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Fulltext An Adaptive Early Stopping Technique for DenseNet169-Based Knee Osteoarthritis Detection Model

Al-Rimy BAS, Saeed F, Al-Sarem M, Albarrak AM, Qasem SN

Diagnostics (Basel), 2023 May 29;13(11).
PMID: 37296755 DOI: 10.3390/diagnostics13111903

Knee osteoarthritis (OA) detection is an important area of research in health informatics that aims to improve the accuracy of diagnosing this debilitating condition. In this paper, we investigate the ability of DenseNet169, a deep convolutional neural network architecture, for knee osteoarthritis detection using X-ray images. We focus on the use of the DenseNet169 architecture and propose an adaptive early stopping technique that utilizes gradual cross-entropy loss estimation. The proposed approach allows for the efficient selection of the optimal number of training epochs, thus preventing overfitting. To achieve the goal of this study, the adaptive early stopping mechanism that observes the validation accuracy as a threshold was designed. Then, the gradual cross-entropy (GCE) loss estimation technique was developed and integrated to the epoch training mechanism. Both adaptive early stopping and GCE were incorporated into the DenseNet169 for the OA detection model. The performance of the model was measured using several metrics including accuracy, precision, and recall. The obtained results were compared with those obtained from the existing works. The comparison shows that the proposed model outperformed the existing solutions in terms of accuracy, precision, recall, and loss performance, which indicates that the adaptive early stopping coupled with GCE improved the ability of DenseNet169 to accurately detect knee OA.
Fulltext Shockproof Deformable Infrared Radiation Sensors Based on a Polymeric Rubber and Organic Semiconductor H2Pc-CNT Composite

Chani MTS, Karimov KS, Kamal T, Fatima N, Rahman MM, Asiri AM

Polymers (Basel), 2023 Jun 15;15(12).
PMID: 37376337 DOI: 10.3390/polym15122691

Polymeric rubber and organic semiconductor H2Pc-CNT-composite-based surface- and sandwich-type shockproof deformable infrared radiation (IR) sensors were fabricated using a rubbing-in technique. CNT and CNT-H2Pc (30:70 wt.%) composite layers were deposited on a polymeric rubber substrate as electrodes and active layers, respectively. Under the effect of IR irradiation (0 to 3700 W/m2), the resistance and the impedance of the surface-type sensors decreased up to 1.49 and 1.36 times, respectively. In the same conditions, the resistance and the impedance of the sandwich-type sensors decreased up to 1.46 and 1.35 times, respectively. The temperature coefficients of resistance (TCR) of the surface- and sandwich-type sensors are 1.2 and 1.1, respectively. The novel ratio of the H2Pc-CNT composite ingredients and comparably high value of the TCR make the devices attractive for bolometric applications meant to measure the intensity of infrared radiation. Moreover, given their easy fabrication and low-cost materials, the fabricated devices have great potential for commercialization.
Fulltext Biochar and Arbuscular mycorrhizal fungi mediated enhanced drought tolerance in Okra (Abelmoschus esculentus) plant growth, root morphological traits and physiological properties

Jabborova D, Annapurna K, Al-Sadi AM, Alharbi SA, Datta R, Zuan ATK

Saudi J Biol Sci, 2021 Oct;28(10):5490-5499.
PMID: 34588859 DOI: 10.1016/j.sjbs.2021.08.016

