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1.
Front Artif Intell ; 7: 1345445, 2024.
Article in English | MEDLINE | ID: mdl-38444962

ABSTRACT

Hate Speech Detection in Arabic presents a multifaceted challenge due to the broad and diverse linguistic terrain. With its multiple dialects and rich cultural subtleties, Arabic requires particular measures to address hate speech online successfully. To address this issue, academics and developers have used natural language processing (NLP) methods and machine learning algorithms adapted to the complexities of Arabic text. However, many proposed methods were hampered by a lack of a comprehensive dataset/corpus of Arabic hate speech. In this research, we propose a novel multi-class public Arabic dataset comprised of 403,688 annotated tweets categorized as extremely positive, positive, neutral, or negative based on the presence of hate speech. Using our developed dataset, we additionally characterize the performance of multiple machine learning models for Hate speech identification in Arabic Jordanian dialect tweets. Specifically, the Word2Vec, TF-IDF, and AraBert text representation models have been applied to produce word vectors. With the help of these models, we can provide classification models with vectors representing text. After that, seven machine learning classifiers have been evaluated: Support Vector Machine (SVM), Logistic Regression (LR), Naive Bays (NB), Random Forest (RF), AdaBoost (Ada), XGBoost (XGB), and CatBoost (CatB). In light of this, the experimental evaluation revealed that, in this challenging and unstructured setting, our gathered and annotated datasets were rather efficient and generated encouraging assessment outcomes. This will enable academics to delve further into this crucial field of study.

2.
Virol J ; 21(1): 16, 2024 01 11.
Article in English | MEDLINE | ID: mdl-38212781

ABSTRACT

BACKGROUND: Previous meta-analyses estimating the prevalence of the post-COVID-19 condition (PCC) were confounded by the lack of negative control groups. This may result in an overestimation of the prevalence of those experiencing PCC, as these symptoms are non-specific and common in the general population. In this study, we aimed to compare the burden of persistent symptoms among COVID-19 survivors relative to COVID-19-negative controls. METHODS: A systematic literature search was conducted using the following databases (PubMed, Web of Science, and Scopus) until July 2023 for comparative studies that examined the prevalence of persistent symptoms in COVID-19 survivors. Given that many of the symptoms among COVID-19 survivors overlap with post-hospitalization syndrome and post-intensive care syndrome, we included studies that compare the prevalence of persistent symptoms in hospitalized COVID-19 patients relative to non-COVID-19 hospitalized patients and in non-hospitalized COVID-19 patients relative to healthy controls that reported outcomes after at least 3 months since infection. The results of the meta-analysis were reported as odds ratios with a 95% confidence interval based on the random effects model. RESULTS: Twenty articles were included in this study. Our analysis of symptomatology in non-hospitalized COVID-19 patients compared to negative controls revealed that the majority of symptoms examined were not related to COVID-19 infection and appeared equally prevalent in both cohorts. However, non-COVID-19 hospitalized patients had higher odds of occurrence of certain symptoms like anosmia, ageusia, fatigue, dyspnea, and brain fog (P < 0.05). Particularly, anosmia and ageusia showed substantially elevated odds relative to the negative control group at 11.27 and 9.76, respectively, P < 0.05. In contrast, analysis of hospitalized COVID-19 patients compared to those hospitalized for other indications did not demonstrate significantly higher odds for the tested symptoms. CONCLUSIONS: The persistent symptoms in COVID-19 survivors may result from hospitalization for causes unrelated to COVID-19 and are commonly reported among the general population. Although certain symptoms exhibited higher odds in non-hospitalized COVID-19 patients relative to controls, these symptoms are common post-viral illnesses. Therefore, the persistent symptoms after COVID-19 may not be unique to SARS-CoV-2. Future studies including well-matched control groups when investigating persistent symptoms in COVID-19 survivors are warranted to draw a firm conclusion.


