MyMedR

Displaying publications 1 - 20 of 75 in total

Abstract:

Sort:

Degradation of two acetanilide herbicides in a tropical soil

Sahid IB, Wei CC

Bull Environ Contam Toxicol, 1993 Jan;50(1):24-8.
PMID: 8418934
Matched MeSH terms: Half-Life
Fulltext Radionuclide concentration of spent resins from puspati triga reactor coolant purification system

Muhamat Omar, Zalina Laili, Julia Abdul Karim, Zarina Masood, Nik Marzukee Nik Ibrahim, Mohd Abd Wahab Yusof

Jurnal Sains Nuklear Malaysia, 2012;24(2):14-18.
MyJurnal

A study to assess the concentration of radionuclides in spent resins of the PUSPATI TRIGA Mark II reactor coolant purification system has been carried out. Fresh spent resins collected and analysed in May 2010, after the changing of leaked heat exchanger in Sept. 2009 was found to contain 24Na, 122Sb, 51Cr, 124Sb, 58Co, 65Zn, 54Mn and 60Co. Old spent resins removed in 2001 and 2002 but analysed in 2010 indicated the presence of 60Co and 152Eu as radionuclides with half-lives of < 1 year might have already been decayed out. These results can be used to establish radionuclide inventory of the spent resins as part of radiation protection programme.

Matched MeSH terms: Half-Life
Triamterene measurements in the aqueous humor of rabbits

Hamid O, Tajuddin AA

J Ocul Pharmacol Ther, 2000 Dec;16(6):565-9.
PMID: 11132903

The kinetics of topical triamterene penetration were estimated from the time-course measurements of triamterene (in Dyazide) concentrations in the anterior chamber of six rabbits (n=12, left and right eyes). The two-compartment model of Jones and Maurice (1) was fitted to the measurements. We found the apparent elimination rate constant oftriamterene A = 0.33 +/- 0.12 hr(-1), the apparent absorption rate constant of triamterene B = 2.68 +/- 0.55 hr(-1), the cornea-aqueous transfer coefficient in reference to the corneal volume of triamterene kc.ca = 0.28 +/- 0.05 hr(-1), the loss coefficient of triamterene from the anterior chamber ko = 0.43 +/- 0.16 hr(-1) and the amount of triamterene in the cornea at time zero Mo = 483 +/- 125 ng/ml. The mean of ko = 0.43 hr(-1) is significantly lower (p = 0.04% using ZTEST) than the lower limit of aqueous loss coefficient = 0.58 hr(-1) usually found in rabbits (2). We conclude that Dyazide lowers the aqueous flow rate in the positive direction, considering glaucoma treatment. Peak triamterene concentration in the anterior chamber was P = 120 +/- 32 ng/ml. Half-life for elimination from the aqueous humor was T1/2 = 1.84 +/- 0.65 hr (Mean +/- SD).

Matched MeSH terms: Half-Life
Fulltext Physico-chemical properties of spray-dried red pitaya (Hylocereus polyrhizus) peel powder during storage

Ee, S.C., Bakar, J., Kharidah, M., Dzulkifly, M.H., Noranizan, A.

International Food Research Journal, 2014;21(3):1213-1218.
MyJurnal

The physico-chemical properties of spray-dried pitaya peel powders kept at accelerated (45 ± 2°C) and room temperature (28 ± 2°C) for 14 weeks and 6 months, respectively were evaluated. Changes in physico-chemical properties of the peel powder were used as indicators of stability, while changes of the betacyanin pigment retention was used to calculate the shelf-life of the powder. Storage temperatures significantly (p < 0.05) affected all the studied parameters and Hunter a value had the most significant change. The pigment retention of peel powder was approximately 87% at 45°C and 89% at room temperature storage. Degradation of betacyanin pigment in the powder followed the first order reaction kinetics with the half-life (t1/2) of approximately 76 weeks at 45°C and 38 months at 28°C. The spray-dried pitaya peel powder had a solubility of 87 to 92% and low in powder hygroscopicity. The final Aw of the powder did not exceed 0.6 for both storage temperatures.

