beyond the sigmoid colon and obesity, whereas intraoperative predictors were adhesions and bleeding. Laparoscopic-converted colon resection is associated with significantly greater morbidity, particularly wound complications and greater length of hospital stay, compared to open or laparoscopic colectomies. Prompt conversion (

Purpose Rectal prolapse is a known postoperative problem in children with anorectal malformations. The aims of this study were to determine the incidence of significant rectal prolapse (>5 mm), to objectively quantify its predisposing factors, and to offer recommendations as to its prevention and surgical treatment. Methods The authors reviewed their series of 1619 patients with anorectal malformations; 1169 underwent primary posterior sagittal anorectoplasty (PSARP) at their institution between 1980 and 2002, and complete records were available for 833. The series was analyzed for incidence of prolapse, type of anorectal malformation, status of the sacrum, muscle quality, associated vertebral and spinal anomalies, and postoperative constipation. A specific technique for prolapse repair was used. Results Of 833 patients, 45 developed significant rectal prolapse (3.8%). The mean age at the time of PSARP was 0.73 years (range, 0.19-5 years). The average time to recognition of prolapse following PSARP was 13.1 months. Of these 45 patients, 32 required surgical repair and of those, 3 required a second surgical repair. The incidence of prolapse varied by complexity of anorectal defect: cloaca (6.2%), rectobladder neck fistula (6.8%), rectourethral fistula (5.4%), rectovestibular fistula (1.2%), rectal atresia (0%), and rectoperineal fistula (0%). There was a significantly increased incidence of prolapse in patients with a low muscle quality score and in patients with vertebral anomalies (20% vs 3.2%). The presence of a tethered cord and an abnormal sacral ratio did not correlate with an increased incidence of prolapse. Twenty-two patients developed prolapse following colostomy closure, and of these, 12 (55%) suffered from constipation. Conclusions The overall incidence of significant rectal prolapse following PSARP is low. Prevention of prolapse with the PSARP technique may be because of key technical steps. Patients with higher anorectal malformations, poorer muscle quality, and vertebral anomalies had a greater risk of developing postoperative rectal prolapse. The presence of tethered cord and quality of the sacrum were not predictive of postoperative prolapse. Constipation seems to be a factor in the development of prolapse.

The authors have previously demonstrated that insulin-like growth factor binding protein-3 (IGFBP-3) is depleted in plasma for 1 to 3 days after major open surgery (OS), but not after laparoscopic surgery (LS). After surgery, IGFP-3 cleavage occurs rapidly and is likely attributable to altered plasma proteolytic activity. This study aimed to assess plasma proteolysis after both open and closed colorectal resection and, if possible, to identify a protease/protease inhibitor system affected by surgery.Plasma from 88 patients with colorectal cancer (stages I-III) who underwent resection was obtained preoperatively (pre-OP) and on postoperative days (POD) 1 to 3. Plasma proteolytic activity was assessed via zymography. On the basis of the results, specific protease and protease inhibitor concentrations were next measured via enzyme-linked immunoassay (ELISA). Statistical analysis was performed using Wilcoxon's test.Early after surgery, zymography showed a predominant band representing a 92-kDa gelatinase corresponding to a proform of matrix metalloproteinase-9 (MMP-9), a protease known to cleave IGFBP-3. In OS patients, the mean concentration of plasma MMP-9 was significantly higher on POD 1 than at pre-OP (p0.003). On POD 2 and 3, no differences were noted. In the LS group, the mean levels of MMP-9 before and after surgery were comparable. The levels of a natural MMP-9 inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), also were measured. In the OS group, the level of TIMP-1 was significantly higher on POD 1 (p0.0003) and POD 2 (p0.01) and 3 (p0.01) than at pre-OP. In the LS group, a smaller but significant increase in TIMP-1 levels was found between the pre-OP sample and the POD 1 (p0.01) and POD 2 (p0.01) samples. No difference was noted on POD 3 (p = 0.1).Open surgery, but not laparoscopic surgery, is accompanied by a short-lived significant increase in MMP-9 levels, which likely accounts for the decrease in IGFBP-3 levels observed after OS. The transitory nature of MMP-9 imbalance may be attributable to the increase in TIMP-1 levels postoperatively.

