Displaying all 11 publications

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  1. Ng S, Xie Y, Schaefer HF
    J Mol Model, 2024 Sep 14;30(10):333.
    PMID: 39276285 DOI: 10.1007/s00894-024-06135-4
    CONTEXT: 2,2,2-Trifluoroethanol (TFE) is known as a membrane mimetic solvent. The IR spectrum, 1H NMR spectrum, 13C NMR spin‒lattice relaxation times (T1), and nuclear Overhauser effect (NOE) data are consistent with extensive hydrogen bonding in TFE, but do not lead to structural features of the hydrogen bonding. Hence, DFT computations were carried out. The results predict the existence of a set of H-bonded dimers and trimers. The bond lengths and dihedral angles in these complexes are obtained, together with their dissociation energies. Computations were also performed for the geometry of the two conformers of the isolated monomer. The structure of one of the dimers consists of a 7-member cyclic fragment with a free CF3CH2 side chain. One set of the trimer structures involves the OH of a third monomer H-bonding to one of the F atoms in the CF3 group of the side chain of this dimer, thereby creating three trimer isomers. A fourth trimer cluster is formed from three monomers in which three OH∙∙∙O bonds create a cyclic fragment with three CF3CH2 side chains. The high dissociation energy (with respect to three monomers) indicates the high stability of the trimer complexes. The structural features of the trimer complexes resemble the structure of a conventional liquid crystal molecule and are postulated to resemble the latter in properties and function in solution, but at a much shorter timescale because of the noncovalent bonding. This hydrogen bonding phenomenon of TFE may be related to its function as a membrane memetic solvent.

    METHODS: Initially, IR and NMR spectroscopic methods were used. Standard procedures were followed. For the computations, a hybrid DFT method with empirical dispersion, ωB97X-D, was used. The basis set, 6-311++G**, is of triple-ζ quality, in which polarization functions and diffuse functions were added for all atoms.

  2. Bundhun A, Abdallah HH, Ramasami P, Schaefer HF
    J Phys Chem A, 2010 Dec 23;114(50):13198-212.
    PMID: 21090692 DOI: 10.1021/jp1078955
    A systematic investigation of the X-Ge-CY(3) (X = H, F, Cl, Br, and I; Y = F, Cl, Br, and I) species is carried out using density functional theory. The basis sets used for all atoms (except iodine) in this work are of double-ζ plus polarization quality with additional s- and p-type diffuse functions, and denoted DZP++. Vibrational frequency analyses are performed to evaluate zero-point energy corrections and to determine the nature of the stationary points located. Predicted are four different forms of neutral-anion separations: adiabatic electron affinity (EA(ad)), zero-point vibrational energy corrected EA(ad(ZPVE)), vertical electron affinity (EA(vert)), and vertical detachment energy (VDE). The electronegativity (χ) reactivity descriptor for the halogens (X = F, Cl, Br, and I) is used as a tool to assess the interrelated properties of these germylenes. The topological position of the halogen atom bound to the divalent germanium center is well correlated with the trend in the electron affinities and singlet-triplet gaps. For the expected XGeCY(3) structures (X = H, F, Cl, Br, and I; Y = F and Cl), the predicted trend in the electron affinities is well correlated with simpler germylene derivatives (J. Phys. Chem. A 2009, 113, 8080). The predicted EA(ad(ZPVE)) values with the BHLYP functional range from 1.66 eV (FGeCCl(3)) to 2.20 eV (IGeCF(3)), while the singlet-triplet splittings range from 1.28 eV (HGeCF(3)) to 2.22 eV (FGeCCl(3)). The XGeCY(3) (Y = Br and I) species are most often characterized by three-membered cyclic systems involving the divalent germanium atom, the carbon atom, and a halogen atom.
  3. Loo GH, Marzuki F, Henry F
    BJR Case Rep, 2018 Dec;4(4):20180017.
    PMID: 30931138 DOI: 10.1259/bjrcr.20180017
    Barium enema investigation is regarded as a safe investigative procedure. Rarely, it may cause complications such as colonic perforation and barium intravasation. Barium intravasation may be caused by the inadvertent introduction of the catheter into the vagina, thereby into the vaginal venous plexus. It may also occur through mechanical colonic perforation with the catheter, or via diseased bowel conditions. This may lead to complications such as liver microabscesses, massive pulmonary embolism, hypovolemic shock, disseminated intravascular coagulopathy and even sudden death. With that in mind, we would like to report an interesting case of barium intravasation into the portal venous system via the vagina venous plexus. The patient experienced abdominal discomfort with mild per vaginal bleed and went into disseminated intravascular coagulopathy. She received supportive management and she made a full recovery.
  4. Ng S, Sathasivam RV, Lo KM, Xie Y, Schaefer HF
    J Phys Chem A, 2005 Dec 29;109(51):12059-63.
    PMID: 16366662
    The Woessner approach is applied to the 13C relaxation data for tetraphenyltin (1) and tetra(p-tolyl)tin (2) in CDCl3 solution over the temperature range 5-42 degrees C to obtain correlation times for rotational motions and hence the activation barriers. Quantum mechanical computations were carried out to obtain the rotational energy barriers for comparison. For 2 the relaxation data indicate (1) slower ring rotation than in 1, (2) highly hindered internal rotation of the methyl group. IR and chemical shift data support the hypothesis of hyperconjugation of the methyl correlated with interaction between the pi-electrons and the 5d orbitals of tin in the (p-tolyl)Sn moiety to account for the hindrances to the rotations of the ring and the methyl. The activation barrier for the tolyl group rotation is found to be much higher than that for the phenyl rotation. However, the Woessner approach yields an anomalously high barrier for the methyl rotation. An explanation based on correlated rotations of the tolyl ring and the methyl is offered.
  5. Ahmed HMA, Nagendrababu V, Duncan HF, Peters OA, Dummer PMH
    Int Endod J, 2023 Jul;56(7):788-791.
    PMID: 37300405 DOI: 10.1111/iej.13918
  6. Ahmed HMA, El-Karim I, Duncan HF, Krastl G, Galler K
    Clin Oral Investig, 2023 Nov;27(11):6357-6369.
    PMID: 37870593 DOI: 10.1007/s00784-023-05284-9
    OBJECTIVES: This review aims to discuss the implications of anatomy of the root, pulp chamber, and canals on pulpotomy and revitalization procedures (RPs) as treatment alternatives to root canal treatment procedures.