Drought is a major abiotic factor limiting plant growth and crop production. There is limited information on effect of interaction between biochar and Arbuscular mycorrhizal fungi (AMF) on okra growth, root morphological traits and soil enzyme activities under drought stress. We studied the influence of biochar and AMF on the growth of Okra (Abelmoschus esculentus) in pot experiments in a net house under drought condition. The results showed that the biochar treatment significantly increased plant growth (the plant height by 14.2%, root dry weight by 30.0%) and root morphological traits (projected area by 22.3% and root diameter by 22.7%) under drought stress. In drought stress, biochar treatment significantly enhanced the chlorophyll 'a' content by 32.7%, the AMF spore number by 22.8% and the microbial biomass as compared to the control. Plant growth parameters such as plant height, shoot and root dry weights significantly increased by AMF alone, by 16.6%, 21.0% and 40.0% respectively under drought condition. Other plant biometrics viz: the total root length, the root volume, the projected area and root diameter improved significantly with the application of AMF alone by 38.3%, 60.0%,16.8% and 15.9% respectively as compared with control. Compared to the control, AMF treatment alone significantly enhanced the total chlorophyll content by 36.6%, the AMF spore number by 39.0% and the microbial biomass by 29.0% under drought condition. However, the highest values of plant growth parameters (plant height, shoot dry weight, root dry weight) and root morphological traits (the total root length, root volume, projected area, root surface area) were observed in the combined treatment of biochar and AMF treatment viz: 31.9%, 34.2%, 60.0% and 68.6%, 66.6%, 45.5%, 41.8%, respectively compared to the control under drought stress. The nitrogen content, total chlorophyll content and microbial biomass increased over un-inoculated control. The soil enzymes; alkaline phosphatase, dehydrogenase and fluorescein diacetate enzyme activities significantly increased in the combined treatment by 55.8%, 68.7% and 69.5%, respectively as compared to the control under drought stress. We conclude that biochar and AMF together is potentially beneficial for cultivation of okra in drought stress conditions.
Fulltext Co-crystallization of a neutral mol-ecule and its zwitterionic tautomer: structure and Hirshfeld surface analysis of 5-methyl-4-(5-methyl-1H-pyrazol-3-yl)-2-phenyl-2,3-di-hydro-1H-pyrazol-3-one 5-methyl-4-(5-methyl-1H-pyrazol-2-ium-3-yl)-3-oxo-2-phenyl-2,3-di-hydro-1H-pyrazol-1-ide monohydrate

Asiri AM, Alzahrani KAH, Faidallah HM, Alamry KA, Jotani MM, Tiekink ERT

Acta Crystallogr E Crystallogr Commun, 2019 May 01;75(Pt 5):565-570.
PMID: 31110787 DOI: 10.1107/S2056989019004389

The title compound, 2C14H14N4O·H2O, comprises a neutral mol-ecule containing a central pyrazol-3-one ring flanked by an N-bound phenyl group and a C-bound 5-methyl-1H-pyrazol-3-yl group (at positions adjacent to the carbonyl substituent), its zwitterionic tautomer, whereby the N-bound proton of the central ring is now resident on the pendant ring, and a water mol-ecule of crystallization. Besides systematic variations in geometric parameters, the two independent organic mol-ecules have broadly similar conformations, as seen in the dihedral angle between the five-membered rings [9.72 (9)° for the neutral mol-ecule and 3.32 (9)° for the zwitterionic tautomer] and in the dihedral angles between the central and pendant five-membered rings [28.19 (8) and 20.96 (8)° (neutral mol-ecule); 11.33 (9) and 11.81 (9)°]. In the crystal, pyrazolyl-N-H⋯O(carbon-yl) and pyrazolium-N-H⋯N(pyrazol-yl) hydrogen bonds between the independent organic mol-ecules give rise to non-symmetric nine-membered {⋯HNNH⋯NC3O} and {⋯HNN⋯HNC3O} synthons, which differ in the positions of the N-bound H atoms. These aggregates are connected into a supra-molecular layer in the bc plane by water-O-H⋯N(pyrazolide), water-O-H⋯O(carbon-yl) and pyrazolyl-N-H⋯O(water) hydrogen bonding. The layers are linked into a three-dimensional architecture by methyl-C-H⋯π(phen-yl) inter-actions. The different inter-actions, in particular the weaker contacts, formed by the organic mol-ecules are clearly evident in the calculated Hirshfeld surfaces, and the calculated electrostatic potentials differentiate the tautomers.
Fulltext Effects of solder temperature on pin through-hole during wave soldering: thermal-fluid structure interaction analysis

