Displaying publications 1 - 20 of 107 in total

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  1. Han R, San Martin P, Ahmed N, Guzman-Holst A, Mohy A, Pinto T, et al.
    Infect Dis Ther, 2024 Apr;13(4):761-778.
    PMID: 38493411 DOI: 10.1007/s40121-024-00945-y
    INTRODUCTION: Herpes zoster (HZ) can cause substantial patient morbidity and lead to large healthcare costs. However, the disease burden of HZ in Southeast Asia may be underestimated. This study aimed to estimate the public health burden of HZ and the impact of vaccinating adults aged ≥ 50 years old in five Southeast Asian countries (Indonesia, Malaysia, Philippines, Thailand, and Vietnam), with adjuvanted recombinant zoster vaccine (RZV) compared with no vaccination.

    METHODS: For each country, we adapted a static multicohort Markov model developed with a 1-year cycle length and lifetime horizon. Demographics were obtained from the World Health Organization, HZ incidence from a worldwide meta-regression reporting Asian-specific values, proportions of postherpetic neuralgia (PHN) and non-PHN complications from local/regional studies, and vaccine efficacy from a long-term follow-up trial. First-dose coverage and second-dose compliance were assumed to be 30% and 70%, respectively. A one-way deterministic sensitivity analysis (OWSA) and probabilistic sensitivity analysis (PSA) were performed to assess the robustness and uncertainty of inputs for each country.

    RESULTS: Without RZV, it was estimated that there would be a total of approximately 10 million HZ cases, 2.1 million PHN cases, and 1.4 million non-PHN complications in individuals aged ≥ 50 years included in the model. Introducing RZV under 30% coverage could avoid approximately 2.2 million (22%) HZ cases, almost 500,000 (21%) PHN cases, and around 300,000 (22%) non-PHN complications. OWSA showed that first-dose coverage and initial HZ incidence had the largest impact on the estimated number of HZ cases avoided. The number needed to vaccinate ranged from 15 to 21 to prevent one case of HZ and from 68 to 104 to prevent one case of PHN across each country.

    CONCLUSIONS: This study demonstrated that there is substantial HZ disease burden in older adults for the five selected countries in Southeast Asia, negatively impacting national healthcare systems. Introducing RZV could potentially reduce this burden. A graphical abstract is available with this article.

  2. Munksgaard NC, Kurita N, Sánchez-Murillo R, Ahmed N, Araguas L, Balachew DL, et al.
    Sci Rep, 2019 10 08;9(1):14419.
    PMID: 31595004 DOI: 10.1038/s41598-019-50973-9
    We present precipitation isotope data (δ2H and δ18O values) from 19 stations across the tropics collected from 2012 to 2017 under the Coordinated Research Project F31004 sponsored by the International Atomic Energy Agency. Rainfall samples were collected daily and analysed for stable isotopic ratios of oxygen and hydrogen by participating laboratories following a common analytical framework. We also calculated daily mean stratiform rainfall area fractions around each station over an area of 5° x 5° longitude/latitude based on TRMM/GPM satellite data. Isotope time series, along with information on rainfall amount and stratiform/convective proportions provide a valuable tool for rainfall characterisation and to improve the ability of isotope-enabled Global Circulation Models to predict variability and availability of inputs to fresh water resources across the tropics.
  3. Taha M, Rahim F, Khan AA, Anouar EH, Ahmed N, Shah SAA, et al.
    Sci Rep, 2020 05 14;10(1):7969.
    PMID: 32409737 DOI: 10.1038/s41598-020-64729-3
    The current study describes synthesis of diindolylmethane (DIM) derivatives based-thiadiazole as a new class of urease inhibitors. Diindolylmethane is natural product alkaloid reported to use in medicinal chemistry extensively. Diindolylmethane-based-thiadiazole analogs (1-18) were synthesized and characterized by various spectroscopic techniques 1HNMR, 13C-NMR, EI-MS and evaluated for urease (jack bean urease) inhibitory potential. All compounds showed excellent to moderate inhibitory potential having IC50 value within the range of 0.50 ± 0.01 to 33.20 ± 1.20 µM compared with the standard thiourea (21.60 ± 0.70 µM). Compound 8 (IC50 = 0.50 ± 0.01 µM) was the most potent inhibitor amongst all derivatives. Structure-activity relationships have been established for all compounds. The key binding interactions of most active compounds with enzyme were confirmed through molecular docking studies.
  4. Inn FX, Ahmed N, Hou LG, Abidin ZAZ, Yi LL, Zainuddin ZM
    Int Urol Nephrol, 2019 Nov;51(11):1949-1953.
    PMID: 31441009 DOI: 10.1007/s11255-019-02262-7
    PURPOSE: The internal drainage provided by a ureteral stent helps with the relief and prevention of ureteral obstruction. By definition, correct stent placement is one with a complete loop in both the renal pelvis and bladder. This prevents stent migration proximally or distally despite urinary flow, patient movement, and ureteral peristalsis.

