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Search Results: 1 - 10 of 8684 matches for " Elizabeth Mambo "
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Horseradish Peroxidase Biosensor to Detect Zinc Ions in Aqueous Solutions  [PDF]
Mambo Moyo
Open Journal of Applied Biosensor (OJAB) , 2014, DOI: 10.4236/ojab.2014.31001
Abstract: Maize tassel-multiwalled carbon nanotube (MT-MWCNT) composite has been used as a matrix for physical adsorption of horseradish peroxidase (HRP) onto the surface of a glassy carbon electrode through electrostatic interactions. The HRP/MT-MWCNT biosensor was applied for the detection of Zn2+ in aqueous solution. The biosensor designed was able to determine Zn2+ in the range of 0.35 - 12 mg/L with a detection limit of 7.5 μg/L. The inhibition was found to be reversible and uncompetitive when data were modeled using the Dixon and Cornish-Bowden plots. The biosensor was found to have good repeatability, reproducibility and high selectivity. The developed biosensor can be used to detect other HRP inhibiting trace metal ions.
Targeting of mutant hogg1 in mammalian mitochondria and nucleus: effect on cellular survival upon oxidative stress
Aditi Chatterjee, Elizabeth Mambo, Yonggang Zhang, Theodore DeWeese, David Sidransky
BMC Cancer , 2006, DOI: 10.1186/1471-2407-6-235
Abstract: We over-expressed wild type and R229Q mutant hOGG1 in the nucleus and mitochondria of cells lacking mitochondrial hOGG1 expression through an expression vector containing nuclear and mitochondrial targeting sequence respectively. We used quantitative real time PCR to analyze mtDNA integrity after exposure to oxidative damaging agents, in cells transfected with or without mitochondrially-targeted mutant hogg1.Over-expression of wild type hOgg1 in both nucleus and mitochondria resulted in increased cellular survival when compared to vector or mutant over-expression of hOGG1. Interestingly, mitochondrially-targeted mutant hogg1 resulted in more cell death than nuclear targeted mutant hogg1 upon exposure of cells to oxidative damage. Additional we examined mitochondrial DNA integrity after oxidative damage exposure using real-time quantitative PCR. The presence of mutant hogg1 in the mitochondria resulted in reduced mitochondrial DNA integrity when compared to the wild type. Our work indicates that the R229Q hOGG1 mutation failed to protect cells from oxidative damage and that such mutations in cancer may be more detrimental to cellular survival when present in the mitochondria than in the nucleus.These findings suggest that deficiencies in hOGG1, especially in the mitochondria may lead to reduced mitochondrial DNA integrity, consequently resulting in decreased cell viability.The detection of mitochondrial DNA (mtDNA) mutations in several human diseases has stimulated interest in understanding how the integrity of the mitochondrial genome is maintained [1-4]. It is believed that these mutations likely result from the exposure of mtDNA to reactive oxygen species (ROS). mtDNA is continuously exposed to ROS which are formed as byproducts of normal cell metabolism and during exposure to physical and chemical agents such as γ-irradiation, UV-irradiation or H2O2. Lack of protective histones, proximity to oxidative phosphorylation and limited capacity for repair of DNA damage
Bioremediation of Lead(II) from Polluted Wastewaters Employing Sulphuric Acid Treated Maize Tassel Biomass  [PDF]
Mambo Moyo, Linda Chikazaza
American Journal of Analytical Chemistry (AJAC) , 2013, DOI: 10.4236/ajac.2013.412083

The ability to modify a waste by-product precursor, maize tassel biomass using sulfuric acid as the activating agent with specific focus on Lead(II) ion from water has been proposed. The treating of maize tassel using sulphuric acid is believed to enhance sorption capacity of Lead(II) ions. For this, batch adsorption mode was adopted for which the effects of initial pH, adsorbent dosage, contact time and initial concentration were investigated. Consequently, it was found that the adsorbent capacity depends on pH; since it increases up to 4.5 and then decreases. The highest percentage of Lead(II) ion removal was achieved in the adsorbent dosage of 1.2 g and at an initial concentration of 10 mg/L metal ion. In an attempt to determine the capacity and rate of Lead(II) removal, isotherm and kinetic data were modeled using appropriate equations. To this end, the adsorption data fitted best into the Langmuir model with an R2 (0.9997) while kinetically the Lead(II) adsorption followed the pseudo-second-order model. Furthermore, as a way to address issues related to sustainability, maize tassel is recommended since the process is considered to be a dual solution for environmental cleaning. From one side, it represents a better way to dispose the maize tassel which has no use after fertilization and on the other hand it is an economic source of carbonaceous materials.