Aziz MS, Abdullah MZ, Khor CY

ScientificWorldJournal, 2014;2014:482363.
PMID: 25225638 DOI: 10.1155/2014/482363

An efficient simulation technique was proposed to examine the thermal-fluid structure interaction in the effects of solder temperature on pin through-hole during wave soldering. This study investigated the capillary flow behavior as well as the displacement, temperature distribution, and von Mises stress of a pin passed through a solder material. A single pin through-hole connector mounted on a printed circuit board (PCB) was simulated using a 3D model solved by FLUENT. The ABAQUS solver was employed to analyze the pin structure at solder temperatures of 456.15 K (183(°)C) < T < 643.15 K (370(°)C). Both solvers were coupled by the real time coupling software and mesh-based parallel code coupling interface during analysis. In addition, an experiment was conducted to measure the temperature difference (ΔT) between the top and the bottom of the pin. Analysis results showed that an increase in temperature increased the structural displacement and the von Mises stress. Filling time exhibited a quadratic relationship to the increment of temperature. The deformation of pin showed a linear correlation to the temperature. The ΔT obtained from the simulation and the experimental method were validated. This study elucidates and clearly illustrates wave soldering for engineers in the PCB assembly industry.
Experimental infection of brown-marbled grouper, Epinephelus fuscoguttatus (Forskal), with Vibrio parahaemolyticus identifies parvalbumin beta-2 subunit I, alpha-2-macroglobulin, nattectin and immunoglobulin light chain, differentially expressed in resistant grouper

Low CF, Shamsudin MN, Abdullah M, Chee HY, Aliyu-Paiko M

J Fish Dis, 2015 Jan;38(1):17-25.
PMID: 24397626 DOI: 10.1111/jfd.12195

The mechanisms through which brown-marbled grouper accomplishes resistance to infection, particularly against Vibrios, are not yet fully understood. In this study, brown-marbled grouper fingerlings were experimentally infected with Vibrio parahaemolyticus, to identify disease resistance grouper, and the serum proteome profiles were compared between resistant and susceptible candidates, via two-dimensional gel electrophoresis (2-DE). The results showed that putative parvalbumin beta-2 subunit I, alpha-2-macroglobulin, nattectin and immunoglobulin light chain proteins were among proteins that significantly overexpressed in the resistant fish as compared to the susceptible group of fish, whereas apolipoprotein E and immunoglobulin light chain proteins were observed to be differentially overexpressed in the susceptible fish. Further analysis by peptide sequencing revealed that the immunoglobulin light chain proteins identified in the resistant and susceptible groups differed in amino acid composition. Taken together, the results demonstrated for the first time that putative parvalbumin beta-2 subunit I, alpha-2-macroglobulin, nattectin and immunoglobulin light chain are among important proteins participating to effect disease resistance mechanism in fish and were overexpressed to function collectively to resist V. parahaemolyticus infection. Most of these molecules are mediators of immune response.
Fulltext Leptospirosis, an emerging zoonotic disease in Malaysia

Thayaparan S, Robertson ID, Fairuz A, Suut L, Abdullah MT

Malays J Pathol, 2013 Dec;35(2):123-32.
PMID: 24362475 MyJurnal

Leptospirosis is an endemic disease in Malaysia and recently has received increasing attention mainly due to several recent incidents that have resulted in human mortality which have alarmed health professionals in Malaysia. The increasing incidence of leptospirosis in forested regions is associated with the bacteria infecting small wild mammals other than rats. Infection in wildlife could result in the introduction of new serovars to humans and domesticated animals. More research on leptospirosis and the screening of wildlife and humans near wildlife habitats is required to have a better understanding of the involvement of wildlife in the disease.
Biochemical characterisation during seed development of oil palm (Elaeis guineensis)

