John Melissas
University of Crete
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Featured researches published by John Melissas.
Obesity Surgery | 2001
Emmanuel M. Kanoupakis; Dimitrios Michaloudis; Othon Fraidakis; Fragiskos I. Parthenakis; Panos E. Vardas; John Melissas
Background: It is well established that morbid obesity affects the respiratory system and the diastolic function of the heart. During exercise, cardiopulmonary reserve is exhausted because of augmented requirements, leading to a significant intolerance. A study was undertaken to investigate the influence of body weight loss on the characteristics of the left ventricle (LV) and on exercise capacity in obese patients before and 6 months following vertical banded gastroplasty (VBG). Methods: 16 morbidly obese individuals (BMI >40 kg/m2) scheduled for VBG were studied. A symptomlimited cardiopulmonary exercise test and a complete transthoracic echocardiogram were performed 1 day before operation and 6 months postoperatively (after the patients achieved a body weight loss of ≥ 20% of their pre-operative values). Results: Exercise duration increased significantly 6 months following surgery.The mean O2 consumption at peak exercise (peak VO2) and at the anaerobic threshold (VO2AT) was significantly higher after weight loss. 6 months after VBG the LV thickness decreased significantly. Regarding the diastolic indices, isovolumic relaxation time (IVRT) and early/late (E/A) velocity ratio, there was a significant improvement after weight loss. Simple linear regression analysis revealed that peak VO2 and VO2AT were significantly correlated with IVRT and E/A velocity ratio. Conclusions: Weight loss after VBG improves the cardiac diastolic function and this is associated with an improvement in cardiopulmonary exercise performance. Left ventricular filling variables could be considered among the most important determinants of exercise intolerance in obese individuals.
Obesity Surgery | 2008
John Melissas
Surgery is now recognized as the only effective treatment for the morbidly obese patient with long-term sustained weight loss and postoperative complete resolution or significant improvement in the obesity comorbidities. However, this highly demanding and challenging surgical therapy necessitates the appropriate training and experience on the part of the surgeon. It is vital that the surgeon, beyond the optimal theoretical knowledge, also has the necessary technical skills in open and/or laparoscopic surgery, performs meticulous preand postoperative care, and is committed to long-term patient follow-up. Moreover, institutional commitment to the excellent multidisciplinary care of the morbidly and super-obese patient, who have an exceptional surgical and anesthetic risk, is essential to ensure the safe and effective performance of bariatric surgery. The necessary ancillary services, including specialized nursing staff, dieticians, psychologists and exercise advisors, and a multidisciplinary bariatric medical team of surgeons, cardiologists, anesthesiologists, ICU specialists and psychiatrists, etc., may be extremely valuable. Modern medical and surgical facilities, such as operating room tables, instruments, furniture, and radiology equipment capable of handling morbidly obese patients, are of course essential resources for any institution that seeks to treat bariatric patients.
Obesity Surgery | 2006
John Melissas; John Mouzas; Dimetrios Filis; Markos Daskalakis; Erminia Matrella; John A. Papadakis; Nikos Sevrisarianos; Demetris Charalambides
Background: Intragastric balloon placement in association with diet for weight reduction is steadily gaining popularity. However, long-term follow-up studies on the effect of this method in maintaining weight loss are lacking. This study evaluated the long-term outcome following balloon removal in morbidly obese patients who had selected this method for weight loss. Methods: 140 morbidly obese patients who refused bariatric surgery because of fear of complications and mortality, underwent intragastric balloon placement and were followed over a 6- to 30-month period (mean 18.3 months) after balloon extraction. The 34 males and 106 females, with median age 38 years (range 16-62), median weight 122 kg (range 85-203), median BMI 42.3 kg/m2 (range 35-61.3) and median excess weight (EW) 59 kg (range 29-132), received a Bioenterics Intragastric Balloon (BIB). Excess weight loss (EWL) ≥25% when the BIB was removed was considered a success. Weight fluctuations and any further interventional therapy requested by the patients after balloon removal were recorded. Results: 100 patients (71.4%) lost ≥25% of their EW on balloon extraction and were categorized as successes, while 40 patients (28.6%) did not achieve that weight loss and were categorized as failures of the method. During the follow-up period, 44 of the originally successful patients (31.4%) regained weight and were categorized as recurrences, while the remaining 56 patients (40%) maintained their EWL of ≥25% and were considered long-term successes. During follow-up, 45 patients (32.1%) requested and underwent bariatric surgery for their morbid obesity (21 Adjustable Gastric Band, 11 Laparoscopic Sleeve Gastrectomy, 13 Laparoscopic Gastric Bypass). Of these, 13 (32.5%) were from the group of 40 patients categorized as failures on BIB removal, 28 (63.6%) were from the group of 44 patients whose obesity recurred, and 4 (7.1%) were from the 56 patents who although they maintained successful weight loss requested further weight reduction. Conclusions: The BIB served as a first step and a smooth introduction to bariatric surgery for morbidly obese patients who initially refused surgical intervention. The incidence of surgical intervention was double in patients who initially experienced the benefits of weight loss and then had obesity recurrence, compared with patients in whom the method failed. Indeed, a significant number of patients were assisted in their efforts to lose and maintain an acceptable weight loss over a 6- to 30-month follow-up period.
