Displaying publications 1 - 20 of 179 in total

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  1. S-band multiwavelength Brillouin/Raman distributed Bragg reflector fiber lasers
    Zulkifli MZ, Ahmad H, Taib JM, Muhammad FD, Dimyati K, Harun SW
    Appl Opt, 2013 Jun 1;52(16):3753-6.
    PMID: 23736330 DOI: 10.1364/AO.52.003753
    A multiwavelength Brillouin/Raman distributed Bragg reflector fiber laser operating in the S-band region is proposed and demonstrated. The laser uses a 7.7 km long dispersion-shifted fiber with an effective mode area of 15 μm(2) as the Brillouin and Raman gain media simultaneously. Two 1420 nm laser diodes with a combined power of 372 mW are used as pump sources, while a fiber Bragg grating with a center wavelength of 1500 nm is used as a reflector in the cavity. The setup is capable of generating 6 clearly defined Stokes lines at the highest pump power, spanning from 1499.8 to 1500.3 nm with the even Stokes having relatively higher peak powers, between 1.4 and 3.5 dBm as compared to the odd Stokes, which have peak powers between -4.7 and -5.0 dBm. The output of the laser is very stable and shows little to no fluctuations over a monitoring period of 50 min.
  2. Fulltext Dual Regime Mode-Locked and Q-Switched Erbium-Doped Fiber Laser by Employing Graphene Filament-Chitin Film-Based Passive Saturable Absorber
    Zuikafly SNF, Ahmad H, Ismail MF, Abdul Rahman MA, Yahya WJ, Abu Husain N, et al.
    Micromachines (Basel), 2023 May 14;14(5).
    PMID: 37241671 DOI: 10.3390/mi14051048
    We investigate the dynamics of high energy dual regime unidirectional Erbium-doped fiber laser in ring cavity, which is passively Q-switched and mode-locked through the use of an environmentally friendly graphene filament-chitin film-based saturable absorber. The graphene-chitin passive saturable absorber allows the option for different operating regimes of the laser by simple adjustment of the input pump power, yielding, simultaneously, highly stable and high energy Q-switched pulses at 82.08 nJ and 1.08 ps mode-locked pulses. The finding can have applications in a multitude of fields due to its versatility and the regime of operation that is on demand.
  3. Mode-locked thulium-bismuth codoped fiber laser using graphene saturable absorber in ring cavity
    Zen DI, Saidin N, Damanhuri SS, Harun SW, Ahmad H, Ismail MA, et al.
    Appl Opt, 2013 Feb 20;52(6):1226-9.
    PMID: 23434993 DOI: 10.1364/AO.52.001226
    We demonstrate mode locking of a thulium-bismuth codoped fiber laser (TBFL) operating at 1901.6 nm, using a graphene-based saturable absorber (SA). In this work, a single layer graphene is mechanically exfoliated using the scotch tape method and directly transferred onto the surface of a fiber pigtail to fabricate the SA. The obtained Raman spectrum characteristic indicates that the graphene on the core surface has a single layer. At 1552 nm pump power of 869 mW, the mode-locked TBFL self starts to generate an optical pulse train with a repetition rate of 16.7 MHz and pulse width of 0.37 ps. This is a simple, low-cost, stable, and convenient laser oscillator for applications where eye-safe and low-photon-energy light sources are required, such as sensing and biomedical diagnostics.
  4. Fulltext Investigation on the Effects of the Formation of a Silver "Flower-Like Structure" on Graphene
    Zakaria R, Yusoff SFAZ, Law KC, Lim CS, Ahmad H
    Nanoscale Res Lett, 2017 Dec;12(1):50.
    PMID: 28101853 DOI: 10.1186/s11671-016-1793-y
    In this report, we experimentally investigate the formation of "flower-like silver structures" on graphene. Using an electrochemical deposition technique with deposition times of 2.5 and 5 min, agglomerations of silver nanoparticles (AgNPs) were deposited on the graphene surfaces, causing the formation of "flower-like structures" on the graphene substrate. Localized surface plasmon resonance (LSPR) was observed in the interaction between the structures and the graphene substrate. The morphology of the samples was observed using a field-emission scanning electron microscope (FESEM) and Raman spectroscopy. Thereafter, the potential of the flower-like Ag microstructures on graphene for use in Raman spectroscopic applications was examined. The signal showed a highest intensity value after a deposition time of 5 min, as portrayed by the intense local electromagnetic fields. For a better understanding, the CST Microwave Studio software, based on the finite element method (FEM), was applied to simulate the absorption characteristics of the structures on the graphene substrate. The absorption peak was redshifted due to the increment of the nanoparticle size.