Kok SY, Namasivayam P, Ee GC, Ong-Abdullah M

J Plant Res, 2013 Jul;126(4):539-47.
PMID: 23575803 DOI: 10.1007/s10265-013-0560-8

Developmental biochemical information is a vital base for the elucidation of seed physiology and metabolism. However, no data regarding the biochemical profile of oil palm (Elaeis guineensis Jacq.) seed development has been reported thus far. In this study, the biochemical changes in the developing oil palm seed were investigated to study their developmental pattern. The biochemical composition found in the seed differed significantly among the developmental stages. During early seed development, the water, hexose (glucose and fructose), calcium and manganese contents were present in significantly high levels compared to the late developmental stage. Remarkable changes in the biochemical composition were observed at 10 weeks after anthesis (WAA): the dry weight and sucrose content increased significantly, whereas the water content and hexose content declined. The switch from a high to low hexose/sucrose ratio could be used to identify the onset of the maturation phase. At the late stage, dramatic water loss occurred, whereas the content of storage reserves increased progressively. Lauric acid was the most abundant fatty acid found in oil palm seed starting from 10 WAA.
Inhibitory effects of palm α-, γ- and δ-tocotrienol on lipopolysaccharide-induced nitric oxide production in BV2 microglia

Tan SW, Ramasamy R, Abdullah M, Vidyadaran S

Cell Immunol, 2011;271(2):205-9.
PMID: 21839427 DOI: 10.1016/j.cellimm.2011.07.012

Anti-inflammatory actions of the vitamin E fragment tocotrienol have not been described for microglia. Here, we screened palm α-, γ- and δ-tocotrienol isoforms and Tocomin® 50% (contains spectrum of tocotrienols and tocopherols) for their ability to limit nitric oxide (NO) production by BV2 microglia. Microglia were treated with varying doses of tocotrienols for 24h and stimulated with 1 μg/ml lipopolysaccharide (LPS). All tocotrienol isoforms reduced NO release by LPS-stimulated microglia, with 50 μM being the most potent tocotrienol dose. Of the isoforms tested, δ-tocotrienol lowered NO levels the most, reducing NO by approximately 50% at 48 h post-LPS treatment (p
Fulltext Mesenchymal stem cells inhibit proliferation of lymphoid origin haematopoietic tumour cells by inducing cell cycle arrest

Sarmadi VH, Tong CK, Vidyadaran S, Abdullah M, Seow HF, Ramasamy R

Med J Malaysia, 2010 Sep;65(3):209-14.
PMID: 21939170

We have previously shown that mesenchymal stem cells (MSC) inhibit tumour cell proliferation, thus promising a novel therapy for treating cancers. In this study, MSC were generated from human bone marrow samples and characterised based on standard immunophenotyping. When MSC were co-cultured with BV173 and Jurkat tumour cells, the proliferation of tumour cells were profoundly inhibited in a dose dependent manner mainly via cell to cell contact interaction. Further cell cycle analysis reveals that MSC arrest tumour cell proliferation in G0/G1 phase of cell cycle thus preventing the entry of tumour cells into S phase of cell cycle.
Multivariate and Geoaccumulation Index evaluation in mangrove surface sediment of Mengkabong lagoon, Sabah

Praveena SM, Ahmed A, Radojevic M, Abdullah MH, Aris AZ

Bull Environ Contam Toxicol, 2008 Jul;81(1):52-6.
PMID: 18506379 DOI: 10.1007/s00128-008-9460-3