Obesity Surgery | 2003
John Melissas; Evaggelos Volakakis; Alexander Hadjipavlou
Background: Although low-back pain (LBP) is a common health problem and a source of significant discomfort, disability and work absences, its incidence, severity and outcome have not been extensively investigated in morbidly obese patients undergoing bariatric surgery. Methods: 50 morbidly obese candidates for vertical banded gastroplasty (VBG) were asked to fill in a questionnaire, to assess the incidence and severity of any existing LBP symptoms. 50 non-obese patients, admitted to our surgical unit for management of several benign conditions, were also asked to fill in the same questionnaire and served as controls. 24 months after VBG, the morbidly obese patients were again evaluated for their LBP symptoms. Results: LBP was identified in 29 morbidly obese patients (58%) preoperatively and in only 12 (24%) of the lean controls (P<0.01). 2 years after VBG, with a significant excess weight loss (P<0.0001), only 10 patients continued to have LBP but less frequently and requiring reduced doses of medications compared with the preoperative condition. In the remaining 19 patients with preoperative positive LBP history, the postoperative weight loss was associated with complete resolution of the symptoms. Conclusion: The frequency of LBP is significantly higher in morbidly obese patients than in lean subjects. Surgical weight reduction results in significant improvement and even disappearance of this obesity co-morbidity.
Annals of Surgery | 2013
Efstathios Dimitriadis; Markos Daskalakis; Marilena Kampa; Anastasia Peppe; John A. Papadakis; John Melissas
Objective:To evaluate the effect of laparoscopic sleeve gastrectomy (LSG) on fasting and meal-stimulated release of the gut hormones ghrelin, pancreatic polypeptide (PP), peptide-YY (PYY), glucagon-like peptide-1 (GLP-1), and amylin and of the adipocytokine leptin. Background:Mounting evidence suggests that the mechanisms of weight loss and the improvement in glucose metabolism seen after LSG are related not only to gastric restriction but also to neurohormonal changes. Methods:Fasting and postprandial levels at 60 and 120 minutes after a standard test meal of the above peptides and glucose metabolism indices were evaluated in 15 consecutive morbidly obese (MO) subjects before and 6 and 12 months after LSG. As study controls, 15 lean subjects matched for age and sex were also assessed. Results:Body mass index values notably decreased at 6 and 12 months (P < 0.01), postoperatively. In addition, an overall improvement of the glycemic profile of MO patients was noted. After LSG, markedly decreased fasting and postprandial levels of ghrelin, amylin, and leptin were observed. A significant postprandial increase of PYY and GLP-1 levels was also noted postoperatively. Interestingly, significantly increased levels of PP were noted only at 60 minutes postprandially after LSG. Conclusions:LSG markedly improved glucose homeostasis and generated significant changes in ghrelin, PP, PYY, GLP-1, amylin, and leptin levels. These multiple hormonal actions may have several beneficial effects on the underlying mechanism of weight loss, demonstrating that LSG could be more than just a restrictive bariatric operation.