Matched MeSH terms: Half-Life
Fulltext General purpose nuclear irradiation chamber

Nurul Fadzlin Hasbullah, Nuurul Iffah Che Omar, Nahrul Khair Alang Md Rashid, Jaafar Abdullah

Journal of Nuclear and Related Technologies, 2013;2013(2):70-76.
MyJurnal

Nuclear technology has found a great need for use in medicine, industry, and research. Smoke
detectors in our homes, medical treatments and new varieties of plants by irradiating its seeds are just a few examples of the benefits of nuclear technology. Portable neutron source such as Californium-252, available at Industrial Technology Division (BTI/PAT), Malaysian Nuclear Agency, has a 2.645 year half-life. However, 252 Cf is known to emit gamma radiation from the source. Thus, this chamber aims to provide a proper gamma shielding for samples to distinguish the use of mixed neutron with gamma-rays or pure neutron radiation. The chamber is compatible to be used with other portable neutron sources such as 241 Am-Be as well as the reactor TRIGA PUSPATI for higher neutron dose. This chamber was designed through a collaborative effort of Kulliyyah Engineering, IIUM with the Bahagian Teknologi Industri (BTI) team, Agency Nuklear Malaysia.

Matched MeSH terms: Half-Life
Fulltext Chronic gamma irradiation for crops improvement and agrobiotechnology

Azhar Mohamad

Buletin Persatuan Genetik Malaysia, 2011;18(1):31-32.
MyJurnal

The Gamma Green House (GGH) is a chronic irradiation facility located at MINT Tech Park, Nuclear Malaysia, Jalan Dengkil. GGH is used for induction of mutation in plants and other biological samples with low dose radiation over period of time depending on the nature and sensitivity of the plant species. Gamma Greenhouse facility at Malaysian Nuclear Agency comprises an open topped
irradiation area consisting of circular green house with 30 meters radius, control room and irradiator with interlock system. The irradiation source is a REVISS RSL6050 double encapsulated 800 Ci 137Cs (half-life 30.1 years for 137Cs) pencils and allowed to be exposed only when the entire 300 m diameter site is free from personnel. The irradiator system is secured by a sophisticated interlock system, which only allows the source to be exposed when all the prerequisite safety conditions are met, and automatically returns the source to the safe
storage position if any safety device is compromised.

Matched MeSH terms: Half-Life
Fulltext An open labelled randomized clinical trial of Fluoxetine versus Dapoxetine treatment among men with premature ejaculation and its effect on marital satisfaction

Mohammad Che Man, Faridah Mohd Zain, Najib Majdi Yaacob, Shahidah Che Alhadi, Shaiful Bahri Ismail

International Medical Journal Malaysia, 2017;16(11):34-34.
MyJurnal

Premature ejaculation (PE) reduces sexual satisfaction and quality of life.
Both SSRI Fluoxetine and Dapoxetine have been used in the treatment of PE. Fluoxetine
is used as off-label treatment meanwhile Dapoxetine is the first SSRI specifically
designed for PE with short half-life and few side effects. (Copied from article).

Matched MeSH terms: Half-Life
Development of a novel ionic liquid-curcumin complex to enhance its solubility, stability, and activity

Chowdhury MR, Moshikur RM, Wakabayashi R, Tahara Y, Kamiya N, Moniruzzaman M, et al.

Chem Commun (Camb), 2019 Jun 11.
PMID: 31184357 DOI: 10.1039/c9cc02812a

We report a one-step emulsification and rapid freeze-drying process to develop a curcumin-ionic liquid (CCM-IL) complex that could be readily dispersed in water with a significantly enhanced solubility of ∼8 mg mL-1 and half-life (t1/2) of ∼260 min compared with free CCM (solubility ∼30 nM and t1/2 ∼ 20 min). This process using an IL consisting of a long chain carbon backbone as a surfactant, may provide an alternative way of enhancing the solubility of poorly water-soluble drugs.