    METHODS: We performed a comparative prospective cross-sectional study assessing the impact of intravesical stent position on the quality of life in 46 patients with a ureteral stent. This is done using the Ureteral Stent Symptom Questionnaire (USSQ).

    RESULTS: 52.5% of patients had an ipsilateral positioned intravesical stent, while the remaining had their stent positioned contralaterally. Intravesical stent position significantly influenced the quality of life. The USSQ score was worse for the contralateral group. Subscore analysis found that urinary symptoms and body pain index contribute significantly to the morbidity. Majority of patients in the ipsilateral group reported no discomfort as compared to the contralateral group.

    CONCLUSIONS: To the best of our knowledge, this is the first study assessing the impact of intravesical stent position on the quality of life in the Asian population. Intravesical stent position has a significant influence on patient's morbidity and quality of life in particular towards their urinary irritative symptoms and body pain. It is imperative to ensure correct distal placement of ureteric stent that does not cross the midline to the contralateral site. We believe that the USSQ should be used in daily clinical practice in assessing the symptoms related to indwelling ureteric stents.

  5. Al-Mhanna SB, Wan Ghazali WS, Maqsood A, Mohamed M, Ahmed N, Afolabi HA, et al.
    SAGE Open Med, 2023;11:20503121231158981.
    PMID: 36909796 DOI: 10.1177/20503121231158981
    Coronavirus disease 2019 is a severe communicable pulmonary medical problem that has been a challenging disease for everyone in the globe, but vaccines development and administration against this severe acute respiratory syndrome-inducing disease (coronavirus disease 2019) are currently yielding fabulous results. The mean duration of the coronavirus disease 2019 pandemic for this study spanned from 2020 until 2022. These manifestations are accompanied by symptoms of respiratory tract illnesses such as non-productive cough, sore throat, and nasal discharge. Relevant reviews on coronavirus disease 2019 manifestations and outcomes, consisting mainly of the infections/outbreaks, experimental information, and pre- and post-serovaccination details that occurred, were described. After a typical vaccination course, the study aims to summarize and understand more about the effectiveness of exercise on the pre-and post-coronavirus disease 2019 vaccination and its implementations. Physical activity is an immunological function adjuvant to decrease communicable disease risk and enhance immunity post-viral infection vaccination. Moderate-intensity resistance exercisesession directly before getting the influenza vaccine decreases vaccine responses in older adults, such as redness, pain, or inflammation at the injection spot or other adverse consequences compared to the inactive circumstance. However, it was reported that exercise after a shot is generally safe as long as vaccinated people feel well enough. Though exercise before or after vaccination has no negative impact on the protection afforded by the vaccine, people can exercise immediately after receiving the vaccine, as any changes in blood flow will not affect the vaccine's response. One episode of light-to-moderate-intensifying exercise after vaccination may improve the antibody reactions to influenza or the coronavirus disease 2019 vaccine. Vaccination administered pre- and post-regular exercise is an effective approach for boosting antibody responses due to its immunostimulant effects. Future research should investigate how different vaccine antibodies respond to low, moderate, and high physical activity levels.
  6. Kamangar S, Badruddin IA, Ameer Ahamad N, Soudagar MEM, Govindaraju K, Nik-Ghazali N, et al.
    Biomed Mater Eng, 2017;28(3):257-266.
    PMID: 28527189 DOI: 10.3233/BME-171672
    The current study investigates the effect of multi stenosis on the hemodynamic parameters such as wall pressure, velocity and wall shear stress in the realistic left coronary artery. Patients CT scan image data of normal and diseased left coronary artery was chosen for the reconstruction of 3D coronary artery models. The diseased 3D model of left coronary artery shows a narrowing of more than 70% and 80% of area stenosis (AS) at the left main stem (LMS) and left circumflex (LCX) respectively. The results show that the decrease in pressure was found downstream to the stenosis as compared to the coronary artery without stenosis. The maximum pressure drop was noted across the 80% AS at the left circumflex branch. The recirculation zone was also observed immediate to the stenosis and highest wall shear stress was found across the 80% area stenosis. Our analysis provides an insight into the distribution of wall shear stress and pressure drop, thus improving our understanding on the hemodynamics in realistic coronary artery.
