Dougbeh-chris Nyan - Academia.edu (original) (raw)
Papers by Dougbeh-chris Nyan
International Journal of Infectious Diseases, Feb 1, 2016
Hepatitis C virus (HCV) is a single-stranded RNA virus of the Flaviviridae family. 1 Transmitted ... more Hepatitis C virus (HCV) is a single-stranded RNA virus of the Flaviviridae family. 1 Transmitted through modes including injection drug use, contaminated needle-stick injuries, and unsafe blood transfusion, infection with HCV may lead to chronic active hepatitis and hepatocellular carcinoma. 2-4 Approximately 185 million people are infected with HCV worldwide, with developing countries of Sub-Saharan Africa, Asia, North and South America, and the Middle East most affected. 5-7 There are seven major genotypes of HCV with 67 subtypes found in different regions of the world. 8-10 Globally, HCV genotype 1 is the most common, accounting for about 46% of all infections. This is followed by genotype 3, accounting for 22% of the global HCV burden, and genotypes 2 and 4, each accounting for 13%. 5-7 The detection of HCV infection in blood derivatives and the identification of the genotypes are therefore important in clinical diagnostics and antiviral treatment, ensuring blood safety, and providing epidemiological information about HCV prevalence. 11-13 A plethora of molecular diagnostic methods have been designed and used for the detection and genotyping of HCV infection. While these tests are highly sensitive, they remain expensive and laborious and require well-trained personnel, as well as sophisticated laboratory facilities. 14-17 Furthermore, the application of these tests may be limited regarding their ability to detect and simultaneously identify the specific HCV genotypes. 18 Besides, several (reverse transcription) loop-mediated isothermal amplification (RT)-LAMP assays have been designed for the detection of
Scientific Reports, Dec 8, 2015
A rapid multiplex isothermal amplification assay has been developed for detection and identificat... more A rapid multiplex isothermal amplification assay has been developed for detection and identification of multiple blood-borne viruses that infect millions of people worldwide. These infections may lead to chronic diseases or death if not diagnosed and treated in a timely manner. Sets of virusspecific oligonucleotides and oligofluorophores were designed and used in a reverse-transcription loop-mediated multiplexed isothermal amplification reaction for detection and gel electrophoretic identification of human Immunodeficiency virus (HIV), hepatitis-B virus (HBV), hepatitis-C virus (HCV), hepatitis-E virus (HEV), dengue virus (DENV), and West Nile (WNV) virus infection in blood plasma. Amplification was catalyzed with two thermostable enzymes for 30-60 minutes under isothermal condition, utilizing a simple digital heat source. Electrophoretic analysis of amplified products demonstrated simultaneous detection of 6 viruses that were distinctly identified by unique ladder-like banding patterns. Naked-eye fluorescent visualization of amplicons revealed intensely fluorescing products that indicated positive detection. The test demonstrated a 97% sensitivity and a 100% specificity, with no cross-reaction with other viruses observed. This portable detection tool may have clinical and field utility in the developing and developed world settings. This may enable rapid diagnosis and identification of viruses for targeted therapeutic intervention and prevention of disease transmission. Blood-borne pathogens such as hepatitis B virus (HBV), hepatitis C virus (HCV), and the emerging hepatitis E virus (HEV) together infect over 800 million people globally and may lead to chronic active hepatitis and hepatocellular carcinoma 1-3. Infection with the human immunodeficiency virus (HIV) compromises the immune system, while dengue virus (DENV) and West Nile virus (WNV) infections may lead to hemorrhagic fever and neuroinflammatory conditions in infected patients, respectively 4,5. These viruses are transmitted through blood-borne routes and may co-infect a patient or co-circulate in various geographic regions as indicated by the prevalence of HIV, HCV, HEV, and HBV in North America, Africa, Asia, and Europe. Outbreaks of DENV and WNV have occurred in regions throughout the world, particularly in the Middle East, Europe, Africa, the United States, South America, and the Caribbean 6-10. The global distribution of these pathogens coupled with the clinical manifestations of their disease spectra emphasizes the need for simple, but efficient diagnostic point-of-care tools. Such tools may enable rapid detection and differentiation of viruses that present similar clinical symptoms, aid in targeted