Serum microRNA Biomarkers for Detection of Non-Small Cell Lung Cancer
Patrick T. Hennessey, Tiffany Sanford, Ashish Choudhary, Wojciech W. Mydlarz, David Brown, Alex Tamas Adai, Michael F. Ochs, Steven A. Ahrendt, Elizabeth Mambo, Joseph A. Califano
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0032307
Abstract: Non small cell lung cancer (NSCLC) is the leading cause of cancer-related mortality world-wide and the majority of cases are diagnosed at late stages of disease. There is currently no cost-effective screening test for NSCLC, and the development of such a test is a public health imperative. Recent studies have suggested that chest computed tomography screening of patients at high risk of lung cancer can increase survival from disease, however, the cost effectiveness of such screening has not been established. In this Phase I/II biomarker study we examined the feasibility of using serum miRNA as biomarkers of NSCLC using RT-qPCR to examine the expression of 180 miRNAs in sera from 30 treatment naive NSCLC patients and 20 healthy controls. Receiver operating characteristic curves (ROC) and area under the curve were used to identify differentially expressed miRNA pairs that could distinguish NSCLC from healthy controls. Selected miRNA candidates were further validated in sera from an additional 55 NSCLC patients and 75 healthy controls. Examination of miRNA expression levels in serum from a multi-institutional cohort of 50 subjects (30 NSCLC patients and 20 healthy controls) identified differentially expressed miRNAs. A combination of two differentially expressed miRNAs miR-15b and miR-27b, was able to discriminate NSCLC from healthy controls with sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 100% in the training set. Upon further testing on additional 130 subjects (55 NSCLC and 75 healthy controls), this miRNA pair predicted NSCLC with a specificity of 84% (95% CI 0.73–0.91), sensitivity of 100% (95% CI; 0.93–1.0), NPV of 100%, and PPV of 82%. These data provide evidence that serum miRNAs have the potential to be sensitive, cost-effective biomarkers for the early detection of NSCLC. Further testing in a Phase III biomarker study in is necessary for validation of these results.
Somatic mutation and gain of copy number of PIK3CA in human breast cancer
Guojun Wu, Mingzhao Xing, Elizabeth Mambo, Xin Huang, Junwei Liu, Zhongmin Guo, Aditi Chatterjee, David Goldenberg, Susanne M Gollin, Saraswati Sukumar, Barry Trink, David Sidransky
Breast Cancer Research , 2005, DOI: 10.1186/bcr1262
Abstract: Fifteen breast cancer cell lines and 92 primary breast tumors (33 with matched normal tissue) were used to check somatic mutation and gene copy number of PIK3CA. For the somatic mutation study, we specifically checked exons 1, 9, and 20, which have been reported to be hot spots in colon cancer. For the analysis of the gene copy number, we used quantitative real-time PCR and fluorescence in situ hybridization. We also treated several breast cancer cells with the PIK3CA inhibitor LY294002 and compared the apoptosis status in cells with and without PIK3CA mutation.We identified a 20.6% (19 of 92) and 33.3% (5 of 15) PIK3CA somatic mutation frequency in primary breast tumors and cell lines, respectively. We also found that 8.7% (8 of 92) of the tumors harbored a gain of PIK3CA gene copy number. Only four cases in this study contained both an increase in the gene copy number and a somatic mutation. In addition, mutation of PIK3CA correlated with the status of Akt phosphorylation in some breast cancer cells and inhibition of PIK3CA-induced increased apoptosis in breast cancer cells with PIK3CA mutation.Somatic mutation rather than a gain of gene copy number of PIK3CA is the frequent genetic alteration that contributes to human breast cancer progression. The frequent and clustered mutations within PIK3CA make it an attractive molecular marker for early detection and a promising therapeutic target in breast cancer.Phosphatidylinositol 3-kinases (PI3Ks) are a group of lipid kinases composed of 85-kDa and 110-kDa subunits. The 85-kDa subunit lacks PI3K activity and acts as adaptor, coupling the 110-kDa subunit (P110) to activated protein tyrosine kinases and generating second messengers by phosphorylating membrane inositol lipids at the D3 position. The resulting phosphatidylinositol derivatives then permit activation of downstream effectors that are involved in cell proliferation, survival, metabolism, cytoskeletal reorganization, and membrane trafficking [1,2].PIK3CA, the g