  7. Kamangar S, Badruddin IA, Badarudin A, Nik-Ghazali N, Govindaraju K, Salman Ahmed NJ, et al.
    Comput Methods Biomech Biomed Engin, 2017 Mar;20(4):365-372.
    PMID: 27612619 DOI: 10.1080/10255842.2016.1233402
    The current study investigates the hyperemic flow effects on heamodynamics parameters such as velocity, wall shear stress in 3D coronary artery models with and without stenosis. The hyperemic flow is used to evaluate the functional significance of stenosis in the current era. Patients CT scan data of having healthy and coronary artery disease was chosen for the reconstruction of 3D coronary artery models. The diseased 3D models of coronary artery shows a narrowing of >50% lumen area. Computational fluid dynamics was performed to simulate the hyperemic flow condition. The results showed that the recirculation zone was observed immediate to the stenosis and highest wall shear stress was observed across the stenosis. The decrease in pressure was found downstream to the stenosis as compared to the coronary artery without stenosis. Our analysis provides an insight into the distribution of wall shear stress and pressure drop, thus improving our understanding of hyperemic flow effect under both conditions.
  8. Yusof W, Irekeola AA, Wada Y, Engku Abd Rahman ENS, Ahmed N, Musa N, et al.
    Life (Basel), 2021 Nov 11;11(11).
    PMID: 34833100 DOI: 10.3390/life11111224
    Since its first detection in December 2019, more than 232 million cases of COVID-19, including 4.7 million deaths, have been reported by the WHO. The SARS-CoV-2 viral genomes have evolved rapidly worldwide, causing the emergence of new variants. This systematic review and meta-analysis was conducted to provide a global mutational profile of SARS-CoV-2 from December 2019 to October 2020. The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA), and a study protocol was lodged with PROSPERO. Data from 62 eligible studies involving 368,316 SARS-CoV-2 genomes were analyzed. The mutational data analyzed showed most studies detected mutations in the Spike protein (n = 50), Nucleocapsid phosphoprotein (n = 34), ORF1ab gene (n = 29), 5'-UTR (n = 28) and ORF3a (n = 25). Under the random-effects model, pooled prevalence of SARS-CoV-2 variants was estimated at 95.1% (95% CI; 93.3-96.4%; I2 = 98.952%; p = 0.000) while subgroup meta-analysis by country showed majority of the studies were conducted 'Worldwide' (n = 10), followed by 'Multiple countries' (n = 6) and the USA (n = 5). The estimated prevalence indicated a need to continuously monitor the prevalence of new mutations due to their potential influence on disease severity, transmissibility and vaccine effectiveness.
  9. Kalil MNA, Yusof W, Ahmed N, Fauzi MH, Bakar MAA, Sjahid AS, et al.
    Diagnostics (Basel), 2021 Nov 30;11(12).
    PMID: 34943482 DOI: 10.3390/diagnostics11122245
    The antigen rapid diagnostic test (Ag-RDT) is an immunodiagnostic test that detects the presence of viral proteins (antigens) expressed by the COVID-19 virus in a sample from a patient's respiratory tract. This study focused on evaluating the performance of self-conduct buccal and nasal swabs RTK-antigen test compared to nasopharyngeal swab RTK-based COVID-19 diagnostic assays, Panbio™ COVID-19 Ag Rapid Test Device (Nasopharyngeal) (Abbott Rapid Diagnostics Jena GmbH, Jena, Germany) used in hospitals for first-line screening. The sensitivity and specificity of the paired RTK-Ag test in detecting the an-tigen were calculated at 96.4% and 100%, respectively. Fisher exact tests showed the association between nasopharyngeal swabs RTK-Ag assay and buccal-nasal swabs RTK-Ag from ProdetectTM is significant (p-values < 0.001). The result showed that a self-conducted buccal and nasal RTK-antigen rapid test by the patients is comparable to the results obtained from a rapid test device conducted by trained medical personnel using a nasopharyngeal swab.
  10. Ejaz U, Afzal M, Mazhar M, Riaz M, Ahmed N, Rizg WY, et al.
    Int J Nanomedicine, 2024;19:453-469.
    PMID: 38250190 DOI: 10.2147/IJN.S446017
    INTRODUCTION: Silver nanoparticles (AgNPs) have been found to exhibit unique properties which show their potential to be used in various therapies. Green synthesis of AgNPs has been progressively gaining acceptance due to its cost-effectiveness and energy-efficient nature.