therapeutic intervention, and facilitate implementation of medical counter measures for disease control and prevention. Several amplification-based multiplex methods, including the quantitative reverse-transcription polymerase chain reaction (qRT-PCR) have been developed and used to detect and quantitate pathogen load 11,12. However, these methods exhibit drawbacks as they are time-consuming, expensive, and require the use of heavy equipment and highly trained personnel to perform. Despite their outstanding performance, these characteristics present limitations in their point-of-care use in field and resource-limited environments. Besides, many (reverse transcription) loop-mediated isothermal amplification assays (RT)-LAMP have been designed, but have hardly demonstrated
World Academy of Science, Engineering and Technology, International Journal of Medical and Health Sciences, 2015
International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases, Jan 11, 2015
Hepatitis C virus (HCV) is probably the leading cause of liver cirrhosis and hepatocellular carci... more Hepatitis C virus (HCV) is probably the leading cause of liver cirrhosis and hepatocellular carcinoma globally. Diagnostic tools conventionally used for detection and identification of HCV infection are technically demanding, time-consuming and costly for resource-limited environments. This study reports the development of the first rapid loop-mediated reverse-transcription isothermal-amplification assay that rapidly detects and identifies HCV genotypes in blood components. RNA extracted from donor plasma and serum specimens were applied to a one-step reverse transcription loop-mediated isothermal-amplification reaction performed with HCV-specific oligonucleotides. Reactions were conducted at 63.5°C for 30-60minutes. The assay's diagnostic characteristics were investigated and validated with clinical specimens. Electrophoretic analysis of amplification revealed detection and identification of HCV genotypes 1-6. Positive amplification revealed unique ladder-like banding-patterns ...
Scientific reports, 2015
A rapid multiplex isothermal amplification assay has been developed for detection and identificat... more A rapid multiplex isothermal amplification assay has been developed for detection and identification of multiple blood-borne viruses that infect millions of people world-wide. These infections may lead to chronic diseases or death if not diagnosed and treated in a timely manner. Sets of virus-specific oligonucleotides and oligofluorophores were designed and used in a reverse-transcription loop-mediated multiplexed isothermal amplification reaction for detection and gel electrophoretic identification of human Immunodeficiency virus (HIV), hepatitis-B virus (HBV), hepatitis-C virus (HCV), hepatitis-E virus (HEV), dengue virus (DENV), and West Nile (WNV) virus infection in blood plasma. Amplification was catalyzed with two thermostable enzymes for 30-60 minutes under isothermal condition, utilizing a simple digital heat source. Electrophoretic analysis of amplified products demonstrated simultaneous detection of 6 viruses that were distinctly identified by unique ladder-like banding pa...
Neuropeptides, 2008
The melanocortin 3-receptor is involved in regulating energy metabolism, body fluid composition a... more The melanocortin 3-receptor is involved in regulating energy metabolism, body fluid composition and inflammatory responses. Melanocortin receptors function by activating membrane bound adenylate cyclase. However, the literature reports indicate that some G protein coupled receptors (GPCRs) can also activate mitogen activated protein kinase (MAPK) or phosphoinositide 3 kinase (PI3K) signaling pathways consequent to their endocytosis. These studies were undertaken to evaluate the role of these pathways in MC3R signaling in brain-stem neuronal cells. Recruitment of arrestins is implicated in the activation of secondary pathways by GPCRs and our data shows the colocalization of either arrestin B1 or B2 with MC3R in endosomes. An alteration in PKB phosphorylation pattern was observed in MC3R expressing cells independent of agonist stimulation. MC3R transfectants exhibited increased proliferation rates and inhibition of PKB pathway with triciribine abrogated cell proliferation in both vector control and MC3R transfectants. PKB is constitutively active in proliferating CAD cells but could be further activated by culturing the cells in differentiation medium. These studies suggest that the AKT/PKB pathway plays an important role in the proliferation of CAD cells and suggest a link between MC3R and cell growth pathways that may involve the alteration of AKT/PKB signaling pathway.
