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  1. Bapat RA, Mak KK, Pichika MR, Pang JC, Lin SL, Khoo SP, et al.
    BMC Oral Health, 2024 Mar 25;24(1):382.
    PMID: 38528501 DOI: 10.1186/s12903-024-04069-0
    AIMS AND OBJECTIVES: To analyze anti-MMP mode of action of Quaternary Ammonium Silane (QAS, codenamed as k21) by binding onto specific MMP site using computational molecular simulation and Anti-Sortase A (SrtA) mode of action by binding onto specific site using computational molecular simulation.

    MATERIALS AND METHODS: In silico Molecular Dynamics (MD) was used to determine the interactions of K21 inside the pocket of the targeted protein (crystal structure of fibroblast collagenase-1 complexed to a diphenyl-ether sulphone based hydroxamic acid; PDB ID: 966C; Crystal structure of MMP-2 active site mutant in complex with APP-derived decapeptide inhibitor. MD simulations were accomplished with the Desmond package in Schrödinger Drug Discovery Suite. Blood samples (~ 0.5 mL) collected into K2EDTA were immediately transferred for further processing using the Litron MicroFlow® PLUS micronucleus analysis kit for mouse blood according to the manufacturer's instructions. Bacterial Reverse Mutation Test of K21 Molecule was performed to evaluate K21 and any possible metabolites for their potential to induce point mutations in amino acid-requiring strains of Escherichia coli (E. coli) (WP2 uvrA (tryptophan-deficient)).

    RESULTS: Molecular Simulation depicted that K21 has a specific pocket binding on various MMPs and SrtA surfaces producing a classical clouting effect. K21 did not induce micronuclei, which are the result of chromosomal damage or damage to the mitotic apparatus, in the peripheral blood reticulocytes of male and female CD-1 mice when administered by oral gavage up to the maximum recommended dose of 2000 mg/kg. The test item, K21, was not mutagenic to Salmonella typhimurium (S. typhimurium) strains TA98, TA100, TA1535 and TA1537 and E. coli strain WP2 uvrA in the absence and presence of metabolic activation when tested up to the limit of cytotoxicity or solubility under the conditions of the test.

    CONCLUSION: K21 could serve as a potent protease inhibitor maintaining the physical and biochemical properties of dental structures.

  2. Daood U, Omar H, Qasim S, Nogueira LP, Pichika MR, Mak KK, et al.
    J Mech Behav Biomed Mater, 2020 10;110:103927.
    PMID: 32957222 DOI: 10.1016/j.jmbbm.2020.103927
    OBJECTIVE: Here we describe a novel formulation, based on quaternary ammonium (QA) and riboflavin (RF), which combines antimicrobial activities and protease inhibitory properties with collagen crosslinking without interference to bonding capabilities, was investigated.

    METHODS: Experimental adhesives modified with different fractions of dioctadecyldimethyl ammonium bromide quaternary ammonium and riboflavin (QARF) were formulated. Dentine specimens were bonded to resincomposites with control or the experimental adhesives to be evaluated for bond strength, interfacial morphology, micro-Raman analysis, nano-CT and nano-leakage expression. In addition, the antibacterial and biocompatibilities of the experimental adhesives were investigated. The endogenous proteases activities and their molecular binding-sites were studied.

    RESULTS: Modifying the experimental adhesives with QARF did not adversely affect micro-tensile bond strength or the degree of conversion along with the demonstration of anti-proteases and antibacterial abilities with acceptable biocompatibilities. In general, all experimental adhesives demonstrated favourable bond strength with increased and improved values in 1% QARF adhesive at 24 h (39.2 ± 3.0 MPa) and following thermocycling (34.8 ± 4.3 MPa).

    SIGNIFICANCE: It is possible to conclude that the use of QARF with defined concentration can maintain bond strength values when an appropriate protocol is used and have contributed in ensuring a significant decrease in microbial growth of biofilms. Incorporation of 1% QARF in the experimental adhesive lead to simultaneous antimicrobial and anti-proteolytic effects with low cytotoxic effects, acceptable bond strength and interfacial morphology.

