Displaying publications 1 - 20 of 153 in total

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  1. Lenz M, Kard B, Creffield JW, Evans TA, Brown KS, Freytag ED, et al.
    J Econ Entomol, 2013 Jun;106(3):1395-403.
    PMID: 23865207
    A comparative field study was conducted to evaluate the ability of subterranean termites to damage a set of four different plastic materials (cable sheathings) exposed below- and above-ground. Eight pest species from six countries were included, viz., Coptotermes formosanus (Shiraki) in China, Japan, and the United States; Coptotermes gestroi (Wasmann) in Thailand and Malaysia; Coptotermes curvignathus (Holmgren) and Coptotermes kalshoveni (Kemner) in Malaysia; Coptotermes acinaciformis (Froggatt) with two forms of the species complex and Mastotermes darwiniensis (Froggatt) in Australia; and Reticulitermes flavipes (Kollar) in the United States. Termite species were separated into four tiers relative to decreasing ability to damage plastics. The first tier, most damaging, included C. acinaciformis, mound-building form, and M. darwiniensis, both from tropical Australia. The second tier included C. acinaciformis, tree-nesting form, from temperate Australia and C. kalshoveni from Southeast Asia. The third tier included C. curcignathus and C. gestroi from Southeast Asia and C. formosanus from China, Japan, and the United States, whereas the fourth tier included only R. flavipes, which caused no damage. A consequence of these results is that plastics considered resistant to termite damage in some locations will not be so in others because of differences in the termite fauna, for example, resistant plastics from the United States and Japan will require further testing in Southeast Asia and Australia. However, plastics considered resistant in Australia will be resistant in all other locations.
  2. Jiang S, Chang L, Luo J, Zhang J, Liu X, Lee CY, et al.
    Analyst, 2021 Oct 11;146(20):6170-6177.
    PMID: 34522939 DOI: 10.1039/d1an01359a
    Triphenyltin chloride (TPhT) is an organotin compound that causes intensive toxicological risk to the environment and humans. A detection method with high sensitivity and stability is therefore desired to better detect TPhT. In this study, a novel SERS substrate was prepared by sputtering an ultra-thin Au layer on a honeycomb-like silver nanoarray fabricated via the nanosphere lithography method. The ultra-thin Au layer was formed by sputtering the intermittent Au nanoparticles on the silver nanoarray, resulting in bimetallic coupling with dramatically increased hotspots and extremely high SERS enhancement with an analytical enhancement factor (AEF) of 6.08 × 109 using Rhodamine 6G (R6G) as the probe molecule. Based on density functional theory (DFT) simulations, the Raman characteristic peaks of TPhT at 999 cm-1 and 655 cm-1 were selected for TPhT detection. The AEF of the SERS substrate HC5-AgAu was calculated to be 3.38 × 106 with the detection concentration of TPhT down to 10-10 M. The as-prepared honeycomb-like silver-gold bimetallic SERS substrate demonstrated great stability and sensitivity for TPhT detection, which might also be applied in monitoring many other environmental pollutants.
  3. Chang L, Liu X, Lee CY, Zhang W
    Anal Chim Acta, 2023 Oct 23;1279:341825.
    PMID: 37827623 DOI: 10.1016/j.aca.2023.341825
    Triphenyltin is an estrogen like pollutant that poses significant environmental threats due to its highly accumulative toxicity. To improve regulation, a fast and sensitive detection method is urgently needed. SERS can capture fingerprint information and is capable of trace detection, making it an ideal solution. Here, we present a sprayed substrate comprised of lightconfining structures and gold nanorod assemblies that are easy to prepare, low-cost, and can form dense hotspots under confined evaporation. The substrates are three-layered: initially, a gold nanorod layer is sprayed as a support, then sputter Ag film on the surface to form a lightconfining