Infection and Immunity, 2004
Helicobacter pylori infection status following experimental inoculation of mice presently require... more Helicobacter pylori infection status following experimental inoculation of mice presently requires euthanasia. The purpose of this study was to develop a method for following the time course of H. pylori infection in live experimental animals. Twenty-six C57BL/6, Helicobacter-free female mice were inoculated with H. pylori Sydney strain 1, and 16 mice were sham inoculated. The mice were repeatedly tested during a period of about 1 year with an H. pylori species-specific primer-based PCR analysis of DNA extracted from fecal pellets of mice. The mice were euthanized at 6 months (n = 15) and 10 months (n = 15) to determine their infection status by histology, culture, and PCR of gastric specimens. H. pylori-inoculated mice were tested via the PCR method at 6 and 10 months prior to necropsy. Nine of 13 (69%) and 10 of 13 (77%) mice tested at 6 and 10 months, respectively, were positive. All sham-inoculated mice were negative. These two PCR results suggested a specificity of 100% with a ...
Clinical Infectious Diseases an Official Publication of the Infectious Diseases Society of America, Apr 4, 2014
Background. Hepatitis B virus (HBV) is an important blood-borne pathogen that causes hepatic infl... more Background. Hepatitis B virus (HBV) is an important blood-borne pathogen that causes hepatic inflammation and can lead to liver cirrhosis and hepatocellular carcinoma. Conventional methods of HBV detection are time consuming and require highly trained personnel and elaborate equipment. This report describes the development of a rapid, simple, specific, and sensitive loop-mediated isothermal amplification assay (LAMP) for detection of HBV genotypes A, B, C, D, E, and F in blood samples. Methods. HBV standard plasma panels and clinical donor plasma specimens were used for the development and validation of the LAMP assay. Amplification was performed at 60°C for 60 minutes using extracted DNA or heattreated plasma specimens without DNA extraction. The assay was evaluated for its ability to detect various HBV genotypes and for its sensitivity, specificity, and time-point of detection. Results. The LAMP assay detected HBV genotypes A-F and demonstrated a sensitivity of 10-100 IU per reaction of HBV DNA. The assay also detected 69 of 75 (92%) HBV-positive donor plasma specimens tested and demonstrated a specificity of 100%. Conclusions. These results demonstrate that our HBV-LAMP assay is rapid, sensitive and specific, and capable of detecting the major HBV genotypes. This assay could be used in clinical point-of-care settings, mainly in endemic and resource-limited environments for HBV diagnostics, donor screening, epidemiological studies, and therapeutic monitoring of patients undergoing antiviral treatment.
International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases, Jan 11, 2015
Hepatitis C virus (HCV) is probably the leading cause of liver cirrhosis and hepatocellular carci... more Hepatitis C virus (HCV) is probably the leading cause of liver cirrhosis and hepatocellular carcinoma globally. Diagnostic tools conventionally used for detection and identification of HCV infection are technically demanding, time-consuming and costly for resource-limited environments. This study reports the development of the first rapid loop-mediated reverse-transcription isothermal-amplification assay that rapidly detects and identifies HCV genotypes in blood components. RNA extracted from donor plasma and serum specimens were applied to a one-step reverse transcription loop-mediated isothermal-amplification reaction performed with HCV-specific oligonucleotides. Reactions were conducted at 63.5°C for 30-60minutes. The assay's diagnostic characteristics were investigated and validated with clinical specimens. Electrophoretic analysis of amplification revealed detection and identification of HCV genotypes 1-6. Positive amplification revealed unique ladder-like banding-patterns ...