Surgical resection remains the mainstay of definitive treatment of colon cancer patients.1 Unfortunately, after “curative” surgery, some patients develop recurrent disease either from unrecognized tissue microfoci of tumor cells or from viable cells that persist in the circulation.2,3 There are numerous variables that, together, determine whether or not a metastasis develops. The tendency of colorectal tumors to invade locally or spread via the bloodstream or lymphatics varies considerably. Also, although less often considered, there is variability among patients in regards to their ability to prevent tumor metastases from developing. Finally, the host's defenses against tumors likely vary from one time period to another. There is convincing experimental evidence that, after surgical trauma, tumor growth is accelerated and the host is at increased risk of metastases.4–14 Of note, in the majority of experimental studies that assessed both open and closed surgical methods, the latter were associated with significantly smaller increases in tumor growth or metastases formation when compared with results after open bowel resection or sham laparotomy.7,11–14 There is experimental evidence that procedure-related immunosuppression, plasma compositional changes, and tumor cell alterations account, at least in part, for the increased tumor growth noted after surgery.8,9,15 In humans, open colectomy and gastric bypass are associated with plasma depletion of the tumor inhibitor Insulin-like Growth Factor Binding Protein 3 (IGFBP-3); furthermore, postoperative plasma has been shown to stimulate in vitro tumor growth.16,17 Other plasma proteins whose levels are altered after surgery and that may impact tumor growth include Matrix Metalloproteinase 9 (MMP-9) and Tissue Inhibitor of Metalloproteinase -1 (TIMP-1).18 Undoubtedly, there are other undiscovered surgery-influenced proteins or factors that impact tumor growth and development after surgery. Of note, to date, little attention has been paid to angiogenesis in the postoperative period. Angiogenesis, the formation of new blood vessels, is critical in wound healing because of the need to supply nutrients and oxygen to the injured area. Angiogenesis is also critical for tumor establishment, growth, and survival.19 Many tumors, including colon cancer, cannot grow more than 2 to 3 mm without new vessel development.20 Recognition of the importance of tumor angiogenesis has resulted in a determined effort to identify proangiogenic agents and, subsequently, to develop angiogenesis inhibitors. Vascular endothelial growth factor (VEGF) is the most potent inducer of angiogenesis found, to date. It directly induces endothelial cell proliferation, migration, and tube formation.21 VEGF is also a potent tumor growth promoter.22 Preresection, cancer patients have been noted to have significantly higher mean blood VEGF levels when compared with tumor-free control populations.23–31 The extent of elevation in colon cancer patients has been shown to correlate with disease stage and/or prognosis.23,32–35 Although others have assessed preresection VEGF levels and also documented lower serum and plasma levels months later, to our knowledge, there has been no large-scale study of blood VEGF levels during the first 3 days after surgery.26,29,31 The release of VEGF after surgery could have undesirable effects on residual tumor cells and may enhance tumor growth and metastasis formation. This study's purpose was to determine perioperative plasma VEGF levels in patients undergoing open or laparoscopic major abdominal surgery. In addition to colon cancer patients, those with benign colonic disease and a third group undergoing gastric bypass were also studied. The patients with benign disease were included to determine if surgery's impact on VEGF levels was related to surgical indication.

Any linear phase sampling algorithm can be described as a linear filter characterized by its frequency response. In traditional phase sampling interferometry the phase of the frequency response has been ignored because the impulse responses can be made real selecting the correct sample offset. However least squares methods and recursive filters can have a complex frequency response. In this paper, we derive the quadrature equations for a general phase sampling algorithm and describe the role of the filter phase.