    OBJECTIVE: In the current study, aqueous extract of Thymus vulgaris (T. vulgaris) was used to synthesize the AgNPs using green synthesis techniques followed by checking the effectiveness and various biological activities of these AgNPs.

    METHODS: At first, the plant samples were proceeded for extraction of aqueous extracts followed by chromatography studies to measure the phenolics and flavonoids. The synthesis and characterization of AgNPs were done using green synthesis techniques and were confirmed using Fourier transform infra-red (FT-IR) spectroscopy, UV-visible spectroscopy, scanning electron microscope (SEM), zeta potential, zeta sizer and X-Ray diffraction (XRD) analysis. After confirmation of synthesized AgNPs, various biological activities were checked.

    RESULTS: The chromatography analysis detected nine compounds accounting for 100% of the total amount of plant constituents. The FT-IR, UV-vis spectra, SEM, zeta potential, zeta sizer and XRD analysis confirmed the synthesis of AgNPs and the variety of chemical components present on the surface of synthesized AgNPs in the plant extract. The antioxidant activity of AgNPs showed 92% inhibition at the concentration of at 1000 µg/mL. A greater inhibitory effect in anti-diabetic analysis was observed with synthesized AgNPs as compared to the standard AgNPs. The hemolytic activity was low, but despite low concentrations of hemolysis activity, AgNPs proved not to be toxic or biocompatible. The anti-inflammatory activity of AgNPs was observed by in-vitro and in-vivo approaches in range at various concentrations, while maximum inhibition occurs at 1000 µg (77.31%).

    CONCLUSION: Our data showed that the potential biological activities of the bioactive constituents of T. vulgaris can be enhanced through green synthesis of AgNPs from T. vulgaris aqueous extracts. In addition, the current study depicted that AgNPs have good potential to cure different ailments as biogenic nano-medicine.

  11. Gupta T, Connors M, Tan JW, Manosroi W, Ahmed N, Ting PY, et al.
    Am J Hypertens, 2017 Dec 08;31(1):124-131.
    PMID: 28985281 DOI: 10.1093/ajh/hpx146
    BACKGROUND: Understanding the interactions between genetics, sodium (Na+) intake, and blood pressure (BP) will help overcome the lack of individual specificity in our current treatment of hypertension. This study had 3 goals: expand on the relationship between striatin gene (STRN) status and salt-sensitivity of BP (SSBP); evaluate the status of Na+ and volume regulating systems by striatin risk allele status; evaluate potential SSBP mechanisms.

