ABSTRACT
Cholecystoenteric fistulas are rare complications of cholelithiasis, with cholecystogastric fistulas (CGFs) being the rarest. Recommended treatment is surgery; however, select asymptomatic patients can be managed conservatively. The population frequently involved is old age with multiple comorbidities. Open surgery comes with its added morbidities, especially in this subgroup and hence laparoscopic surgery might be beneficial. Sometimes, these fistulas can be incomplete. Here, we describe a case of incomplete CGF managed by laparoscopic cholecystectomy and omental patching along with a brief review of the literature.
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BACKGROUND: Obesity has been consistently associated with a higher incidence of ventral hernia. It is preferable to treat both obesity and hernia in such patients because, with weight loss, the risk of recurrence of hernia is reduced. Bariatric surgery offers the best treatment for obesity and its associated co-morbidities and in combination with intraperitoneal onlay mesh repair (IPOM) provides the best treatment in such patients. The bariatric surgical team often faces the dilemma of whether to offer concomitant bariatric surgery with IPOM or a staged procedure in such patients because the safety of a concomitant procedure still creates doubt. OBJECTIVES: In this study we present our long-term results of the concomitant approach in such patients to analyze its long-term safety and efficacy. SETTING: Tertiary care teaching hospital, India. METHODS: We have performed a retrospective evaluation of all patients who underwent concomitant bariatric surgery with IPOM for primary or recurrent ventral hernia from January 2003 to July 2017 who completed a minimum follow-up of 12 months. RESULTS: A total of 156 patients of underwent concomitant bariatric surgery with IPOM, 120 patients (body mass index : 43.64 ± 6.8) underwent sleeve gastrectomy, and 36 patients (body mass index: 42.49 ± 8.57) underwent Roux-en-Y gastric bypass. One-hundred and seventeen patients were operated for primary hernia and 39 for recurrent hernia. There were no postoperative mesh infections and only 1 patient had recurrence. CONCLUSION: Bariatric surgery with IPOM provides the patient with a 1-stage treatment for both obesity and ventral hernia along with reduced risk of recurrence as a result of weight loss. It is safe to do a combined procedure in high volume centers with adequate expertise.
Subject(s)
Bariatric Surgery , Hernia, Ventral/complications , Hernia, Ventral/surgery , Herniorrhaphy , Obesity, Morbid/complications , Obesity, Morbid/surgery , Adult , Female , Gastrectomy , Humans , India , Laparoscopy , Male , Middle Aged , Retrospective Studies , Surgical Mesh , Treatment Outcome , Weight LossABSTRACT
BACKGROUND: To evaluate the predisposing factors and characteristics of recurrent ventral hernia (RVH) along with the feasibility and outcome of laparoscopy in managing RVH. METHODS: This study is a retrospective analysis of all patients with reducible or irreducible, uncomplicated RVH who underwent surgical management from January 2012 to June 2018. RESULTS: Out of 222 patients, 186 (83.8%) were female, and 36 (16.2%) were male. The mean age was 54.1 ± 10.1 years; an average body mass index was 31 kg/m2 (19-47.9). The most common previous abdominal operations among female patients were cesarean sections (43.5%) and abdominal hysterectomy (36.6%). Most of the patients had a history of open mesh repair (43.7%) and open anatomical repair (36.9%). The median time of recurrence was 4 years (1-33 years). The median defect size was 10 cm2 (range 2-150 cm2), and 73% defects were in the midline. Total 181 of 222 (81.6%) patients underwent laparoscopic intraperitoneal onlay mesh plus (L-IPOM+), 19 (8.5%) laparoscopic-assisted IPOM+, 17(7.7%) laparoscopic anatomical repair, while remaining 5 (2.3%) patients required open mesh reconstruction. The median size of the composite mesh used was 300 cm2 (150-600 cm2). The mean operating time was 145 (30-330) min, and median blood loss was 15 (5-110) ml. The median hospital stay was 3 days, and median follow-up period was 37 months. The post-operative symptomatic seroma rate was 3.1%, and re-recurrence rate was 1.4%. CONCLUSION: Obesity, old age, female sex, previous lower abdominal surgeries, and previous open repair of a hernia are factors associated with recurrence. Laparoscopic repair is feasible with excellent outcome in most of the patients.