  5. Perturbations in Amino Acid Metabolism in Reserpine-Treated Zebrafish Brain Detected by 1H Nuclear Magnetic Resonance-Based Metabolomics
    Zakaria F, Akhtar MT, Wan Ibrahim WN, Abu Bakar N, Muhamad A, Shohaimi S, et al.
    Zebrafish, 2021 02;18(1):42-54.
    PMID: 33538644 DOI: 10.1089/zeb.2020.1895
    Depression is a complex and disabling psychiatric disorder, which is expected to be a leading cause for disability by 2030. According to World Health Organization, about 350 million people are suffering with mental health disorders around the globe, especially depression. However, the mechanisms involved in stress-induced depression have not been fully elucidated. In this study, a stress-like state was pharmacologically induced in zebrafish using reserpine, a drug widely used to mediate depression in experimental animal models. Zebrafish received single intraperitoneal (i.p.) injections of 20, 40, and 80 mg/kg body weight reserpine doses and were subjected to open-field test at 2, 24, 48, 72, and 96 h after the treatment. Along with observed changes in behavior and measurement of cortisol levels, the fish were further examined for perturbations in their brain metabolites by 1H nuclear magnetic resonance (NMR)-based metabolomics. We found a significant increase in freezing duration, whereas total distance travelled was decreased 24 h after single intraperitoneal injection of reserpine. Cortisol level was also found to be higher after 48 h of reserpine treatment. The 1H NMR data showed that the levels of metabolites such as glutamate, glutamine, histamine, valine, leucine and histidine, lactate, l-fucose, betaine and γ-amino butyric acid (GABA), β-hydroxyisovalerate, and glutathione were significantly decreased in the reserpine-treated group. This study provided some insights into the molecular nature of stress that could contribute toward a better understanding of depression disorder.
  6. Centella asiatica (L.) Urb. Extract ameliorates branched-chain amino acid (BCAA) metabolism in acute reserpine-induced stress zebrafish model via 1H Nuclear Magnetic Resonance (NMR)-based metabolomics approach
    Zakaria F, Akhtar MT, Wan Norhamidah WI, Noraini AB, Muhamad A, Shohaimi S, et al.
    Comp Biochem Physiol C Toxicol Pharmacol, 2023 Feb;264:109501.
    PMID: 36336330 DOI: 10.1016/j.cbpc.2022.109501
    Depression is a common mental disorder that can adversely affect psychosocial function and quality of life. However, the exact aetiology and pathogenesis of depression are still unclear. Stress plays a major role in the pathogenesis of depression. The use of currently prescribed antidepressants has many side effects. Centella asiatica (C. asiatica) has shown promising antidepressant activity in rodent models. Here, we developed a reserpine-induced zebrafish stress-like model and performed behavioural analysis, cortisol measurement and 1H-Nuclear Magnetic Resonance (1H NMR) spectroscopy-based metabolomics analysis to test the anti-stress activity of ethanolic extract of C. asiatica (RECA). A significant increase in total distance travelled (F(8,8) = 8.905, p = 0.0054) and a reduction in freezing duration (F(9, 9) = 10.38, p = 0.0018) were found in the open field test (OFT). Asiaticoside, one of tested C.asiatica's triterpenoid gives a significant increase in contact duration (F(5,5) = 142.3, (p = 0.0330) at 2.5 mg/kg). Eight biomarkers were found, i.e. ß-hydroxyisovaleric acid, leucine, threonine, scylloinositol, lactate, betaine, valine, choline and l-fucose, to be responsible for the class separation between stress and RECA-treated groups. Metabolic pathway alteration in zebrafish brain upon treatment with RECA was identified as valine, leucine and isoleucine biosynthesis, while alanine, aspartate, glutamate and glycerophospholipid metabolism was involved after fluoxetine treatment.
  7. Fulltext A Review on Therapeutic Effects of Labisia pumila on Female Reproductive Diseases
    Zakaria AA, Noor MHM, Ahmad H, Hassim HA, Mazlan M, Latip MQA
    Biomed Res Int, 2021;2021:9928199.