Matched MeSH terms: Half-Life
Kinetic modeling and half life study on bioremediation of crude oil dispersed by Corexit 9500

Zahed MA, Aziz HA, Isa MH, Mohajeri L, Mohajeri S, Kutty SR

J Hazard Mater, 2011 Jan 30;185(2-3):1027-31.
PMID: 21041026 DOI: 10.1016/j.jhazmat.2010.10.009

Hydrocarbon pollution in marine ecosystems occurs mainly by accidental oil spills, deliberate discharge of ballast waters from oil tankers and bilge waste discharges; causing site pollution and serious adverse effects on aquatic environments as well as human health. A large number of petroleum hydrocarbons are biodegradable, thus bioremediation has become an important method for the restoration of oil polluted areas. In this research, a series of natural attenuation, crude oil (CO) and dispersed crude oil (DCO) bioremediation experiments of artificially crude oil contaminated seawater was carried out. Bacterial consortiums were identified as Acinetobacter, Alcaligenes, Bacillus, Pseudomonas and Vibrio. First order kinetics described the biodegradation of crude oil. Under abiotic conditions, oil removal was 19.9% while a maximum of 31.8% total petroleum hydrocarbons (TPH) removal was obtained in natural attenuation experiment. All DCO bioreactors demonstrated higher and faster removal than CO bioreactors. Half life times were 28, 32, 38 and 58 days for DCO and 31, 40, 50 and 75 days for CO with oil concentrations of 100, 500, 1000 and 2000 mg/L, respectively. The effectiveness of Corexit 9500 dispersant was monitored in the 45 day study; the results indicated that it improved the crude oil biodegradation rate.

Matched MeSH terms: Half-Life
Convenient and Efficient Method for Quality Control Analysis of 18F-Fluorocholine: For a Small Scale GMP-based Radiopharmaceuticals Laboratory Set-up

Hassan H, Abu Bakar S, Halim KN, Idris J, Nordin AJ

Curr Radiopharm, 2016;9(2):128-36.
PMID: 26013570

BACKGROUND AND OBJECTIVE: Prostate cancer continues to be the most prevalent cancer in men in Malaysia. As time progresses, the prospect of PET imaging modality in diagnosis of prostate cancer is promising, with on-going improvement on novel tracers. Among all tracers, 18F-Fluorocholine is reported to be a reputable tracer and reliable diagnostic technique for prostate imaging. Nonetheless, only 18F-Fluorodeoxyglucose (18F-FDG) is available and used in most oncology cases in Malaysia. With a small scale GMP-based radiopharmaceuticals laboratory set-up, initial efforts have been taken to put Malaysia on 18F-Fluorocholine map. This article presents a convenient, efficient and reliable method for quality control analysis of 18F-Fluorocholine. Besides, the aim of this research work is to assist local GMP radiopharmaceuticals laboratories and local authority in Malaysia for quality control analysis of 18F-Fluorocholine guideline.
METHODS: In this study, prior to synthesis, quality control analysis method for 18F-Fluorocholine was developed and validated, by adapting the equipment set-up used in 18F-Fluorodeoxyglucose (18FFDG) routine production. Quality control on the 18F-Fluorocholine was performed by means of pH, radionuclidic identity, radio-high performance liquid chromatography equipped with ultraviolet, radio- thin layer chromatography, gas chromatography and filter integrity test.
RESULTS: Post-synthesis; the pH of 18F-Fluorocholine was 6.42 ± 0.04, with half-life of 109.5 minutes (n = 12). The radiochemical purity was consistently higher than 99%, both in radio-high performance liquid chromatography equipped with ultraviolet (r-HPLC; SCX column, 0.25 M NaH2PO4: acetonitrile) and radio-thin layer chromatography method (r-TLC). The calculated relative retention time (RRT) in r-HPLC was 1.02, whereas the retention factor (Rf) in r-TLC was 0.64. Potential impurities from 18F-Fluorocholine synthesis such as ethanol, acetonitrile, dimethylethanolamine and dibromomethane were determined in gas chromatography. Using our parameters, (capillary column: DB-200, 30 m x 0.53 mm x 1 um) and oven temperature of 35°C (isothermal), all compounds were well resolved and eluted within 3 minutes. Level of ethanol and acetonitrile in 18F-Fluorocholine were detected below threshold limit; less than 5 mg/ml and 0.41 mg/ml respectively. Meanwhile, dimethylethanolamine and dibromomethane were undetectable.
CONCLUSION: A convenient, efficient and reliable quality control analysis work-up procedure for 18FFluorocholine has been established and validated to comply all the release criteria. The convenient method of quality control analysis may provide a guideline to local GMP radiopharmaceutical laboratories to start producing 18F-Fluorocholine as a tracer for prostate cancer imaging.