Subject(s)
Hernia, Ventral/surgery , Herniorrhaphy/adverse effects , Incisional Hernia , Reoperation , Female , Herniorrhaphy/methods , Humans , Incisional Hernia/diagnosis , Incisional Hernia/etiology , Incisional Hernia/surgery , Laparoscopy/methods , Male , Middle Aged , Prognosis , Recurrence , Reoperation/instrumentation , Reoperation/methods , Retrospective Studies , Risk Assessment , Risk Factors , Surgical MeshABSTRACT
In the present study, an attempt has been made to explore the antifouling potential of bioactive compound isolated from sponge associated bacterium Halobacillus kuroshimensis SNSAB01. The crude extract of SNSAB01 strongly inhibited the growth of fouling bacterial strains with least minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The bioactive compound was characterized through FT-IR, HPLC, GCMS and NMR predicted as 'pyrrolo". From the mass spectral library, structure was elucidated as pyrrolo [1, 2-a] pyrazine-1, 4-dione, hexahydro. The in silico studies provided encouraging docking scores with two interactions by GLN 200 and GLU 304. The extract inhibited 89% diatom adhesion at 350 µg/ml concentration against Amphora sp. An EC50 value of 150 µg/ml for 50% inhibition of byssal thread of Perna viridis and LC50 was found to be 500 µg/ml. The LC50/EC50 ratio of 3.0 indicated nontoxic to nature. The result suggested that pyrrolo[1,2-a]pyrazine-1,4-dione can be used for antifouling coating.
Subject(s)
Anti-Infective Agents/pharmacology , Bivalvia/drug effects , Diatoms/drug effects , Halobacillus/chemistry , Pyrazines/pharmacology , Pyrroles/pharmacology , Acetylglucosamine/analogs & derivatives , Acetylglucosamine/metabolism , Animals , Anti-Infective Agents/chemistry , Anti-Infective Agents/isolation & purification , Binding Sites , Bivalvia/growth & development , Complex Mixtures/chemistry , Diatoms/growth & development , Extracellular Matrix/chemistry , Halobacillus/classification , Microbial Sensitivity Tests , Molecular Docking Simulation , Phylogeny , Porifera/microbiology , Pyrazines/chemistry , Pyrazines/isolation & purification , Pyrroles/chemistry , Pyrroles/isolation & purification , Symbiosis/physiologyABSTRACT
Bariatric surgery can be safely combined with laparoscopic intraperitoneal onlay mesh (IPOM) repair. In case of large ventral hernias, laparoendoscopic component separation can also be combined to achieve tension-free closure of the defect. Concomitant bariatric surgery and hernia repair also offer the additional benefit of reduction in recurrence of hernias as obesity, one of the risk factors, is treated in the process. We present a case of 60-year-old man with a body mass index of 45.3 kg/m2 with a large recurrent ventral hernia. We performed a lap sleeve gastrectomy with laparoendoscopic anterior component separation with IPOM. The operative steps included hernia contents reduction, conventional sleeve gastrectomy, anterior component separation on either side, intra-corporeal closure of hernia defect and placement of a composite mesh. Patient recovery was uneventful. Concomitant bariatric surgery with laparoendoscopic component separation with IPOM may be safe, but more studies are required.
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Bariatric surgery has proven benefits for morbid obesity and its associated comorbidities. Laparoscopic approach is well established for bariatric surgery. Single-incision laparoscopic surgery (SILS) offers even more minimally invasive approach for the same with the added advantage of better cosmesis. We have developed and standardised the SILS approach at our institute. We share our experience and technical "tips" and modifications which we have learnt over the years. Technical details of performing sleeve gastrectomy and Roux-en-Y gastric bypass with special attention to liver retraction, techniques of dissection in difficult areas, creation of anastomoses and suturing have all been described. In our experience and in experience of others, single-incision bariatric surgery is feasible. Use of conventional laparoscopic instruments makes single-incision approach practical for day-to-day practice. Supervised training is essential to learn these techniques.