Spatial variations in estuarine intertidal sediment have been often related to such environmental variables as salinity, sediment types, heavy metals and base cations. However, there have been few attempts to investigate the difference condition between high and low tides relationships and to predict their likely responses in an estuarine environment. This paper investigates the linkages between environmental variables and tides of estuarine intertidal sediment in order to provide a basis for describing the effect of tides in the Mengkabong lagoon, Sabah. Multivariate statistical technique, principal components analysis (PCA) was employed to better interpret information about the sediment and its controlling factors in the intertidal zone. The calculation of Geoaccumulation Index (I(geo)) suggests the Mengkabong mangrove sediments are having background concentrations for Al, Cu, Fe, and Zn and unpolluted for Pb. Extra efforts should therefore pay attention to understand the mechanisms and quantification of different pathways of exchange within and between intertidal zones.
Fulltext Cell engineering and molecular pharming for biopharmaceuticals

Abdullah MA, Rahmah AU, Sinskey AJ, Rha CK

Open Med Chem J, 2008;2:49-61.
PMID: 19662143 DOI: 10.2174/1874104500802010049

Biopharmaceuticals are often produced by recombinant E. coli or mammalian cell lines. This is usually achieved by the introduction of a gene or cDNA coding for the protein of interest into a well-characterized strain of producer cells. Naturally, each recombinant production system has its own unique advantages and disadvantages. This paper examines the current practices, developments, and future trends in the production of biopharmaceuticals. Platform technologies for rapid screening and analyses of biosystems are reviewed. Strategies to improve productivity via metabolic and integrated engineering are also highlighted.
Computed tomographic evaluation of the odontoid process for two-screw fixation in type-II fracture: a Malaysian perspective

Yusof MI, Yusof AH, Abdullah MS, Hussin TM

J Orthop Surg (Hong Kong), 2007 Apr;15(1):67-72.
PMID: 17429121

To measure the diameter of the odontoid process in a Malaysian population using computed tomographic (CT) scan and determine the feasibility of treating type-II odontoid fractures using 2 cortical screws.
Time-domain reconstruction using sensitivity coefficients for limited view ultrawide band tomography

Abdullah MZ, Yin W, Bilal M, Armitage DW, Mackin R, Peyton AJ

Rev Sci Instrum, 2007 Aug;78(8):084703.
PMID: 17764343

This article addresses time-domain ultrawide band (UWB) electromagnetic tomography for reconstructing the unknown spatial characteristic of an object from observations of the arrivals of short electromagnetic (EM) pulses. Here, the determination of the first peak arrival of the EM traces constitutes the forward problem, and the inverse problem aims to reconstruct the EM property distribution of the media. In this article, the finite-difference time-domain method implementing a perfectly matched layer is used to solve the forward problem from which the system sensitivity maps are determined. Image reconstruction is based on the combination of a linearized update and regularized Landweber minimization algorithm. Experimental data from a laboratory UWB system using targets of different contrasts, sizes, and shapes in an aqueous media are presented. The results show that this technique can accurately detect and locate unknown targets in spite of the presence of significant levels of noise in the data.
Which mild head injured patients should have follow-up after discharge from an accident and emergency ward? A study in a university hospital setting in Kelantan, Malaysia

Chan HC, Adnan WA, Jaalam K, Abdullah MR, Abdullah J

Southeast Asian J. Trop. Med. Public Health, 2005 Jul;36(4):982-93.
PMID: 16295557

Mild head injury (MHI) is a common presentation to many hospitals in both rural and urban settings in Southeast Asia, but it is not well studied. We studied 330 patients that presented to Hospital Universiti Sains Malaysia Emergency Department with possible MHI, with the intentions to identify prognostic factors that may improve the diagnosis of MHI in the emergency setting as well as to determine which patients would need follow-up. Patients' one-year outcomes were classified as discharged well (DW) for patients without post-traumatic signs and symptoms and discharged with long term follow-up (DFU) for patients with such signs and symptoms. Four patients died and 82 were DFU. An abnormal skull X ray was associated with mode of accident and type of transportation, older age, presence of vomiting, confusion, bleeding from ear, nose or throat, abnormal pupil size on the right side associated with orbital trauma, unequal pupillary reflexes, absence of loss of consciousness (LOC), a lower Glasgow Coma Scale (GCS) score, multiple clinical presentations, and DFU. An abnormal CT scan was associated with older age, multiple clinical presentation, skull X-ray findings, and DFU. A similar analysis on outcomes revealed that mode of accident, older age, vomiting, confusion, headache, bleeding from ear, nose and throat, neurological deficits, absence of LOC, pupil size, multiple presentation, abnormal skull X ray, CT scan of the brain, and a GCS of 13 was associated with DFU. In conclusion, all patients involved in motor vehicle accidents (MVAs), especially motorcycles, aged over 30 years of age, with multiple clinical presentations, including a lower GCS, and with abnormal radiological findings should have a longer follow-up due to persistent post-traumatic symptomatology.
Fulltext Seroepidemiological study of leptospirosis among the communities living in periurban areas of Sarawak, Malaysia

