Displaying publications 21 - 40 of 192 in total

Abstract:
Sort:
  1. Cheong, CS, Gan, GG, Chen, TM, Lim, CC, Nadarajan, VS, Bee, PC
    JUMMEC, 2016;19(2):12-16.
    MyJurnal
    Haemophagocytic lymphohistiocytosis (HLH) is a clinico-pathologic entity caused by increased proliferation
    and activation of benign macrophages with haemophagocytosis throughout the reticulo-endothelial system.
    Virus-associated HLH is a well-recognised entity. Although majority of parvovirus B19 associated HLH does not
    require any specific treatment and carries good prognosis, outcome of children is worse than adults. We report
    here a case of HLH associated with acute parvovirus B19 infection in a young healthy patient with underlying
    hereditary spherocytosis, with bone marrow findings typical of parvovirus infection. Although this patient
    had spontaneous recovery of cell counts, he succumbed due to complication from prolonged ventilation.
    Unexpectedly, his immunoglobulin levels were inappropriately normal despite on-going ventilator associated
    pneumonia, which reflects inadequate humoral immune response towards infection.
    Matched MeSH terms: Cell Count
  2. Govindasamy V, Ronald VS, Totey S, Din SB, Mustafa WM, Totey S, et al.
    In Vitro Cell Dev Biol Anim, 2010 Oct;46(9):764-73.
    PMID: 20725801 DOI: 10.1007/s11626-010-9332-0
    Stem cells isolated from dental pulp possess the capacity for self-renewal and the potential for multi-lineage differentiation. However, dental pulp stem cells have different characteristics in terms of their culture conditions. The success of stem cells culture is governed by its micro-environmental niche. Therefore, we studied the effects of culture niche on long-term expansion of dental pulp stem cells in terms of cell morphology, growth kinetics, senescence pattern, cell surface marker expression differentiation capacity, and seeding plating density of dental pulp stem cells in four different, widely used media composition Among the various basal media tested, α-minimum essential media and knock out-minimum essential media supplemented with 10% fetal bovine serum were found to be the most optimal media composition in preserving the phenotypic characteristics and differentiation potential for prolonged periods as compared with DMEM-F12 and DMEM-LG. Plating density has been shown to affect overall yield. As a conclusion, the adoption of an appropriate culture system significantly improved cell yield, thus enabling the attainment of sufficient yields for therapeutic applications economizing in terms of cost of production and minimizing seeding cell density for maximum yield.
    Matched MeSH terms: Cell Count
  3. Shaikh LH, Zhou J, Teo AE, Garg S, Neogi SG, Figg N, et al.
    J Clin Endocrinol Metab, 2015 Jun;100(6):E836-44.
    PMID: 25915569 DOI: 10.1210/jc.2015-1734
    CONTEXT: Aldosterone synthesis and cellularity in the human adrenal zona glomerulosa (ZG) is sparse and patchy, presumably due to salt excess. The frequency of somatic mutations causing aldosterone-producing adenomas (APAs) may be a consequence of protection from cell loss by constitutive aldosterone production.

    OBJECTIVE: The objective of the study was to delineate a process in human ZG, which may regulate both aldosterone production and cell turnover.

    DESIGN: This study included a comparison of 20 pairs of ZG and zona fasciculata transcriptomes from adrenals adjacent to an APA (n = 13) or a pheochromocytoma (n = 7).

    INTERVENTIONS: Interventions included an overexpression of the top ZG gene (LGR5) or stimulation by its ligand (R-spondin-3).

    MAIN OUTCOME MEASURES: A transcriptome profile of ZG and zona fasciculata and aldosterone production, cell kinetic measurements, and Wnt signaling activity of LGR5 transfected or R-spondin-3-stimulated cells were measured.