Expert Review of Anticancer Therapy | 2009
Eelco de Bree; R.B. Keus; John Melissas; Dimitris D. Tsiftsis; Frits van Coevorden
Desmoid tumor, also known as aggressive fibromatosis or desmoid-type fibromatosis, is a rare monoclonal, fibroblastic proliferation arising in musculoaponeurotic structures. Although histologically benign, desmoids are often locally invasive and associated with a high local recurrence rate after resection. Since it is a heterogeneous disease, in particular regarding clinical presentation, anatomic location and biological behavior, treatment should be individualized to reduce local tumor control failure with concurrently acceptable morbidity and preservation of quality of life. Many issues regarding optimal treatment of desmoids remain controversial. However, wide surgical excision remains the treatment of choice, except when surgery is mutilating and is associated with considerable function loss or major morbidity. Involvement of surgical margins is probably associated with an increased risk of local recurrence. Postoperative radiotherapy results in a significant reduction of the local recurrence rate, but only in the case of involved surgical margins. Radiotherapy for gross disease is considerably effective, but is associated with a relatively high rate of complications, which are usually mild or moderate and radiation dose dependent. Radiotherapy should only be applied where anatomic constraints preclude complete resection and radiotherapy is not too toxic. Risk factors for local tumor control failure include young age, large size, presentation as recurrent disease, limb/girdle or intra-abdominal location, involved surgical margins, omission of radiotherapy, radiation dose less than 50 Gy and insufficient radiation field size. Increased comprehension of the pathogenesis and biological behavior of desmoids resulted in the emerging applicability of systemic therapies and a wait-and-see policy. Systemic treatment may be indicated in patients that have anatomic barriers to effective surgery or radiotherapy. Considering the significant morbidity of surgery and/or radiotherapy for certain locations, especially mutilation and loss of function, and the tumor’s natural history, which is often characterized by prolonged periods of stability or even regression, a period of watchful waiting may compose the most appropriate management in selected asymptomatic patients. Attempts to complete eradication of the disease may be worse than the disease itself.
Annals of Surgery | 2013
John Melissas; Leventi A; Klinaki I; Perisinakis K; Koukouraki S; de Bree E; Karkavitsas N
Objectives: To evaluate the role of sleeve gastrectomy (SG) in gastrointestinal motility. Background: SG is a widely used bariatric operation leading to weight loss and early improvement of patients metabolic profile. Current data indicate faster postoperative gastric emptying, but detailed studies on alterations in small bowel motility are missing. Design: We evaluated 21 morbidly obese patients who underwent laparoscopic SG before and 4 months after the procedure. After consumption of a semisolid radiolabeled meal, their gastric and intestinal transit times were studied with a gamma camera. Particularly the times of 10% gastric emptying, 50% gastric emptying, maximal intestinal filling, 10% terminal ileum filling, duodenal to terminal ileum transit, cecal filling initiation, and ileocecal valve transit (T ICVt) were studied pre- and postoperatively. Results: Ten percent gastric emptying and 50% gastric emptying were decreased postoperatively as well as maximal intestinal filling, indicating faster gastric emptying and intestinal filling. Duodenal to terminal ileum transit and 10% terminal ileum filling also decreased as small bowel transit time accelerated and the meal reached the terminal ileum more rapidly. Contrary opening of the ileocecal valve and food transit through it were delayed, with postoperative increase in cecal filling initiation and T ICVt, respectively. Conclusions: SG accelerates gastric emptying and small bowel transit of semisolids. In addition, it delays the initiation of cecal filling and T ICVt. This early and prolonged contact of food with the distal small bowel mucosa may explain the metabolic effects of SG occurring before substantial weight loss.