    PMID: 34568497 DOI: 10.1155/2021/9928199
    The Labisia pumila (LP) is a traditional plant that is locally known as Kacip Fatimah, Selusuh Fatimah, or Pokok Ringgang by the Malaysian indigenous people. It is believed to facilitate their childbirth, treating their postchild birth and menstrual irregularities. The water extract of LP has shown to contain bioactive compounds such as flavonoids, ascorbic acid, β-carotene, anthocyanin, and phenolic acid, which contribute extensive antioxidant, anti-inflammatory, antimicrobial, and antifungal. The LP ethanolic extract exhibits significant estrogenic effects on human endomentrial adenocarcinoma cell in estrogen-free basal medium and promoting an increase in secretion of alkaline phosphate. Water based has been used for many generations, and studies had reported that it could displace in binding the antibodies and increase the estradiol production making it similar to esterone and estradiol hormone. LP extract poses a potential and beneficial aspect in medical and cosmeceutical applications. This is mainly due to its phytoestrogen properties of the LP. However, there is a specific functionality in the application of LP extract, due to specific functional group in phytoconstituent of LP. Apart from that, the extraction solvent is important in preparing the LP extract as it poses some significant and mild side effects towards consuming the LP extracts. The current situation of women reproductive disease such as postmenopausal syndrome and polycystic ovary syndrome is increasing. Thus, it is important to find ways in alternative treatment for women reproductive disease that is less costly and low side effects. In conclusion, these studies proven that LP has the potential to be an alternative way in treating female reproductive related diseases such as in postmenopausal and polysystic ovarian syndrome women.
  8. Metallointercalator [Ru(dppz)2(PIP)]2+ Renders BRCA Wild-Type Triple-Negative Breast Cancer Cells Hypersensitive to PARP Inhibition
    Yusoh NA, Leong SW, Chia SL, Harun SN, Rahman MBA, Vallis KA, et al.
    ACS Chem. Biol., 2020 02 21;15(2):378-387.
    PMID: 31898884 DOI: 10.1021/acschembio.9b00843
    There is a need to improve and extend the use of clinically approved poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi), including for BRCA wild-type triple-negative breast cancer (TNBC). The demonstration that ruthenium(II) polypyridyl complex (RPC) metallointercalators can rapidly stall DNA replication fork progression provides the rationale for their combination alongside DNA damage response (DDR) inhibitors to achieve synergism in cancer cells. The aim of the present study was to evaluate use of the multi-intercalator [Ru(dppz)2(PIP)]2+ (dppz = dipyrido[3,2-a:2',3'-c]phenazine, PIP = (2-(phenyl)imidazo[4,5-f][1,10]phenanthroline, Ru-PIP) alongside the PARPi olaparib and NU1025. Cell proliferation and clonogenic survival assays indicated a synergistic relationship between Ru-PIP and olaparib in MDA-MB-231 TNBC and MCF7 human breast cancer cells. Strikingly, low dose Ru-PIP renders both cell lines hypersensitive to olaparib, with a >300-fold increase in olaparib potency in TNBC, the largest nongenetic PARPi enhancement effect described to date. A negligible impact on the viability of normal human fibroblasts was observed for any combination tested. Increased levels of DNA double-strand break (DSB) damage and olaparib abrogation of Ru-PIP-activated pChk1 signaling are consistent with PARPi-facilitated collapse of Ru-PIP-associated stalled replication forks. This results in enhanced G2/M cell-cycle arrest, apoptosis, and decreased cell motility for the combination treatment compared to single-agent conditions. This work establishes that an RPC metallointercalator can be combined with PARPi for potent synergy in BRCA-proficient breast cancer cells, including TNBC.
  9. Fulltext Synergy of ruthenium metallo-intercalator, [Ru(dppz)2(PIP)]2+, with PARP inhibitor Olaparib in non-small cell lung cancer cells
    Yusoh NA, Chia SL, Saad N, Ahmad H, Gill MR
    Sci Rep, 2023 Jan 26;13(1):1456.