International Journal of Infectious Diseases, Feb 1, 2016
Hepatitis C virus (HCV) is a single-stranded RNA virus of the Flaviviridae family. 1 Transmitted ... more Hepatitis C virus (HCV) is a single-stranded RNA virus of the Flaviviridae family. 1 Transmitted through modes including injection drug use, contaminated needle-stick injuries, and unsafe blood transfusion, infection with HCV may lead to chronic active hepatitis and hepatocellular carcinoma. 2-4 Approximately 185 million people are infected with HCV worldwide, with developing countries of Sub-Saharan Africa, Asia, North and South America, and the Middle East most affected. 5-7 There are seven major genotypes of HCV with 67 subtypes found in different regions of the world. 8-10 Globally, HCV genotype 1 is the most common, accounting for about 46% of all infections. This is followed by genotype 3, accounting for 22% of the global HCV burden, and genotypes 2 and 4, each accounting for 13%. 5-7 The detection of HCV infection in blood derivatives and the identification of the genotypes are therefore important in clinical diagnostics and antiviral treatment, ensuring blood safety, and providing epidemiological information about HCV prevalence. 11-13 A plethora of molecular diagnostic methods have been designed and used for the detection and genotyping of HCV infection. While these tests are highly sensitive, they remain expensive and laborious and require well-trained personnel, as well as sophisticated laboratory facilities. 14-17 Furthermore, the application of these tests may be limited regarding their ability to detect and simultaneously identify the specific HCV genotypes. 18 Besides, several (reverse transcription) loop-mediated isothermal amplification (RT)-LAMP assays have been designed for the detection of
Scientific Reports, Dec 8, 2015
A rapid multiplex isothermal amplification assay has been developed for detection and identificat... more A rapid multiplex isothermal amplification assay has been developed for detection and identification of multiple blood-borne viruses that infect millions of people worldwide. These infections may lead to chronic diseases or death if not diagnosed and treated in a timely manner. Sets of virusspecific oligonucleotides and oligofluorophores were designed and used in a reverse-transcription loop-mediated multiplexed isothermal amplification reaction for detection and gel electrophoretic identification of human Immunodeficiency virus (HIV), hepatitis-B virus (HBV), hepatitis-C virus (HCV), hepatitis-E virus (HEV), dengue virus (DENV), and West Nile (WNV) virus infection in blood plasma. Amplification was catalyzed with two thermostable enzymes for 30-60 minutes under isothermal condition, utilizing a simple digital heat source. Electrophoretic analysis of amplified products demonstrated simultaneous detection of 6 viruses that were distinctly identified by unique ladder-like banding patterns. Naked-eye fluorescent visualization of amplicons revealed intensely fluorescing products that indicated positive detection. The test demonstrated a 97% sensitivity and a 100% specificity, with no cross-reaction with other viruses observed. This portable detection tool may have clinical and field utility in the developing and developed world settings. This may enable rapid diagnosis and identification of viruses for targeted therapeutic intervention and prevention of disease transmission. Blood-borne pathogens such as hepatitis B virus (HBV), hepatitis C virus (HCV), and the emerging hepatitis E virus (HEV) together infect over 800 million people globally and may lead to chronic active hepatitis and hepatocellular carcinoma 1-3. Infection with the human immunodeficiency virus (HIV) compromises the immune system, while dengue virus (DENV) and West Nile virus (WNV) infections may lead to hemorrhagic fever and neuroinflammatory conditions in infected patients, respectively 4,5. These viruses are transmitted through blood-borne routes and may co-infect a patient or co-circulate in various geographic regions as indicated by the prevalence of HIV, HCV, HEV, and HBV in North America, Africa, Asia, and Europe. Outbreaks of DENV and WNV have occurred in regions throughout the world, particularly in the Middle East, Europe, Africa, the United States, South America, and the Caribbean 6-10. The global distribution of these pathogens coupled with the clinical manifestations of their disease spectra emphasizes the need for simple, but efficient diagnostic point-of-care tools. Such tools may enable rapid detection and differentiation of viruses that present similar clinical symptoms, aid in targeted therapeutic intervention, and facilitate