Electronic Journal of Biomedicine , 2009,
Abstract: The purpose of our study is to isolate the first molecule of Secamone afzelii and caracterize the family molecular of pure product. The research component is distinguished by a TLC, a luminescence to 366 nm with a front, Rf = 0.6. This molecule is not visible to the naked eye, nor to 254 nm, on the TLC.The column chromatography on silica helped isolate the product search with a yield of purification equal to 18,67 ± 0.72%. The various tests carried out on the phytochemical extracted. The molecule isolated could be considered to coumarin.
Impacts of Environmental Management on the Quality of Traditional Well Water in the Soubré Region (South-West of C?te d’Ivoire)  [PDF]
Ohou-Yao Marie Jeanne Adela?de, Ouattara Leygnima Yaya, Yapo Ossey Bernard, Mambo Veronique
Journal of Water Resource and Protection (JWARP) , 2017, DOI: 10.4236/jwarp.2017.913102
Abstract: Water supply is a global problem. A study was conducted on twelve (12) traditional wells water in Daba Dagnogo and Gnipi 2 to determine their physico-chemical quality. Two sampling campaigns (dry season and rainy season), were performed on 16 physical and chemical parameters. The results show that the water is acidic with an average pH of 6.41 ± 0.4; moderately mineralized with an average conductivity of 731.14 ± 611.98 μS·cm-1; moderately saline with an average rate of 1.56 ± 1.22. The average temperature of 28.07 ± 0.86°C is above the norm for all wells. All major ions are consistent with WHO standards except calcium and potassium. 41.67% of wells exceed the standard ammonium ion whose average was 1.43 ± 2.79 mg·L-1 nitrate and 100% with an average of 492.42 ± 434.02 mg·L-1. The ion concentrations are highest in the urban area and are higher in the dry season. The quality of the water sampled wells deteriorated. Several factors affect the degradation, namely the shallow wells, their proximity to toilet, the lack of sanitation and poor management of household waste. It will carry out a campaign to educate people to protect the immediate environment of the water points, avoiding the deposit of garbage and to provide the appropriate wells lids.
Qualitative Determination of Photodegradation Products of Progesterone and Testosterone in Aqueous Solution  [PDF]
Ladji Méité, Baba Donafologo Soro, Narcisse Kouassi Aboua, Véronique Mambo, Karim Sory Traoré, Patrick Mazellier, Joseh De Laat
American Journal of Analytical Chemistry (AJAC) , 2016, DOI: 10.4236/ajac.2016.71003
Abstract: Direct photochemical degradations of progesterone (PR) and testosterone (TR), two naturally produced hormones, have been conducted in non-buffered aqueous solution (pH ranging between 5.5 and 6.0). The irradiation experiments were carried out in a batch reactor upon monochromatic (254 nm) and polychromatic (λ > 290 nm) at 25°C. GLC/MS and LC/UV-DAD/MS analyses were performed to investigate phototransformation products after a solid phase extraction (SPE) step for analytes concentration. For each compound several by-products have been identified and are the same ones under both irradiation conditions. Because of the presence of the same chromophore (α, β-unsaturated group) absorbing UV radiations in both hormones, the majority of chromatographic peaks correspond to by-products formed according to identical mechanisms involving isomerization, enolization, oxidation and hydration to lead to the generation of lumiketone, cyclopentenone, spiro-hydration, oxidation and hydroxylation photoproducts.