    PMID: 36702871 DOI: 10.1038/s41598-023-28454-x
    Poly(ADP-ribose) polymerase (PARP) are critical DNA repair enzymes that are activated as part of the DNA damage response (DDR). Although inhibitors of PARP (PARPi) have emerged as small molecule drugs and have shown promising therapeutic effects, PARPi used as single agents are clinically limited to patients with mutations in germline breast cancer susceptibility gene (BRCA). Thus, novel PARPi combination strategies may expand their usage and combat drug resistance. In recent years, ruthenium polypyridyl complexes (RPCs) have emerged as promising anti-cancer candidates due to their attractive DNA binding properties and distinct mechanisms of action. Previously, we reported the rational combination of the RPC DNA replication inhibitor [Ru(dppz)2(PIP)]2+ (dppz = dipyrido[3,2-a:2',3'-c]phenazine, PIP = 2-(phenyl)-imidazo[4,5-f][1,10]phenanthroline), "Ru-PIP", with the PARPi Olaparib in breast cancer cells. Here, we expand upon this work and examine the combination of Ru-PIP with Olaparib for synergy in lung cancer cells, including in 3D lung cancer spheroids, to further elucidate mechanisms of synergy and additionally assess toxicity in a zebrafish embryo model. Compared to single agents alone, Ru-PIP and Olaparib synergy was observed in both A549 and H1975 lung cancer cell lines with mild impact on normal lung fibroblast MRC5 cells. Employing the A549 cell line, synergy was confirmed by loss in clonogenic potential and reduced migration properties. Mechanistic studies indicated that synergy is accompanied by increased double-strand break (DSB) DNA damage and reactive oxygen species (ROS) levels which subsequently lead to cell death via apoptosis. Moreover, the identified combination was successfully able to inhibit the growth of A549 lung cancer spheroids and acute zebrafish embryos toxicity studies revealed that this combination showed reduced toxicity compared to single-agent Ru-PIP.
  10. Fulltext Discovery of Ruthenium(II) Metallocompound and Olaparib Synergy for Cancer Combination Therapy
    Yusoh NA, Tiley PR, James SD, Harun SN, Thomas JA, Saad N, et al.
    J Med Chem, 2023 May 25;66(10):6922-6937.
    PMID: 37185020 DOI: 10.1021/acs.jmedchem.3c00322
    Synergistic drug combinations can extend the use of poly(ADP-ribose) polymerase inhibitors (PARPi) such as Olaparib to BRCA-proficient tumors and overcome acquired or de novo drug resistance. To identify new synergistic combinations for PARPi, we screened a "micro-library" comprising a mix of commercially available drugs and DNA-binding ruthenium(II) polypyridyl complexes (RPCs) for Olaparib synergy in BRCA-proficient triple-negative breast cancer cells. This identified three hits: the natural product Curcumin and two ruthenium(II)-rhenium(I) polypyridyl metallomacrocycles. All combinations identified were effective in BRCA-proficient breast cancer cells, including an Olaparib-resistant cell line, and spheroid models. Mechanistic studies indicated that synergy was achieved via DNA-damage enhancement and resultant apoptosis. Combinations showed low cytotoxicity toward non-malignant breast epithelial cells and low acute and developmental toxicity in zebrafish embryos. This work identifies RPC metallomacrocycles as a novel class of agents for cancer combination therapy and provides a proof of concept for the inclusion of metallocompounds within drug synergy screens.
  11. Fulltext Combining PARP Inhibition with Platinum, Ruthenium or Gold Complexes for Cancer Therapy
    Yusoh NA, Ahmad H, Gill MR
    ChemMedChem, 2020 Nov 18;15(22):2121-2135.
    PMID: 32812709 DOI: 10.1002/cmdc.202000391
    Platinum drugs are heavily used first-line chemotherapeutic agents for many solid tumours and have stimulated substantial interest in the biological activity of DNA-binding metal complexes. These complexes generate DNA lesions which trigger the activation of DNA damage response (DDR) pathways that are essential to maintain genomic integrity. Cancer cells exploit this intrinsic DNA repair network to counteract many types of chemotherapies. Now, advances in the molecular biology of cancer has paved the way for the combination of DDR inhibitors such as poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) and agents that induce high levels of DNA replication stress or single-strand break damage for synergistic cancer cell killing. In this review, we summarise early-stage, preclinical and clinical findings exploring platinum and emerging ruthenium anti-cancer complexes alongside PARPi in combination therapy for cancer and also describe emerging work on the ability of ruthenium and gold complexes to directly inhibit PARP activity.
  12. Contemporary evidence of workplace violence against the primary healthcare workforce worldwide: a systematic review
    Yusoff HM, Ahmad H, Ismail H, Reffin N, Chan D, Kusnin F, et al.