Subject(s)
Bariatric Surgery/standards , Bariatric Surgery/trends , Laparoscopy/standards , Laparoscopy/trends , Obesity, Morbid/surgery , Adult , Bariatric Surgery/methods , Female , Gastrectomy/adverse effects , Gastrectomy/methods , Gastrectomy/trends , Gastric Bypass/adverse effects , Gastric Bypass/methods , Gastric Bypass/trends , Humans , Laparoscopy/methods , Male , Middle Aged , Obesity, Morbid/pathology , Reference Standards , Surgical Wound/pathology , Suture Techniques/standards , Sutures/standards , Treatment Outcome , Young AdultABSTRACT
Tumours of the presacral space are rare to present. Most of them are benign masses, very rarely malignant. Surgery is the mainstay of treatment as it establishes the diagnosis and prevents the adverse consequences associated with malignant degeneration and secondary bacterial infection. Their surgical excision is often difficult because of their anatomic location. Very few cases have been reported so far concerning a laparoscopic management of presacral tumour. We hereby present a young girl with recurrent presacral teratoma. She underwent laparoscopic successful excision of tumour with uneventful post-operative recovery. Here, we are highlighting the importance of laparoscopic approach for this scenario in terms additional advantages of minimally invasive approach such as better visualisation of the deep structures in the narrow presacral space, precise dissection in a limited space between the tumour and neighbouring structures with avoiding injury to neurovascular structure.
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Gallbladder duplication is a rare congenital malformation that occurs in about 1:4000 cases. Congenital anomalies of the gallbladder and anatomical variations of their position are associated with an increased risk of complications during laparoscopic cholecystectomy. We report a case of gallbladder duplication with symptomatic cholelithiasis, who presented with recurrent episodes of biliary colic and subsequently underwent laparoscopic cholecystectomy with intraoperative cholangiography. We also discussed in brief about the available literature support in relation to incidence of this disorder, imaging modalities used, intraoperative strategies and recommended measures for safe outcomes.
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BACKGROUND: Obesity is associated with increased mortality due to higher cardiovascular risk. A proportion of this risk is attributed to impaired lipid profile in the form of high levels of serum total cholesterol, triglycerides, and low levels of HDL cholesterol. Both sleeve gastrectomy (LSG) and gastric bypass (LGB) have been shown to have favourable effects on lipid profile with some variability in improvement. We aimed to study the difference in changes in lipid profile after LSG and LGB. METHODS: We performed a retrospective case-matched study comparing effects of LSG and LGB on lipid profile of patients who underwent bariatric surgery from September 2014 to September 2015. The matching was done based on criteria of age and body mass index (BMI). RESULTS: Out of a total of 92 selected patients, 69 patients underwent LSG and 23 patients underwent LGB. There was a significant improvement in serum triglycerides and HDL cholesterol with no significant reduction in serum total cholesterol in both LSG and LGB group. There was a significant reduction in cardiovascular risk calculated as total cholesterol: HDL cholesterol ratio following bariatric surgery (p = 0.002). CONCLUSION: Both LSG and LGB have similar effects on lipid profile cardiovascular risk attributed to it in Indian obese. Thus, sleeve gastrectomy may be considered as effective as a gastric bypass for dyslipidaemia improvement in Indian patients.
Subject(s)
Gastrectomy , Gastric Bypass , Lipids/blood , Metabolome/physiology , Obesity, Morbid/surgery , Adult , Asian People , Case-Control Studies , Cholesterol, HDL/blood , Female , Gastrectomy/methods , Gastric Bypass/methods , Humans , India , Male , Middle Aged , Obesity, Morbid/blood , Obesity, Morbid/metabolism , Retrospective Studies , Risk Factors , Triglycerides/blood , Weight Loss/physiology , Young AdultABSTRACT
BACKGROUND: Bariatric surgery has emerged to be the most effective treatment strategy for the treatment of obesity and type 2 diabetes mellitus (T2DM) achieving high remission rates. Many factors have been evaluated with a potential to predict the improvement of glycemic control following bariatric procedures. This study aims to study the various predictive factors for T2DM and the ABCD score in obese diabetic patients undergoing bariatric surgery in a South Indian population. METHODS: A total of 53 obese patients (BMI > 30 k/m2) with T2DM who underwent laparoscopic sleeve gastrectomy (LSG) and laparoscopic gastric bypass (LGB) from March 2014 to March 2015 were selected for the study. The patients were followed up to study the effects of various predictors of T2DM remission at 1 year. RESULTS: Out of the 53 patients, 35 (66%) underwent LSG and 18 (34%) underwent LGB. Patients (81.1%) had T2DM remission. Mean HbA1c values decreased from 8.07 ± 1.98 to 6.0 ± 0.71. Only higher pre-operative body weight (p = 0.04) and lower HbA1c level (p = 0.04) were significantly associated with T2DM remission. Higher absolute weight loss (p = 0.03) after surgery was also significantly associated with T2DM remission. ABCD score was not significantly associated with T2DM remission although patients with ABCD score higher than 7 demonstrated 100% remission rate. CONCLUSION: Among all the factors, only higher pre-operative weight and better glycaemic control along with better post-operative weight loss were significantly associated with the remission of T2DM. Although not significantly associated with remission of T2DM, higher ABCD scores had higher likelihood of remission.