    METHODS: We assessed the relationship between STRN status in humans (HyperPATH cohort) and SSBP and on volume regulated systems in humans and a striatin knockout mouse (STRN+/-).

    RESULTS: The previously identified association between a striatin risk allele and systolic SSBP was demonstrated in a new cohort (P = 0.01). The STRN-SSBP association was significant for the combined cohort (P = 0.003; β = +5.35 mm Hg systolic BP/risk allele) and in the following subgroups: normotensives, hypertensives, men, and older subjects. Additionally, we observed a lower epinephrine level in risk allele carriers (P = 0.014) and decreased adrenal medulla phenylethanolamine N-methyltransferase (PNMT) in STRN+/- mice. No significant associations were observed with other volume regulated systems.

    CONCLUSIONS: These results support the association between a variant of striatin and SSBP and extend the findings to normotensive individuals and other subsets. In contrast to most salt-sensitive hypertensives, striatin-associated SSBP is associated with normal plasma renin activity and reduced epinephrine levels. These data provide clues to the underlying cause and a potential pathway to achieve, specific, personalized treatment, and prevention.

  12. Nandanwar N, Janssen T, Kühl M, Ahmed N, Ewers C, Wieler LH
    Int J Med Microbiol, 2014 Oct;304(7):835-42.
    PMID: 25037925 DOI: 10.1016/j.ijmm.2014.06.009
    Extraintestinal pathogenic Escherichia coli (ExPEC) strains of certain genetic lineages are frequently implicated in a wide range of diseases in humans and birds. ExPEC strains belonging to the phylogenetic lineage/sequence type complex 95 (STC95) are one such prominent lineage that is commonly isolated from extraintestinal infections such as systemic disease in poultry and urinary tract infections (UTIs), neonatal meningitis and sepsis in humans. Several epidemiological studies have indicated that ST95 strains obtained from such infections may share similar virulence genes and other genomic features. However, data on their ability to establish infections in vivo as deduced from the manifestation of similar virulence phenotypes remain elusive. In the present study, 116 STC95 ExPEC isolates comprising 55 human and 61 avian strains, possessing similar virulence gene patterns, were characterized in vitro using adhesion, invasion, biofilm formation and serum bactericidal assays. Overall, STC95 strains from both groups, namely human and birds, were equally capable of adhering to and invading the two mammalian kidney cell lines. Similarly, these strains were able to form strong biofilms in M63 medium. Furthermore, they were equally resistant to the bactericidal activity of human and avian serum. Our cumulative data reinforce the understanding that ST95 strains from poultry present a potential zoonotic risk and therefore need a One Health strategy for a successfull intervention.
  13. Anwar S, Madkor HR, Ahmed N, Wagih ME
    Indian J Pharmacol, 2018 9 1;50(3):108-115.
    PMID: 30166747 DOI: 10.4103/ijp.IJP_660_16
    OBJECTIVE: Silymarin, extracted from the seeds of Silybum marianum L. (Milk thistle), is traditionally used for treating various illnesses such as diabetes, cancer, inflammation, hepatitis, liver cirrhosis, and renal problems. Acute cytotoxicity and genotoxicity studies have been reported with ambiguous outcomes; however, its relevant anticlastogenic potential is not yet evaluated. This study was aimed to evaluate in vivo subacute anticlastogenic properties of silymarin to validate its use as a medicinal agent.

    MATERIALS AND METHODS: Silymarin was isolated from seeds of milk thistle. Various genotoxicity bioassays of silymarin were performed using mice. First, the bone marrow cell proliferation was estimated by calculating mitotic index. Second, the chromosomal abnormalities in mice bone marrow cells were studied. Third, micronucleated polychromatic erythrocytes (MPE) test and in vivo activation of sister chromatid exchanges (SCEs) were carried out in mice bone marrow cells. Finally, primary spermatocytes were analyzed to estimate genotoxic effect of silymarin on germ cells.