    Hum Resour Health, 2023 Oct 13;21(1):82.
    PMID: 37833727 DOI: 10.1186/s12960-023-00868-8
    Violence against healthcare workers recently became a growing public health concern and has been intensively investigated, particularly in the tertiary setting. Nevertheless, little is known of workplace violence against healthcare workers in the primary setting. Given the nature of primary healthcare, which delivers essential healthcare services to the community, many primary healthcare workers are vulnerable to violent events. Since the Alma-Ata Declaration of 1978, the number of epidemiological studies on workplace violence against primary healthcare workers has increased globally. Nevertheless, a comprehensive review summarising the significant results from previous studies has not been published. Thus, this systematic review was conducted to collect and analyse recent evidence from previous workplace violence studies in primary healthcare settings. Eligible articles published in 2013-2023 were searched from the Web of Science, Scopus, and PubMed literature databases. Of 23 included studies, 16 were quantitative, four were qualitative, and three were mixed method. The extracted information was analysed and grouped into four main themes: prevalence and typology, predisposing factors, implications, and coping mechanisms or preventive measures. The prevalence of violence ranged from 45.6% to 90%. The most commonly reported form of violence was verbal abuse (46.9-90.3%), while the least commonly reported was sexual assault (2-17%). Most primary healthcare workers were at higher risk of patient- and family-perpetrated violence (Type II). Three sub-themes of predisposing factors were identified: individual factors (victims' and perpetrators' characteristics), community or geographical factors, and workplace factors. There were considerable negative consequences of violence on both the victims and organisations. Under-reporting remained the key issue, which was mainly due to the negative perception of the effectiveness of existing workplace policies for managing violence. Workplace violence is a complex issue that indicates a need for more serious consideration of a resolution on par with that in other healthcare settings. Several research gaps and limitations require additional rigorous analytical and interventional research. Information pertaining to violent events must be comprehensively collected to delineate the complete scope of the issue and formulate prevention strategies based on potentially modifiable risk factors to minimise the negative implications caused by workplace violence.
  13. Binding of tetrabutylammonium bromide based deep eutectic solvent to DNA by spectroscopic analysis
    Yusof R, Jumbri K, Ahmad H, Abdulmalek E, Abdul Rahman MB
    Spectrochim Acta A Mol Biomol Spectrosc, 2021 May 15;253:119543.
    PMID: 33636491 DOI: 10.1016/j.saa.2021.119543
    The binding characteristics of DNA in deep eutectic solvents (DESs), particularly the binding energy and interaction mechanism, are not widely known. In this study, the binding of tetrabutylammonium bromide (TBABr) based DES of different hydrogen bond donors (HBD), including ethylene glycol (EG), glycerol (Gly), 1,3-propanediol (1,3-PD) and 1,5-pentanediol (1,5-PD), to calf thymus DNA was investigated using fluorescence spectroscopy. It was found that the shorter the alkyl chain length (2 carbons) and higher EG ratios of TBABr:EG (1:5) increased the binding constant (Kb) between DES and DNA up to 5.75 × 105 kJ mol-1 and decreased the binding of Gibbs energy (ΔGo) to 32.86 kJ mol-1. Through displacement studies, all synthesised DESs have been shown to displace DAPI (4',6-diamidino-2-phenylindole) and were able to bind on the minor groove of Adenine-Thymine (AT)-rich DNA. A higher number of hydroxyl (OH) groups caused the TBABr:Gly to form more hydrogen bonds with DNA bases and had the highest ability to quench DAPI from DNA, with Stern-Volmer constants (Ksv) of 115.16 M-1. This study demonstrated that the synthesised DESs were strongly bound to DNA through a combination of electrostatic, hydrophobic, and groove binding. Hence, DES has the potential to solvate and stabilise nucleic acid structures.
  14. Fulltext Recent Advances in Metal Decorated Nanomaterials and Their Various Biological Applications: A Review
    Yaqoob AA, Ahmad H, Parveen T, Ahmad A, Oves M, Ismail IMI, et al.
    Front Chem, 2020;8:341.