Subject(s)
Bariatric Surgery/rehabilitation , Diabetes Mellitus, Type 2/surgery , Obesity/surgery , Adult , Asian People , Bariatric Surgery/methods , Blood Glucose/metabolism , Body Mass Index , Diabetes Mellitus, Type 2/complications , Diabetes Mellitus, Type 2/diagnosis , Diabetes Mellitus, Type 2/ethnology , Female , Humans , India/epidemiology , Male , Middle Aged , Obesity/complications , Obesity/diagnosis , Obesity/ethnology , Postoperative Period , Predictive Value of Tests , Prognosis , Remission Induction , Research Design , Retrospective Studies , Treatment Outcome , Weight Loss/physiologyABSTRACT
The Tamil Nadu model of public health is renowned for its success in providing quality health services at an affordable cost especially to the rural people. Tamil Nadu is the only state with a distinctive public health cadre in the district level and also the first state to enact a Public Health Act in 1939. Tamil Nadu has gained significant ground in the various aspects of health in the last few decades largely because of the significant reforms in its health sector which dates back to 1980s which saw rigorous expansion of rural health infrastructure in the state besides deployment of thousands of multipurpose health workers as village health nurses in rural areas. Effective implementation of Universal Immunization Programme, formation of Tamil Nadu Medical Services Corporation for regulating the drug procurement and promoting generic drugs, early incorporation of indigenous system of medicine into health care service, formulation of a health policy in 2003 by the state with special emphasis on low-income, disadvantaged communities alongside efficient implementation of The Tamil Nadu Health Systems Project (TNHSP) are the major factors which contributed for the success of the state. The importance of good political commitment and leadership in the health gains of the state warrants special mention. Moreover, the economic growth of the state, improved literacy rate, gender equality, and lowered fertility rate in the last few decades and contributions from the private sector have their share in the public health success of the state. In spite of some flaws and challenges, the Tamil Nadu Model remains the prototype health care delivery system in resource-limited settings which can be emulated by other states also toward a better health care delivery system.
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AIM: Ligation of the intersphincteric fistula tract (LIFT) is a new sphincter-sparing surgical technique increasingly used to treat fistulae-in-ano yielding good results. The aim of this study was to evaluate its effectiveness in the treatment of complex fistulae-in-ano and to determine factors associated with recurrence and its subsequent management. METHOD: A prospective observational study was performed of 167 patients with complex fistula-in-ano treated by LIFT from June 2013 to January 2014. In all patients a LIFT with partial core-out of the fistula tract was performed. RESULTS: There were 167 patients of mean age 43.6 ± 12.8 years. Thirty-three fistulae were recurrent. 150 were trans-sphincteric, 16 were intersphincteric and one was a suprasphincteric fistula. The median postoperative stay was 2 (range: 1-14) days (mean = 2.4 days). At follow up there was no change in continence. The median healing time was 4 (range: 1-8) weeks. Two patients developed an intersphincteric abscess needing surgical drainage healing uneventfully. The mean follow up was 12.8 [median = 12 (range: 4-22)] months. The healing rate was 94.1%. Ten (5.9%) patients developed a recurrent fistula that was managed by a second LIFT procedure in seven, a sinus tract excision with curettage in two and seton placement in one. Recurrence was significantly associated with diabetes mellitus and perianal collections and showed an increased incidence with tract abscesses and multiple tracts. CONCLUSION: LIFT has a high success rate in complex fistulae-in-ano. Recurrence is related to diabetes mellitus, perianal collections, tract abscesses and multiple tracts and a second LIFT procedure may be feasible and efficient.
