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Krein MP, Sukumar N. Exploration of the Topology of Chemical Spaces with Network Measures. J Phys Chem A 2011; 115:12905-18. [DOI: 10.1021/jp204022u] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Kourinov I, Ealick SE, Capel M, Banerjee S, Murphy F, Neau D, Perry K, Rajashankar K, Schuermann J, Sukumar N. NE-CAT crystallography beamlines for challenging structural biology research. Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311087770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Thong KY, Jose B, Sukumar N, Cull ML, Mills AP, Sathyapalan T, Shafiq W, Rigby AS, Walton C, Ryder REJ. Safety, efficacy and tolerability of exenatide in combination with insulin in the Association of British Clinical Diabetologists nationwide exenatide audit*. Diabetes Obes Metab 2011; 13:703-10. [PMID: 21410858 DOI: 10.1111/j.1463-1326.2011.01393.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
AIM To assess the extent, safety, efficacy and tolerability of reported off-licence exenatide use through a nationwide audit. METHODS The Association of British Clinical Diabetologists hosted a password-protected, online collection of anonymized data of exenatide use in real clinical practice. Three hundred and fifteen contributors from 126 centres across UK provided data on 6717 patients. HbA1c and weight changes, exenatide discontinuation, adverse events and treatment satisfaction were compared between non-insulin and insulin-treated patients. RESULTS Four thousand eight hundred and fifty-seven patients had baseline and follow-up treatment status with mean (±s.d.) baseline HbA1c 9.45 ± 1.69% and BMI 40.0 ± 8.2 kg/m(2) . Of the 4857 patients, 1921 (39.6%) used exenatide with insulin. Comparing patients who continued insulin with exenatide with non-insulin-treated patients, mean (±s.e.) latest HbA1c and weight reduction (median 26 weeks) were 0.51 ± 0.06 versus 0.94 ± 0.04% (p < 0.001) and 5.8 ± 0.2 versus 5.5 ± 0.1 kg (p = 0.278). Insulin-treated patients had higher rates of exenatide discontinuation (31.0 vs. 13.9%, p < 0.001), hypoglycaemia (8.9 vs. 6.1%, p < 0.001), gastrointestinal side effects (28.4 vs. 25.0%, p = 0.008) and treatment dissatisfaction (20.8 vs. 5.7%, p < 0.001). However, 34.2% of the patients continuing insulin still achieved HbA1c reduction ≥1%. There was significant insulin discontinuation, dose reduction and greater sulphonylurea discontinuation among insulin-treated patients. CONCLUSIONS Addition of exenatide to obese, insulin-treated patients can improve glycaemia and weight. Adverse events were statistically but probably not clinically significantly higher, but combination treatment was less well tolerated. Overall, exenatide was less effective in lowering HbA1c among insulin-treated patients, although significant number of insulin-treated patients still achieved significant HbA1c, weight and insulin reductions. Further research into identifying obese, insulin-treated patients who will tolerate and benefit from exenatide treatment is urgently needed.
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Sukumar N, Mathews FS, Langan P, Davidson VL. A joint x-ray and neutron study on amicyanin reveals the role of protein dynamics in electron transfer. Proc Natl Acad Sci U S A 2010; 107:6817-22. [PMID: 20351252 PMCID: PMC2872398 DOI: 10.1073/pnas.0912672107] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The joint x-ray/neutron diffraction model of the Type I copper protein, amicyanin from Paracoccus denitrificans was determined at 1.8 A resolution. The protein was crystallized using reagents prepared in D(2)O. About 86% of the amide hydrogen atoms are either partially or fully exchanged, which correlates well with the atomic depth of the amide nitrogen atom and the secondary structure type, but with notable exceptions. Each of the four residues that provide copper ligands is partially deuterated. The model reveals the dynamic nature of the protein, especially around the copper-binding site. A detailed analysis of the presence of deuterated water molecules near the exchange sites indicates that amide hydrogen exchange is primarily due to the flexibility of the protein. Analysis of the electron transfer path through the protein shows that residues in that region are highly dynamic, as judged by hydrogen/deuterium exchange. This could increase the rate of electron transfer by transiently shortening through-space jumps in pathways or by increasing the atomic packing density. Analysis of C-HX bonding reveals previously undefined roles of these relatively weak H bonds, which, when present in sufficient number can collectively influence the structure, redox, and electron transfer properties of amicyanin.