Obesity Surgery | 2001
John Melissas; M. Christodoulakis; G. Schoretsanitis; E Sanidas; E Ganotakis; Dimitris Michaloudis; Dimitris D. Tsiftsis
Background: The amount of excess weight which must be lost in order to cure or to improve disorders associated with obesity remains unknown. This study was designed to compare super obese and morbidly obese patients in terms of weight reduction following VBG and to investigate the effects of postoperative weight changes to preexisting co-morbidities. Methods: 125 patients underwent VBG. Group A consisted of 80 morbidly obese patients (64%) and group B consisted of 45 super obese patients (36%). Preoperative examination was planned to identify and determine the severity of any disorders associated with obesity, that the patients may have had. Following VBG, all patients were followed-up at regular time periods, for at least 2 and up to 4 years. The progress of preexisting co-morbidities was evaluated and carefully recorded. Results: Among the 80 patients of Group A, there were 240 total co-morbidities (3 per patient), and in group B there were 196 co-morbidities (4.35 per patient) preoperatively. Dyspnea during fatigue and arthritis were found at statistically higher incidence in the super obese category. At the end of the second postoperative year, greater weight loss in terms of number kilograms was seen in patients in group B, but these patients did not reach a BMI lower than 35, while patients in group A had mean BMI below 30. In group A, 66% of the co-morbidities completely resolved, 19% significantly diminished and 15% remain unchanged. In group B, the respective percentages were 53% , 27.5% and 19.5%. However, after weight reduction by VBG a significant number of co-morbidities remain in the super obese patients (92 or 2.044 per/patient), and this is believed to be due to the greater remaining excess weight. Conclusion: Reduction of body weight by VBG is associated with resolution or improvement of a significant number of the obesity-associated disorders. However, super obese patients remain obese after surgery, and this results in two-fold higher remaining morbidity.
Obesity Surgery | 2006
John Melissas; Niki Malliaraki; John A. Papadakis; Panagiotis Taflampas; Marilena Kampa; Elias Castanas
Background: Oxidative stress may play a critical role in the pathogenesis and development of obesity-associated co-morbidities. Reactive oxygen and nitrogen species are produced as a consequence of normal aerobic metabolism and removed and/or inactivated in vivo by both endogenous (uric acid, bilirubin, thiols) and diet-derived (exogenous) antioxidants. The purpose of this study is to measure the total plasma antioxidant capacity (TAC), as well as the corrected TAC (cTAC, an index of exogenous provided antioxidants) in morbidly obese patients before and after surgical weight reduction. Methods: 16 morbidly obese (5 male and 11 female) candidates for surgical intervention, median age 34 (range 22-56) years, median weight 128 (range 96-186) kg, median excess weight 62 (range 28-115) kg and median BMI 44.4 (range 33.7-60.1) kg/m2 were evaluated before and 6 months after implantation of an intragastric balloon. 15 healthy blood donors (4 male and 11 female) on a normal diet, median age 35 (range 21-52) years, median weight 64.3 (range 46-78) kg and median BMI 24.2 (range 23.7-25.2) kg/m2 were also evaluated. Blood samples for routine clinical chemistry, TAC and cTAC determination were drawn, and weight and BMI calculation were performed once in the control group, and in the morbidly obese patients (MO) before and 6 months after the balloon implantation. Results: 6 months after balloon placement, weight and BMI of the MO patients were statistically significantly reduced from the preoperative values (P<0.001). Plasma TAC and cTAC values in the MO group were significantly lower preoperatively, compared to the control group (P<0.05 and P<0.001 respectively). cTAC values in the MO patients increased significantly following weight loss (P<0.001) and were restored to normal. However, the postoperative TAC values in the MO group did not change significantly and remained lower than in the normal controls. A significant decrease (P<0.001) in uric acid values was also noticed in the MO group after weight loss. Conclusion: Plasma TAC and cTAC values are impaired in morbidly obese patients. Weight loss from an intragastric balloon is associated with significant increase in plasma cTAC values. Plasma TAC values, after the weight loss remain unchanged, possibly due to a decrease in uric acid, an important endogenous antioxidant.
Journal of Surgical Oncology | 2010
Eelco de Bree; Antonios Makrigiannakis Md; John Askoxylakis; John Melissas; Dimitris D. Tsiftsis
Pregnancy after breast cancer treatment has become an important issue since many young breast cancer patients have not completed their family. Generally, these patients should not be discouraged to become pregnant when they want to, since published data suggest no adverse effect of pregnancy on survival. As fertility may be impaired by chemotherapy, different fertility preserving strategies have been developed. Births seem to sustain no adverse effects, while breastfeeding appears to be feasible and safe. J. Surg. Oncol. 2010; 101:534–542.