Subject(s)
Anal Canal/surgery , Ligation/methods , Rectal Fistula/surgery , Adult , Female , Follow-Up Studies , Humans , India , Length of Stay , Ligation/adverse effects , Male , Middle Aged , Postoperative Complications/etiology , Postoperative Complications/surgery , Prospective Studies , Recurrence , Tertiary Care Centers , Treatment OutcomeABSTRACT
The present study aimed at exploring mahua (Madhuca indica) oil cake as a novel substrate for the production of biosurfactant by Serratia rubidaea SNAU02 under solid-state fermentation (SSF). Response surface methodology showed followings as the optimal conditions for the production of biosurfactant: mahua oil cake 7.48 g, 2.5 ml inoculum size (1×10(8) cells/ml), and pH 7.22 and 31 °C temperature. The characterization of the biosurfactant by TLC, FT-IR and GC-MS revealed the presence of rhamnolipid. The presence of rhamnosyl transferase gene responsible for biosynthesis of rhamnolipid was identified. The strain SNAU02 exhibited antifungal activity and demonstrated no toxicity against the seeds of Brassica oleracea and Artemia salina employed as a bio-indicator. The present findings indicated the potential of mahua oil cake as suitable substrate for the production of rhamnolipids in SSF by S. rubidaea SNAU02 and application potential of the biosurfactant produced as biocontrol agent against plant pathogens.
Subject(s)
Fermentation , Glycolipids/metabolism , Lipid Metabolism , Serratia/metabolism , Chromatography, Thin Layer , Gas Chromatography-Mass Spectrometry , Spectroscopy, Fourier Transform InfraredABSTRACT
BACKGROUND: Leaks following oesophageal surgery are considered to be amongst the most dreaded complications and contributory to postoperative mortality. Controversies still exist regarding the best option for the management of oesophageal leaks due to lack of standardized treatment protocols. This study was designed to analyse the feasibility outcome and complications associated with placement of removable, fully covered, self-expanding metallic stents for oesophageal leaks with concomitant minimally invasive drainage when appropriate. METHODS: The study group included 32 patients from a prospectively maintained database of oesophageal leaks, with the majority being anastomotic leaks after minimally invasive oesophagectomy (n = 28), followed by laparoscopic cardiomyotomy (n = 3) and extended total gastrectomy (n = 1). The procedures took place between March 2007 and April 2013. RESULTS: Most patients had an intrathoracic leak (n = 22), with a mean time to detection of the leak following surgery of 7.50 days (SD = 2.23). Subsequent to endoscopic stenting, enteral feeding via a nasojejunal tube was started on the second day and oral feeding was delayed until the 14th day (n = 31). Six patients underwent thoracoscopic (n = 5) or laparoscopic drainage (n = 1) along with stenting for significant mediastinal and intra-abdominal contamination. The stent migration rate of our study was 8.54%. The overall success in terms of preventing mortality was 96%. CONCLUSION: Endoscopic stenting should be considered a primary option for managing oesophageal leaks. Delayed oral intake may reduce the incidence of stent migration. Larger stents (bariatric or colorectal stents) serve as a useful option in case of migrated stents. Combined minimally invasive procedures can be safely adapted in appropriate clinical circumstances and may contribute to better outcomes.