    RESULTS: We found that silymarin is capable of inducing a significant increase (P ≤ 0.05) in cell proliferation of bone marrow cells. There is no increase in chromosomal aberrations following silymarin treatments. Results clearly showed that it significantly (P ≤ 0.05) decreased the MPE. Likewise, it was found to be a negative inducer of SCEs. It decreased in total abnormal metaphase, SCEs, MPE, and aberrant diakinesis.

    CONCLUSION: The results demonstrated that silymarin has a strong anticlastogenic activity upon mice genome in somatic and germ cells, indicating its safe use as a medicinal substance. Furthermore, it is not only safe but also has protective effect from clastogens.

  14. Abbasi MS, Ahmed N, Irfan AB, Al-Saleh S, Abduljabbar T, Vohra F
    Case Rep Dent, 2022;2022:2686983.
    PMID: 35154831 DOI: 10.1155/2022/2686983
    Microstomia is an abnormally reduced oral aperture. In the literature, it is not classified by any particular size criteria, rather defined by its effects on function and esthetics. Prosthodontic management of edentulous patients with microstomia is a challenging task. Use of conventional methods for recording an impression and fabricating prosthesis is not effective in such patients. To fabricate well-fitting prosthesis, accuracy of impression recording important anatomic landmarks is essential. Formation of an exacting custom tray and diagnostic cast is critical for final impression accuracy. Provision of a well-fitting prosthesis in microstomia patient will restore esthetics, comfort, and function with oral and systemic patient wellbeing. This paper presents a case report of managing an edentulous microstomia patient with sectional removable prosthesis. Furthermore, it proposes a novel classification system for microstomia patients according to severity of the condition.
  15. Ahmed N, Loke MF, Kumar N, Vadivelu J
    Helicobacter, 2013 Sep;18 Suppl 1:1-4.
    PMID: 24011237 DOI: 10.1111/hel.12069
    We describe features of key additions to the existing pool of publicly accessible Helicobacter pylori genome sequences and sequences of Helicobacter pylori phages from April 2012 to March 2013. In addition, important studies involving H. pylori genomes, especially those pertaining to genomic diversity, disease outcome, H. pylori population structure and evolution are reviewed. High degree of homologous recombination contributes to increased diversity of H. pylori genomes. New methods of resolving H. pylori population structure to an ultrafine level led to the proposal of new subpopulations. As the magnitude of diversity in the H. pylori gene pool becomes more and more clear, geographic and demographic factors should be brought to analysis while identifying disease-specific biomarkers and defining new virulence mechanisms.
  16. Yap KP, Gan HM, Teh CS, Baddam R, Chai LC, Kumar N, et al.
    J Bacteriol, 2012 Nov;194(21):5970-1.
    PMID: 23045488 DOI: 10.1128/JB.01416-12
    Salmonella enterica serovar Typhi is a human pathogen that causes typhoid fever predominantly in developing countries. In this article, we describe the whole genome sequence of the S. Typhi strain CR0044 isolated from a typhoid fever carrier in Kelantan, Malaysia. These data will further enhance the understanding of its host persistence and adaptive mechanism.
  17. Yap KP, Teh CS, Baddam R, Chai LC, Kumar N, Avasthi TS, et al.
    J Bacteriol, 2012 Sep;194(18):5124-5.
    PMID: 22933756 DOI: 10.1128/JB.01062-12
    Salmonella enterica serovar Typhi is the causative agent of typhoid fever, which causes nearly 21.7 million illnesses and 217,000 deaths globally. Herein, we describe the whole-genome sequence of the Salmonella Typhi strain ST0208, isolated from a sporadic case of typhoid fever in Kuala Lumpur, Malaysia. The whole-genome sequence and comparative genomics allow an in-depth understanding of the genetic diversity, and its link to pathogenicity and evolutionary dynamics, of this highly clonal pathogen that is endemic to Malaysia.
  18. Ahmed N, Anwar S, Thet Htar T
    Front Chem, 2017;5:36.
    PMID: 28664157 DOI: 10.3389/fchem.2017.00036