Thayaparan S, Robertson ID, Fairuz A, Suut L, Gunasekera UC, Abdullah MT

Med J Malaysia, 2015 Oct;70(5):288-94.
PMID: 26556117 MyJurnal

INTRODUCTION: Leptospirosis is endemic to tropical regions of the world and is re-emerging as a new danger to public health in Malaysia. the purpose of this particular study was to determine the common leptospiral serovars present in human communities living around wildlife reserves/disturbed forest habitats. the objective of this study was to estimate the seroprevalence of leptospirosis and finding infecting serovars in villages surrounded habitats where wildlife lives in Sarawak, Malaysia.

METHODS: A cross-sectional serological survey of 198 humans was conducted in four villages around Kuching, Sarawak between January 2011 and March 2012.

RESULTS: A seroprevalence of 35.9% (95%cI 29.2-43.0) to the MAt was detected in the tested humans. Antibodies to serovar Lepto 175 Sarawak were most commonly detected (31.3%; 95%cI 24.9-38.3) and were detected in individuals at all four locations. the presence of skin wounds (Or 3.1), farm animals (Or 2.5) and rats (Or 11.2) were all significantly associated with seropositivity in a multivariable logistic regression model.

CONCLUSIONS: the results of the current study are important as wildlife may act as reservoirs of leptospires for humans. Health authorities should expand disease control measures to minimise the spill-over from wildlife to humans visiting, living or working in the sampled locations. the pathogenic status of serovar Lepto 175 Sarawak also requires further investigation.
Comparison between gutta-percha and resin-coated gutta-percha using different obturation techniques

Al-Afifi NA, Abdullah M, Al-Amery SM, Abdulmunem M

J Appl Biomater Funct Mater, 2016 Jul 26;14(3):e307-13.
PMID: 27149939 DOI: 10.5301/jabfm.5000273

BACKGROUND: The aim of this study was to evaluate and compare the obturation quality between canals obturated with gutta-percha/AH Plus sealer (GP group) and resin-coated GP/EndoREZ® sealer (ER group).
METHODS: A total sample of 90 mandibular premolar teeth was divided into 2 groups (2 × 45 canals): the GP group and ER group. Each group was further divided into 3 subgroups (n = 15): cold lateral compaction (CLC), warm lateral compaction (WLC) and single cone (SC). The teeth were subsequently embedded in resin and sectioned horizontally at 1, 3, 6 and 9 mm. All sections were then viewed with a stereomicroscope at ×40 magnification. The area occupied by core filling materials was determined using Cell^D software.
RESULTS: With CLC, the percentage of core filling materials in the ER group was significantly higher than in the GP group at the 1- and 3-mm levels. Similarly, with WLC, the percentage of core filling material in the ER group was significantly higher than in the GP group at the 1-, 3- and 9-mm levels. With SC, the percentage of core filling materials in the ER group was significantly higher than in the GP group at all levels.
CONCLUSIONS: It can be concluded that the resin-coated GP/EndoREZ® sealer is superior to the gutta-percha/AH Plus in the percentage of core filling material.
A genus- and species-specific nested polymerase chain reaction malaria detection assay for epidemiologic studies