implementation of medical counter measures for disease control and prevention. Several amplification-based multiplex methods, including the quantitative reverse-transcription polymerase chain reaction (qRT-PCR) have been developed and used to detect and quantitate pathogen load 11,12. However, these methods exhibit drawbacks as they are time-consuming, expensive, and require the use of heavy equipment and highly trained personnel to perform. Despite their outstanding performance, these characteristics present limitations in their point-of-care use in field and resource-limited environments. Besides, many (reverse transcription) loop-mediated isothermal amplification assays (RT)-LAMP have been designed, but have hardly demonstrated
World Academy of Science, Engineering and Technology, International Journal of Medical and Health Sciences, 2015
International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases, Jan 11, 2015
Hepatitis C virus (HCV) is probably the leading cause of liver cirrhosis and hepatocellular carci... more Hepatitis C virus (HCV) is probably the leading cause of liver cirrhosis and hepatocellular carcinoma globally. Diagnostic tools conventionally used for detection and identification of HCV infection are technically demanding, time-consuming and costly for resource-limited environments. This study reports the development of the first rapid loop-mediated reverse-transcription isothermal-amplification assay that rapidly detects and identifies HCV genotypes in blood components. RNA extracted from donor plasma and serum specimens were applied to a one-step reverse transcription loop-mediated isothermal-amplification reaction performed with HCV-specific oligonucleotides. Reactions were conducted at 63.5°C for 30-60minutes. The assay's diagnostic characteristics were investigated and validated with clinical specimens. Electrophoretic analysis of amplification revealed detection and identification of HCV genotypes 1-6. Positive amplification revealed unique ladder-like banding-patterns ...
Scientific reports, 2015
A rapid multiplex isothermal amplification assay has been developed for detection and identificat... more A rapid multiplex isothermal amplification assay has been developed for detection and identification of multiple blood-borne viruses that infect millions of people world-wide. These infections may lead to chronic diseases or death if not diagnosed and treated in a timely manner. Sets of virus-specific oligonucleotides and oligofluorophores were designed and used in a reverse-transcription loop-mediated multiplexed isothermal amplification reaction for detection and gel electrophoretic identification of human Immunodeficiency virus (HIV), hepatitis-B virus (HBV), hepatitis-C virus (HCV), hepatitis-E virus (HEV), dengue virus (DENV), and West Nile (WNV) virus infection in blood plasma. Amplification was catalyzed with two thermostable enzymes for 30-60 minutes under isothermal condition, utilizing a simple digital heat source. Electrophoretic analysis of amplified products demonstrated simultaneous detection of 6 viruses that were distinctly identified by unique ladder-like banding pa...
Neuropeptides, 2008
The melanocortin 3-receptor is involved in regulating energy metabolism, body fluid composition a... more The melanocortin 3-receptor is involved in regulating energy metabolism, body fluid composition and inflammatory responses. Melanocortin receptors function by activating membrane bound adenylate cyclase. However, the literature reports indicate that some G protein coupled receptors (GPCRs) can also activate mitogen activated protein kinase (MAPK) or phosphoinositide 3 kinase (PI3K) signaling pathways consequent to their endocytosis. These studies were undertaken to evaluate the role of these pathways in MC3R signaling in brain-stem neuronal cells. Recruitment of arrestins is implicated in the activation of secondary pathways by GPCRs and our data shows the colocalization of either arrestin B1 or B2 with MC3R in endosomes. An alteration in PKB phosphorylation pattern was observed in MC3R expressing cells independent of agonist stimulation. MC3R transfectants exhibited increased proliferation rates and inhibition of PKB pathway with triciribine abrogated cell proliferation in both vector control and MC3R transfectants. PKB is constitutively active in proliferating CAD cells but could be further activated by culturing the cells in differentiation medium. These studies suggest that the AKT/PKB pathway plays an important role in the proliferation of CAD cells and suggest a link between MC3R and cell growth pathways that may involve the alteration of AKT/PKB signaling pathway.