Subject(s)
COVID-19 , Post-Acute COVID-19 Syndrome , Adult , Child , Humans , Ageusia/etiology , Anosmia/etiology , COVID-19/complications , COVID-19/epidemiology , Post-Acute COVID-19 Syndrome/complications , Post-Acute COVID-19 Syndrome/epidemiology
3.
Heliyon ; 9(9): e19848, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37810168

ABSTRACT

A non-linear system of differential equations was used to explain the spread of the COVID-19 virus and a SEIQR model was developed and tested to provide insights into the spread of the pandemic. This article, which is related to the aforementioned work as well as other work covering variations of SIR models, Hermite Wavelets Transform, and also the Generalized Compartmental COVID-19 model, we develop a mathematical control model and apply it to represent optimal vaccination strategy against COVID-19 using Pontryagin's Maximum Principle and also factoring in the effect of facemasks on the spread of the virus. As background work, we analyze the mathematical epidemiology model with the facemask effect on both reproduction number and stability, we also analyze the difference between confirmed COVID-19 cases of the Quarantine class and anonymous cases of the Infectious class that is expected to recover. We also apply control theory to mine insights for effective virus spread prevention strategies. Our models are validated using Matlab mathematical model validation tools. Statistical tests against data from Jordan are used to validate our work including the modeling of the relation between the facemask effect and COVID-19 spread. Furthermore, the relation between control measure ξ, cost, and Infected cases is also studied.

4.
BMC Infect Dis ; 23(1): 151, 2023 Mar 10.
Article in English | MEDLINE | ID: mdl-36899311

ABSTRACT

BACKGROUND: Hepatitis B infection seriously threatens global public health, especially in developing nations. Despite several investigations on HBV incidence, the national pooled prevalence remains unknown, particularly in populations at-risk at whom interventions should be primarily aimed. METHODS: A comprehensive literature search of the following databases: Medline [PubMed], Scopus, Google Scholar, and Web of Science was conducted following the PRISMA guidelines. I-squared and Cochran's Q were used to measure the heterogeneity between the studies. Publications that matched the following were included: Primary studies published in Egypt from 2000 to 2022 reported HBV prevalence based on HBsAg. We excluded any studies that were not performed on Egyptians or that were performed on patients suspected of acute viral hepatitis or studies focusing on occult hepatitis or vaccination evaluation studies, or national surveys. RESULTS: The systematic review included 68 eligible studies reporting a total of 82 incidences of HBV infection based on hepatitis B surface antigen with a total sample size of 862,037. The pooled national prevalence among studies was estimated to be 3.67% [95% CI; 3: 4.39]. Children under 20 with a history of HBV vaccination during infancy had the lowest prevalence of 0.69%. The pooled prevalence of HBV infection among pregnant women, blood donors, and healthcare workers was 2.95%, 1.8%, and 1.1%, respectively. While patients with hemolytic anemia and hemodialysis patients, patients with malignancies, HCC patients, and chronic liver disease patients had the highest prevalences at 6.34%, 25.5%, 18.6%, and 34%, respectively. Studies reporting HBV prevalence in urban settings compared to rural settings revealed a similar HBV prevalence of 2.43% and 2.15%, respectively. Studies comparing HBV prevalence in males and females revealed a higher prevalence among males (3.75%) than females (2.2%). CONCLUSION: In Egypt, hepatitis B infection is a significant public health issue. The blocking of mother-to-infant hepatitis B transmission, the scaling up of the scope of the existing vaccination program, and implementing new strategies, including screen-and-treat, may reduce the prevalence of the disease.


Subject(s)
Carcinoma, Hepatocellular , Hepatitis B , Liver Neoplasms , Male , Child , Humans , Female , Pregnancy , Hepatitis B Surface Antigens , Hepatitis B virus , Egypt , Seroepidemiologic Studies , Hepatitis B/epidemiology , Antigens, Surface , Prevalence
5.
Diagnostics (Basel) ; 12(11)2022 Nov 19.
Article in English | MEDLINE | ID: mdl-36428930