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Kulshrestha P, Sukumar N, Murray JS, Giese RF, Wood TD. Computational Prediction of Antibody Binding Sites on Tetracycline Antibiotics: Electrostatic Potentials and Average Local Ionization Energies on Molecular Surfaces. J Phys Chem A 2009; 113:756-66. [DOI: 10.1021/jp8089165] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Sukumar N, Mathews FS, Gordon MM, Ealick SE, Alpers DH. Postcrystallization Analysis of the Irreproducibility of the Human Intrinsic Factor-Cobalamin Complex Crystals. CRYSTAL GROWTH & DESIGN 2009; 9:348-351. [PMID: 19884970 PMCID: PMC2631276 DOI: 10.1021/cg800509f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Approximately 15% (w/w) of human intrinsic factor (IF) is comprised of carbohydrate side chains, making crystallization problematic. In addition, IF is sensitive to proteolysis. To understand the role of these factors in crystallization, we carried out dynamic light scattering studies and assessed their correlation with crystallization. The packing of the IF-cobalamin complex and the known properties of the protein in solution were also analyzed to explore the irreproducibility of the IF-cobalamin complex crystals and the difficulty in obtaining apo-IF crystals suitable for crystallographic analysis. The results indicate that although glycosylation may in general be inhibitory for crystallization, time-dependent proteolysis appears to play a much more important role in the process of crystallization of IF. Thus, the presence of cobalamin and of domain fragments that can form incomplete dimers lacking one of two β-domains appears to promote the crystallization of IF.
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Gulrajani ML, Sukumar N. Further Optimisation of a Single-stage Preparatory Process: Effect of phi Buffers. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1478-4408.1985.tb00991.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Kourinov I, Ealick E, Capel M, Lynch E, Murphy F, Rajashankar K, Sukumar N, Unik P, Withrow J. NorthEastern Collaborative Access Team (NE-CAT) beam lines at the Advanced Photon Source. Acta Crystallogr A 2008. [DOI: 10.1107/s0108767308094300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Sukumar N, Krein M, Breneman CM. Bioinformatics and cheminformatics: where do the twain meet? CURRENT OPINION IN DRUG DISCOVERY & DEVELOPMENT 2008; 11:311-319. [PMID: 18428084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Bridging the domains of cheminformatics and bioinformatics in the post-genomic era requires the convergence of goals, tools, techniques and annotations. This article reviews recent research at the interface of the domains that shows evidence of this convergence. While graph theoretical representations have long been used to develop simple topological descriptions of molecules, graph theory-based network concepts are also widely employed in systems biology. Shape and conformation are important for understanding intermolecular interactions, and several structure-based cheminformatic descriptors have been developed and applied to drug-like molecules and biomolecules. Data fusion methods and shared ontologies can also help integrate data from multiple sources in order to generate a holistic picture of the shared molecular informatics domain.
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Lukman MR, Sangar P, Sukumar N. Obstructed paraesophageal hernia in a nonagenerian treated by laparoscopic anterior gastropexy. THE MEDICAL JOURNAL OF MALAYSIA 2007; 62:83-4. [PMID: 17682583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Paraesophageal hernias have been historically associated with risk of substantial morbidity and mortality. We report a case of a 92 year old lady with acute gastric outlet obstruction due to a chronic paraesophageal hernia that was successfully treated by minimal invasive surgery. Anterior gastropexy was performed after the stomach was reduced. The hiatal opening was enlarged to reduce the risk of obstruction in the future. She was discharged well on the third day.
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Razman J, Shaharin S, Lukman MR, Sukumar N, Jasmi AY. Initial experience of laparoscopic incisional hernia repair. THE MEDICAL JOURNAL OF MALAYSIA 2006; 61:142-6. [PMID: 16898302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Laparoscopic repair of ventral and incisional hernia has become increasingly popular as compared to open repair. The procedure has the advantages of minimal access surgery, reduction of post operative pain and the recurrence rate. A prospective study of laparoscopic incisional hernia repair was performed in our center from August 2002 to April 2004. Eighteen cases (n: 18) were performed during the study period. Fifteen cases (n: 15) had open hernia repair previously. Sixteen patients (n: 16) had successful repair of the hernia with the laparoscopic approach and two cases were converted to open repair. The mean hernia defect size was 156cm2. There was no intraoperative or immediate postoperative complication. The mean operating time was 100 +/- 34 minutes (75 - 180 minutes). The postoperative pain was graded as mild to moderate according to visual analogue score. The mean day of discharge after surgery was two days (1 - 3 days). During follow up, three patients (16.7%) developed seroma at the hernia sac which was resolved with conservative management after three weeks. One (5.6%) patient developed recurrence six months after surgery. In conclusion, laparoscopic repair of incisional hernia particularly recurrent hernia has been shown to be safe and effective in our centre. However, careful patient selection and acquiring the necessary advanced laparoscopic surgical skills coupled with the proper use of equipment are mandatory before embarking on this procedure.