Singh B, Bobogare A, Cox-Singh J, Snounou G, Abdullah MS, Rahman HA

Am J Trop Med Hyg, 1999 Apr;60(4):687-92.
PMID: 10348249

A nested polymerase chain reaction (PCR) assay that uses Plasmodium genus-specific primers for the initial PCR (nest 1) amplification and either genus- or species-specific primers for the nest 2 amplifications was tested on laboratory and field samples. With in vitro cultured Plasmodium falciparum-infected blood samples, it was capable of detecting six parasites/microl of blood using DNA prepared from 25-microl blood spots on filter paper. The assay was evaluated on fingerprick blood samples collected on filter paper from 129 individuals living in a malaria-endemic area in Malaysia. Malaria prevalence by genus-specific nested PCR was 35.6% (46 of 129) compared with 28.7% (37 of 129) by microscopy. The nested PCR detected seven more malaria samples than microscopy in the first round of microscopic examination, malaria in three microscopically negative samples, six double infections identified as single infections by microscopy and one triple infection identified as a double infection by microscopy. The nested PCR assay described is a sensitive technique for collecting accurate malaria epidemiologic data. When coupled with simple blood spot sampling, it is particularly useful for screening communities in remote regions of the world.
Short report: differences in dihydrofolate reductase but not dihydropteroate synthase alleles in Plasmodium falciparum isolates from geographically distinct areas in Malaysia

Cox-Singh J, Zakaria R, Abdullah MS, Rahman HA, Nagappan S, Singh B

Am J Trop Med Hyg, 2001 6 27;64(1-2):28-31.
PMID: 11425158

Dihydropteroate synthase (dhps) and dihydrofolate reductase (dhfr) alleles were typed in 67 Malaysian Plasmodium falciparum isolates. The isolates were collected from two geographically distinct locations: 51 from Sabah, Malaysian Borneo, where sulfadoxine/pyrimethamine (SDX/PYR) is used to treat uncomplicated malaria and 16 from Peninsular Malaysia where in vivo resistance to SDX/PYR has been reported. A total of seven dhps alleles were identified with no significant difference in allele frequency between the 2 populations. Two of the dhps alleles described here have not been previously reported. Four dhfr alleles were detected in 67 P. falciparum isolates. Eighty-seven percent of the isolates from the Peninsula, where clinical SDX/PYR failure has been reported, had dhfr alleles with triple point mutations while all of the isolates from Sabah had dhfr alleles with 2 or less point mutations. The difference in dhfr allele frequency between the two populations was highly significant. There was no correlation between in vitro PYR response and accumulation of dhfr point mutations.
Growth and anthraquinone production of Morinda elliptica cell suspension cultures in a stirred-tank bioreactor

Abdullah MA, Ariff AB, Marziah M, Ali AM, Lajis NH

J Agric Food Chem, 2000 Sep;48(9):4432-8.
PMID: 10995375

The effects of medium strategy, number of impellers, aeration mode, and mode of operation on Morinda elliptica cell suspension cultures in a stirred-tank bioreactor are described. A lower number of impellers and continuous aeration contributed toward high cell growth rate, whereas a higher number of impellers reduced cell growth rate, although not anthraquinone yield. The semicontinuous mode could indirectly imitate the larger scale version of production medium strategy and improved anthraquinone production even with 0. 012% (v/v) antifoam addition. Production medium promoted both growth (maximum dry cell weight of 24.6 g/L) and anthraquinone formation (maximum content of 19.5 mg/g of dry cell weight), without any necessity for antifoam addition. Cultures in production medium or with higher growth rate and anthraquinone production were less acidic than cultures in growth medium or with lower growth rate and anthraquinone production. Using the best operating variables, growth of M. elliptica cells (24.6 g/L) and anthraquinone yield (0.25 g/L) were 45% and 140%, respectively, lower than those using a shake flask culture after 12 days of cultivation.

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