structure, followed by another gold nanorod layer sprayed on the Ag film. The coupling of nanorod assembly with lightconfining Ag films leads to 10-fold sensitivity. In addition, sample droplet evaporation in a limited area called confined evaporation contributes to nanorod migration and reassembly on the corner of the substrate, enhancing analytes absorption, and substantially lowered the detection limits. By systematically evaluating the substrate performance, we were able to obtain an average enhancement factor of 3.31 × 106. After confined evaporation, the detection limit reached 10-18 M for R6G and for triphenyltin, it achieved 10-9 M. This novel method represents a significant advancement toward SERS application in detecting trace pollutants.
  4. Chang L, Liu X, Luo J, Lee CY, Zhang J, Fan X, et al.
    Adv Mater, 2024 Mar;36(13):e2310469.
    PMID: 38193751 DOI: 10.1002/adma.202310469
    Metastructures are widely used in photonic devices, energy conversion, and biomedical applications. However, to fabricate multiple patterns continuously in single etching protocol with highly tunable photonic properties is challenging. Here, a simple and robust dynamic nanosphere lithography is proposed by inserting a spacer between the nanosphere assembly and the wafer. The nanosphere diameter decrease and uneven penetration of the spacer during etching lead to a dynamic masking process. Coupled anisotropic physical ion sputtering and ricocheting with isotropic chemical radical etching achieve highly tunable structures with various 3D patterns continuously forming through a single etching process. Specifically, the nanosphere diameters define the periodicity, the etched spacer forms the upper parts, and the wafer forms the lower parts. Each part of the structure is highly tunable through changing nanosphere diameter, spacer thickness, and etch conditions. Using this protocol, numerous structures of varying sizes including nanomushrooms, nanocones, nanopencils, and nanoneedles with diverse shapes are realized as proof of concepts. The broadband antireflection ability of the nanostructures and their use in surface-enhanced Raman spectroscopy are also demonstrated for practical application. This method substantially simplifies the fabrication procedure of various metastructures, paving the way for its application in multiple disciplines especially in photonic devices.
  5. Lee CY, Nurul Zaidah AS, Nur Amalina G, Muhammad Azree E, Das S, Zar CT
    Clin Ter, 2014;165(5):269-77.
    PMID: 25366948 DOI: 10.7417/CT.2014.1758
    Increase in prevalence of disease related oxidative stress disorders have been on the rise in the entire world since the past decades. Significant positive effects with few antioxidant properties in the modern drugs pave for the alternative medicines in managing the disease. Piper betel (P. betel), a herb, is known to possess high anti-oxidant, anti-diabetic, anti-atherosclerosis, anti-hyperlipidemic, anti-cancer and neuroprotective property. This review focused on the effect of P. betel on diabetes mellitus, atherosclerosis and chronic kidney disease, Alzheimer's disease and breast cancer. P. betel proved to show positive effects with specific outcomes towards these diseases. Moreover, the promising effect of P. betel in vitro studies was also highlighted in the present review. It is believed that the findings obtained in this review will draw the attention of the medical professionals and general public towards P. betel and it will open the door for further detailed research.
  6. Lee CY, Yusof HM, Zakaria NS
    Malays J Med Sci, 2019 Sep;26(5):122-131.
    PMID: 31728124 MyJurnal DOI: 10.21315/mjms2019.26.5.11
    Background: Body-image perception is one of the determinants in weight management, especially among adolescents. This study aimed to assess weight-control knowledge, attitude and behaviours along with body-image perceptions among Chinese high school students in order to compare the weight-control behaviours with those perceptions.