Matched MeSH terms: Half-Life
Mobility and persistence of metolachlor in two common Malaysian agricultural soils

Ismail BS, Quirinus L

Bull Environ Contam Toxicol, 2000 Oct;65(4):530-6.
PMID: 10960146
Matched MeSH terms: Half-Life
Persistence of terbuthylazine in soils

Sahid IB, Teoh SS

Bull Environ Contam Toxicol, 1994 Feb;52(2):226-30.
PMID: 8123982
Matched MeSH terms: Half-Life
A sequential algorithm for the non-linear dual-sorption model of percutaneous drug absorption

Gumel AB, Kubota K, Twizell EH

Math Biosci, 1998 Aug 15;152(1):87-103.
PMID: 9727298

A sequential algorithm is developed for the non-linear dual-sorption model developed by Chandrasekaran et al. [1,2] which monitors pharmacokinetic profiles in percutaneous drug absorption. In the experimental study of percutaneous absorption, it is often observed that the lag-time decreases with the increase in the donor concentration when two or more donor concentrations of the same compound are used. The dual-sorption model has sometimes been employed to explain such experimental results. In this paper, it is shown that another feature observed after vehicle removal may also characterize the dual-sorption model. Soon after vehicle removal, the plots of the drug flux versus time become straight lines on a semilogarithmic scale as in the linear model, but the half-life is prolonged thereafter when the dual-sorption model prevails. The initial half-life after vehicle removal with a low donor concentration is longer than that with a higher donor concentration. These features, if observed in experiments, may be used as evidence to confirm that the dual-sorption model gives an explanation to the non-linear kinetic behaviour of a permeant.

Matched MeSH terms: Half-Life
Fulltext Toxicity assessment of gallic acid loaded graphene oxide (GAGO) nano-formulation in zebrafish (Danio Rerio) embryos

Ahmad Ashraful Hadi Abdul Ghafor, Nurhuda Elias, Suhaili Shams, Faizah Md Yasin, Sarchio, Seri Narti Edayu

Pertanika Journal of Science & Technology, 2020;28(1):311-326.
MyJurnal

Gallic acid (GA) is a phenolic compound found in almost all plants and has been reported to possess powerful health benefits such as anti-oxidant, anti-inflammatory, anti-cancer, and anti-diabetic properties. However, GA suffers a short half-life when administered in vivo. Recent studies have employed graphene oxide (GO), a biocompatible and cost-effective graphene derivative, as a nanocarrier for GA. However, the toxicity effect of this formulated nano-compound has not been fully studied. Thus, the present study aims to evaluate the toxicity and teratogenicity of GA loaded GO (GAGO) against zebrafish embryogenesis to further advance the development of GA as a therapeutic agent. GAGO was exposed to zebrafish embryos (n ≥ 10; 24hr post fertilization (hpf)) at different concentrations (0-500 μg/ml). The development of zebrafish was observed and recorded twice daily for four days. The toxicity of pure GO and GA was also observed at similar concentrations. Distilled water was used as control throughout the experiment. A significantly high mortality rate, delayed hatching rate and low heartbeat were recorded in embryos exposed to GO at concentrations of ≥ 150 μg/ml at 48 hr (p

Matched MeSH terms: Half-Life
Polymer Based Protein Therapeutics

Bhawani SA, Husaini A, Ahmad FB, Asaruddin MR

Curr Protein Pept Sci, 2018;19(10):972-982.
PMID: 28828988 DOI: 10.2174/1389203718666170821162823

Proteins have played a very important role in the drug industry for developing treatments of various diseases such as auto-immune diseases, cancer, diabetes, mental disorder, metabolic disease, and others. Therapeutic proteins have high activity and specificity but they have some limitations such as short half-life, poor stability, low solubility and immunogenicity, so they cannot prolong their therapeutic activity. These shortcomings have been rectified by using polymers for the conjugation with proteins. The conjugates of protein-polymer improves the half-lives, stability and makes them non-immunogenic. Poly(ethylene glycol) (PEG), is widely used in the delivery of proteins because it is the current gold standard for stealth polymers in the emerging field of polymer-based delivery as compared to various biodegradable polymers. PEGylation enhances the retention of therapeutic proteins, effectively alters the pharmacokinetics and enhances the pharmaceutical value. Smart polymer have been used to cope with the pathophysiological environment of target site and have imposed less toxic effects.The contents of this article are challenges in formulation of therapeutic proteins, synthetic routes of conjugates, smart polymer-protein conjugates and also some advantages/disadvantages of polymers as a carrier system of proteins.

Matched MeSH terms: Half-Life
Fulltext Judgment on the presence of radionuclides in sample analysis: A case study

Muhamat Omar, Zalina Laili, Mohd Suhaimi Hamzah

Jurnal Sains Nuklear Malaysia, 2012;24(1):33-42.
MyJurnal

Qualitative and quantitative analysis of samples require good judgment from the analysts. These two aspects in gamma spectrometric analysis of Proficiency Test and solid radioactive waste samples for the determination of radionuclides are discussed. It is vital to judge and decide what energy peaks belong to which radionuclides prior to the creation of customized radionuclide library for the analysis of specific samples. Corrections due to radionuclide decay and growth, and the half-life assigned to a particular radionuclide in the uranium and thorium series are also discussed. Discussion on judgment to confirm the presence of thorium in food samples based on gamma spectrometry and neutron activation analysis is also provided.

Matched MeSH terms: Half-Life
Fulltext An immunohistochemical study of p53 in oral epithelium dysplasia and squamous cell carcinoma

Ma, M.S.

Malaysian Dental Journal, 2007;28(2):78-82.
MyJurnal

Squamous cell carcinoma (SCC) is the commonest cancer in the mouth. Multiple risk factors, such as smoking, alcohol consumption, irradiation, viruses infection and chronic irritation are thought to be responsible for the formation of oral squamous cell carcinoma. Although SCC can develop through a series of precancerous stages manifested as various degrees of epithelial dysplasia, this is not always the case. p53 is the commonest mutated gene in human cancers. Mis-sense mutation of the gene or complexing of the protein with viral or cellular proteins prolongs its half-life and leads to its detection by immunohistochemistry. This study was designed with the aim of demonstrating any possible relationship between p53 and oral squamous cell carcinoma by immunohistochemical staining techniques. A total of 66 specimens from the oral cavity (10 normal mucosa, 11 hyperkeratosis without dysplasia, 11 mild dysplasia, 11 moderate dysplasia, 10 severe dysplasia and 13 SCC) were examined for the presence of p53. The results show p53 was not expressed in normal mucosa, but was found with increasing frequency in increasingly severe dysplasia and SCC. In conclusion, this study shows p53 mutation is common in oral squamous cell carcinoma and probably occurs early in the multisteps of oral carcinogenesis.

Matched MeSH terms: Half-Life
Fulltext Enhanced Carbofuran Degradation Using Immobilized and Free Cells of Enterobacter sp. Isolated from Soil

Umar Mustapha M, Halimoon N, Wan Johari WL, Abd Shukor MY

Molecules, 2020 Jun 16;25(12).
PMID: 32560037 DOI: 10.3390/molecules25122771

Extensive use of carbofuran insecticide harms the environment and human health. Carbofuran is an endocrine disruptor and has the highest acute toxicity to humans than all groups of carbamate pesticides used. Carbofuran is highly mobile in soil and soluble in water with a lengthy half-life (50 days). Therefore, it has the potential to contaminate groundwater and nearby water bodies after rainfall events. A bacterial strain BRC05 was isolated from agricultural soil characterized and presumptively identified as Enterobacter sp. The strain was immobilized using gellan gum as an entrapment material. The effect of different heavy metals and the ability of the immobilized cells to degrade carbofuran were compared with their free cell counterparts. The results showed a significant increase in the degradation of carbofuran by immobilized cells compared with freely suspended cells. Carbofuran was completely degraded within 9 h by immobilized cells at 50 mg/L, while it took 12 h for free cells to degrade carbofuran at the same concentration. Besides, the immobilized cells completely degraded carbofuran within 38 h at 100 mg/L. On the other hand, free cells degraded the compound in 68 h. The viability of the freely suspended cell and degradation efficiency was inhibited at a concentration greater than 100 mg/L. Whereas, the immobilized cells almost completely degraded carbofuran at 100 mg/L. At 250 mg/L concentration, the rate of degradation decreased significantly in free cells. The immobilized cells could also be reused for about nine cycles without losing their degradation activity. Hence, the gellan gum-immobilized cells of Enterobacter sp. could be potentially used in the bioremediation of carbofuran in contaminated soil.

Matched MeSH terms: Half-Life
Characterisation, in-vitro and in-vivo evaluation of valproic acid-loaded nanoemulsion for improved brain bioavailability

Tan SF, Kirby BP, Stanslas J, Basri HB

J Pharm Pharmacol, 2017 Nov;69(11):1447-1457.
PMID: 28809443 DOI: 10.1111/jphp.12800

OBJECTIVE: This study was aimed to investigate the potential of formulated valproic acid-encapsulated nanoemulsion (VANE) to improve the brain bioavailability of valproic acid (VPA).
METHODS: Valproic acid-encapsulated nanoemulsions were formulated and physically characterised (osmolarity, viscosity, drug content, drug encapsulation efficiency). Further investigations were also conducted to estimate the drug release, cytotoxic profile, in-vitro blood-brain barrier (BBB) permeability, pharmacokinetic parameter and the concentration of VPA and VANE in blood and brain.
KEY FINDINGS: Physical characterisation confirmed that VANE was suitable for parenteral administration. Formulating VPA into nanoemulsion significantly reduced the cytotoxicity of VPA. In-vitro drug permeation suggested that VANEs crossed the BBB as freely as VPA. Pharmacokinetic parameters of VANE-treated rats in plasma and brain showed F3 VANE had a remarkable improvement in AUC, prolongation of half-life and reduction in clearance compared to VPA. Given the same extent of in-vitro BBB permeation of VPA and VANE, the higher bioavailability of VANE in brain was believed to have due to higher concentration of VANE in blood. The brain bioavailability of VPA was improved by prolonging the half-life of VPA by encapsulating it within the nanoemulsion-T80.
CONCLUSIONS: Nanoemulsion containing VPA has alleviated the cytotoxic effect of VPA and improved the plasma and brain bioavailability for parenteral delivery of VPA.

Matched MeSH terms: Half-Life
Bioavailability and pharmacokinetics of acyclovir tablet preparation

Yuen KH, Peh KK, Billa N, Chan KL, Toh WT

Drug Dev Ind Pharm, 1998 Feb;24(2):193-6.
PMID: 15605452

The bioavailability of a generic preparation of acyclovir (Avorax) was compared with the innovator product, Zovirax. Twelve healthy volunteers participated in the study, conducted according to a randomized, two-way crossover design. The preparations were compared using the parameters area under the plasma concentration time curve (AUC(0-infinity), peak plasma concentration (Cmax), and time to reach peak plasma concentration (Tmax). No statistically significant difference was observed between the Tmax or the logarithmic transformed AUC(0-infinity) and C(max) values of the two preparations. In addition, the 90% confidence interval for the ratio of the logarithmic transformed AUC(0-infinity) values of Avorax over those of Zovirax was found to lie between 0.85 and 1.06, while that of the logarithmic transformed Cmax values was between 0.95 and 1.25, being within the bioequivalence limit of 0.80-1.25. Moreover, the elimination rate constant (k(e)), elimination half-life (t(1/2)), and apparent volume of distribution (Vd) values obtained with the two preparations were comparable and not significantly different statistically.

Matched MeSH terms: Half-Life

Filters

Please provide feedback to Administrator ([email protected])

External Links