Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Fotis Kalfarentzos is active.

Publication


Featured researches published by Fotis Kalfarentzos.


Annals of Surgery | 2008

Weight Loss, Appetite Suppression, and Changes in Fasting and Postprandial Ghrelin and Peptide-YY Levels After Roux-en-Y Gastric Bypass and Sleeve Gastrectomy A Prospective, Double Blind Study

Stavros N. Karamanakos; Konstantinos Vagenas; Fotis Kalfarentzos; Theodore K. Alexandrides

Background:Bariatric surgery is currently the most effective treatment in morbidly obese patients, leading to durable weight loss. Objective:In this prospective double blind study, we aim to evaluate and compare the effects of laparoscopic Roux-en-Y gastric bypass (LRYGBP) with laparoscopic sleeve gastrectomy (LSG) on body weight, appetite, fasting, and postprandial ghrelin and peptide-YY (PYY) levels. Methods:After randomization, 16 patients were assigned to LRYGBP and 16 patients to LSG. Patients were reevaluated on the 1st, 3rd, 6th, and 12th postoperative month. Blood samples were collected after an overnight fast and in 6 patients in each group after a standard 420 kcal mixed meal. Results:Body weight and body mass index (BMI) decreased markedly (P < 0.0001) and comparably after either procedure. Excess weight loss was greater after LSG at 6 months (55.5% ± 7.6% vs. 50.2% ± 6.5%, P = 0.04) and 12 months (69.7% ± 14.6% vs. 60.5% ± 10.7%, [P = 0.05]). After LRYGBP fasting ghrelin levels did not change significantly compared with baseline (P = 0.19) and did not decrease significantly after the test meal. On the other hand, LSG was followed by a marked reduction in fasting ghrelin levels (P < 0.0001) and a significant suppression after the meal. Fasting PYY levels increased after either surgical procedure (P ≤ 0.001). Appetite decreased in both groups but to a greater extend after LSG. Conclusion:PYY levels increased similarly after either procedure. The markedly reduced ghrelin levels in addition to increased PYY levels after LSG, are associated with greater appetite suppression and excess weight loss compared with LRYGBP.


Obesity Surgery | 2002

Comparison of Nutritional Deficiencies after Roux- en-Y Gastric Bypass and after Biliopancreatic Diversion with Roux-en-Y Gastric Bypass

George Skroubis; George Sakellaropoulos; Konstantinos Pouggouras; Nancy Mead; George Nikiforidis; Fotis Kalfarentzos

Background: Patients undergoing either Roux-en-Y gastric bypass (RYGBP) or biliopancreatic diversion (BPD) with RYGBP are at risk of developing metabolic sequelae secondary to malabsorption.We compared the differences in nutritional complications between these two bariatric operations. Methods: A retrospective analysis of a prospective database was done. From June 1994 to December 2001, 243 morbidly obese patients underwent various bariatric procedures at our institution. Of these patients, 79 (BMI 45.6 ± SD=4.9) who underwent RYGBP (gastric pouch 15 ± 5ml, biliopancreatic limb 60-80 cm, alimentary limb 80-100 cm and common limb the remainder of the small intestine), and 95 super obese (BMI 57.2 ± 6.1) who underwent a BPD (gastric pouch 15 ± 5ml, biliopancreatic limb 150-200 cm, common limb 100 cm and alimentary limb the remainder of the small intestine), were selected and studied for the incidence of micronutrient deficiencies and level of serum albumin at yearly intervals postoperatively. A variety of nutritional parameters including Hb, Fe, ferritin, folic acid, vitamin B12 and serum albumin were measured preoperatively and compared postoperatively at 1, 3, 6, 12, 18 and 24 months, and yearly thereafter. Results: Nutritional parameters were compared preoperatively and at similar periods postoperatively. No statistically significant (P <0.05) difference in the occurrence of deficiency was observed between the groups for any of the nutritional parameters studied, except for ferritin, which showed a significant difference at the 2-year follow-up (37.7% low ferritin levels after RYGBP vs. 15.2% after BPD, P =0.0294). All of these deficiencies were mild, without clinical symptomatology and were easily corrected with additional supplementation of the deficient micronutrient, with no need for hospitalization. Regarding serum albumin, there was only one patient with a level below 3 g/dl in the RYGBP group and two in the BPD group.These three patients were hospitalized and received total parenteral nutrition for 3 weeks, without further complications. Conclusion:There was no significant difference in the incidence of deficiency of the nutritional parameters studied, except for ferritin, following RYGBP vs. BPD with RYGBP.The most common deficiencies encountered were of iron and vitamin B12. The incidence of hypoalbuminemia was negligible in both groups, with mean values above 4 g/dl.


