Displaying publications 21 - 40 of 259 in total

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  1. Effect of attachment flash on clear aligner force delivery: an in vitro study
    Kiong M, Ashari A, Zamani NSM, How RAWM, Wahab RMA, Mohamed AMFS, et al.
    BMC Oral Health, 2024 May 07;24(1):538.
    PMID: 38715004 DOI: 10.1186/s12903-024-04284-9
    BACKGROUND: The introduction of auxiliaries such as composite attachment has improved the force delivery of clear aligner (CA) therapy. However, the placement of the attachment may give rise to a flash, defined as excess resin around the attachment which may affect CA force delivery. This in vitro study aims to determine the differences in the force generated by the attachment in the presence or absence of flash in CA.

    MATERIALS AND METHODS: Tristar Trubalance aligner sheets were used to fabricate the CAs. Thirty-four resin models were 3D printed and 17 each, were bonded with ellipsoidal or rectangular attachments on maxillary right central incisors. Fuji Prescale pressure film was used to measure the force generated by the attachment of CA. The images of colour density produced on the films were processed using a calibrated pressure mapping system utilising image processing techniques and topographical force mapping to quantify the force. The force measurement process was repeated after the flash was removed from the attachment using tungsten-carbide bur on a slow-speed handpiece.

    RESULTS: The intraclass correlation coefficient showed excellent reliability (ICC = 0.96, 95% CI = 0.92-0.98). The average mean force exerted by ellipsoidal attachments with flash was 8.05 ± 0.16 N, while 8.11 ± 0.18 N was without flash. As for rectangular attachments, the average mean force with flash was 8.48 ± 0.27 N, while 8.53 ± 0.13 N was without flash. Paired t-test revealed no statistically significant difference in the mean force exerted by CA in the presence or absence of flash for both ellipsoidal (p = 0.07) and rectangular attachments (p = 0.41). Rectangular attachments generated statistically significantly (p  0.05).

    Matched MeSH terms: In Vitro Techniques
  2. Growth optimization and organogenesis of Gerbera jamesonii Bolus ex. Hook f. in vitro
    Hasbullah NA, Taha RM, Awal A
    Pak J Biol Sci, 2008 Jun 01;11(11):1449-54.
    PMID: 18817245
    Regeneration potentials in Gerbera jamesonii Bolus ex. Hook f. from tissues culture system was studied using leaf, petiole and root explants. In vitro regeneration, callus induction and root formation were optimized by manipulation of growth regulators during organogenesis. Various kinds of plant growth regulators such as 6-Benzylaminopurine (BAP), alpha-Naphthalene acetic acid (NAA), 2, 4-Dichlorophenoxyacetic acid (2,4-D), Indole-3-acetic acid (IAA), Indole-3-Butyric acid (IBA), N6-[2-Isopentenyl]adenine (2iP), Kinetin and Zeatin were used to initiate cultures. These plant growth regulators were added to Murashige and Skoog medium in different combinations and concentrations. Adventitious shoots were obtained from petiole explants cultured on Murashige and Skoog (MS) medium supplemented with 2.0 mg L(-1) BAP and 0.5 mg L(-1) NAA. Effectiveness of shoot regeneration medium, type of growth regulator used and duration of induction period were investigated. Leaf explants cultured on MS medium supplemented with 1.0 mg L(-1) BAP and 2.0 mg L(-1) 2, 4-D showed the best results for callus induction. Root explants were found to be non-regenerative in all experiments conducted. Petiole segment was identified as the best explant for regeneration of this species. Regenerated plants were rooted on Murashige and Skoog basal medium. Plantlets were then transferred to field with 75% survival rate.
    Matched MeSH terms: In Vitro Techniques
  3. A survey of antibodies to Adenovirus 8 and Coxsackievirus A21 in human sera
    Chapple PJ
    Bull World Health Organ, 1966;34(2):243-8.
    PMID: 5296130
    Studies have recently been published of surveys of antibodies to common respiratory viruses in human sera from several parts of the world. The present article reports the findings of a survey of antibodies to two more viruses (adenovirus type 8 and coxsackievirus type A21) in human sera mainly collected from six widely separated geographical regions (Alaska, England, Marshall Islands, Sarawak, South-West Africa and Tunisia).A world-wide geographical distribution of infection with these two viruses was found. However, antibodies to individual viruses were not found with the same frequency in all countries; and, in marked contrast to the findings in the earlier surveys of antibodies to the common respiratory viruses, the frequency of antibodies was not the same for each virus in sera from the same country. It was not possible to draw any final conclusions as to the reasons for the observed differences.