  3. Wan Mansor WN, Abdullah S, Che Wan Othman CWMN, Jarkoni MNK, Chao HR, Lin SL
    Data Brief, 2020 Jun;30:105440.
    PMID: 32300616 DOI: 10.1016/j.dib.2020.105440
    Energy has a significant influence on Malaysia's industry. It is used in electricity generation, refineries, gas processing plants and end-user applications such as transportation, residential, agriculture and fishing. These burning fossil fuel activities produce greenhouse gases (GHG) emissions. This article presents the emissions data of fuel used in power plants in Malaysia during the year of 1990 until 2017. The fuel used in power plants is coal and coke, natural gas, diesel oil and residual fuel oil. The energy data used in power plants were gathered from the Malaysia Energy Information Hub, published by the Malaysian Energy Commission. The GHG emissions data were calculated using the emission factors method. The climate impact of different GHGs in terms of CO2-equivalent (CO2-e) was also calculated using global warming potentials. The article also presents population data in Malaysia during the year. A correlation between the fuels, GHG emission and the population is also investigated using statistical analysis. The data presented here may facilitate the Malaysian government to identify the source of the pollutants and undertake a climate change mitigation plan.
  4. Lai HW, Chang YL, Chandrachamnong K, See MH, Huang HI, Lin SL, et al.
    World J Surg Oncol, 2023 Jul 26;21(1):222.
    PMID: 37491239 DOI: 10.1186/s12957-023-03107-5
    BACKGROUND: The current study aims to evaluate the nipple and skin sensation following nipple-sparing mastectomy (NSM) and identify patient-, surgical-, or treatment-related factors affecting nipple or skin sensation in this cohort.

    METHODS: Patients who received NSM with postoperative nipple and skin sensation test evaluation at a single institution over the past 10 years were retrospectively retrieved from a prospectively collected breast cancer surgery database.

    RESULTS: A total of 460 NSM procedures were included in this current study, with the mean age of 48.3 ± 9.1. Three-hundred eighty-three (83.3%) patients had breast reconstructions. One-hundred seventy-four (37.8%) received conventional NSM (C-NSM), 195 (42.4%) endoscopic-assisted NSM (E-NSM), and 91 (19.8%) robotic-assisted NSM (R-NSM) procedures. For nipple sensation assessment, 15 (3.3%) were grade 0, 83 (18.2%) grade I, 229 (49.7%) grade II, and 133 (28.9%) grade III (normal sensation), respectively, with mean grade score of 2.1 ± 0.7. The preserved (grade III) nipple sensation rate was 36.2% (63/174) in the C-NSM group, 26.7% (52/195) in the E-NSM group, and 19.7% (18/91) in the R-NSM group (P = 0.06). The "time since surgery to last evaluation" was significantly longer in the C-NSM group (45.6 ± 34 months) or E-NSM group (44.7 ± 35.8 months) as compared to R-NSM group (31.8 ± 16 months, P  60 months vs. ≦ 12 months: nipple odds ratio (OR) = 5.75, P 

  5. Imad R, Sheikh Z, Rao Pichika M, Kit-Kay M, Siddiqui RA, Nawaid Shah SN, et al.
    Exp Cell Res, 2023 Sep 01;430(1):113687.
    PMID: 37356748 DOI: 10.1016/j.yexcr.2023.113687
    BACKGROUND: The ability of cancer cells to be invasive and metastasize depend on several factors, of which the action of protease activity takes center stage in disease progression.

    PURPOSE/OBJECTIVE: To analyze function of new K21 molecule in the invasive process of oral squamous cell carcinoma (OSCC) cell line.

    MATERIALS & METHODS: The Fusobacterium (ATCC 23726) streaks were made, and pellets were resuspended in Cal27 (ATCC CRL-2095) OSCC cell line spheroid cell microplate. Cells were seeded and Lysotracker staining performed for CathepsinK red channel. Cell and morphology were evaluated using Transmission Electron microscopy. Thiobarbituric acid assay was performed. OSCC was analyzed for Mic60. Raman spectra were collected from the cancer cell line. L929 dermal fibroblast cells were used for Scratch Assay. ELISA muti arrays were used for cytokines and matrix molecules. Internalization ability of fibroblast cells were also analyzed. Structure of K21 as a surfactant molecule with best docked poses were presented.

    RESULTS: Decrease in lysosomal staining was observed after 15 and 30 min of 0.1% treatment. Tumor clusters were associated with cell membrane destruction in K21 primed cells. There was functional silencing of Mic60 via K21, especially with 1% concentration with reduced cell migration and invasiveness. Raman intensity differences were seen at 700 cm-1, 1200 cm-1 and 1600 cm-1 regions. EVs were detected within presence of fibroblast cells amongst K21 groups. Wound area and wound closure showed the progress of wound healing.

    CONCLUSION: Over expression of CatK can be reduced by a newly developed targeted K21 based drug delivery system leading to reduced migration and adhesion of oral squamous cell carcinoma cells. The K21 drug formulation can have great potential for cancer therapies due to targeting and cytotoxicity effects.

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