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Malathy Sony SM, Saraboji K, Sukumar N, Ponnuswamy MN. Role of amino acid properties to determine backbone τ(N–Cα–C′) stretching angle in peptides and proteins. Biophys Chem 2006; 120:24-31. [PMID: 16269209 DOI: 10.1016/j.bpc.2005.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2005] [Revised: 07/27/2005] [Accepted: 07/28/2005] [Indexed: 11/22/2022]
Abstract
The analysis of the basic geometry of amino acid residues of protein structures has demonstrated the invariability of all the bond lengths and bond angles except for tau, the backbone N-Calpha-C' angle. This angle can be widened or contracted significantly from the tetrahedral geometry to accommodate various other strains in the structure. In order to accurately determine the cause for this deviation, a survey is made for the tau angles using the peptide structures and the ultrahigh resolution protein structures. The average deviation of N-Calpha-C' angles from tetrahedral geometry for each amino acid in all the categories were calculated and then correlated with forty-eight physiochemical, energetic and conformational properties of amino acids. Linear and multiple regression analysis were carried out between the amino acid deviation and the 48 properties. This study confirms the deviation of tau angles in both the peptide and protein structures but similar forces do not influence them. The peptide structures are influenced by physical properties whereas as expected the conformational properties influence the protein structures. And it is not any single property that dominates the deviation but the combination of different factors contributes to the tau angle deviation.
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Hamidon BB, Abdullah SA, Zawawi MF, Sukumar N, Aminuddin A, Raymond AA. A prospective comparison of percutaneous endoscopic gastrostomy and nasogastric tube feeding in patients with acute dysphagic stroke. THE MEDICAL JOURNAL OF MALAYSIA 2006; 61:59-66. [PMID: 16708735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Dysphagia following stroke is common problem and is of particular concern because of its potental for malnutrition. Nasogastric (NG) and percutaneous endoscopic gastrostomy (PEG) tube feeding are recognized methods for nutritional support for patients with persistent neurologic dysphagia. However, the former is associated with tube dislodgement and blockage that might compromise the patients' nutritional status. There have been few randomized prospective studies to date comparing the efficacy and safety of these 2 modes of dysphagia management in stroke patients. The objective of this study was to compare PEG with NG tube feeding after acute dysphagic stroke in terms of nutritional status and treatment failure. This was a randomized prospective clinical trial. A total of 23 consecutive patients who fulfilled the criteria were recruited from the medical wards in Hospital Universiti Kebangsaan Malaysia. The diagnosis of stroke (acute cerebral infarct) was based on clinical and brain computed tomographic (CT scan) findings; and the diagnosis of dysphagia was done clinically by using the 'swallowing test'. At recruitment, upper-arm skin fold thickness (triceps and biceps) and mid-arm circumference were measured; and blood was drawn for serum albumin level. They were then followed up at 4 weeks where the above tests were repeated. A total of 22 patients completed the study (12 patients in the NG group and 10 patients in the PEG group). Serum albumin levels (p = 0.045) were significantly higher in the PEG as compared to the NG group at 4 weeks post-intervention. There were statistically significant improvements in serum albumin level (p = 0.024) in the PEG group; and statistically significant reductions in serum albumin level (p = 0.047) in the NG group 4 weeks after the intervention. However, there were no significant differences in anthropometric parameters between the two groups and no significant changes in these parameters for each group 4 weeks after the intervention. Treatment failure occurred in 5 out of 10 patients (50.0%) in the NG group, but none in PEG group (p = 0.036). PEG tube feeding is more effective than NG tube feeding in improving the nutritional status (in terms of the serum albumin level) of patients with dysphagic stroke. NG tube feeding, in fact, reduced the nutritional status (in terms of the serum albumin level) of the patients.