    Matched MeSH terms: In Vitro Techniques
  4. Fulltext Novel swellable polymer of orchidaceae family for gastroretentive drug delivery of famotidine
    Razavi M, Nyamathulla S, Karimian H, Noordin MI
    Drug Des Devel Ther, 2014;8:1315-29.
    PMID: 25246773 DOI: 10.2147/DDDT.S68517
    This study aimed to develop hydrophilic, gastroretentive matrix tablets of famotidine with good floating and swelling properties. A novel gastroretentive drug delivery formulation was designed using salep, also known as salepi, a flour obtained from grinding dried palmate tubers of Orchis morio var mascula (Orchidaceae family). The main polysaccharide content of salep is glucomannan, highly soluble in cold and hot water, which forms a viscous solution. Salep was characterized for physicochemical properties, thermal stability, chemical interaction, and surface morphology using X-ray diffraction analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy. Ten different formulations (S1-S10) were prepared using famotidine to salep ratios from 1:0.5 to 1:5. Results demonstrated that all formulations were able to sustain the drug release for more than 24 hours. The S5 formulation, with a famotidine to salep ratio of 1:2.5, had the shortest floating lag time of 35 seconds and 100% drug release within 24 hours. The dissolution data were fitted into popular mathematical models to assess the mechanism of drug release. S5 showed Zero order release (R=0.9746) with Higuchi diffusion (R=0.9428). We conclude that salep, a novel polymer, can be used in controlled release formulations to sustain release for 24 hours, due to inherent swelling and gelling properties.
    Matched MeSH terms: In Vitro Techniques
  5. Synthesis and in vitro urease inhibitory activity of N,N'-disubstituted thioureas
    Khan KM, Naz F, Taha M, Khan A, Perveen S, Choudhary MI, et al.
    Eur J Med Chem, 2014 Mar 3;74:314-23.
    PMID: 24486414 DOI: 10.1016/j.ejmech.2014.01.001
    Thiourea derivatives (1-38) were synthesized and evaluated for their urease inhibition potential. The synthetic compounds showed a varying degree of in vitro urease inhibition with IC50 values 5.53 ± 0.02-91.50 ± 0.08 μM, most of which are superior to the standard thiourea (IC₅₀ = 21.00 ± 0.11 μM). In order to ensure the mode of inhibition of these compounds, the kinetic study of the most active compounds has been carried out. Most of these inhibitors were found to be mixed-type of inhibitors, except compounds 13 and 30 which were competitive, while compound 19 was identified as non-competitive inhibitor with Ki values between 8.6 and 19.29 μM.
    Matched MeSH terms: In Vitro Techniques
  6. Transgene expression from CpG-reduced lentiviral gene delivery vectors in vitro
    Low PT, Lai MI, Ngai SC, Abdullah S
    Gene, 2014 Jan 1;533(1):451-5.
    PMID: 24120896 DOI: 10.1016/j.gene.2013.09.075
    Current viral gene delivery vectors for gene therapy are inefficient due to short-lived transgene expression attributed to the cytosine-phosphate-guanine (CpG) motifs in the transgene. Here we assessed the effects of CpG motif reduction in lentiviral (LV) gene delivery context on the level and duration of reporter gene expression in Chinese Hamster Ovary (CHO) cells, Human Immortalized Myelogenous Leukemia (K562) cells and hematopoietic stem cells (HSCs). The cells were transduced with LV carrying Zero-CpG green fluorescent protein (ZGFP) reporter gene, LV/CMV/ZGFP. The GFP expression was compared to its non CpG-depleted GFP reporter gene LV (LV/CMV/GFP) counterpart. The LV/CMV/ZGFP exhibited prolonged transgene expression in CHO cells and HSCs up to 10 days and 14 days, in the respective cells. This effect was not seen in the transduced K562 cells, which may be due to the DNA hypomethylation status of the cancer cell line. Transgene copy number analysis verified that the GFP expression was not from pseudo-transduction and the transgene remained in the genome of the cells throughout the period of the study. The modest positive effects from the LV/CMV/ZGFP suggest that the reduction of CpG in the LV construct was not substantial to generate higher and more prolonged transgene expression.
    Matched MeSH terms: In Vitro Techniques
  7. Long-term in vitro expansion of human adipose-derived stem cells showed low risk of tumourigenicity
    Zaman WS, Makpol S, Sathapan S, Chua KH
    J Tissue Eng Regen Med, 2014 Jan;8(1):67-76.