    Methods: A cross-sectional study was conducted among 277 Chinese students in Form 1 and Form 2 in Pulau Pinang, Malaysia using convenience sampling. The following outcomes were evaluated: weight-control knowledge, attitude and behaviours (weight-related knowledge and attitude questionnaire; weight control strategies scale) and body-image perceptions (figure rating scale).

    Results: Both genders were found to have high weight-control knowledge, with female adolescents scoring significantly higher than male adolescents (P = 0.010). However, only half of the adolescents (50.9%) perceived that obesity is bad for health. Although only 44.4% of adolescents were dissatisfied with their current weight status, 62.8% intended to change their present weight status. Male adolescents significantly engaged more in physical activity (PA) (P = 0.035) and self-monitoring (SM) (P = 0.014) compared to their female counterparts. Furthermore, male adolescents chose their current body size as their ideal body image, but female adolescents preferred a slimmer ideal figure. The percentage of male and female adolescents who desired a smaller body figure was 39.6% and 54.5%, respectively. Lastly, there was no significant difference between weight-control behaviours and adolescents' body-image perceptions.

    Conclusion: Female Chinese adolescents had higher weight-control knowledge and preferred a slimmer body size, yet males were more likely to engage in PA and SM behaviours. Essentially, imprecise attitude towards obesity among half of the Chinese high school students is of particular concern.
  7. Tan Lee CY, Ngatirin NR, Zainol Z
    MyJurnal
    Personality represents the mixture of features and qualities that built an individual’s distinctive characters including thinking, feeling and behaving. Traditionally, self-assessment method via questionnaire is the most common means to identify personality. Since recommender systems and advertisement
    campaigns have evolved rapidly, personality computing has become a popular research field to provide personalisation to users. Currently, researchers have utilised social media data for automatically predicting personality. However, it is complex to mine the social media data as they are noisy, free-format, and
    of varying length and multimedia. This paper proposes a decision tree C4.5 algorithm to automatically predict personality based on Big Five model. The Big Five Inventory and ZeroR algorithm were included to be served as the baseline for performance evaluation. Experimental evaluation demonstrated that C4.5
    performs better than ZeroR in terms of accuracy.
    Keywords: Big Five, decision tree, personality, social media
  8. Zainal Z, Lee CY, Hussein MZ, Kassim A, Yusof NA
    J Hazard Mater, 2007 Jul 19;146(1-2):73-80.
    PMID: 17196740
    Mixed dye consists of six commercial dyes and textile effluents from cotton dyeing process were treated by electrochemical-assisted photodegradation under halogen lamp illumination. Two types of effluents were collected which are samples before and after undergone pre-treatment at the factory wastewater treatment plant. The photodegradation process was studied by evaluating the changes in concentration employing UV-vis spectrophotometer (UV-vis) and total organic carbon (TOC) analysis. The photoelectrochemical degradation of mixed dye was found to follow the Langmuir Hinshelwood pseudo-first order kinetic while pseudo-second order kinetic model for effluents by using TOC analyses. The chemical oxygen demand (COD) and biochemical oxygen demand (BOD) values of mixed dye and raw effluents were reported. Photoelectrochemical characteristic of pollutants was studied using the cyclic voltammetry technique. Raw effluent was found to exhibit stronger reduction behaviour at cathodic bias potential but slightly less photoresponse at anodic bias than mixed dye.
  9. Zainal Z, Lee CY, Hussein MZ, Kassim A, Yusof NA
    J Hazard Mater, 2005 Feb 14;118(1-3):197-203.
    PMID: 15721544
    Electrochemical-assisted photodegradation of methyl orange has been investigated using TiO2 thin films. The films were prepared by sol-gel dip-coating method. Several operational parameters to achieve optimum efficiency of this electrochemical-assisted photodegradation system have been tested. Photoelectrochemical degradation was studied using different light sources and light intensity. The light sources chosen ranged from ultraviolet to visible light. The effect of agitation of the solution at different speeds has also been studied. Slight improvement of photodegradation rate was observed by applying higher agitation speed. Investigation on the electrode after repeated usages show the electrode can be reused up to 20 times with percentage of deficiency less than 15%. The study on the effect of solution temperature indicated that the activation energy of the methyl orange degradation is 18.63 kJ mol(-1).
  10. Lee CC, Nakao H, Tseng SP, Hsu HW, Lin GL, Tay JW, et al.
    Front. Zool., 2017;14:24.
    PMID: 28503187 DOI: 10.1186/s12983-017-0210-4
    BACKGROUND: Reproductive division of labor is one of the key features of social insects. Queens are adapted for reproduction while workers are adapted for foraging and colony maintenance. In many species, however, workers retain functional ovaries and can lay unfertilized male eggs or trophic eggs. Here we report for the first time on the occurrence of physogastric workers and apparent worker reproduction in the invasive yellow crazy ant Anoplolepis gracilipes (Fr. Smith). We further examined the reproductive potential and nutritional role of physogastric workers through multidisciplinary approaches including morphological characterization, laboratory manipulation, genetic analysis and behavioral observation.

    RESULTS: Egg production with two types of eggs, namely reproductive and trophic eggs, by physogastric workers was found. The reproductive egg was confirmed to be haploid and male-destined, suggesting that the workers produced males via arrhenotokous parthenogenesis as no spermatheca was discovered. Detailed observations suggested that larvae were mainly fed with trophic eggs. Along with consumption of trophic eggs by queens and other castes as part of their diet, the vital role of physogastric workers as "trophic specialist" is confirmed.

    CONCLUSION: We propose that adaptive advantages derived from worker reproduction for A. gracilipes may include 1) trophic eggs provisioned by physogastric workers likely assist colonies of A. gracilipes in overcoming unfavorable conditions such as paucity of food during critical founding stage; 2) worker-produced males are fertile and thus might offer an inclusive fitness advantage for the doomed orphaned colony.