    METHODS: This narrative review was undertaken to address two main questions - why remove vital pulp tissue in teeth with complex canal anatomy when it can be preserved? And why replace the necrotic pulp in teeth with mature roots with a synthetic material when we can revitalize? This review also aims to discuss anatomical challenges with pulpotomy and revitalization procedures.

    RESULTS: Maintaining the vitality of the pulp via partial or full pulpotomy procedures avoids the multiple potential challenges faced by clinicians during root canal treatment. However, carrying out pulpotomy procedures requires a meticulous understanding of the pulp chamber anatomy, which varies from tooth to tooth. Literature shows an increased interest in the application of RPs in teeth with mature roots; however, to date, the relation between the complexity of the root canal system and outcomes of RPs in necrotic multi-rooted teeth with mature roots is unclear and requires further robust comparative research and long-term follow-up.

    CONCLUSIONS: Whenever indicated, pulpotomy procedures are viable treatment options for vital teeth with mature roots; however, comparative, adequately powered studies with long-term follow-up are needed as a priority in this area. RPs show promising outcomes for necrotic teeth with mature roots that warrant more evidence in different tooth types with long-term follow-ups.  CLINICAL RELEVANCE: Clinicians should be aware of the pulp chamber anatomy, which is subject to morphological changes by age or as a defensive mechanism against microbial irritation, before practicing partial and full pulpotomy procedures. RP is a promising treatment option for teeth with immature roots, but more evidence is needed for its applications in teeth with mature roots. A universal consensus and considerably more robust evidence are needed for the standardization of RPs in teeth with mature roots.