Novel Insight into Mutational Landscape of Head and Neck Squamous Cell Carcinoma
Daria A. Gaykalova, Elizabeth Mambo, Ashish Choudhary, Jeffery Houghton, Kalyan Buddavarapu, Tiffany Sanford, Will Darden, Alex Adai, Andrew Hadd, Gary Latham, Ludmila V. Danilova, Justin Bishop, Ryan J. Li, William H. Westra, Patrick Hennessey, Wayne M. Koch, Michael F. Ochs, Joseph A. Califano, Wenyue Sun
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0093102
Abstract: Development of head and neck squamous cell carcinoma (HNSCC) is characterized by accumulation of mutations in several oncogenes and tumor suppressor genes. We have formerly described the mutation pattern of HNSCC and described NOTCH signaling pathway alterations. Given the complexity of the HNSCC, here we extend the previous study to understand the overall HNSCC mutation context and to discover additional genetic alterations. We performed high depth targeted exon sequencing of 51 highly actionable cancer-related genes with a high frequency of mutation across many cancer types, including head and neck. DNA from primary tumor tissues and matched normal tissues was analyzed for 37 HNSCC patients. We identified 26 non-synonymous or stop-gained mutations targeting 11 of 51 selected genes. These genes were mutated in 17 out of 37 (46%) studied HNSCC patients. Smokers harbored 3.2-fold more mutations than non-smokers. Importantly, TP53 was mutated in 30%, NOTCH1 in 8% and FGFR3 in 5% of HNSCC. HPV negative patients harbored 4-fold more TP53 mutations than HPV positive patients. These data confirm prior reports of the HNSCC mutational profile. Additionally, we detected mutations in two new genes, CEBPA and FES, which have not been previously reported in HNSCC. These data extend the spectrum of HNSCC mutations and define novel mutation targets in HNSCC carcinogenesis, especially for smokers and HNSCC without HPV infection.
Recent Advances in Polymeric Materials Used as Electron Mediators and Immobilizing Matrices in Developing Enzyme Electrodes
Mambo Moyo,Jonathan O. Okonkwo,Nana M. Agyei
Sensors , 2012, DOI: 10.3390/s120100923
Abstract: Different classes of polymeric materials such as nanomaterials, sol-gel materials, conducting polymers, functional polymers and biomaterials have been used in the design of sensors and biosensors. Various methods have been used, for example from direct adsorption, covalent bonding, crossing-linking with glutaraldehyde on composites to mixing the enzymes or use of functionalized beads for the design of sensors and biosensors using these polymeric materials in recent years. It is widely acknowledged that analytical sensing at electrodes modified with polymeric materials results in low detection limits, high sensitivities, lower applied potential, good stability, efficient electron transfer and easier immobilization of enzymes on electrodes such that sensing and biosensing of environmental pollutants is made easier. However, there are a number of challenges to be addressed in order to fulfill the applications of polymeric based polymers such as cost and shortening the long laboratory synthetic pathways involved in sensor preparation. Furthermore, the toxicological effects on flora and fauna of some of these polymeric materials have not been well studied. Given these disadvantages, efforts are now geared towards introducing low cost biomaterials that can serve as alternatives for the development of novel electrochemical sensors and biosensors. This review highlights recent contributions in the development of the electrochemical sensors and biosensors based on different polymeric material. The synergistic action of some of these polymeric materials and nanocomposites imposed when combined on electrode during sensing is discussed.
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