    PMID: 22552847 DOI: 10.1002/term.1501
    In the field of cell-based therapy and regenerative medicine, clinical application is the ultimate goal. However, one major concern is: does in vitro manipulation during culture expansion increases tumourigenicity risk on the prepared cells? Therefore, the aim of this study was to investigate the effect of long-term in vitro expansion on human adipose-derived stem cells (ASCs). The ASCs were harvested from lipo-aspirate samples and cultured until passage 20 (P20), using standard culture procedures. ASCs at P5, P10, P15 and P20 were analysed for morphological changes, DNA damage (Comet assay), tumour suppressor gene expression level (quantitative PCR), p53 mutation, telomerase activity, telomere length determination and in vivo tumourigenicity test. Our data showed that ASCs lost their fibroblastic feature in long-term culture. The population doubling time of ASCs increased with long-term culture especially at P15 and P20. There was an increase in DNA damage at later passages (P15 and P20). No significant changes were observed in both p53 and p21 genes expression throughout the long-term culture. There was also no p53 mutation detected and no significant changes were recorded in the relative telomerase activity (RTA) and mean telomere length (TRF) in ASCs at all passages. In vivo implantation of ASCs at P15 and P20 into the nude mice did not result in tumour formation after 4 months. The data showed that ASCs have low risk of tumourigenicity up to P20, with a total population doubling of 42 times. This indicates that adipose tissue should be a safe source of stem cells for cell-based therapy.
    Matched MeSH terms: In Vitro Techniques
  8. Impact of process parameters in the generation of novel aspirin nanoemulsions--comparative studies between ultrasound cavitation and microfluidizer
    Tang SY, Shridharan P, Sivakumar M
    Ultrason Sonochem, 2013 Jan;20(1):485-97.
    PMID: 22633626 DOI: 10.1016/j.ultsonch.2012.04.005
    In the present investigation, the operating efficiency of a bench-top air-driven microfluidizer has been compared to that of a bench-top high power ultrasound horn in the production of pharmaceutical grade nanoemulsions using aspirin as a model drug. The influence of important process variables as well as the pre-homogenization and drug loading on the resultant mean droplet diameter and size distribution of emulsion droplets was studied in an oil-in-water nanoemulsion incorporated with a model drug aspirin. Results obtained show that both the emulsification methods were capable of producing very fine nanoemulsions containing aspirin with the minimum droplet size ranging from 150 to 170 nm. In case of using the microfluidizer, it has been observed that the size of the emulsion droplets obtained was almost independent of the applied microfluidization pressure (200-600 bar) and the number of passes (up to 10 passes) while the pre-homogenization and drug loading had a marginal effect in increasing the droplet size. Whereas, in the case of ultrasound emulsification, the droplet size was generally decreased with an increase in sonication amplitude (50-70%) and period of sonication but the resultant emulsion was found to be dependent on the pre-homogenization and drug loading. The STEM microscopic observations illustrated that the optimized formulations obtained using ultrasound cavitation technique are comparable to microfluidized emulsions. These comparative results demonstrated that ultrasound cavitation is a relatively energy-efficient yet promising method of pharmaceutical nanoemulsions as compared to microfluidizer although the means used to generate the nanoemulsions are different.
    Matched MeSH terms: In Vitro Techniques
  9. Biocompatibility test of polyhydroxybutyrate on human cell line
    Raouf AA, Samsudin AR, Al-Joudi FS, Shamsuria O
    Med J Malaysia, 2004 May;59 Suppl B:101-2.
    PMID: 15468838
    The human fibroblast MRC-5 cells incubated with PHB granules (TM) added at a final concentration of 4 mg/ml showed a time-course pattern of survival. The percentages of dead cells obtained were at the rate of 3.8% after 7 days, respectively. When the MRC-5 cells grown in different material, using the test concentration of 4 mg/ml PCM, they were found to show a similar time-course increasing pattern of death as that obtained with PHB. However, the death was noted in the cells incubated for 7 days, the death rates obtained was 40.54% respectively.
    Matched MeSH terms: In Vitro Techniques
  10. Health Risk Assessment using in vitro digestion model in assessing bioavailability of heavy metal in rice: A preliminary study
    Omar NA, Praveena SM, Aris AZ, Hashim Z
    Food Chem, 2015 Dec 1;188:46-50.