  11. Lee CY, Liu KT, Lu HT, Mohd Ali R, Fong AYY, Wan Ahmad WA
    PLoS One, 2021;16(2):e0246474.
    PMID: 33556136 DOI: 10.1371/journal.pone.0246474
    BACKGROUND: Sex and gender differences in acute coronary syndrome (ACS) have been well studied in the western population. However, limited studies have examined the trends of these differences in a multi-ethnic Asian population.

    OBJECTIVES: To study the trends in sex and gender differences in ACS using the Malaysian NCVD-ACS Registry.

    METHODS: Data from 24 hospitals involving 35,232 ACS patients (79.44% men and 20.56% women) from 1st. Jan 2012 to 31st. Dec 2016 were analysed. Data were collected on demographic characteristics, coronary risk factors, anthropometrics, treatments and outcomes. Analyses were done for ACS as a whole and separately for ST-segment elevation myocardial infarction (STEMI), Non-STEMI and unstable angina. These were then compared to published data from March 2006 to February 2010 which included 13,591 ACS patients (75.8% men and 24.2% women).

    RESULTS: Women were older and more likely to have diabetes mellitus, hypertension, dyslipidemia, previous heart failure and renal failure than men. Women remained less likely to receive aspirin, beta-blocker, angiotensin-converting enzyme inhibitor (ACE-I) and statin. Women were less likely to undergo angiography and percutaneous coronary intervention (PCI) despite an overall increase. In the STEMI cohort, despite a marked increase in presentation with Killip class IV, women were less likely to received primary PCI or fibrinolysis and had longer median door-to-needle and door-to-balloon time compared to men, although these had improved. Women had higher unadjusted in-hospital, 30-Day and 1-year mortality rates compared to men for the STEMI and NSTEMI cohorts. After multivariate adjustments, 1-year mortality remained significantly higher for women with STEMI (adjusted OR: 1.31 (1.09-1.57), p<0.003) but were no longer significant for NSTEMI cohort.

    CONCLUSION: Women continued to have longer system delays, receive less aggressive pharmacotherapies and invasive treatments with poorer outcome. There is an urgent need for increased effort from all stakeholders if we are to narrow this gap.

  12. Khalid MF, Lee CY, Doggett SL, Veera Singham G
    PLoS One, 2019;14(6):e0218343.
    PMID: 31206537 DOI: 10.1371/journal.pone.0218343
    Many insect species display daily variation of sensitivity to insecticides when they are exposed to the same concentration at different times during the day. To date, this has not been investigated in bed bugs. To address this, we explored circadian rhythms in insecticide susceptibility, xenobiotic metabolizing (XM) gene expressions, and metabolic detoxification in the common bed bug, Cimex lectularius. An insecticide susceptible Monheim strain of C. lectularius was most tolerant of deltamethrin during the late photophase at ZT9 (i.e. nine hours after light is present in the light-dark cycle (LD) cycle) and similarly repeated at CT9 (i.e. nine hours into the subjective day in constant darkness (DD)) suggesting endogenous circadian involvement in susceptibility to deltamethrin. No diel rhythm was observed against imidacloprid insecticide despite significant daily susceptibility in both LD and DD conditions. Rhythmic expressions of metabolic detoxification genes, GSTs1 and CYP397A1 displayed similar expression patterns with total GST and P450 enzyme activities in LD and DD conditions, respectively. The oscillation of mRNA levels of GSTs1 and CYP397A1 was found consistent with peak phases of deltamethrin susceptibility in C. lectularius. This study demonstrates that circadian patterns of metabolic detoxification gene expression occur within C. lectularius. As a consequence, insecticide efficacy can vary dramatically throughout a 24 hour period.
  13. Kang IN, Lee CY, Tan SC
    Heliyon, 2019 Jul;5(7):e02156.
    PMID: 31388587 DOI: 10.1016/j.heliyon.2019.e02156
    Whilst the potential of neural stem cell (NSC)-based treatment is recognized worldwide and seems to offer a promising therapeutic option for stroke treatments, there is currently no full understanding regarding the effects of hypoxic and baicalein-enriched fraction (BEF) preconditioning approaches on the therapeutic potential of these cells for stroke. The potential of preconditioned NSC can be determined based on the expression of several key neuroprotective genes using qRT-PCR technique. However, prior to that, it is imperative and extremely important to carefully select reference gene(s) for accurate qRT-PCR data normalization to avoid error in data interpretation. This study aimed to evaluate the stability of ten candidate reference genes via comprehensive analysis using three algorithms software: geNorm, NormFinder and BestKeeper. Our results revealed that HPRT1 and RPL13A were the most reliable reference genes for BEF-preconditioned NSCs, but ironically, HPRT1 was ranked as the least stable reference gene for hypoxic-preconditioned NSCs. On the other hand, RPLP1 and RPL13A were selected as the most stably expressed pair of reference genes for hypoxic-preconditioned NSCs. In conclusion, this study has pointed out the importance of identifying valid reference genes and has presented the first significant validation on best reference genes recommended for qRT-PCR study involves NSC preconditioned with hypoxia or with BEF extracted from Oroxylum indicum medicinal plant.
  14. Beom JY, Low W, Park KS, Yoon TR, Lee CY, Song H
    Hip Pelvis, 2023 Dec;35(4):268-276.
    PMID: 38125274 DOI: 10.5371/hp.2023.35.4.268
    PURPOSE: Resection remains the most reliable treatment for established heterotopic ossification, despite questions regarding its effectiveness due to the potential for complications. This study evaluated the clinical outcomes and complications of neurogenic heterotopic ossification (NHO) resection in stroke patients' ankylosed hips.