    PMID: 32509720 DOI: 10.3389/fchem.2020.00341
    Nanoparticles (nanoparticles) have received much attention in biological application because of their unique physicochemical properties. The metal- and metal oxide-supported nanomaterials have shown significant therapeutic effect in medical science. The mechanisms related to the interaction of nanoparticles with animal and plant cells can be used to establish its significant role and to improve their activity in health and medical applications. Various attempts have been made to discuss the antibiotic resistance and antimicrobial activity of metal-supported nanoparticles. Despite all these developments, there is still a need to investigate their performance to overcome modern challenges. In this regard, the present review examines the role of various types of metal-supported nanomaterials in different areas such as antibacterial, antifungal, anticancer, and so on. Based on the significant ongoing research and applications, it is expected that metal-supported nanomaterials play an outstanding role not only in medical but also in other important areas.
  15. Reflection spectra of etched FBGs under the influence of axial contraction and stress-induced index change
    Yang HZ, Lim KS, Qiao XG, Chong WY, Cheong YK, Lim WH, et al.
    Opt Express, 2013 Jun 17;21(12):14808-15.
    PMID: 23787668 DOI: 10.1364/OE.21.014808
    We present a new theoretical model for the broadband reflection spectra of etched FBGs which includes the effects of axial contraction and stress-induced index change. The reflection spectra of the etched FBGs with several different taper profiles are simulated based on the proposed model. In our observation, decaying exponential profile produces a broadband reflection spectrum with good uniformity over the range of 1540-1560 nm. An etched FBG with similar taper profile is fabricated and the experimental result shows good agreement with the theoretical model.
  16. Fulltext A polyphenol-enriched diet and Ascaris suum infection modulate mucosal immune responses and gut microbiota composition in pigs
    Williams AR, Krych L, Fauzan Ahmad H, Nejsum P, Skovgaard K, Nielsen DS, et al.
    PLoS One, 2017;12(10):e0186546.
    PMID: 29028844 DOI: 10.1371/journal.pone.0186546
    Polyphenols are a class of bioactive plant secondary metabolites that are thought to have beneficial effects on gut health, such as modulation of mucosal immune and inflammatory responses and regulation of parasite burdens. Here, we examined the interactions between a polyphenol-rich diet supplement and infection with the enteric nematode Ascaris suum in pigs. Pigs were fed either a basal diet or the same diet supplemented with grape pomace (GP), an industrial by-product rich in polyphenols such as oligomeric proanthocyanidins. Half of the animals in each group were then inoculated with A. suum for 14 days to assess parasite establishment, acquisition of local and systemic immune responses and effects on the gut microbiome. Despite in vitro anthelmintic activity of GP-extracts, numbers of parasite larvae in the intestine were not altered by GP-supplementation. However, the bioactive diet significantly increased numbers of eosinophils induced by A. suum infection in the duodenum, jejunum and ileum, and modulated gene expression in the jejunal mucosa of infected pigs. Both GP-supplementation and A. suum infection induced significant and apparently similar changes in the composition of the prokaryotic gut microbiota, and both also decreased concentrations of isobutyric and isovaleric acid (branched-chain short chain fatty acids) in the colon. Our results demonstrate that while a polyphenol-enriched diet in pigs may not directly influence A. suum establishment, it significantly modulates the subsequent host response to helminth infection. Our results suggest an influence of diet on immune function which may potentially be exploited to enhance immunity to helminths.
  17. A Self-Assembled Metallomacrocycle Singlet Oxygen Sensitizer for Photodynamic Therapy
    Walker MG, Jarman PJ, Gill MR, Tian X, Ahmad H, Reddy PA, et al.
    Chemistry, 2016 Apr 18;22(17):5996-6000.
    PMID: 27000412 DOI: 10.1002/chem.201600852
    Although metal-ion-directed self-assembly has been widely used to construct a vast number of macrocycles and cages, it is only recently that the biological properties of these systems have begun to be explored. However, up until now, none of these studies have involved intrinsically photoexcitable self-assembled structures. Herein we report the first metallomacrocycle that functions as an intracellular singlet oxygen sensitizer. Not only does this Ru2 Re2 system possess potent photocytotoxicity at light fluences below those used for current medically employed systems, it offers an entirely new paradigm for the construction of sensitizers for photodynamic therapy.
  18. Fulltext Radical resection for naso-lacrimal duct tumour
    Vickers PG, Shue CL, Ahmad H
    Med J Malaysia, 1999 Jun;54(2):277-9.