Cancer | 1998

Dietary omega-3 polyunsaturated fatty acids plus vitamin E restore immunodeficiency and prolong survival for severely ill patients with generalized malignancy

Charalambos Gogos; Panayiotis Ginopoulos; Bassilis Salsa; Euterpi Apostolidou; Nikolas C. Zoumbos; Fotis Kalfarentzos

The aim of the current prospective, randomized control study was to investigate the effect of dietary omega‐3 polyunsaturated fatty acids plus vitamin E on the immune status and survival of well‐nourished and malnourished patients with generalized malignancy.


Obesity Surgery | 2001

Prophylaxis of Venous Thromboembolism Using Two Different Doses of Low-Molecular-Weight Heparin (Nadroparin) in Bariatric Surgery: A Prospective Randomized Trial

Fotis Kalfarentzos; Spyros Yarmenitis; Ioannis Kehagias; Maria Karamesini; Athanasios Dimitrakopoulos; Aliki Maniati; Fotini Stavropoulou

Background: Obese patients undergoing bariatric surgery are at a high risk of developing fatal pulmonary embolism or post-thrombotic syndrome.The prophylactic use of low molecular weight heparins (LMWHs) is correlated with a significant reduction in post-operative venous thrombosis in patients undergoing orthopedic or general surgery. In morbidity obese patients, the limited number of comparative trials are too sparse to allow a consensus on the effective dose and dosing schedule. Methods: In a prospective study to evaluate the effect of two doses of nadroparin as prophylaxis for venous thromboembolism following bariatric surgery, 60 consecutive patients undergoing Rouxen-Y gastric bypass were randomized to receive either 0.6 ml (5700 IU) or 1.0 ml (9500 IU) of nadroparin started pre-operatively and then given once daily post-operatively until discharge. Results: No statistically significant differences between the two groups were detected in any of the measured coagulation parameters either preoperatively or at days 1, 3 and 5 postoperatively.No thrombotic events were observed pre- or post- operatively, and no patient developed meta-thrombotic syndrome at the 3 and 6 months follow-up. No bleeding events occurred in the patients given the lower dose compared with two major hemorrhages in those given the higher dose. Conclusion: Our results indicate that 0.6 ml (5700 IU) of nadroparin once daily is safe and well-tolerated, and it is as effective in prophylaxis of venous thromboembolism as the higher dose of 1 ml (9500 IU), in such high risk patients.


Obesity Surgery | 2006

Roux-en-Y Gastric Bypass versus a Variant of Biliopancreatic Diversion in a Non-Superobese Population: Prospective Comparison of the Efficacy and the Incidence of Metabolic Deficiencies

George Skroubis; Stathis Anesidis; Ioannis Kehagias; Nancy Mead; Kostas Vagenas; Fotis Kalfarentzos

Background: In the non-superobese population, an agreement has not been made as to the optimal bariatric operation. The present study reports the results of a prospective comparison of Roux-en-Y gastric bypass (RYGBP) and a variant of biliopancreatic diversion (BPD) in a non-superobese population. Methods: From a cohort of 130 patients with BMI 35 to 50 kg/m2, 65 patients were randomly selected to undergo RYGBP and 65 to undergo BPD. All patients underwent complete follow-up evaluation at 1, 3, 6, and 12 months postoperatively and every year thereafter. Results: Patients in both groups have completed their second postoperative year. Mean % excess weight loss (%EWL) was significantly better after BPD at all time periods (12 months, P=0.0001 and 24 months, P=0.0003), and the %EWL was >50% in all BPD patients compared to 88.7% in the RYGBP patients at 2-year follow-up. No statistically significant differences were observed between the 2 groups in early and late non-metabolic complications. Hypoalbuminemia occurred in only 1 patient (1.5%) after RYGBP and in 6 patients after BPD (9.2%). Only 1 patient from each group was hospitalized and received total parenteral nutrition. Glucose intolerance, hypercholesterolemia, hypertriglyceridemia and sleep apnea completely resolved in all patients in both groups, although mean total cholesterol level was significantly lower in BPD patients at the second year follow-up (t-test, P<0.0001). Diabetes completely resolved in all BPD patients and in 7 of the 10 diabetic RYGBP patients. Conclusion: Both RYGBP and BPD were safe and effective procedures when offered to non-superobese patients. Weight loss after BPD was consistently better than that after RYGBP, as was the resolution of diabetes and hypercholesterolemia. Because the nutritional deficiencies that occurred following this type of BPD were not severe and were not significantly different between the 2 operations, both may be offered to non-superobese patients, keeping in mind the severity and type of preoperative co-morbidities as well as the desired weight loss.


Journal of Hypertension | 2007

Weight loss after bariatric surgery improves aortic elastic properties and left ventricular function in individuals with morbid obesity: a 3-year follow-up study.