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Teoh CM, Gunasegaram T, Chan KY, Sukumar N, Sagap I. Review of risk factors associated with the anastomosis leakage in anterior resection in Hospital Universiti Kebangsaan Malaysia. THE MEDICAL JOURNAL OF MALAYSIA 2005; 60:275-80. [PMID: 16379179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
This is a retrospective study evaluating the risk factors for clinical anastomotic leakage after anterior resection in 64 patients with rectal cancer operated from November 2001 till August 2003. The percentage of anastomosis leakage was higher in those patients with diabetic, low albumin level, neoadjuvant radiotherapy, higher staging, and poorly differentiated tumour. However, these differences were statistically not significant. There was a significant difference (p=0.03) of anastomosis leakage in those patients with very distal tumour of < 4cm from anal verge (42%), when compare to those patients with proximal tumor of > 15cm from anal verge (4.3%). The mortality associated with this complication was 30%. Hence, a surgeon may consider a covering stoma or be more vigilant in operating patients with multiple risk factors.
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Kalyani A, Teoh CM, Sukumar N. I jejunal patch repair of a duodenal perforation. THE MEDICAL JOURNAL OF MALAYSIA 2005; 60:237-8. [PMID: 16114169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A patient with duodenal ulcer who developed iatrogenic perforation post endoscopy is presente. We present t is case that was treated successfully treated by jejunal serosal patch.
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Sukumar N, Langan P, Mathews FS, Jones LH, Thiyagarajan P, Schoenborn BP, Davidson VL. A preliminary time-of-flight neutron diffraction study on amicyanin from Paracoccus denitrificans. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2005; 61:640-2. [PMID: 15858277 DOI: 10.1107/s090744490500541x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2004] [Accepted: 02/17/2005] [Indexed: 11/10/2022]
Abstract
Crystals of the blue copper protein amicyanin suitable for neutron diffraction were grown by the sitting-drop method, followed by repeated macroseeding using solutions prepared with D(2)O. Although the crystal sizes were the same, crystals grown using solutions made up in H(2)O in the initial stages of macroseeding and solutions with D(2)O in later stages did not diffract neutrons well. However, when the protein was initially exchanged with buffered D(2)O and then crystallized and also macroseeded using solutions made up in D(2)O throughout, the crystals diffracted neutrons to high resolution. One of those crystals was used to collect a data set to a resolution of 1.9 A.
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Chan KY, Teoh CM, Sukumar N. Case report of a difficult venous access: retroperitoneal approach of inserting an improved non-heparinised port for long-term use. THE MEDICAL JOURNAL OF MALAYSIA 2005; 60:94-6. [PMID: 16250289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
This is a case report of a patient with difficult venous access following thrombosis of major superficial and deep veins of the limbs as documented by ultrasound doppler and venography. The insertion of a few central ports were infected and the vein thrombosed. Venography revealed that central venous access was no longer feasible. The previous laparotomies had resulted in dense intra-peritoneal adhesions, and rendered further laparotomy virtually impossible. The patient had occasional adhesion colics, vomiting and hypoglycemic episodes. A rarely performed retro-peritoneal approach of inserting an improved non-heparinised port proved to be effective for long-term management of this patient. The surgical approach and the selected port are discussed.
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Marjmin O, Badrulhisham B, Teoh CM, Sukumar N, Ahmad Zakuan K. Metastatic cervical carcinoma in the caecum. THE MEDICAL JOURNAL OF MALAYSIA 2005; 60:97-8. [PMID: 16250290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
A patient who presented with acute intestinal obstruction had a right hemicolectomy for a caecal tumour. The histopathology report confirmed metastatic carcinoma in the caecum from the cervical carcinoma. Caecum is a very rare site of metastasis from cervical carcinoma. From our literature review, there have been no such cases reported.