Subject(s)
Anastomotic Leak/therapy , Drainage/methods , Esophagectomy , Stents , Anastomosis, Surgical/adverse effects , Anastomotic Leak/diagnosis , Cardia/surgery , Device Removal , Enteral Nutrition , Feasibility Studies , Female , Fluoroscopy , Foreign-Body Migration/etiology , Foreign-Body Migration/surgery , Gastrectomy , Humans , Laparoscopy , Male , Middle Aged , Retrospective Studies , Stents/adverse effects , ThoracoscopyABSTRACT
The aim of the study was to characterize and optimize the growth media for biosurfactant production from Serratia rubidaea SNAU02 isolated from hydrocarbon-contaminated soil from Cuddalore district, Tamilnadu, India. The biosurfactant produced by S. rubidaea SNAU02, was able to reduce the surface tension to 34.4 mN m(-1) in MSM medium. The biosurfactant was characterized by FT-IR and GC-MS analysis. The GC-MS analysis shows that dirhamnolipid was detected in abundance as predominant congener than monorhamnolipid. The response surface methodology (RSM) -central composite design (CCD) was performed to optimize the media for biosurfactant production. The maximum emulsification index was obtained under the optimal condition of 29.31 g L(-1) mannitol; 2.06 g L(-1) yeast extract, medium pH 6.97 and 5.69 g L(-1) NaCl. The biosurfactant produced by S. rubidaea recovered 92% of used engine oil adsorbed to a sand sample, suggested the potential application in microbial enhanced oil recovery and bioremediation.
Subject(s)
Hydrocarbons/metabolism , Serratia/metabolism , Soil Pollutants/metabolism , Surface-Active Agents/metabolismABSTRACT
Understanding and controlling how carbon nanotubes interact with phospholipid membranes is necessary for preventing adverse effects of these relatively new, but still exciting, materials. Futuristic applications envision incorporating carbon nanotubes in liposomes for personalized medicine, controlled delivery, and imaging. Because of their ability to penetrate phospholipid bilayers, nanotubes could serve as nanoscale syringes to deliver molecular cargo and develop gene therapy. Several experimental reports available on the subject demonstrate the need for a better understanding, at the molecular level, of whether carbon nanotubes penetrate, reside, and perturb phospholipid bilayers. Using all-atom molecular dynamics simulations, we quantify how short carbon nanotubes (~6 nm in length) embedded within a DOPC phospholipid membrane perturb the structure, organization, and dynamics of the lipid molecules within the membrane. It is found that the structural perturbation is very short-ranged, although it becomes pronounced when bundles of carbon nanotubes are formed within the membrane. The presence of the nanotubes is found to reduce the mobility of lipid molecules within the membrane and to perturb the structure of interfacial water. Our observations suggest that the local perturbations in the lipid structure caused by the nanotubes could lead to enhanced penetration of molecular compounds across the membrane.
Subject(s)
Lipid Bilayers/chemistry , Nanotubes, Carbon/chemistry , Phosphatidylcholines/chemistry , Algorithms , Models, Molecular , Molecular Dynamics SimulationABSTRACT
Individuals suffering from neurosis suffer from social and occupational disabilities similar to that of psychoses. Though understanding of disabilities in neurosis is essential in management of the clients, the relevant interventional studies are very limited. The present study attempted to evaluate the effect of nursing interventions in reducing social and occupational disabilities in neurotic patients. Sixty neurotic patients diagnosed as per ICD 9 criteria were randomly assigned to experimental and control groups followed by pre-assessment by Groningen social disability schedule. Of the 10 sessions of nursing intervention, 3 were individual sessions with clients, 5 with clients and family members and 2 with small group of clients with similar problems; nursing intervention group and non-nursing intervention group received the routine drug treatment at rural community mental health centre, NIMHANS, Bengaluru. The post-assessment was carried out first, second, and the third month followed by the nursing intervention. The findings revealed statistically significant reduction in social and occupational disabilities. A community-based psychosocial intervention led by community health nurses catering to the needs of neurotic patients is indicated by the results.