    RESULTS: LGR5 was the top gene up-regulated in ZG (25-fold). The gene for its cognate ligand R-spondin-3, RSPO3, was 5-fold up-regulated. In total, 18 genes associated with the Wnt pathway were greater than 2-fold up-regulated. ZG selectivity of LGR5, and its absence in most APAs, were confirmed by quantitative PCR and immunohistochemistry. Both R-spondin-3 stimulation and LGR5 transfection of human adrenal cells suppressed aldosterone production. There was reduced proliferation and increased apoptosis of transfected cells, and the noncanonical activator protein-1/Jun pathway was stimulated more than the canonical Wnt pathway (3-fold vs 1.3-fold). ZG of adrenal sections stained positive for apoptosis markers.

    CONCLUSION: LGR5 is the most selectively expressed gene in human ZG and reduces aldosterone production and cell number. Such conditions may favor cells whose somatic mutation reverses aldosterone inhibition and cell loss.

    Matched MeSH terms: Cell Count
  4. Lassale C, Curtis A, Abete I, van der Schouw YT, Verschuren WMM, Lu Y, et al.
    Sci Rep, 2018 02 19;8(1):3290.
    PMID: 29459661 DOI: 10.1038/s41598-018-21661-x
    All blood cells (white blood cells [WBC], red blood cells [RBC] and platelets) can play a role in atherosclerosis. Complete blood count (CBC) is widely available in clinical practice but utility as potential risk factors for cardiovascular disease (CVD) is uncertain. Our aim was to assess the associations of pre-diagnostic CBC with incidence of CVD in 14,362 adults free of CVD and aged 47.8 (±11.7) years at baseline, followed-up for 11.4 years (992 incident cases). Cox proportional hazards regressions were used to estimate HRs and 95%CI. Comparing the top (T3) to bottom (T1) tertile, increased total WBC, lymphocyte, monocyte and neutrophil counts were associated with higher CVD risk: 1.31 (1.10; 1.55), 1.20 (1.02; 1.41), 1.21 (1.03; 1.41) and 1.24 (1.05; 1.47), as well as mean corpuscular volume (MCV: 1.23 [1.04; 1.46]) and red cell distribution width (RDW: 1.22 [1.03; 1.44]). Platelets displayed an association for count values above the clinically normal range: 1.49 (1.00; 2.22). To conclude, total and differential WBC count, MCV, RDW and platelet count likely play a role in the aetiology of CVD but only WBC provide a modest improvement for the prediction of 10-year CVD risk over traditional CVD risk factors in a general population.
    Matched MeSH terms: Blood Cell Count
  5. Alias MA, Buenzli PR
    Biophys J, 2017 Jan 10;112(1):193-204.
    PMID: 28076811 DOI: 10.1016/j.bpj.2016.11.3203
    The growth of several biological tissues is known to be controlled in part by local geometrical features, such as the curvature of the tissue interface. This control leads to changes in tissue shape that in turn can affect the tissue's evolution. Understanding the cellular basis of this control is highly significant for bioscaffold tissue engineering, the evolution of bone microarchitecture, wound healing, and tumor growth. Although previous models have proposed geometrical relationships between tissue growth and curvature, the role of cell density and cell vigor remains poorly understood. We propose a cell-based mathematical model of tissue growth to investigate the systematic influence of curvature on the collective crowding or spreading of tissue-synthesizing cells induced by changes in local tissue surface area during the motion of the interface. Depending on the strength of diffusive damping, the model exhibits complex growth patterns such as undulating motion, efficient smoothing of irregularities, and the generation of cusps. We compare this model with in vitro experiments of tissue deposition in bioscaffolds of different geometries. By including the depletion of active cells, the model is able to capture both smoothing of initial substrate geometry and tissue deposition slowdown as observed experimentally.
    Matched MeSH terms: Cell Count
  6. Lim PY, Hickey AC, Jamiluddin MF, Hamid S, Kramer J, Santos R, et al.
    Vaccine, 2015 Nov 4;33(44):6017-24.
    PMID: 26271825 DOI: 10.1016/j.vaccine.2015.05.108
    A vaccine against human enterovirus 71 (EV-A71) is urgently needed to combat outbreaks of EV-A71 and in particular, the serious neurological complications that manifest during these outbreaks. In this study, an EV-A71 virus-like-particle (VLP) based on a B5 subgenogroup (EV-A71-B5 VLP) was generated using an insect cell/baculovirus platform. Biochemical analysis demonstrated that the purified VLP had a highly native procapsid structure and initial studies in vivo demonstrated that the VLPs were immunogenic in mice. The impact of VLP immunization on infection was examined in non-human primates using a VLP prime-boost strategy prior to EV-A71 challenge. Rhesus macaques were immunized on day 0 and day 21 with VLPs (100 μg/dose) containing adjuvant or with adjuvant alone (controls), and were challenged with EV-A71 on day 42. Complete blood counts, serum chemistry, magnetic resonance imaging (MRI) scans, and histopathology results were mostly normal in vaccinated and control animals after virus challenge demonstrating that the fatal EV-A71-B3 clinical isolate used in this study was not highly virulent in rhesus macaques. Viral genome and/or infectious virus were detected in blood, spleen or brain of two of three control animals, but not in any specimens from the vaccinated animals, indicating that VLP immunization prevented systemic spread of EV-A71 in rhesus macaques. High levels of IgM and IgG were detected in VLP-vaccinated animals and these responses were highly specific for EV-A71 particles and capsid proteins. Serum from vaccinated animals also exhibited similar neutralizing activity against different subgenogroups of EV-A71 demonstrating that the VLPs induced cross-neutralizing antibodies. In conclusion, our EV-A71-B5 VLP is safe, highly immunogenic, and prevents systemic EV-A71-B3 infection in nonhuman primates making it a viable attractive vaccine candidate for EV-A71.
    Matched MeSH terms: Blood Cell Count
  7. Tan KH, How KY, Tan JY, Yin WF, Chan KG
    Front Microbiol, 2017;8:72.
    PMID: 28197135 DOI: 10.3389/fmicb.2017.00072
    The process of intercellular communication among bacteria, termed quorum sensing (QS), is mediated by small diffusible molecules known as the autoinducers. QS allows the population to react to the change of cell density in unison, in processes such as biofilm formation, plasmid conjugation, virulence, motility and root nodulation. In Gram-negative proteobacteria, N-acyl homoserine lactone (AHL) is the common "language" to coordinate gene expression. This signaling molecule is usually synthesized by LuxI-type proteins. We have previously discovered that a rare bacterium, Cedecea neteri, exhibits AHL-type QS activity. With information generated from genome sequencing, we have identified the luxIR gene pair responsible for AHL-type QS and named it cneIR. In this study, we have cloned and expressed the 636 bp luxI homolog in an Escherichia coli host for further characterization. Our findings show that E. coli harboring cneI produced the same AHL profile as the wild type C. neteri, with the synthesis of AHL known as N-butyryl-homoserine lactone. This 25 kDa LuxI homolog shares high similarity with other AHL synthases from closely related species. This work is the first documentation of molecular cloning and characterization of luxI homolog from C. neteri.
    Matched MeSH terms: Cell Count
  8. Cheah PL, Looi LM, Chan LL
    Histopathology, 1996 Jan;28(1):49-54.
    PMID: 8838120
    Wilms' tumour (nephroblastoma) has been associated with chromosomal abnormalities at the 11p13, 11p15 and 16q regions. A study into the possibility of mutations occurring within p53, the ubiquitous adult tumour suppressor gene, in Wilms' tumour was carried out. Thirty-eight cases were studied. Of these 36 were categorised into the favourable histology group and two into the unfavourable histology group based on the National Wilms' Tumour Study criteria. Archival formalin-fixed, paraffin-embedded tissue sections from each case were stained with a polyclonal (AB565:Chemicon) and a monoclonal (DO7:Dako) antibody raised against p53 protein using a peroxidase-labelled streptavidin biotin kit (Dako). 'Cure' (disease-free survival of 60 months or longer) was documented in 39% of cases with favourable histology tumours. Eleven percent in this group succumbed to the disease. Both cases with unfavourable histology died. Four out of 36 (11%) tumours with favourable histology demonstrated weak to moderate staining with both AB565 and DO7 in more than 75% of tumour cells. In contrast, p53 protein expression in unfavourable histology tumours was significantly increased compared with the favourable histology group (P = 0.021) with both cases demonstrating immunopositivity in > 75% of tumour cells when stained with AB565 and DO7. The intensity of staining ranged from moderate to strong in both cases. It appears from this preliminary study that the immunohistochemical expression of p53 protein in Wilms' tumour, presumably a result of mutation in the p53 tumour suppressor gene, correlates with histological classification, histological categorisation being one of the useful features in the prognostic assessment of Wilms' tumours.
    Matched MeSH terms: Cell Count
  9. Kuan JW, Su AT, Wong SP, Sim XY, Toh SG, Ong TC, et al.
    Transfus Apher Sci, 2015 Oct;53(2):196-204.
    PMID: 25910537 DOI: 10.1016/j.transci.2015.03.017
    There are few randomized trials comparing filgrastim and pegfilgrastim in peripheral blood stem cell mobilization (PBSCM). None of the trials studied the effects of the timing of pegfilgrastim administration on the outcomes of mobilization. We conducted a randomized triple blind control trial comparing the outcomes of filgrastim 5 µg/kg daily from day 3 onwards, 'early' pegfilgrastim 6 mg on day 3 and 'delayed' pegfilgrastim 6 mg on day 7 in cyclophosphamide PBSCM in patients with no previous history of mobilization. Peripheral blood (PB) CD34+ cell count was checked on day 8 and day 11 onward. Apheresis was started when PB CD34+ ≥ 10/µl from day 11 onward. The primary outcome was the successful mobilization rate, defined as cumulative collection of ≥2 × 10(6)/kg CD34+ cells in three or less apheresis. The secondary outcomes were the day of neutrophil and platelet engraftment post transplantation. There were 156 patients randomized and 134 patients' data analyzed. Pegfilgrastim 6 mg day 7 produced highest percentage of successful mobilization, 34 out of 48 (70.8%) analyzed patients, followed by daily filgrastim, 28 out of 44 (63.6%) and day 3 pegfilgrastim, 20 out of 42 (47.6%) (p = 0.075). Pegfilgrastim day 7 and daily filgrastim reported 1.48 (p = 0.014) and 1.49 (p = 0.013) times higher successful mobilization rate respectively as compared to pegfilgrastim day 3 after adjusting for disease, gender and exposure to myelotoxic agent. Multiple myeloma patients were three times more likely to achieve successful mobilization as compared to acute leukemia or lymphoma patients. Pegfilgrastim avoided the overshoot of white cells compared to filgrastim. There was no difference in the duration of both white cells and platelet recovery post transplantation between the three interventional arms.
    Matched MeSH terms: Cell Count
  10. Chan, Y.Y., Kim, K.H., Cheah, S.H.
    JUMMEC, 2011;14(2):1-4.
    MyJurnal
    Tyrosinase is a key enzyme that catalyzes melanogenesis in human skin. It oxidizes tyrosine to L-3,4-dihydroxyphenylalanine (L-DOPA) and subsequently to dopachrome, which further polymerizes to melanin pigments. Therefore finding an effective tyrosinase inhibitor, either from synthetic or natural sources, is not only useful as skin whitening agents in cosmetic application, but also beneficial in treating melanin-related disorders. The present study reports of the optimized and validated results of a cell-based tyrosinase assay using B16F10 murine melanoma cell line, which produces melanin pigments and has been used extensively in antimelanogenesis studies. The optimization studies involved 3 parameters (1) optimal seeding cell number per well for total protein extraction; (2) optimal dopachrome formation from enzymatic reaction between total protein (tyrosinase source) and L-DOPA (substrate); and (3) optimal incubation period after the addition of substrate. The present study demonstrates that using seeding cell number of 2 × 105 cells/well, total protein of 40 μg, L-Dopa of 5 mM,and at an incubation period of 1 hour at 37°C provided the optimal response on cultured melanoma cells. Kojic acid, a standard tyrosinase inhibitor, was used as a positive control in the optimized cell-based tyrosinase assay to validate the usefulness of the assay. CONCLUSION: The use of the mentioned protocol is sensitive to determine changes in melanoma cells as the result of tyrosine inhibitors.
    Matched MeSH terms: Cell Count
  11. Fish-Low CY, Abubakar S, Othman F, Chee HY
    Malays J Pathol, 2019 Apr;41(1):41-46.
    PMID: 31025636
    INTRODUCTION: Dengue virus (DENV), the causative agent of dengue disease exists in sylvatic and endemic ecotypes. The cell morphological changes and viral morphogenesis of two dengue ecotypes were examined at the ultrastructural level to identify potential similarities and differences in the surrogate model of enzootic host.

    MATERIALS AND METHODS: Vero cells were inoculated with virus at a multiplicity of infection (MOI) of 0.1. Cell cultures were harvested over a time course and processed for transmission electron microscopic imaging.

    RESULTS: The filopodia protrusions on cell periphery preceded virus entry. Additionally, sylvatic DENV infection was found spreading slower than the endemic DENV. Morphogenesis of both dengue ecotypes was alike but at different level of efficiency in the permissive cells.

    CONCLUSIONS: This is the first ultrastructural study on sylvatic DENV and this comparative study revealed the similarities and differences of cellular responses and morphogenesis of two dengue ecotypes in vitro. The study revealed the weaker infectivity of sylvatic DENV in the surrogate model of enzootic host, which supposed to support better replication of enzootic DENV than endemic DENV.

    Matched MeSH terms: Cell Count
  12. Chee, Yik Chang
    MyJurnal
    A 24-year-old female complained of a 2-week history of fever and right-eye swelling. There was no ocular pain, blurring of vision, or history of prior trauma to the affected eye. On examination, she was febrile and not in respiratory distress. The right lower eyelid appeared swollen with skin erythema (Figure 1), while the visual acuity was normal. The white cell count was 14.8 × 103/μL (normal range = 4 – 10 × 103/μL). Her liver and renal function tests were within the normal range. The abdominal ultrasonography revealed multiple splenic microabscesses, while chest radiograph was normal. Contrast-enhanced computed tomography of the orbit showed a right lower eyelid abscess with extension into the right nasolacrimal duct (Figure 2). Incision and drainage of the eyelid abscess were performed and the culture of the pus, as well as the blood, yielded Burkholderia pseudomallei. She received intravenous ceftazidime 2 g every 8 hours for 4 weeks, followed by oral trimethoprim-sulfamethoxazole for 20 weeks’ duration. The right eyelid abscess and splenic microabscesses resolved completely post-treatment. Please interpret the figures and suggest the provisional diagnosis.
    Matched MeSH terms: Cell Count
  13. Mohd-Ali B, Chen LY
    Cont Lens Anterior Eye, 2021 02;44(1):72-75.
    PMID: 32624364 DOI: 10.1016/j.clae.2020.06.007
    PURPOSE: To analyse and compare the alterations in corneal endothelium morphology induced by different materials and durations of wearing soft contact lenses (CL) among young adults living in Kuala Lumpur.

    METHODS: Healthy soft CL wearers were invited to participate in this study. Visual acuity (VA) was measured using the Snellen chart, and subjective refraction was performed using cross-cylinder technique. Standard ocular assessments were conducted using a slit lamp biomicroscope and morphology of corneal endothelial cells (endothelial cell density, ECD, coefficient variation, COV, hexagonality, HEX and central corneal thickness, CCT) were evaluated using a non-contact specular microscope. Statistical analysis was conducted using ANOVA and data from the right eye only is included.

    RESULTS: A total of 72 subjects (32 SiHy and 40 HCL wearers) and 24 non-CL wearers (control) participated in this study. The gender distribution for study subjects was 13 males and 59 females, with a mean age 22.15 ± 1.84 years old. The mean refraction was -1.86 ± 1.25DS. The duration of wearing CL ranged from 1 to 9 years. Subjects were later divided into 2 groups following duration of CL wear: Group 1 (<5 years) and Group 2 (≥5 years) for analysis purposes. Statistical analysis showed significant alterations in ECD, COV and HEX of CL wearers (p cells. Contact lens material and duration of CL wear (in years) are factors that affect the alterations. Optometrists are recommended to regularly evaluate the morphology of corneal endothelial cells in CL wearers and provide necessary intervention when required.

    Matched MeSH terms: Cell Count
  14. Tiong KH, Chang JK, Pathmanathan D, Hidayatullah Fadlullah MZ, Yee PS, Liew CS, et al.
    Biotechniques, 2018 12;65(6):322-330.
    PMID: 30477327 DOI: 10.2144/btn-2018-0072
    We describe a novel automated cell detection and counting software, QuickCount® (QC), designed for rapid quantification of cells. The Bland-Altman plot and intraclass correlation coefficient (ICC) analyses demonstrated strong agreement between cell counts from QC to manual counts (mean and SD: -3.3 ± 4.5; ICC = 0.95). QC has higher recall in comparison to ImageJauto, CellProfiler and CellC and the precision of QC, ImageJauto, CellProfiler and CellC are high and comparable. QC can precisely delineate and count single cells from images of different cell densities with precision and recall above 0.9. QC is unique as it is equipped with real-time preview while optimizing the parameters for accurate cell count and needs minimum hands-on time where hundreds of images can be analyzed automatically in a matter of milliseconds. In conclusion, QC offers a rapid, accurate and versatile solution for large-scale cell quantification and addresses the challenges often faced in cell biology research.
    Matched MeSH terms: Cell Count/economics; Cell Count/methods*
  15. Hussin HN, Zulkifli FN, Phang KS, Cheong SK
    Malays J Pathol, 2009 Dec;31(2):105-12.
    PMID: 20514853 MyJurnal
    Dendritic cells (DC) are specialized antigen presenting cells (APC) that have important roles in host defenses and in generating anti-tumour immune response. Altered frequency and maturation of DC have been reported in malignant tumours. We studied the distribution and maturation status of DC by immunohistochemistry, on the formalin-fixed, paraffin-embedded lymph node tissues of 32 histologically diagnosed lymphomas and 40 inflammatory conditions that were retrieved from the Department of Pathology, UKM Medical Centre, Kuala Lumpur. Our study showed a significant reduction in the total DC counts in the lymphoma tissues compared to the inflammatory conditions. The mature and immature DC counts were both significantly reduced (p = 0.008 and 0.001 respectively), although a greater reduction was observed in mature DC numbers. We also observed compartmentalization of DC where the immature DC were seen within the tumour tissues and the mature DC were more in peri-tumoural areas. Our findings were similar to other reports, suggesting that reduced numbers of DC appears to be a factor contributing to lack of tumour surveillance in these cases.
    Matched MeSH terms: Cell Count
  16. Ag Z, Cheong SK
    Malays J Pathol, 1995 Dec;17(2):77-81.
    PMID: 8935130
    A system for computerising full blood picture reporting developed in-house using dBASE IV on IBM-compatible microcomputers in a local area network environment is described. The software package has a user-friendly interface which consists of a horizontal main menu bar with associated pull-down submenus. The package captures data directly from an automatic blood cell counter and provides options to modify or delete records, search for records, print interim, final or cumulative reports, record differential counts with an emulator, facilitate house-keeping activities which include backing-up databases and repairing corrupted indices. The implementation of this system has helped to improve the efficiency of reporting full blood picture in the haematology laboratory.
    Matched MeSH terms: Blood Cell Count/instrumentation*; Blood Cell Count/methods*
  17. Sabariah, M.N., Leong, C.F., Cheong, S.K.
    MyJurnal
    Peripheral blood (PB) CD34+ cells enumeration is currently the most reliable method to guide the timing of stem cell harvest. However, its usage is restricted by being technically challenging, costly, and time-consuming. Immature reticulocyte fraction (IRF) determination, which is simpler and cheaper and has a faster turn-around time, has been proposed for a similar purpose. The purpose of this study is to evaluate the value of IRF in guiding stem cell harvest and examine the correlation between IRF and PB CD34+ cells count. Daily pre-harvest tests, i.e. PB CD34+ cells and IRF from 21 patients scheduled for autologous PBSC transplant were assessed. Stem cells harvests were commenced when the PB CD34+ cell count were more than 10 cell/ul. A total of 205 pre-harvest tests were analysed. Following stem cell mobilisations, both the IRF and PB CD 34+ cell counts rose with a variable pattern. In this study, we observed that the IRF peaks preceded the PB CD34+ count by 2 days. On the day of stem cell harvest, all the peak IRF values were >0.3. The PB CD34+ cell counts correlated with the harvested stem cell yield, whereby r2 = 0.77, p < 0.021. In autologous stem cell mobilisation, we believe that IRF is a useful screening tool to predict the rise of the PB CD34+ cell counts as it is a simple, fast and less costly. An IRF of > 0.3 may be used as a cut-off value for the initiation of PB CD34+ quantification prior to stem cell harvest.
    Matched MeSH terms: Blood Cell Count
  18. Chua GK, Abdul-Rahman B, Chisti Y
    Biotechnol Prog, 2013 Jan-Feb;29(1):154-64.
    PMID: 23125182 DOI: 10.1002/btpr.1656
    The hybridoma 192 was used to produce a monoclonal antibody (MAb) against 17-hydroxyprogesterone (17-OHP), for possible use in screening for congenital adrenal hyperplasia (CAH). The factors influencing the MAb production were screened and optimized in a 2 L stirred bioreactor. The production was then scaled up to a 20 L bioreactor. All of the screened factors (aeration rate, stirring speed, dissolved oxygen concentration, pH, and temperature) were found to significantly affect production. Optimization using the response surface methodology identified the following optimal production conditions: 36.8°C, pH 7.4, stirring speed of 100 rpm, 30% dissolved oxygen concentration, and an aeration rate of 0.09 vvm. Under these conditions, the maximum viable cell density achieved was 1.34 ± 0.21 × 10(6) cells mL(-1) and the specific growth rate was 0.036 ± 0.004 h(-1) . The maximum MAb titer was 11.94 ± 4.81 μg mL(-1) with an average specific MAb production rate of 0.273 ± 0.135 pg cell(-1) h(-1) . A constant impeller tip speed criterion was used for the scale-up. The specific growth rate (0.040 h(-1) ) and the maximum viable cell density (1.89 × 10(6) cells mL(-1) ) at the larger scale were better than the values achieved at the small scale, but the MAb titer in the 20 L bioreactor was 18% lower than in the smaller bioreactor. A change in the culture environment from the static conditions of a T-flask to the stirred bioreactor culture did not affect the specificity of the MAb toward its antigen (17-OHP) and did not compromise the structural integrity of the MAb.
    Matched MeSH terms: Cell Count
  19. Lim CS, Rosli R, Seow HF, Chong PP
    Int J Med Microbiol, 2011 Aug;301(6):536-46.
    PMID: 21371935 DOI: 10.1016/j.ijmm.2010.12.002
    Systemic infections of Candida albicans, the most prevalent fungal pathogen in humans, are on the rise in recent years. However, the exact mode of pathogenesis of this fungus is still not well elucidated. Previous studies using C. albicans mutants locked into the yeast form via gene deletion found that this form was avirulent and did not induce significant differential expression of host genes in vitro. In this study, a high density of C. albicans was used to infect human umbilical vein endothelial cells (HUVEC), resulting in yeast-form infections, whilst a low density of C. albicans resulted in hyphae infections. Transcriptional profiling of HUVEC response to these infections showed that high densities of C. albicans induced a stronger, broader transcriptional response from HUVEC than low densities of C. albicans infection. Many of the genes that were significantly differentially expressed were involved in apoptosis and cell death. In addition, conditioned media from the high-density infections caused a significant reduction in HUVEC viability, suggesting that certain molecules released during C. albicans and HUVEC interactions were capable of causing cell death. This study has shown that C. albicans yeast-forms, at high densities, cannot be dismissed as avirulent, but instead could possibly contribute to C. albicans pathogenesis.
    Matched MeSH terms: Cell Count
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links