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Song M, Breneman CM, Sukumar N. Three-dimensional quantitative structure-activity relationship analyses of piperidine-based CCR5 receptor antagonists. Bioorg Med Chem 2004; 12:489-99. [PMID: 14723967 DOI: 10.1016/j.bmc.2003.10.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The CCR5 chemokine receptor has recently been found to play a crucial role in the viral entry stage of HIV infection and has therefore become an attractive potential target for anti-HIV therapeutics. On the other hand, the lack of CCR5 crystal structure data has impeded the development of structure-based CCR5 antagonist design. In this paper, we compare two three-dimensional Quantitative Structure-Activity Relationship (3D-QSAR) methods: Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) on a series of piperidine-based CCR5 antagonists as an alternative approach to investigate the interaction between CCR5 antagonists and their receptor. Superimposition of antagonist structures was performed using two alignment rules: atomic/centroid rms fit and rigid body field fit techniques. The 3D QSAR models were derived from a training set of 72 compounds, and were found to have predictive capability for a set of 19 holdout test compounds. The resulting contour maps produced by the best CoMFA and CoMSIA models were used to identify the structural features relevant to biological activity in this series of compounds. Further analyses of these interaction-field contour maps also showed a high level of internal consistency.
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Sukumar N, Teoh CM. Heterotopic pancreas in the stomach. THE MEDICAL JOURNAL OF MALAYSIA 2004; 59:541-3. [PMID: 15779591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
A patient diagnosed with gastrointestinal stromal tumour of the stomach underwent gastrectomy. Post-operatively, histopathology was reported as heterotopic pancreas of the stomach. Heterotopic pancreas is very rare and though most of them appear asymptomatic, surgical resection is advisable.
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Sukumar N, Shaharin S, Razman J, Jasmi AY. Bogota bag in the treatment of abdominal wound dehiscence. THE MEDICAL JOURNAL OF MALAYSIA 2004; 59:281-3. [PMID: 15559181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
A patient who underwent emergency laparotomy for rectal prolapse developed repeated abdominal wound dehiscence and subsequently an enteric fistula. The management of abdominal wound dehiscence is discussed, specifically with regards to the Bogota bag. Use of Bogota bag has been reported worldwide but this may be the first report here.
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Breneman CM, Sundling CM, Sukumar N, Shen L, Katt WP, Embrechts MJ. New developments in PEST shape/property hybrid descriptors. J Comput Aided Mol Des 2004; 17:231-40. [PMID: 13677489 DOI: 10.1023/a:1025334310107] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent investigations have shown that the inclusion of hybrid shape/property descriptors together with 2D topological descriptors increases the predictive capability of QSAR and QSPR models. Property-Encoded Surface Translator (PEST) descriptors may be computed using ab initio or semi-empirical electron density surfaces and/or electronic properties, as well as atomic fragment-based TAE/RECON property-encoded surface reconstructions. The RECON and PEST algorithms also include rapid fragment-based wavelet coefficient descriptor (WCD) computation. These descriptors enable a compact encoding of chemical information. We also briefly discuss the use of the RECON/PEST methodology in a virtual high-throughput mode, as well as the use of TAE properties for molecular surface autocorrelation analysis.
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Malathy Sony SM, Sukumar N, Ponnuswamy MN, Jayakumar R. Presence of pseudo-peptide bond in the crystal structure of n-(t-butoxycarbonyl)-ɛ-n′-benzyloxycarbony-l-lysyl-l-isoleucine (boc-lys(obzl)-ile). CRYSTAL RESEARCH AND TECHNOLOGY 2004. [DOI: 10.1002/crat.200310197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Tugcu N, Song M, Breneman CM, Sukumar N, Bennett KP, Cramer SM. Prediction of the Effect of Mobile-Phase Salt Type on Protein Retention and Selectivity in Anion Exchange Systems. Anal Chem 2003; 75:3563-72. [PMID: 14570211 DOI: 10.1021/ac0263519] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study examines the effect of different salt types on protein retention and selectivity in anion exchange systems. Particularly, linear retention data for various proteins were obtained on two structurally different anion exchange stationary-phase materials in the presence of three salts with different counterions. The data indicated that the effects are, for the most part, nonspecific, although various specific effects could also be observed. Quantitative structure retention relationship (QSRR) models based on support vector machine feature selection and regression models were developed using the experimental chromatographic data in conjunction with various molecular descriptors computed from protein crystal structure geometries. Star plots for each descriptor used in the final model were generated to aid in interpretation. The resulting QSRR models were predictive, with cross-validated r2 values of 0.9445, 0.9676, and 0.8897 for Source 15Q and 0.9561, 0.9876, and 0.9760 for Q Sepharose resins in the presence of three different salts. The predictive power of these models was validated using a set of test proteins that were not used in the generation of these models. Interpretation of the models revealed that particular trends for proteins and salts could be captured using QSRR techniques.
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