Biomedical subjects
Publications and source records attributed to George Bouras.
Long-read-metagenomic sequencing is the best method for analyzing the sinus microbiome. 16s-rRNA-sequencing (both long and short read) results in PCR amplification bias that significantly distorts the sinus microbiome.
BACKGROUND: Homocystinemia is a metabolic abnormality associated with endothelial dysfunction and increased cardiovascular disease risk. The underlying mechanisms of these effects, however, are obscure. OBJECTIVE: We examined the effect of asymmetrical dimethylarginine (ADMA) on endothelial dysfunction in methionine-induced and chronic homocystinemia and evaluated the regulatory role of oxidative stress and proinflammatory cytokines on the release of ADMA. DESIGN: In this double-blind, placebo-controlled parallel group study, 30 subjects of both sexes (15 with homocystinemia and 15 healthy controls) underwent methionine loading, with simultaneous administration of a combination of vitamin C (2 g) plus alpha-tocopherol (800 IU) or placebo. Endothelial function in forearm resistance vessels and concentrations of ADMA, oxidized LDL, and proinflammatory cytokines were determined at baseline and 4 h after methionine loading. RESULTS: Both chronic and methionine-induced homocystinemia were associated with increased oxidized LDL (P < 0.01), higher expression of the proinflammatory cytokine interleukin 6 (P < 0.05), and endothelial dysfunction (P < 0.01). Although ADMA rapidly increased in acute homocystinemia (P < 0.01) and was correlated with forearm hyperemic response at 4 h after methionine loading (r = -0.722, P = 0.0001), it was not higher in subjects with high versus low fasting homocysteine. High-dose antioxidant treatment prevented methionine-induced elevation of oxidized LDL and interleukin 6 but failed to prevent the increase in ADMA or endothelial dysfunction. CONCLUSIONS: Both chronic and methionine-induced homocystinemia are characterized by increased oxidative stress and proinflammatory cytokines, which may contribute to the development of endothelial dysfunction. However, the ADMA pathway is activated only in acute homocystinemia by mechanisms not mediated by oxidized LDL or proinflammatory stimuli.
Morbid obesity is a chronic illness of multifactorial aetiology which is defined as Body Mass Index (BMI) greater than 40 kg/sq.m. Non-surgical treatments for this condition have been shown to be ineffective. Surgery is the only effective treatment and obtains the best long-term outcomes. Surgery is indicated when BMI is greater than 40, or BMI is greater than 35 with significant associated co-morbidities. Four types of operations are currently performed: restrictive, malabsorptive, combined procedures (malabsorptive-restrictive) and motility-reducing pro-cedures. With restrictive procedures (adjustable gastric banding and vertical banded gastroplasty), patients can expect a long-term excess weight loss of 44-68%; for combined procedures (Roux-en-Y gastric by-pass) this is 60-70%, whereas for malabsorptive procedures (bilio-pancreatic diversion with or without duodenal switch), this is 75-80%. Intra-gastric stimulation is the least invasive treatment, but induces the lowest excess weight loss (32%) in the first two years after the operation. Gastric banding offers the best results when balancing risks and benefits. All procedures are now performed laparoscopically with comparable results to open surgery. The overall mortality rate in specialized centers is less than 0.3%. Different techniques are indicated according to BMI and the patient's eating habits. Surgery for morbid obesity has proved to improve quality of life and significantly reduce associated co-morbidities.
Minimally invasive techniques have revolutionized operative surgery. Computer aided surgery and robotic surgical systems strive to improve further on currently available minimally invasive surgery and open new horizons. Only several centers are currently using surgical robots and publishing data. In gastrointestinal surgery, robotic surgery is applied to a wide range of procedures, but is still in its infancy. Cholecystectomy, Nissen fundoplication and Heller myotomy are among the most frequently performed operations. The ZEUS (Computer Motion, Goleta, CA) and the da Vinci (Intuitive Surgical, Mountain View, CA) surgical systems are today the most advanced robotic systems used in gastrointestinal surgery. Most studies reported that robotic gastrointestinal surgery is feasible and safe, provides improved dexterity, better visualization, reduced fatigue and high levels of precision when compared to conventional laparoscopic surgery. Its main drawbacks are the absence of force feedback and extremely high costs. At this moment there are no reports to clearly demonstrate the superiority of robotics over conventional laparoscopic surgery. Further research and more prospective randomized trials are needed to better define the optimal application of this new technology in gastrointestinal surgery.