    MATERIALS AND METHODS: We retrospectively analyzed nine hip NHO resections performed on seven patients from 2010 to 2018. The pre- and postoperative range of motion of the operated hip were compared. Analysis of postoperative complications, including infection, recurrence, iatrogenic fracture, and neurovascular injury was performed.

    RESULTS: The mean operative time was 132.78±21.08 minutes, with a mean hemoglobin drop of 3.06±0.82 g/dL within the first postoperative week. The mean duration of postoperative follow-up was 52.08±28.72 months for all patients. Postoperative range of motion showed improvement from preoperative. Flexion and external rotation (mean, 58.89±30.60° and 16.67±18.03°, respectively) showed the greatest gain of motion of the operated hip joint. Postoperative infections resolved in two cases through surgical debridement, and one case required conversion to total hip arthroplasty due to instability. There were no recurrences, iatrogenic fractures, or neurovascular injuries.

    CONCLUSION: Resection is a beneficial intervention for restoring the functional range of motion of the hip in order to improve the quality of life for patients with NHO and neurological disorders. We recommend performance of a minimal resection to achieve a targeted functional arc of motion in order to minimize the risk of postoperative complications.

  15. Cheah KH, Nisar H, Yap VV, Lee CY, Sinha GR
    J Healthc Eng, 2021;2021:5599615.
    PMID: 33859808 DOI: 10.1155/2021/5599615
    Emotion is a crucial aspect of human health, and emotion recognition systems serve important roles in the development of neurofeedback applications. Most of the emotion recognition methods proposed in previous research take predefined EEG features as input to the classification algorithms. This paper investigates the less studied method of using plain EEG signals as the classifier input, with the residual networks (ResNet) as the classifier of interest. ResNet having excelled in the automated hierarchical feature extraction in raw data domains with vast number of samples (e.g., image processing) is potentially promising in the future as the amount of publicly available EEG databases has been increasing. Architecture of the original ResNet designed for image processing is restructured for optimal performance on EEG signals. The arrangement of convolutional kernel dimension is demonstrated to largely affect the model's performance on EEG signal processing. The study is conducted on the Shanghai Jiao Tong University Emotion EEG Dataset (SEED), with our proposed ResNet18 architecture achieving 93.42% accuracy on the 3-class emotion classification, compared to the original ResNet18 at 87.06% accuracy. Our proposed ResNet18 architecture has also achieved a model parameter reduction of 52.22% from the original ResNet18. We have also compared the importance of different subsets of EEG channels from a total of 62 channels for emotion recognition. The channels placed near the anterior pole of the temporal lobes appeared to be most emotionally relevant. This agrees with the location of emotion-processing brain structures like the insular cortex and amygdala.
  16. Lee CY, Cheng HM, Sim SM
    Biofactors, 2007;31(1):25-33.
    PMID: 18806306
    The ability of the antioxidants in the mulberry leaves to protect Sprague-Dawley rats from injuries caused by immobilization stress was studied as an indicator of the tissue bioavailability of antioxidants. Nitrite level, lipid peroxidation and total antioxidant activity (TAA) in the plasma and tissues were measured. There were hypertrophy of the adrenal glands and kidneys, significant increased levels of nitrite in the plasma and adrenal glands, elevated thiobarbituric acid reactive substances (TBARS) in the plasma, kidneys and spleen, and a reduction of TAA in the plasma, liver, adrenal glands, kidneys and spleen of the immobilized rats. Antioxidants in the mulberry leaf extract suppressed the increase of nitrite and TBARS. Adrenal glands appeared to be the target organ of the antioxidants in the leaf extract. The low dose mulberry antioxidants were more effective than pure rutin (4 mg/day) to protect the cells against inflammation and peroxidation induced by stress.