    PMID: 10972044
    Naso-lacrimal duct tumours are uncommon and present with epiphora and swelling. Since the naso-lacrimal duct is embedded in bone for the majority of its anatomical length, the late presentation of proptosis is due to orbital extension of the tumour. Radical surgical treatment is necessary to establish clear margins and facilitate reconstruction.
  19. Fulltext Protective potential of fish oil supplementation against insulin resistance and pancreatic islet damage in STZ-induced Wistar rats
    Titisari N, Fauzi A, Razak ISA, Samsulrizal N, Ahmad H
    Open Vet J, 2023 Aug;13(8):983-990.
    PMID: 37701670 DOI: 10.5455/OVJ.2023.v13.i8.4
    BACKGROUND: Fish oil, which is regarded as the primary source of omega-3 fatty acids, has been long studied for its potential as an antidiabetic therapy. However, its protective ability against insulin resistance and pancreatic islet alteration remains unclear and controversial.

    AIM: To investigate the beneficial effects of fish oil consumption on the progression of insulin resistance and pancreatic islet dysfunction in a rat model of diabetes.

    METHODS: Diabetic rats model (n = 30) were divided into five groups and received; 1) NS injection + NS oral (normal control); 2) NS injection + 3 g/kg fish oil (fish oil control); 3) streptozotocin (STZ) injection + NS oral [diabetes control (DC)]; 4) STZ injection + 1 g/kg fish oil (DFO1); and 5) STZ injection + 3 g/kg fish oil (DFO3). Fasting blood insulin was analyzed by commercial rat insulin enzyme-linked immunosorbent assay; meanwhile, the determination of insulin sensitivity was calculated by homeostatic model assessment of insulin resistance (HOMA-IR) and homeostatic model assessment of beta-cell function. A histological study was conducted on pancreas tissue using H and E staining.

    RESULTS: Fish oil supplementation reduced hyperglycemia and ameliorated HOMA-IR in STZ-induced animal models indicating that fish oil supplementation improved insulin sensitivity. Furthermore, animals treated with fish oil at a dose of 3 g/kg (DFO3) showed an enhancement in pancreatic islets, which was displayed by less abnormal structures than DC animals. This could imply that the administration of fish oil, especially rich in bioactive omega-3 fatty acids effectively inhibits insulin resistance and restore islet of Langerhans alteration in rats injected with STZ.

    CONCLUSION: Thus, the current study suggested that fish oil supplementation could support the treatment of diabetes but should not be considered as an alternative therapy.

  20. Fulltext Protein-protein interactions between A. aegypti midgut and dengue virus 2: two-hybrid screens using the midgut cDNA library
    Tham HW, Balasubramaniam VR, Chew MF, Ahmad H, Hassan SS
    J Infect Dev Ctries, 2015 Dec 30;9(12):1338-49.
    PMID: 26719940 DOI: 10.3855/jidc.6422
    INTRODUCTION: Dengue virus (DENV) is principally transmitted by the Aedes aegypti mosquito. To date, mosquito population control remains the key strategy for reducing the continuing spread of DENV. The focus on the development of new vector control strategies through an understanding of the mosquito-virus relationship is essential, especially targeting the midgut, which is the first mosquito organ exposed to DENV infection.
    METHODOLOGY: A cDNA library derived from female adult A. aegypti mosquito midgut cells was established using the switching mechanism at the 5' end of the RNA transcript (SMART), in combination with a highly potent recombination machinery of Saccharomyces cerevisiae. Gal4-based yeast two-hybrid (Y2H) assays were performed against DENV-2 proteins (E, prM, M, and NS1). Mammalian two-hybrid (M2H) and double immunofluorescence assays (IFA) were conducted to validate the authenticity of the three selected interactions.
    RESULTS: The cDNA library was of good quality based on its transformation efficiency, cell density, titer, and the percentage of insert size. A total of 36 midgut proteins interacting with DENV-2 proteins were identified, some involved in nucleic acid transcription, oxidoreductase activity, peptidase activity, and ion binding. Positive outcomes were obtained from the three selected interactions validated using M2H and double IFA assays.
    CONCLUSIONS: The identified proteins have different biological activities that may aid in the virus replication pathway. Therefore, the midgut cDNA library is a valuable tool for identifying DENV-2 interacting proteins. The positive outcomes of the three selected proteins validated supported the quality of the cDNA library and the robustness of the Y2H mechanisms.
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