BACKGROUND AND AIMS: The diagnosis and treatment of chronic acalculous gallbladder disease (CAGD) remains controversial. Laparoscopic cholecystectomy (LC) is increasingly accepted as the treatment of choice for this condition. The purpose of this study was to analyse the outcomes from LC for CAGD and to identify potential prognostic factors. METHODS: We retrospectively analysed 54 patients with a clinical diagnosis of CAGD. All patients underwent LC. The outcomes were evaluated at 12 months. Outcomes from surgery were graded on a predetermined scoring system (score 1-6) reflecting the effect of surgery on symptomatology. Histopathological analysis was systematically performed on the resection specimens. RESULTS: Post-operatively, 90.8% of patients (49/54) were satisfied with the operation (outcome score 1-2). A pathological abnormality was detected in 40 patients (74.1%). Of those in whom no abnormality detected on histopathological examination, LC achieved a successful outcome (score 1-2) in 85.7% of patients (12/14). The worst outcomes (score 5-6) were observed in 2 patients with a pathological abnormality of the gallbladder. For the 5 patients with outcome scores of 3 to 6 (poor outcome), the mean duration of symptoms was 7.1 months compared to 18.2 months for patients with score of 1 and 2 (good outcome). CONCLUSIONS: There is no significant correlation between outcomes from LC for CAGD and the existence of a definable underlying pathology (p>0.05). Patients with long-standing symptoms were more likely to benefit from LC (p=0.039). LC is an appropriate treatment option for CAGD.
BACKGROUND AND AIMS: Acute appendicitis (AA) in the elderly (over 60 year-old) continues to pose diagnostic problems and carries a high morbidity and mortality rate. The aim of this article is to present our experience and outcomes and to evaluate influencing factors. METHODS: During a period of 5 years 63 patients with a definitive pathological diagnosis of AA were retrospectively analyzed. RESULTS: The primary admission diagnosis was established correctly in 44 patients (69.8%). Nineteen patients (30.1%) required further diagnostic investigations and the mean time to final diagnosis was 26 hours. For 3 patients (4.8%), the final diagnosis was established intra-operatively. The perforation rate was 31.8% (20 patients). Thirty-eight patients (63.3%) had associated co-morbidities. The overall mean duration of pre-hospitalization symptoms was 2.7 days, 2.3 days for non-perforated cases and 3.8 days for perforated AA (p=0.0025). The complication rate was 34.9% (22 patients), complications occurred in 75% of perforated appendicitis and in 16.2% of non-perforated cases (p=0.00001). Overall mortality rate was 6.3%, 15% in the perforated case group and 2.3% in the group with non-perforated appendicitis (p=0.0003). The mean hospital stay was significantly longer for cases with perforated AA (7.2 days) than non-perforated AA (5.1 days) (p=0.0056), and for patients developing complications (9.6 days) than those without complications (5.6 days) (p=0.0031). CONCLUSIONS: Advanced age adversely affects clinical diagnosis, the stage of the disease and the outcomes. Late presentation, delayed diagnosis, presence of perforation and co-morbidities are associated with a poor outcome from surgery.
BACKGROUND: Emphysematous cholecystitis is a rare condition caused by ischemia of the gallbladder wall with secondary gas-producing bacterial proliferation. The pathophysiology and epidemiology of this condition differ from that in gallstone-related acute cholecystitis. This report illustrates a case of emphysematous cholecystitis successfully treated by laparoscopic surgery. METHODS: An 83-year-old female patient was admitted to the hospital with acute abdominal syndrome. Clinical examination and blood tests suggested acute cholecystitis. Plain radiography revealed a circular gas pattern in the right upper quadrant suggestive of emphysematous cholecystitis. Subsequent computed tomography confirmed the presence of gas in the gallbladder wall and a gas-fluid level within the organ. RESULTS: Emergency laparoscopic cholecystectomy was successfully performed during which bubbling of the gallbladder wall was observed. Intraoperative cholangiography revealed no bile duct stones or biliary obstruction. The patient made an unremarkable recovery from surgery with no postoperative complications or admission to the intensive care unit. Pathological analysis revealed full-thickness infarctive necrosis of the gallbladder. Bacterial cultures grew Clostridium perfringens. CONCLUSIONS: This case illustrates a typical case of emphysematous cholecystitis successfully treated by laparoscopic surgery. It contributes to suggestions from other reports that this condition can be safely treated by the laparoscopic approach.