  17. Shaikh MF, Lee CY, Chen WN, Shaikh FA
    Front Pharmacol, 2020;11:465.
    PMID: 32322213 DOI: 10.3389/fphar.2020.00465
    Epilepsy is a severe neurological disorder involving 70 million people around the globe. Epilepsy-related neuropsychiatric comorbidities such as depression, which is the most common, is an additional factor that negatively impacts the living quality of epilepsy patients. There are many theories and complexities associated with both epilepsy and associated comorbidities, one of which is the gut-brain-axis influence. The gut microbiome is hypothesized to be linked with many neurological disorders; however, little conclusive evidence is available in this area. Thus, highlighting the role will create interest in researchers to conduct detailed research in comprehending the influence of gut-brain-axis in the manifestation of depressive symptoms in epilepsy. The hypothesis which is explored in this review is that the gut-brain-axis do play an important role in the genesis of epilepsy and associated depression. The correction of this dysbiosis might be beneficial in treating both epilepsy and related depression. This hypothesis is illustrated through extensive literature discussion, proposed experimental models, and its applicability in the field. There is indirect evidence which revealed some specific bacterial strains that might cause depression in epilepsy.
  18. Matsumura Y, Kamimura Y, Lee CY, Gorb SN, Rajabi H
    Sci Rep, 2021 04 12;11(1):7920.
    PMID: 33846369 DOI: 10.1038/s41598-021-86864-1
    We unveiled the penile penetration mechanics of two earwig species, Echinosoma horridum, whose intromittent organ, termed virga, is extraordinarily long, and E. denticulatum, whose virga is conversely short. We characterised configuration, geometry, material and bending stiffness for both virga and spermatheca. The short virga of E. denticulatum has a material gradient with the stiffer base, whereas the long virga of E. horridum and the spermathecae of both species are homogeneously sclerotised. The long virga of E. horridum has a lower bending stiffness than the spermatheca. The virga of E. denticulatum is overall less flexible than the spermatheca. We compared our results to a previous study on the penetration mechanics of elongated beetle genitalia. Based on the comparison, we hypothesised that the lower stiffness of the male intromittent organ comparing to the corresponding female structure is a universal prerequisite for the penetration mechanics of the elongated intromittent organ in insects.
  19. Loh GOK, Wong EYL, Tan YTF, Wee HC, Ng RS, Lee CY, et al.
    J Pharm Biomed Anal, 2021 Feb 05;194:113758.
    PMID: 33248861 DOI: 10.1016/j.jpba.2020.113758
    A simple, rapid, sensitive, and reproducible LC-MS/MS method was developed for simultaneous quantification of flavoxate and 3-methyl-flavone-8-carboxylic (MFCA) in human plasma, using diphenhydramine HCl as internal standard (IS). The chromatographic separation was achieved using Agilent Poroshell 120 EC-C18 - Fast LC column (100 × 2.1mmID, 2.7 μm) fitted with UHPLC Guard Poroshell 120 EC-C18 (5 × 2.1 mmID, 2.7 μm). The mobile phase consisted of 0.1 % v/v formic acid and acetonitrile (30:70, v/v) run at a flow rate of 0.40 mL/min. The standard calibration curve was linear over the concentration range of 2.00 - 2,000.31 ng/mL and 240.00 - 24,000.04 ng/mL for flavoxate and MFCA. For flavoxate and MFCA, the within-run precision was 0.81-6.67 % and 1.68-4.37 %, while accuracy was 100.21-108.25 % and 103.99-110.28 %. The between-run precision was 2.01-9.14 % and 2.31-11.11 %, and accuracy was 96.09-103.33 % and 102.37-109.52 %. The extended run precision was 7.78-11.04 % and 2.22-3.33 %, while accuracy was 100.72-101.88 % and 102.34-105.60 %. Flavoxate and MFCA in plasma were stable 4 h at bench top (short term), 24 h in autosampler and instrumentation room (post-preparative), after 7 freeze-thaw cycles, and 89 days in the freezer. Both analytes and IS stock solutions were stable for 31 days when kept at room temperature (25 ± 4 °C) and refrigerated (2-8 °C). The validated method was successfully applied to a bioequivalence study of two flavoxate formulations involving 24 healthy volunteers.
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