  7. Emmanuel J, Kollanthavelu S, Henry F, See LT
    Endosc Int Open, 2021 Mar;9(3):E289-E291.
    PMID: 33655023 DOI: 10.1055/a-1336-2213
    Bowel obstruction is one of the most common surgical emergencies and a major cause of morbidity and mortality. Standard supportive measures must be instituted as soon as the diagnosis is confirmed. Anastomotic strictures are a benign etiology of intestinal obstruction, occurring in up to 22 % of patients following colorectal resection. Traditionally, endoscopic balloon dilation (EBD) has been the intervention of choice in such cases; however, it may not be feasible in all settings. We report a novel application of the AXIOS stent and electrocautery-enhanced delivery system (Boston Scientific, Marlborough, Massachusetts, United States) to create a colo-colostomy to bypass a sigmoid colon stricture in a 51-year-old woman who presented with acute intestinal obstruction. Despite stent dislodgment during the procedure, the preexisting tract allowed us to improvise our technique with a second LAMS placement. The patient was discharged well 48 hours after the procedure. However, 4 months later, she required a session of EBD following a presentation for fecal impaction. She is currently asymptomatic and being followed up regularly as an outpatient.
  8. Nagendrababu V, Abbott PV, Boutsioukis C, Duncan HF, Faggion CM, Kishen A, et al.
    Int Endod J, 2022 Jan 18.
    PMID: 35043398 DOI: 10.1111/iej.13682
    High-quality systematic reviews in the field of Dentistry provide the most definitive overarching evidence for clinicians, guideline developers and healthcare policy makers to judge the foreseeable risks, anticipated benefits, and potential harms of dental treatment. In the process of carrying out a systematic review, it is essential that authors appraise the methodological quality of the primary studies they include, because studies which follow poor methodology will have a potentially serious negative impact on the overall strength of the evidence and the recommendations that can be drawn. In Endodontology, systematic reviews of laboratory studies have used quality assessment criteria developed subjectively by the individual authors as there are no comprehensive, well-structured, and universally accepted criteria that can be applied objectively and universally to individual studies included in reviews. Unfortunately, these subjective criteria are likely to be inaccurately defined, unreliably applied, inadequately analysed, unreasonably biased, defective, and non-repeatable. The aim of the present paper is to outline the process to be followed in the development of comprehensive methodological quality assessment criteria to be used when evaluating laboratory studies, that is research not conducted in vivo on humans or animals, included in systematic reviews within Endodontology. The development of new methodological quality assessment criteria for appraising the laboratory-based studies included in systematic reviews within Endodontology will follow a three-stage process. First, a steering committee will be formed by the project leaders to develop a preliminary list of assessment criteria by modifying and adapting those already available, but with the addition of several new items relevant for Endodontology. The initial draft assessment criteria will be reviewed and refined by a Delphi Group (n = 40) for their relevance and inclusion using a nine-point Likert scale. Second, the agreed items will then be discussed in an online or face-to-face meeting by a group of experts (n = 10) to further refine the assessment criteria. Third, based on the feedback received from the online/face-to-face meeting, the steering committee will revise the quality assessment criteria and subsequently a group of authors will be selected to pilot the new system. Based on the feedback collected, the criteria may be revised further before being approved by the steering committee. The assessment criteria will be published in relevant journals, presented at national and international congresses/meetings, and will be freely available on a dedicated website. The steering committee will update the assessment criteria periodically based on feedback received from end-users.
  9. Nagendrababu V, Duncan HF, Fouad AF, Kirkevang LL, Parashos P, Pigg M, et al.
    Int Endod J, 2023 Feb 27.
    PMID: 36851874 DOI: 10.1111/iej.13909
    Observational studies play a critical role in evaluating the prevalence and incidence of conditions or diseases in populations as well as in defining the benefits and potential hazards of health-related interventions. There are currently no reporting guidelines for observational studies in the field of Endodontics. The Preferred Reporting Items for study Designs in Endodontology (PRIDE) team has developed and published new reporting guidelines for observational-based studies called the 'Preferred Reporting items for OBservational studies in Endodontics (PROBE) 2023' guidelines. The PROBE 2023 guidelines were developed exclusively for the speciality of Endodontics by integrating and adapting the 'STrengthening the Reporting of OBservational studies in Epidemiology (STROBE)' checklist and the 'Clinical and Laboratory Images in Publications (CLIP)' principles. The recommendations of the Guidance for Developers of Health Research Reporting Guidelines were adhered to throughout the process of developing the guidelines. The purpose of this document is to serve as a guide for authors by providing an explanation for each of the items in the PROBE 2023 checklist along with relevant examples from the literature. The document also offers advice to authors on how they can address each item in their manuscript before submission to a journal. The PROBE 2023 checklist is freely accessible and downloadable from the PRIDE website (http://pride-endodonticguidelines.org/probe/).
  10. Sagap I, Loo GH, Azman ZAM, Mazlan L, Gan SY, Eng HS, et al.
    Br J Nurs, 2022 Dec 15;31(22):S34-S42.
    PMID: 36519479 DOI: 10.12968/bjon.2022.31.22.S34
    BACKGROUND: Choice of ostomy appliances is based on multiple factors including economic considerations, individual patient requirements and lifestyle. A recently launched two-piece ostomy collection device with an extended tape border is expected to provide a long wear time and increase patients' sense of security.

    AIMS AND METHODS: A randomised controlled, non-blinded, cross-over study involving 38 patients (with colostomies and ileostomies) compared the test device to a similar device from the same manufacturer but without the tape border. The main objective was to assess wear time for non-inferiority as a measure of efficacy. Secondary efficacy assessment included peristomal skin condition using the DET (discolouration, erosion and tissue growth) score and patient acceptability, which was assessed through questionnaires using Likert-scale options. Safety was assessed according to the incidence and intensity of device-related adverse events, and the condition of the peristomal skin.

    RESULTS AND CONCLUSION: Analysis of results in the per-protocol population showed an average wear time of 4.5 days for both devices and demonstrated non-inferiority. DET scores were similar in both groups, and both had low rates of device-related adverse events, all of which related to peristomal skin. Patients said the devices were user friendly. While the two devices are similar, some patients may find one with an adhesive tape more suited to their needs.

  11. Sandrasecra S, Vasan S, Henry F, Abdullah S, Hashim MNM, Merican SRHI, et al.
    Oman Med J, 2023 Jan;38(1):e471.
    PMID: 36825248 DOI: 10.5001/omj.2023.08
    Soft tissue neoplasm is common among patients with neurofibromatosis type 1 (NF-1). We present a case of a middle-aged woman with NF-1 who presented with a painless, insidiously increasing perineal mass for the past eight months. She underwent colonoscopy, computed tomography staging, magnetic resonance imaging of the pelvis, core-needle biopsy, and later wide local excision of left perineum swelling. Histopathological examination showed a high-grade spindle cell sarcoma, which is a rare association among NF-1. Spindle cell sarcoma is a group of malignant soft tissue tumors with locally destructive growth with spindle-shaped neoplastic cells. The solitary spindle cell sarcoma of the perineum is rare, and wide local resection with a clear margin is the only treatment at present-the scarcely available evidence limiting the use of adjuvant chemotherapy, immunotherapy, and radiotherapy.
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