Ignatios Ikonomidis; Andreas Mazarakis; Costas G. Papadopoulos; Nikolaos Patsouras; Fotis Kalfarentzos; John Lekakis; Dimitrios Th. Kremastinos; Dimitrios Alexopoulos

Objective To investigate whether weight loss after bariatric surgery (gastric bypass) is associated with changes in aortic function (an important determinant of left ventricular function) and in left ventricular function, in morbidly obese individuals 3 and 36 months after surgery. Methods We used echocardiography to evaluate 60 obese individuals [body mass index (BMI) > 40 kg/m2] who underwent surgery and 20 obese individuals who neither underwent surgery nor lost weight, at baseline and at 3 and 36 months of follow-up, and 40 lean individuals (BMI < 25 kg/m2) of similar age, sex and risk factors, at baseline. We measured aortic strain, distensibility, stiffness index, pressure–strain modulus and Doppler indices of left ventricular diastolic dysfunction (ratio of peak early to peak atrial flow velocities, isovolumic relaxation time and deceleration time). Results Baseline aortic function and Doppler diastolic indices were impaired in obese individuals compared with those who were lean (P < 0.05). During 3 and 36 months of follow-up, BMI and left ventricular diastolic diameter, volume, mass and wall thickness were reduced, and indices of aortic function and left ventricular diastolic function were normalized, in obese individuals after surgery [aortic distensibility (cm2 × dyn−1 × 10−6): 1.9 before surgery, 3.4 at 3 months after surgery and 4.3 at 3 years after surgery, compared with 3.36 in lean controls; P < 0.01], but not in those who did not lose weight. The reduction in BMI after surgery was related to the concomitant improvement in indices of aortic function (P < 0.01) and isovolumic relaxation time (P < 0.05) after adjustment for age, sex and concomitant reduction in blood pressure, lipids and glucose concentrations. Conclusion Weight reduction after bariatric surgery normalizes aortic function, reduces left ventricular hypertrophy and, thus, improves left ventricular diastolic function in morbidly obese individuals over a 3-year period of follow-up.


Journal of The American College of Nutrition | 1991

Total parenteral nutrition in severe acute pancreatitis.

Fotis Kalfarentzos; Dionissios Karavias; T M Karatzas; B A Alevizatos; John Androulakis

The influence of total parenteral nutrition (TPN) was studied in 67 patients with severe acute pancreatitis having three or more criteria according to Ranson (mean +/- SD = 3.8 +/- 0.21). Although TPN has been reported to not be of benefit in the progress and severity of the disease, we have found that the time TPN is started is important in influencing the course of the disease and in the development of local complications, as well as in the mortality rate. Patients whose TPN was started within the first 72 hours of the disease had a 23.6% complication rate and 13% mortality, in comparison with patients whose TPN was started later in the course of the disease, who had a 95.6% complication rate (p less than 0.01) and a mortality rate of 38% (p less than 0.03). The nutritional status of the patients during TPN administration of 28.4 days was maintained either steady or was improved, as assessed by nitrogen balance, serum levels of transferrin (p less than 0.05), and albumin (p less than 0.05). The administration of fat solution, either to prevent essential fatty acid deficiency or to provide part of the caloric requirements, was found to cause neither clinical nor laboratory worsening of the disease. All pancreatic fistulae that developed during the course of the disease spontaneously closed in patients receiving TPN without operation in a mean period of 33.3 days, and all pseudocysts subsided in an average of 18.3 days. Those who died (overall mortality rate 24%) had had uncontrollable sepsis, which resulted in hypercatabolism and multiple system organ failure.(ABSTRACT TRUNCATED AT 250 WORDS)


Molecular and Cellular Endocrinology | 2000

Growth hormone and insulin-like growth factor I protect intestinal cells from radiation induced apoptosis.

Panagiotis Mylonas; Panagiota Matsouka; Eleni V Papandoniou; Constantine E. Vagianos; Fotis Kalfarentzos; Theodore K. Alexandrides

We studied whether programmed cell death (or apoptosis) is the predominant mechanism in radiation-induced cell damage to rat intestinal mucosa and investigated the mechanism of the protective effect of GH and IGF-I in the same model. Male albino Wistar rats were divided into four groups: controls, radiation, radiation plus GH and radiation plus IGF-I. Radiation was administered on the first day and on day 4. All animals were sacrificed and segments of the terminal ileum were stained with hematoxylin-eosin. Apoptosis of the epithelial cells was identified at the cellular level by the TUNEL stain and was distinguished from necrosis by the characteristic morphology of the cells (cytoplasmic shrinkage, marginal chromatin condensation and generation of nuclear apoptotic bodies). Apoptotic cells in the control animals were few and detected only at the tips of the villi while in the irradiated animals almost all the epithelial cells were apoptotic, distributed from the crypts to the tips of the villi and the mucosa showed severe epithelial atrophy and ulceration. The histologic picture of the mucosa in the GH and IGF-I treated animals was similar to normal controls and apoptotic cells were restricted only at the tips of the villi. DNA and RNA from the mucosa cells were isolated and analyzed by electrophoresis. DNA fragmentation and RNA 28s band ribonuclease cleavage was observed only in the irradiated animals. We have shown that abdominal radiation causes intestinal epithelial cell damage mainly through the induction of apoptosis and the treatment with GH and IGF-I inhibits apoptosis of the cells and preserves the mucosal integrity.