    PMID: 26041162 DOI: 10.1016/j.foodchem.2015.04.087
    Little is known about the bioavailability of heavy metal contamination and its health risks after rice ingestion. This study aimed to determine bioavailability of heavy metal (As, Cd, Cu, Cr, Co, Al, Fe, Zn and Pb) concentrations in cooked rice and human Health Risk Assessment (HRA). The results found Zn was the highest (4.3±0.1 mg/kg), whereas As showed the lowest (0.015±0.001 mg/kg) bioavailability of heavy metal concentration in 22 varieties of cooked rice. For single heavy metal exposure, no potential of non carcinogenic health risks was found, while carcinogenic health risks were found only for As. Combined heavy metal exposures found that total Hazard Quotient (HQtotal) values for adult were higher than the acceptable range (HQTotal<1), whereas total Lifetime Cancer Risk (LCRTotal) values were higher than the acceptable range (LCRTotal values >1×10(-4)) for both adult and children. This study is done to understand that the inclusion of bioavailability heavy metal into HRA produces a more realistic estimation of human heavy metal exposure.
    Matched MeSH terms: In Vitro Techniques
  11. In vitro evaluation and in silico screening of synthetic acetylcholinesterase inhibitors bearing functionalized piperidine pharmacophores
    Brahmachari G, Choo C, Ambure P, Roy K
    Bioorg Med Chem, 2015 Aug 01;23(15):4567-4575.
    PMID: 26105711 DOI: 10.1016/j.bmc.2015.06.005
    A series of densely functionalized piperidine (FP) scaffolds was synthesized following a diastereoselective one-pot multicomponent protocol under eco-friendly conditions. The FPs were evaluated in vitro for their acetylcholinesterase (AChE) inhibitory activity, and in silico studies for all the target compounds were carried out using pharmacophore mapping, molecular docking and quantitative structure-activity relationship (QSAR) analysis in order to understand the structural features required for interaction with the AChE enzyme and the key active site residues involved in the intermolecular interactions. Halogenation, nitration or 3,4-methylenedixoxy-substitution at the phenyl ring attached to the 2- and 6-positions of 1,2,5,6-tetrahydropyridine nucleus in compounds 14-17, 19, 20, 24 and 26 greatly enhanced the AChE inhibitory activity. The docking analysis demonstrated that the inhibitors are well-fitted in the active sites. The in silico studies enlighten the future course of studies in modifying the scaffolds for better therapeutic efficacy against the deadly Alzheimer's disease.
    Matched MeSH terms: In Vitro Techniques
  12. 5-Methoxytryptamine reacts with natural food flavour to produce 6-methoxy tetrahydro-β-carbolines: in vitro investigation of their antioxidant and cytotoxicity properties
    Goh TB, Koh RY, Yam MF, Azhar ME, Mordi MN, Mansor SM
    Food Chem, 2015 Sep 15;183:208-16.
    PMID: 25863630 DOI: 10.1016/j.foodchem.2015.03.044
    Various 6-methoxytetrahydro-β-carboline derivatives, namely BEN (6-methoxy-1-phenyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole), ANI (6-methoxy-1-(4-methoxyphenyl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole), ACE (6-methoxy-1-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole) and VAN (2-methoxy-4-(6-methoxy-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indol-1-l)phenol), were prepared via the Maillard reaction using food flavours and 5-methoxytryptamine in aqueous medium and were investigated for their in vitro antioxidant and cytotoxicity properties. These derivatives were found to exhibit moderate antioxidant properties, based on a combination of DPPH, ABTS and FRAP assays. The results suggested that the Maillard reaction could be used to generate β-carboline antioxidants. It was beneficial that VAN showed the highest antioxidant activity but the least cytotoxic activities on non-tumourous cell lines of NIH/3T3, CCD18-Co and B98-5 using MTT assay. ACE, ANI and BEN showed mild toxicity at effective antioxidative concentrations derived from DPPH and ABTS assays. Furthermore, they are safer compared to 5-fluorouracil, cisplatin and betulinic acid on NIH/3T3, CCD18-Co and B98-5 cells. In conclusion, the antioxidant and cytotoxicity properties of 6-methoxytetrahydro-β-carbolines were demonstrated for the first time.
    Matched MeSH terms: In Vitro Techniques
  13. Screening for antibacterial agents in three species of sea cucumbers from coastal areas of Sabah
    Ridzwan BH, Kaswandi MA, Azman Y, Fuad M
    Gen. Pharmacol., 1995 Nov;26(7):1539-43.