Infection and Immunity, 2004
Helicobacter pylori infection status following experimental inoculation of mice presently require... more Helicobacter pylori infection status following experimental inoculation of mice presently requires euthanasia. The purpose of this study was to develop a method for following the time course of H. pylori infection in live experimental animals. Twenty-six C57BL/6, Helicobacter-free female mice were inoculated with H. pylori Sydney strain 1, and 16 mice were sham inoculated. The mice were repeatedly tested during a period of about 1 year with an H. pylori species-specific primer-based PCR analysis of DNA extracted from fecal pellets of mice. The mice were euthanized at 6 months (n = 15) and 10 months (n = 15) to determine their infection status by histology, culture, and PCR of gastric specimens. H. pylori-inoculated mice were tested via the PCR method at 6 and 10 months prior to necropsy. Nine of 13 (69%) and 10 of 13 (77%) mice tested at 6 and 10 months, respectively, were positive. All sham-inoculated mice were negative. These two PCR results suggested a specificity of 100% with a ...
Clinical Infectious Diseases an Official Publication of the Infectious Diseases Society of America, Apr 4, 2014
Background. Hepatitis B virus (HBV) is an important blood-borne pathogen that causes hepatic infl... more Background. Hepatitis B virus (HBV) is an important blood-borne pathogen that causes hepatic inflammation and can lead to liver cirrhosis and hepatocellular carcinoma. Conventional methods of HBV detection are time consuming and require highly trained personnel and elaborate equipment. This report describes the development of a rapid, simple, specific, and sensitive loop-mediated isothermal amplification assay (LAMP) for detection of HBV genotypes A, B, C, D, E, and F in blood samples. Methods. HBV standard plasma panels and clinical donor plasma specimens were used for the development and validation of the LAMP assay. Amplification was performed at 60°C for 60 minutes using extracted DNA or heattreated plasma specimens without DNA extraction. The assay was evaluated for its ability to detect various HBV genotypes and for its sensitivity, specificity, and time-point of detection. Results. The LAMP assay detected HBV genotypes A-F and demonstrated a sensitivity of 10-100 IU per reaction of HBV DNA. The assay also detected 69 of 75 (92%) HBV-positive donor plasma specimens tested and demonstrated a specificity of 100%. Conclusions. These results demonstrate that our HBV-LAMP assay is rapid, sensitive and specific, and capable of detecting the major HBV genotypes. This assay could be used in clinical point-of-care settings, mainly in endemic and resource-limited environments for HBV diagnostics, donor screening, epidemiological studies, and therapeutic monitoring of patients undergoing antiviral treatment.
International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases, Jan 11, 2015
Hepatitis C virus (HCV) is probably the leading cause of liver cirrhosis and hepatocellular carci... more Hepatitis C virus (HCV) is probably the leading cause of liver cirrhosis and hepatocellular carcinoma globally. Diagnostic tools conventionally used for detection and identification of HCV infection are technically demanding, time-consuming and costly for resource-limited environments. This study reports the development of the first rapid loop-mediated reverse-transcription isothermal-amplification assay that rapidly detects and identifies HCV genotypes in blood components. RNA extracted from donor plasma and serum specimens were applied to a one-step reverse transcription loop-mediated isothermal-amplification reaction performed with HCV-specific oligonucleotides. Reactions were conducted at 63.5°C for 30-60minutes. The assay's diagnostic characteristics were investigated and validated with clinical specimens. Electrophoretic analysis of amplification revealed detection and identification of HCV genotypes 1-6. Positive amplification revealed unique ladder-like banding-patterns ...