Surgery for Obesity and Related Diseases | 2013

Hormone changes and diabetes resolution after biliopancreatic diversion and laparoscopic sleeve gastrectomy: a comparative prospective study

Marina Tsoli; Aikaterini Chronaiou; Ioannis Kehagias; Fotis Kalfarentzos; Theodore K. Alexandrides

BACKGROUND Biliopancreatic diversion (BPD) is the most effective bariatric procedure in terms of weight loss and remission of diabetes type 2 (T2DM), but it is accompanied by nutrient deficiencies. Sleeve gastrectomy (SG) is a relatively new operation that has shown promising results concerning T2DM resolution and weight loss. The objective of this study was to evaluate and compare prospectively the effects of BPD long limb (BPD) and laparoscopic SG on fasting, and glucose-stimulated insulin, glucagon, ghrelin, peptide YY (PYY), and glucagon-like peptide-1 (GLP-1) secretion and also on remission of T2DM, hypertension, and dyslipidemia in morbidly obese patients with T2DM. METHODS Twelve patients (body mass index [BMI] 57.6 ± 9.9 kg/m(2)) underwent BPD and 12 (BMI 43.7 ± 2.1 kg/m(2)) underwent SG. All patients had T2DM and underwent an oral glucose tolerance test (OGTT) before and 1, 3, and 12 months after surgery. RESULTS BMI decreased more after BPD, but percent excess weight loss (%EWL) was similar in both groups (P = .8) and T2DM resolved in all patients at 12 months. Insulin sensitivity improved more after BPD than after SG (P = .003). Blood pressure, total and LDL cholesterol decreased only after BPD (P<.001). Triglycerides decreased after either operation, but HDL increased only after SG (P<.001). Fasting ghrelin did not change after BPD (P = .2), but decreased markedly after SG (P<.001). GLP-1 and PYY responses during OGTT were dramatically enhanced after either procedure (P = .001). CONCLUSIONS SG was comparable to BPD in T2DM resolution but inferior in improving dyslipidemia and blood pressure. SG and BPD enhanced markedly PYY and GLP-1 responses but only SG suppressed ghrelin levels.


Archives of Surgery | 2010

Revisional bariatric surgery: 13-year experience from a tertiary institution.

Charalambos Spyropoulos; Ioannis Kehagias; Spyros Panagiotopoulos; Nancy Mead; Fotis Kalfarentzos

OBJECTIVE To evaluate the safety and effectiveness of revisional bariatric surgery at a tertiary institution. Revisional bariatric operations for unsuccessful weight loss or intolerable complications following the primary intervention are increasing. DESIGN Case series from a prospective database. SETTING Tertiary bariatric referral center. PATIENTS From 1995 to 2008, 56 patients who had been formerly operated on for clinically severe obesity underwent a revisional procedure at our institution. Their mean (SD) age and body mass index were 39.6 (9.6) years and 46.9 (16.4), respectively. They were divided into 3 groups according to the indications for reoperation: (1) unsatisfactory weight loss (n = 39), (2) severe nutritional complications (n = 15), and (3) intolerable adverse effects (n = 2). MAIN OUTCOME MEASURES Effectiveness of the procedures according to the indication of revision and overall morbidity and mortality rates. RESULTS Mean (SD) follow-up was 102 (8) months. There was no mortality but there was an early morbidity rate of 33.9% due to postoperative complications, including 2 cases of acute renal failure (3.6%), 5 anastomotic leaks (13.1%), 8 cases of pneumonia (14.3%), and 1 case each of wound infection, incisional dehiscence, bile leak, and small-bowel obstruction (1.8%). Late complications included stenosis of the gastrojejunal anastomosis in 2 patients (3.6%), hypoalbuminemia in 2 patients (3.6%), and incisional herniation in 9 patients (16.1%). Late morbidity was 23.2%. CONCLUSION Although revisional bariatric surgery is associated with higher risk of perioperative complications compared with the primary procedures, it appears to be safe and effective when performed in experienced centers.

Collaboration


Dive into the Fotis Kalfarentzos's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge