Displaying publications 1 - 20 of 96 in total

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  1. Fulltext Physico-chemical changes and microbiological quality of refrigerated broiler chicken meat slaughtered by two different methods
    Ahmed, H.O., Hassan, Z., Abdul Manap, M.N.
    International Food Research Journal, 2018;25(3):913-920.
    MyJurnal
    Slaughtering is the first step in meat processing. It involves killing an animal for the production of meat. Effectiveness of slaughter is determined by the amount of blood removed from the animal. This study aimed to compare the chemical changes and microbiological quality of broiler chicken meat slaughtered by Halal and Non-Halal slaughter methods during refrigerated storage. A total of sixty (60) broiler chickens were slaughtered by: i) Neck cutting (NC) - by severing the jugular veins, carotid arteries, trachea and the oesophagus according to the Islamic ritual method of slaughter and (ii) Neck poking (NP) - by poking the neck of the bird with a sharp object. Residual blood was quantified by measuring the haem iron content in the breast meat samples. Storage stability of chicken meat was evaluated by measuring the extent of lipid oxidation determined by thiobarbituric acid reactive substances (TBARS) and by assessing the microbiological quality of the meat. Haem iron content decreased significantly (P0.05) on chicken meat lipid oxidation at 1, 3, and 9 day of storage at 4oC. However, at 5 and 7 day of storage, significant differences (P
  2. Fulltext Nano-crystalline lead sulfide thin films using the chemical bath deposition: synthesis and characterization
    Husham, M., Hassan, Z., Ahmed A. Al-Dulaimi
    Science Letters, 2016;11(2):11-14.
    MyJurnal
    Nanocrystalline lead sulfide (PbS) thin films have been successfully grown on glass substrate using the chemical bath deposition technique. Microwave oven was used as a heating source to facilitate the growth process of the thin films. Aqueous solutions of lead nitrate Pb(NO3) and thiourea [SC(NH2)2] were used as lead and sulfur ion sources, respectively. Structural, morphological and optical analyses revealed good quality growth of nanocrystalline PbS thin films. This study introduced a facile and low cost method to prepare high quality nanocrystalline PbS thin films in a relatively short growth time for optoelectronic applications.
  3. The evaluation of new psychoactive drugs
    Müller CP, Hassan Z
    Brain Res Bull, 2016 09;126(Pt 1):1-2.
    PMID: 27235862 DOI: 10.1016/j.brainresbull.2016.05.013
  4. Fulltext Insomnia: Case studies in family practice
    Mohd Ariff M, Abu Hassan Z
    Malays Fam Physician, 2006;1(1):11-4.
    PMID: 26998200 MyJurnal
  5. Antifungal activity of Lactobacillus fermentum Te007, Pediococcus pentosaceus Te010, Lactobacillus pentosus G004, and L. paracasi D5 on selected foods
    Muhialdin BJ, Hassan Z, Sadon SKh
    J Food Sci, 2011 Sep;76(7):M493-9.
    PMID: 21806613 DOI: 10.1111/j.1750-3841.2011.02292.x
    In the search for new preservatives from natural resources to replace or to reduce the use of chemical preservatives 4 strains of lactic acid bacteria (LAB) were selected to be evaluated for their antifungal activity on selected foods. The supernatants of the selected strains delayed the growth of fungi for 23 to 40 d at 4 °C and 5 to 6 d at 20 and 30 °C in tomato puree, 19 to 29 d at 4 °C and 6 to 12 d at 20 and 30 °C in processed cheese, and 27 to 30 d at 4 °C and 12 to 24 d at 20 and 30 °C in commercial bread. The shelf life of bread with added LAB cells or their supernatants were longer than normal bread. This study demonstrates that Lactobacillus fermentum Te007, Pediococcus pentosaceus Te010, L. pentosus G004, and L. paracasi D5 either the cells or their supernatants could be used as biopreservative in bakery products and other processed foods.
  6. Quaternary ultraviolet AlInGaN MQW laser diode performance using quaternary AlInGaN electron blocking layer
    Ghazai AJ, Thahab SM, Abu Hassan H, Hassan Z
    Opt Express, 2011 May 9;19(10):9245-54.
    PMID: 21643179 DOI: 10.1364/OE.19.009245
    The effect of polarization-matched Al(0.25)In(0.08)Ga(0.67)N electron-blocking layer (EBL) on the optical performance of ultraviolet Al(0.08)In(0.08)Ga(0.84)N/Al(0.1)In(0.01)Ga(0.84)N multi-quantum well (MQW) laser diodes (LDs) was investigated. The polarization-matched Al(0.25)In(0.08)Ga(0.67)N electron blocking layer (EBL) was employed in an attempt to reduce the polarization effect inside the active region of the diodes. The device performance which is affected by piezoelectric was studied via drift-diffusion model for carrier transport, optical gain and losses using the simulation program of Integrated System Engineering Technical Computer Aided design (ISE TCAD). The optical performance of the LD using quaternary Al(0.25)In(0.08)Ga(0.67)N EBL was compared with the LD using ternary Al(0.3)Ga(0.7)N EBL where both materials have the same energy band gap of Eg = 3.53 eV. The self-consistent ISE-TCAD simulation program results showed that the polarization-matched quaternary Al(0.25)In(0.08)Ga(0.67)N EBL is beneficial as it confines the electrons inside the quantum well region better than ternary Al(0.3)Ga(0.7)N EBL. The results indicated that the use of Al(0.25)In(0.08)Ga(0.67)N EBL has lower threshold current and higher optical intensity than those for Al(0.3)Ga(0.7)N EBL. The effect of Al(0.25)In(0.08)Ga(0.67)N EBL thickness on the performance of LDs has also been studied. Results at room temperature indicated that lower threshold current, high slope efficiency, high output power, and high differential quantum efficiency DQE occurred when the thickness of Al(0.25)In(0.08)Ga(0.67)N EBL was 0.25 µm.
  7. Fulltext What study design should I choose?
    Abu Hassan Z, Hanafi NS, Teng CL
    Malays Fam Physician, 2006;1(1):29-31.
    PMID: 26998208
  8. Pt-decorated GaN nanowires with significant improvement in H2 gas-sensing performance at room temperature
    Abdullah QN, Yam FK, Hassan Z, Bououdina M
    J Colloid Interface Sci, 2015 Dec 15;460:135-45.
    PMID: 26319330 DOI: 10.1016/j.jcis.2015.07.048
    Superior sensitivity towards H2 gas was successfully achieved with Pt-decorated GaN nanowires (NWs) gas sensor. GaN NWs were fabricated via chemical vapor deposition (CVD) route. Morphology (field emission scanning electron microscopy and transmission electron microscopy) and crystal structure (high resolution X-ray diffraction) characterizations of the as-synthesized nanostructures demonstrated the formation of GaN NWs having a wurtzite structure, zigzaged shape and an average diameter of 30-166nm. The Pt-decorated GaN NWs sensor shows a high response of 250-2650% upon exposure to H2 gas concentration from 7 to 1000ppm respectively at room temperature (RT), and then increases to about 650-4100% when increasing the operating temperature up to 75°C. The gas-sensing measurements indicated that the Pt-decorated GaN NWs based sensor exhibited efficient detection of H2 at low concentration with excellent sensitivity, repeatability, and free hysteresis phenomena over a period of time of 100min. The large surface-to-volume ratio of GaN NWs and the catalytic activity of Pt metal are the most influential factors leading to the enhancement of H2 gas-sensing performances through the improvement of the interaction between the target molecules (H2) and the sensing NWs surface. The attractive low-cost, low power consumption and high-performance of the resultant decorated GaN NWs gas sensor assure their uppermost potential for H2 gas sensor working at low operating temperature.
  9. Prevalence of Listeria spp and Listeria monocytogenes in meat and fermented fish in Malaysia
    Hassan Z, Purwati E, Radu S, Rahim RA, Rusul G
    Southeast Asian J. Trop. Med. Public Health, 2001 Jun;32(2):402-7.
    PMID: 11556596
    Fermented fish and meat samples were purchased from supermarket and wet market for microbiological analysis of Listeria species and Listeria monocytogenes contamination. Listeria species were isolated from 17 (73.9%) of 23 samples of imported frozen beef, 10 (43.5%) of the 23 samples of local beef and 14 (56%) of the 25 samples of fermented fish from wet market. Listeria monocytogenes occurred in 15 (75%) of the frozen beef samples, 6 (30.4%) of the 23 samples of local meat and 3 (12%) of the 25 samples from fermented fish. Listeria species was not isolated from any of the 23 samples of imported frozen beef from supermarket and from the 5 samples of buffalo meat examined. This highlights the possibility of Listeria spp or L. monocytogenes to persist in meat and fermented fish in wet market and raises the problem of illness due to the handling and consumption of Listeria-contaminated meat or fermented fish are likely as evidence by the high contamination rates of samples sold at the wet market.
  10. Isolation of Bifidobacteria infantis and its antagonistic activity against ETEC 0157 and Salmonella typhimurium S-285 in weaning foods
    Yusof RM, Haque F, Ismail M, Hassan Z
    Asia Pac J Clin Nutr, 2000 Jun;9(2):130-5.
    PMID: 24394399
    Probiotic organism Bifidobacteria was isolated from the faeces of breast-fed infants at Universiti Putra Malaysia. Trypticase phytone peptone yeast extract agar (TPY) was used as a selective media for the isolation. Morphological examination of the isolates indicated that Bifidobacteria was Gram-positive rods in nature, curved with characteristics of V and Y shapes. The organisms were non-catalase producing, non-nitrate reducing, non-motile, had an absence of indole and were unable to liquify gelatin. The ratios of acetic and lactic acids were determined using high performance liquid chromatography (HPLC). Using carbohydrate fermentation profile test API-CH-50 kits, 20 Bifidobacteria strains had been identified: they were the species of Bifidobacteria infantis and two different sub-species, mainly infantis and lacentis. Based on a wide zone of inhibition, three suitable strains of B. infantis, Bifi-11, Bifi-19 and Bifi-20, were tested in weaning foods for antimicrobial activity towards two human pathogens: E. coli-0157 (World Health Organization) and Salmonella typhimurium S-285. The pH, titratable acidity of weaning foods and total colony count for Bifidobacteria, enteropathogenic Escherichia coli and S. typhimurium were recorded at 3-h intervals for 30 h. It was found that after 9 h of incubation of weaning foods, the pH declined to < 3.6 from pH 6.0, whereas titratable acidity increased from 0.026 to 0.08%. It was indicated that Bifidobacteria inhibited E. coli better than did S typhimurium due to low pH. After 24 h of incubation, approximately 98% of E. coli was inhibited by Bifidobacteria. It is suggested that the inhibitory effect of Bifidobacteria strains in weaning foods towards the growth of enteropathogenic E. coli and S. typhimurium was solely due to low pH and the production of volatile acid components by the organism.
  11. Characterization of Vibrio vulnificus isolated from cockles (Anadara granosa): antimicrobial resistance, plasmid profiles and random amplification of polymorphic DNA analysis
    Radu S, Elhadi N, Hassan Z, Rusul G, Lihan S, Fifadara N, et al.
    FEMS Microbiol Lett, 1998 Aug 01;165(1):139-43.
    PMID: 9711850
    Antibiotic susceptibility, plasmid profiles and random amplification of polymorphic DNA (RAPD) were used to study strains of Vibrio vulnificus isolated from cockles (Anadara granosa). Thirty-six isolates were analyzed. The prevalent biotypes were 1 (72.2% of the isolates) and 2 (27.8%). Among these, 21 strains of biotype 1 and two strains of biotype 2 contained plasmid DNA bands ranging in size from 1.4 to 9.7 MDa. Thirty-one (83.3%) were found to be resistant to one or more of the antimicrobial agents tested, however no specific correlation between antimicrobial resistance patterns and a single biotype was found. In addition, no particular plasmid profile was predictive of a particular pattern of antibiotic susceptibility. Two primers produced polymorphisms in all strains tested, producing bands ranging from 0.25 to 2.7 kb, indicating a high variability among both biotype 1 and biotype 2 of the V. vulnificus strains investigated. RAPD identity across biotypes was also observed among Vibrio vulnificus strains.
  12. TRPM4 inhibition improves spatial memory impairment and hippocampal long-term potentiation deficit in chronic cerebral hypoperfused rats
    Hazalin NAMN, Liao P, Hassan Z
    Behav Brain Res, 2020 09 01;393:112781.
    PMID: 32619565 DOI: 10.1016/j.bbr.2020.112781
    Chronic cerebral hypoperfusion (CCH) been well characterized as a common pathological status contributing to neurodegenerative diseases such as Alzheimer's disease and vascular dementia. CCH is an important factor that leads to cognitive impairment, but the underlying neurobiological mechanism is poorly understood and no effective treatment is available. Recently, transient receptor potential melastatin 4 (TRPM4) cation channel has been identified as an important molecular element in focal cerebral ischemia. Over activation of the channel is a major molecular mechanism of oncotic cell death. However, the role of TRPM4 in CCH that propagates global brain hypoxia have not been explored. Therefore, the present study is designed to investigate the effect of TRPM4 inhibition on the cognitive functions of the rats following CCH via permanent bilateral occlusion of common carotid arteries (PBOCCA) model. In this model, treatment with siRNA suppressed TRPM4 expression at both the mRNA and protein levels and improved cognitive deficits of the CCH rats without affecting their motor function. Furthermore, treatment with siRNA rescued the LTP impairment in CCH-induced rats. Consistent with the restored of LTP, western blot analysis revealed that siRNA treatment prevented the reduction of synaptic proteins, including calcium/calmodulin-dependent kinase II alpha (CaMKIIα) and brain-derived neurotrophic factor (BDNF) in brain regions of CCH rats. The present findings provide a novel role of TRPM4 in restricting cognitive functions in CCH and suggest inhibiting TRPM4 may represent a promising therapeutic strategy in targeting ion channels to prevent the progression of cognitive deficits induced by ischemia.
  13. Chronic cerebral hypoperfusion-induced memory impairment and hippocampal long-term potentiation deficits are improved by cholinergic stimulation in rats
    Damodaran T, Müller CP, Hassan Z
    Pharmacol Rep, 2019 Jun;71(3):443-448.
    PMID: 31003155 DOI: 10.1016/j.pharep.2019.01.012
    BACKGROUND: Chronic cerebral hypoperfusion (CCH) can induce the accumulation of reactive oxygen species, which leads to oxidative damage, neuronal injury, and central cholinergic dysfunction in vulnerable regions of the brain, such as the hippocampus and cerebral cortex. These effects can lead to significant cognitive impairments in clinical populations of vascular dementia (VaD). The present studies aimed to investigate the role of the cholinergic system in memory functions and hippocampal long-term potentiation (LTP) impairments induced by CCH in rats.

    METHODS: Male Sprague Dawley rats were subjected to permanent bilateral occlusion of common carotid arteries (PBOCCA) or sham surgery. Then, PBOCCA rats received ip injections with, either vehicle (control group), the muscarinic receptor agonist oxotremorine (0.1 mg/kg), or the acetylcholinesterase inhibitor physostigmine (0.1 mg/kg). Cognitive functions were evaluated using a passive avoidance task and the Morris water maze test. In addition, hippocampal LTP was recorded in vivo under anaesthesia.

    RESULTS: The PBOCCA rats exhibited significant deficits in passive avoidance retention and spatial learning and memory tests. They also showed a suppression of LTP formation in the hippocampus. Oxotremorine and physostigmine significantly improved the learning and memory deficits as well as the suppression of LTP in PBOCCA rats.

    CONCLUSIONS: The present data suggest that the cholinergic system plays an important role in CCH-induced cognitive deficits and could be an effective therapeutic target for the treatment of VaD.

  14. Fulltext Upregulation of Brain's Calcium Binding Proteins in Mitragynine Dependence: A Potential Cellular Mechanism to Addiction
    Basheer M, Hassan Z, Gam LH
    Int J Med Sci, 2023;20(1):102-113.
    PMID: 36619231 DOI: 10.7150/ijms.78861
    Background: Mitragyna speciosa Korth or Kratom is widely used traditionally for its medicinal values. The major alkaloid content of kratom leaves is mitragynine, which binds to opioid receptors to give opioid-like effects. This study aimed to analyse the brain proteome of animals that displayed addictive behaviors. Design and Methods: Six groups (n=6-8) of rats made up of negative control, positive control using morphine (10 mg/kg), and treatment groups at low (1mg/kg) and high doses of mitragynine (30 mg/kg) for 1 and 4 days. The rats' behaviors were evaluated and subsequently the rats' brains were harvested for proteomic analysis that was performed by using 2D gel electrophoresis and LC/MS/MS. Results: The rats developed physical dependence only on day 4 following morphine and mitragynine (1 and 30mg/kg) treatments. Among the proteins that were up-regulated in treatment groups were four calcium-binding proteins, namely calretinin, F-actin, annexin A3 and beta-centractin. Conclusions: Upregulation of calretinin acted as low Ca2+ buffering upon the blockage of Ca2+ ion channel by mitragynine in the brain, which subsequently caused a reduction of GABA released and inversely increased the dopamine secretions that contributed to dependence indicators.
  15. Effects of dry cow intramammary therapy on quarter infections in the dry period
    Hassan Z, Daniel RC, O'Boyle D, Frost AJ
    Vet Rec, 1999 Nov 27;145(22):635-9.
    PMID: 10619609
    Quarter milk samples were taken from 150 cows from three dairy farms in south-east Queensland at drying off, two, four and six weeks after drying off, at calving, and one, two and three weeks after calving. In each of the herds, the cows were randomly allocated to three groups of approximately equal size. One group had all the quarters of all the cows treated at drying off with a dry cow antibiotic infusion containing cloxacillin; the second group was given no treatment, and the third group had selected quarters treated on the basis of their high activity of N-acetyl-beta-D-glucosaminidase at drying off. Dry cow treatment resulted in a marked reduction in the number of infected quarters at two and four weeks after drying off, so that the comprehensively treated group had significantly less infected quarters at these times (P<0.02). Twelve dinical cases of mastitis were detected two weeks after drying off in the untreated groups, 10 in the untreated quarters of the selectively treated groups, and no cases in the comprehensively treated groups. These cases were due mainly to Streptococcus uberis and Streptococcus dysgalactiae. The number of infected untreated quarters increased markedly between drying off and two weeks later, but in all three groups there was a marked decrease in the number of infected quarters between six weeks after drying off and calving, suggesting that the mammary glands were more able to overcome infections at this time.
  16. Fulltext Mitragynine inhibits hippocampus neuroplasticity and its molecular mechanism
    Yunusa S, Hassan Z, Müller CP
    Pharmacol Rep, 2023 Dec;75(6):1488-1501.
    PMID: 37924443 DOI: 10.1007/s43440-023-00541-w
    BACKGROUND: Mitragynine (MIT), the primary indole alkaloid of kratom (Mitragyna speciosa), has been associated with addictive and cognitive decline potentials. In acute studies, MIT decreases spatial memory and inhibits hippocampal synaptic transmission in long-term potentiation (LTP). This study investigated the impacts of 14-day MIT treatment on hippocampus synaptic transmission and its possible underlying mechanisms.

    METHODS: Under urethane anesthesia, field excitatory post-synaptic potentials (fEPSP) of the hippocampal CA1 region were recorded in the Sprague Dawley (SD) rats that received MIT (1, 5, and 10 mg/kg), morphine (MOR) 5 mg/kg, or vehicle (ip). The effects of the treatments on basal synaptic transmission, paired-pulse facilitation (PPF), and LTP were assessed in the CA1 region. Analysis of the brain's protein expression linked to neuroplasticity was then performed using a western blot.

    RESULTS: The baseline synaptic transmission's amplitude was drastically decreased by MIT at 5 and 10 mg/kg doses, although the PPF ratio before TBS remained unchanged, the PPF ratio after TBS was significantly reduced by MIT (10 mg/kg). Strong and persistent inhibition of LTP was generated in the CA1 region by MIT (5 and 10 mg/kg) doses; this effect was not seen in MIT (1 mg/kg) treated rats. In contrast to MIT (1 mg/kg), MIT (5 and 10 mg/kg) significantly raised the extracellular glutamate levels. After exposure to MIT, GluR-1 receptor expression remained unaltered. However, NMDAε2 receptor expression was markedly downregulated. The expression of pCaMKII, pERK, pCREB, BDNF, synaptophysin, PSD-95, Delta fosB, and CDK-5 was significantly downregulated in response to MIT (5 and 10 mg/kg) exposure, while MOR (5 mg/kg) significantly raised synaptophysin and Delta fosB expression.

    CONCLUSION: Findings from this work reveal that a smaller dose of MIT (1 mg/kg) poses no risk to hippocampal synaptic transmission. Alteration in neuroplasticity-associated proteins may be a molecular mechanism for MIT (5 and 10 mg/kg)-induced LTP disruption and cognitive impairments. Data from this work posit that MIT acted differently from MOR on neuroplasticity and its underlying mechanisms.

  17. Mitragynine (Kratom)-Withdrawal behaviour and cognitive impairments can be ameliorated by an epigenetic mechanism
    Yunusa S, Müller CP, Hassan Z
    Br J Pharmacol, 2024 Mar 25.
    PMID: 38523471 DOI: 10.1111/bph.16352
    BACKGROUND AND PURPOSE: Kratom is a preparation from Mitragyna speciosa, which is used as a natural drug preparation for many purposes around the world. However, an overdose of Kratom may cause addiction-like problems including aversive withdrawal states resulting in cognitive impairments via unknown mechanisms. Its main psychoactive alkaloid is mitragynine, showing opioid-like properties.

    EXPERIMENTAL APPROACH: Here, we analysed the neuropharmacological effects of mitragynine compared with morphine withdrawal in rats and searched for a pharmacological treatment option that may reverse the occurring cognitive deficits that usually aggravate withdrawal.

    KEY RESULTS: We found that withdrawal from 14-day mitragynine (1-10 mg·kg-1·day-1) treatment caused dose-dependent behavioural withdrawal signs resembling those of morphine (5 mg·kg-1·day-1) withdrawal. However, mitragynine (5 and 10 mg·kg-1·day-1) withdrawal also induced impairments in a passive avoidance task. Mitragynine withdrawal not only reduced hippocampal field excitatory postsynaptic potential (fEPSP) amplitudes in basal synaptic transmission and long-term potentiation (LTP) but also reduced epigenetic markers, such as histone H3K9 and H4K12 expression. At the same time, it up-regulates HDAC2 expression. Targeting the epigenetic adaptations with the HDAC inhibitor, SAHA, reversed the effects of mitragynine withdrawal on epigenetic dysregulation, hippocampal input/output curves, paired-pulse facilitation, LTP and attenuated the cognitive deficit. However, SAHA amplified the effects of morphine withdrawal.

    CONCLUSION AND IMPLICATIONS: The data from this work show that changes in histone expression and downstream hippocampal plasticity may explain mitragynine, but not morphine, withdrawal behaviours and cognitive impairments. Thus, it may provide a new treatment approach for aversive Kratom/mitragynine withdrawal and addiction.

  18. Fulltext Antidiabetic properties and mechanism of action of Gynura procumbens water extract in streptozotocin-induced diabetic rats
    Hassan Z, Yam MF, Ahmad M, Yusof AP
    Molecules, 2010;15(12):9008-23.
    PMID: 21150821 DOI: 10.3390/molecules15129008
    Gynura procumbens (Lour.) Merr (family Compositae) is cultivated in Southeast Asia, especially Indonesia, Malaysia and Thailand, for medicinal purposes. This study evaluated the in vivo hypoglycemic properties of the water extract of G. procumbens following 14 days of treatment and in vitro in RIN-5F cells. Glucose absorption from the intestines and its glucose uptake in abdominal skeletal muscle were assessed. The antidiabetic effect of water extract of G. procumbens leaves was investigated in streptozotocin-induced diabetic rats. The intraperitoneal glucose tolerance test (IPGTT) was performed in diabetic rats treated with G. procumbens water extract for 14 days. In the IPGTT, blood was collected for insulin and blood glucose measurement. After the IPGTT, the pancreases were collected for immunohistochemical study of β-cells of the islets of Langerhans. The possible antidiabetic mechanisms of G. procumbens were assessed through in vitro RIN-5F cell study, intestinal glucose absorption and glucose uptake by muscle. The results showed that G. procumbens significantly decreased blood glucose levels after 14 days of treatment and improved outcome of the IPGTT. However, G. procumbens did not show a significant effect on insulin level either in the in vivo test or the in vitro RIN-5F cell culture study. G. procumbens also showed minimal effects on β-cells of the islets of Langerhans in the pancreas. However, G. procumbens only significantly increased glucose uptake by muscle tissues. From the findings we can conclude that G. procumbens water extract exerted its hypoglycemic effect by promoting glucose uptake by muscles.
  19. Molecular characterization of Salmonella weltevreden isolated from poultry: evidence of conjugal transfer of plasmid and antibiotic resistance
    Radu S, Mutalib SA, Rusul G, Hassan Z, Yeang LK
    Microbios, 2001;104(407):39-47.
    PMID: 11229656
    Ten strains of Salmonella weltevreden isolated from poultry sources were examined and found to contain plasmid DNA ranging in size from 1.8 to 68.5 MD. All isolates were susceptible to carbenicillin, cephalothin, ceftriazone, gentamicin, kanamycin and nalidixic acid, but resistance to bacitracin (100%), penicillin G (100%), rifampicin (100%), sulphamethoxazole (100%), cefuroxime (80%) and tetracycline (60%) was recorded. The 55 MD plasmid of strain SW5 determined resistance to penicillin G and tetracycline, which was transmissible to the E. coli K12 recipient at a frequency of 3.52 x 10(-5) transconjugants per input donor cell. The results of arbitrarily primed polymerase chain reaction (AP-PCR), using two 10-mer oligonucleotides and PCR-ribotyping to differentiate between the ten strains of S. weltevreden were compared. The strains were separated into ten different genome types by AP-PCR but were indistinguishable by PCR-ribotyping. These results suggest that poultry may constitute a reservoir for disseminating antibiotic resistance and that AP-PCR may be a valuable tool for epidemiological studies.
  20. Fulltext Growth and Characterization of Ternary Hf x Ta y O z Films via Nitrogen-Infused Wet Oxidation
    Quah HJ, Ahmad FH, Lim WF, Hassan Z
    ACS Omega, 2020 Oct 20;5(41):26347-26356.
    PMID: 33110962 DOI: 10.1021/acsomega.0c02120
    Nitrogen-infused wet oxidation at different temperatures (400-1000 °C) was employed to transform tantalum-hafnia to hafnium-doped tantalum oxide films. High-temperature wet oxidation at 1000 °C marked an onset of crystallization occurring in the film, accompanied with the formation of an interfacial oxide due to a reaction between the inward-diffusing hydroxide ions, which were dissociated from the water molecules during wet oxidation. The existence of nitrogen has assisted in controlling the interfacial oxide formation. However, high-temperature oxidation caused a tendency for the nitrogen to desorb and form N-H complex after reacting with the hydroxide ions. Besides, the presence of N-H complex implied a decrease in the passivation at the oxide-Si interface by hydrogen. As a consequence, defect formation would happen at the interface and influence the metal-oxide-semiconductor characteristics of the samples. In comparison, tantalum-hafnia subjected to nitrogen-infused wet oxidation at 600 °C has obtained the highest dielectric constant, the largest band gap, and the lowest slow trap density.
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