Subject(s)
Community Health Nursing , Disabled Persons/psychology , Employment , Neurotic Disorders/nursing , Adolescent , Adult , Aged , Chi-Square Distribution , Female , Humans , Male , Middle Aged , Rural PopulationABSTRACT
BACKGROUND: Chronic pancreatitis is mainly managed with drugs, but surgery is required in selected groups of patients. The Partington procedure is still the procedure of choice for patients with a dilated main pancreatic duct but without an inflammatory pancreatic head mass. The same equivalent can be achieved by laparoscopic approach. Laparoendoscopic single-site surgery gained tremendous attention in the past few years. Complex surgeries are being reported using this technique. We report in this paper the first laparoendoscopic single-site lateral pancreaticojejunostomy (LPJ) for chronic calcific pancreatitis with dilated pancreatic duct. PATIENT AND METHOD: The procedure was performed on a 32-year-old female diagnosed to have chronic calcific pancreatitis. A single vertical 2.5-cm umbilical incision and one 10-mm and two 5-mm ports were made. The procedure was completed in 220 min without any intraoperative complication. There were no postoperative complications, and the patient was discharged on day 5 when she started taking routine diet. CONCLUSION: This preliminary experience suggests that single-incision laparoscopic LPJ is feasible and safe when performed by an experienced laparoscopic surgeon. It has a cosmetic advantage over laparoscopic LPJ. However, it remains to be determined if this technique offers additional advantages of decreased analgesia, decreased hospital stay or cost effectiveness. Further studies are required to analyze these factors.
Subject(s)
Laparoscopy/methods , Pancreaticojejunostomy/methods , Pancreatitis, Chronic/surgery , Adult , Calcinosis/surgery , Female , Humans , Pancreas/surgeryABSTRACT
In this quantum chemical study, we explore hydrogen bonding (H-bonding) and stacking interactions in different crystalline cellulose allomorphs; namely, cellulose I(ß) and cellulose III(I). We consider a model system representing a cellulose crystalline core made from six cellobiose units arranged in three layers with two chains per layer. We calculate the contributions of intrasheet and intersheet interactions to the structure and stability in both cellulose I(ß) and cellulose III(I) crystalline cores. Reference structures for this study were generated from molecular dynamics simulations of water-solvated cellulose I(ß) and III(I) fibrils. A systematic analysis of various conformations describing different mutual orientations of cellobiose units is performed using the hybrid density functional theory with the M06-2X with 6-31+G(d,p) basis sets. We dissect the nature of the forces that stabilize the cellulose I(ß) and cellulose III(I) crystalline cores and quantify the relative strength of H-bonding and stacking interactions. Our calculations demonstrate that individual H-bonding interactions are stronger in cellulose I(ß) than in cellulose III(I); however, the total H-bonding contribution to stabilization is larger in cellulose III(I) because of the highly cooperative nature of the H-bonding network. In addition, we observe a significant contribution from cooperative stacking interactions to the stabilization of cellulose I(ß). The theory of atoms-in-molecules (AIM) has been employed to characterize and quantify these intermolecular interactions. AIM analyses highlight the role of nonconventional CH···O H-bonding in the cellulose assemblies. Finally, we calculate molecular electrostatic potential maps for the cellulose allomorphs that capture the differences in chemical reactivity of the systems considered in our study.
Subject(s)
Cellulose/chemistry , Models, Chemical , Molecular Dynamics Simulation , Quantum Theory , Computer Simulation , Hydrogen Bonding , Molecular Structure , Static Electricity , Water/chemistryABSTRACT
Carbohydrates on host membranes are fundamental to many important biological processes. Here, we seek a basic understanding of the nature of the interactions between carbohydrates and phospholipids to dissect their roles in molecular recognition. A hybrid quantum mechanics/quantum mechanics (QM/QM) scheme with two different levels of treatment was used to explore the conformations and energetics of carbohydrate-phospholipid complexes. We investigate the interactions of two phospholipids (POPC and DOPC) with mannose using density functional theory. Carbohydrate-phospholipid interactions are probed with respect to competing interactions with water. Our hybrid QM/QM approach demonstrates that mannose interactions with phospholipids can result in alterations in charge distributions and conformations of phospholipids. The results clearly reveal the interplay between conventional and nonconventional hydrogen bonding; moreover, nonpolar interactions are shown to be crucial in the recognition and further stabilization of carbohydrate-phospholipid complexes. The influence of the acyl chain on phospholipid headgroup orientation is clearly evident in our investigation. The significance of the conventional OH···O and nonconventional CH···O and CH···C interactions in the stabilization of the intermolecular complexes is deduced from the molecular electron density topology using Bader's atoms-in-molecules theory. Finally, we have compared the QM energies with molecular mechanics energies for the same interactions to aid in the refinement of the all-atom lipid-carbohydrate force fields.