    PMID: 8690242
    1. Three species of sea cucumbers found in the Sabah coastal areas were screened for the presence of antibacterial activity using three methods of extraction. Tests were conducted in vitro using the agar absorption method. 2. Both the lipid extract and the methanol-solvent extract from Holothuria atra, Holothuria scabra and Bohadshia argus were found to show no antibacterial activity. 3. Phosphate-buffered saline (PBS) from H. atra and B. argus, however, inhibited the growth of all gram-positive and gram-negative bacteria. 4. Comparisons were also made between extracts from the outer layer of H. atra and its inner part, and it was found that the extract from the outer layer showed less bacterial growth inhibition property. 5. The bacterial growth inhibition property of the PBS extract from H. atra, however, is dependent on the extract's concentration. Bacterial growth inhibition was apparent after 48 hr incubation.
    Matched MeSH terms: In Vitro Techniques
  14. Differentiation of elemental composition of normal and malignant breast tissue by instrumental neutron activation analysis
    Ng KH, Bradley DA, Looi LM, Mahmood CS, Wood AK
    Appl Radiat Isot, 1993 Mar;44(3):511-6.
    PMID: 8472024
    Multi-elemental quantitative analyses of 15 paired samples of normal and malignant human breast tissue by instrumental neutron activation analysis are reported. The elements, Al, Br, Ca, Cl, Co, Cs, Fe, K, Na, Rb, Zn were detected. Significantly elevated concentration levels were found for Al, Br, Ca, Cl, Cs, K, Na, Zn in malignant compared to normal tissue. Although the role of elemental composition in breast cancer is unclear, this finding may be of importance as another parameter for differentiating normal from malignant tissue.
    Matched MeSH terms: In Vitro Techniques
  15. Resistance of Pseudomonas pseudomallei to normal human serum bactericidal action
    Ismail G, Razak N, Mohamed R, Embi N, Omar O
    Microbiol. Immunol., 1988;32(7):645-52.
    PMID: 3193910
    The effect of human normal serum (HNS) on Pseudomonas pseudomallei was determined. It is apparent from our data that the organism is resistant to the normal serum bactericidal mechanism. Ancillary experiments to confirm this serum-resistant property of P. pseudomallei were done by examining the effects of growth phase conditions of the bacteria (i.e., logarithmic and stationary phases) and different buffered systems used as diluent in our bactericidal assay. Results obtained showed similar degree of resistance to serum bactericidal killing by 5 strains of the organisms tested. The possible survival advantage of serum-resistance property to P. pseudomallei as bacterial pathogens known to invade the blood stream is discussed.
    Matched MeSH terms: In Vitro Techniques
  16. A note concerning the possibility that the lesions in scurvy are due to a failure to produce 'compact' collagen fibres
    Candlish J
    Med J Malaya, 1966 Dec;21(2):161-3.
    PMID: 4227387
    Matched MeSH terms: In Vitro Techniques
  17. Biology of the Malaysian strain of Plasmodium juxtanucleare Versiani and Gomes, 1941. 1. Description of the stages in the vertebrate host
    Bennett GF, Warren M
    J Parasitol, 1966 Jun;52(3):565-9.
    PMID: 5942532
    Matched MeSH terms: In Vitro Techniques
  18. Brugia tupaiae spn. n. (Nematoda: Filarioidea) in tree shrews (Tupaia glis) from Malaysia
    Orihel TC
    J Parasitol, 1966 Feb;52(1):162-5.
    PMID: 5910449
    Matched MeSH terms: In Vitro Techniques
  19. Spray-dried alginate-coated Pickering emulsion stabilized by chitosan for improved oxidative stability and in vitro release profile
    Surjit Singh CK, Lim HP, Tey BT, Chan ES
    Carbohydr Polym, 2021 Jan 01;251:117110.
    PMID: 33142647 DOI: 10.1016/j.carbpol.2020.117110
    The commercial application of liquid-state Pickering emulsions in food systems remains a major challenge. In this study, we developed a spray-dried Pickering emulsion powder using chitosan as a Pickering emulsifier and alginate as a coating material. The functionality of the powder was evaluated in terms of its oxidative stability, pH-responsiveness, mucoadhesivity, and lipid digestibility. The Pickering emulsion powder was oxidatively more stable than the conventional emulsion powder stabilized by gum Arabic. The powder exhibited pH-responsiveness, whereby it remained intact in acidic pH, but dissolved to release the emulsion in 'Pickering form' at near-neutral pH. The Pickering emulsion powder was also mucoadhesive and could be digested by lipase in a controlled manner. These findings suggested that the multi-functional Pickering emulsion powder could be a potential delivery system for applications in the food industry.
    Matched MeSH terms: In Vitro Techniques
  20. A survey of Salmonella VI-phage types occurring in Federation of Malaya and Singapore
    Singh RB
    Med J Malaya, 1966 Mar;20(3):215-20.
    PMID: 4223129
    Matched MeSH terms: In Vitro Techniques
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