    The Plasmodium falciparum Lactate Dehydrogenase enzyme (PfLDH) catalyzes inter-conversion of pyruvate to lactate during glycolysis producing the energy required for parasitic growth. The PfLDH has been studied as a potential molecular target for development of anti-malarial agents. In an attempt to find the potent inhibitor of PfLDH, we have used Discovery studio to perform molecular docking in the active binding pocket of PfLDH by CDOCKER, followed by three-dimensional quantitative structure-activity relationship (3D-QSAR) studies of tricyclic guanidine batzelladine compounds, which were previously synthesized in our laboratory. Docking studies showed that there is a very strong correlation between in silico and in vitro results. Based on docking results, a highly predictive 3D-QSAR model was developed with q(2) of 0.516. The model has predicted r(2) of 0.91 showing that predicted IC50 values are in good agreement with experimental IC50 values. The results obtained from this study revealed the developed model can be used to design new anti-malarial compounds based on tricyclic guanidine derivatives and to predict activities of new inhibitors.
  19. Ullah F, Javed F, Mushtaq I, Rahman LU, Ahmed N, Din IU, et al.
    Int J Biol Macromol, 2023 Jan 05;230:123131.
    PMID: 36610570 DOI: 10.1016/j.ijbiomac.2022.123131
    3-D Bioprinting is employed as a novel approach in biofabrication to promote skin regeneration following chronic-wounds and injury. A novel bioink composed of carbohydrazide crosslinked {polyethylene oxide-co- Chitosan-co- poly(methylmethacrylic-acid)} (PEO-CS-PMMA) laden with Nicotinamide and human dermal fibroblast was successfully synthesized via Free radical-copolymerization at 73 °C. The developed bioink was characterized in term of swelling, structural-confirmation by solid state 13C-Nuclear Magnetic Resonance (NMR), morphology, thermal, 3-D Bioprinting via extrusion, rheological and interaction with DNA respectively. The predominant rate of gelation was attributed to the electrostatic interactions between cationic CS and anionic PMMA pendant groups. The morphology of developed bioink presented a porous architecture satisfying the cell and growth-factor viability across the barrier. The thermal analysis revealed two-step degradation with 85 % weight loss in term of decomposition and molecular changes in the bioink moieties By applying low pressure in the range of 25-50 kPa, the optimum reproducibility and printability were determined at 37 °C in the viscosity range of 500-550 Pa. s. A higher survival rate of 92 % was observed for (PEO-CS-PMMA) in comparison to 67 % for pure chitosan built bioink. A binding constant of K ≈ 1.8 × 106 M-1 recognized a thermodynamically stable interaction of (PEO-CS-PMMA) with the Salmon-DNA. Further, the addition of PEO (5.0 %) was addressed with better self-healing and printability to produce skin-tissue constructs to replace the infected skin in human.
  20. Ahamed NU, Ahmed N, Alqahtani M, Altwijri O, Ahmad RB, Sundaraj K
    J Phys Ther Sci, 2015 Jan;27(1):39-40.
    PMID: 25642033 DOI: 10.1589/jpts.27.39
    [Purpose] This study investigated the changes in the slope of EMG-time curves (relationship) at the maximal and different levels of dynamic (eccentric and concentric) and static (isometric) contractions. [Subjects and Methods] The subject was a 17 year-old male adolescent. The surface EMG signal of the dominant arm's biceps brachii (BB) was recorded through electrodes placed on the muscle belly. [Results] The results obtained during the contractions show that the regression slope was very close to 1.00 during concentric contraction, whereas those of eccentric and isometric contractions were lower. Significant differences were found for the EMG amplitude and time lags among the contractions. [Conclusion] The results show that the EMG signal of the BB varies among the three modes of contraction and the relationship of the EMG amplitude with a time lag gives the best fit during concentric contraction.
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