ABSTRACT

Breast cancer is the most common cancer diagnosed in women and the leading cause of cancer-related deaths among women worldwide. The death rate is high because of the lack of early signs. Due to the absence of a cure, immediate treatment is necessary to remove the cancerous cells and prolong life. For early breast cancer detection, it is crucial to propose a robust intelligent classifier with statistical feature analysis that considers parameter existence, size, and location. This paper proposes a novel Multi-Stage Feature Selection with Binary Particle Swarm Optimization (MSFS-BPSO) using Ultra-Wideband (UWB). A collection of 39,000 data samples from non-tumor and with tumor sizes ranging from 2 to 7 mm was created using realistic tissue-like dielectric materials. Subsequently, the tumor models were inserted into the heterogeneous breast phantom. The breast phantom with tumors was imaged and represented in both time and frequency domains using the UWB signal. Consequently, the dataset was fed into the MSFS-BPSO framework and started with feature normalization before it was reduced using feature dimension reduction. Then, the feature selection (based on time/frequency domain) using seven different classifiers selected the frequency domain compared to the time domain and continued to perform feature extraction. Feature selection using Analysis of Variance (ANOVA) is able to distinguish between class-correlated data. Finally, the optimum feature subset was selected using a Probabilistic Neural Network (PNN) classifier with the Binary Particle Swarm Optimization (BPSO) method. The research findings found that the MSFS-BPSO method has increased classification accuracy up to 96.3% and given good dependability even when employing an enormous data sample.

6.
Sensors (Basel) ; 22(18)2022 Sep 08.
Article in English | MEDLINE | ID: mdl-36146163

ABSTRACT

The Internet of Things (IoT) has widely expanded due to its advantages in enhancing the business, industrial, and social ecosystems. Nevertheless, IoT infrastructure is susceptible to several cyber-attacks due to the endpoint devices' restrictions in computation, storage, and communication capacity. As such, distributed denial-of-service (DDoS) attacks pose a serious threat to the security of the IoT. Attackers can easily utilize IoT devices as part of botnets to launch DDoS attacks by taking advantage of their flaws. This paper proposes an Ethereum blockchain model to detect and prevent DDoS attacks against IoT systems. Additionally, the proposed system can be used to resolve the single points of failure (dependencies on third parties) and privacy and security in IoT systems. First, we propose implementing a decentralized platform in place of current centralized system solutions to prevent DDoS attacks on IoT devices at the application layer by authenticating and verifying these devices. Second, we suggest tracing and recording the IP address of malicious devices inside the blockchain to prevent them from connecting and communicating with the IoT networks. The system performance has been evaluated by performing 100 experiments to evaluate the time taken by the authentication process. The proposed system highlights two messages with a time of 0.012 ms: the first is the request transmitted from the IoT follower device to join the blockchain, and the second is the blockchain response. The experimental evaluation demonstrated the superiority of our system because there are fewer I/O operations in the proposed system than in other related works, and thus it runs substantially faster.


Subject(s)
Blockchain , Internet of Things , Computer Security , Delivery of Health Care , Ecosystem , Technology
7.
Cureus ; 14(12): e32426, 2022 Dec.
Article in English | MEDLINE | ID: mdl-36644043

ABSTRACT

Background In Saudi Arabia, traumatic vertebral and spinal injuries (TVSIs) are well-recognized injuries with long-term morbidity and mortality. Al-Qassim is among the five regions in the kingdom with the highest number of TVSIs. Little is known about the characteristics of and outcomes for patients with a TVSI in the Al-Qassim region, and we aimed to explore these further. Methodology Electronic medical records of patients with a TVSI admitted to Buraidah Central Hospital between January 1, 2017, and December 31, 2019, were examined. Characteristics, outcomes, and length of stay (LOS) in the hospital acute care were reported for the patients, along with their scores (A through E) on the American Spinal Injury Association (ASIA) impairment scale at admission and at discharge. Results  The sample included 243 patients with a TVSI (median age 35 years). The majority of the participants were Saudi (70%), admitted due to road traffic accidents (67%), and had an ASIA score of E at admission (83%). The median (interquartile range [IQR]) LOS in acute care was 10.0 (4-18) days. Determinants of a prolonged hospital stay included being non-Saudi, having an ASIA score of A through D at admission, and having associated orthopedic injuries. An ASIA score of A through D at admission was the only significant determinant of having an ASIA score of A through D at discharge. Conclusions Road traffic accidents accounted for the majority of TVSIs in Al-Qassim. Not having a normal and preserved function at admission (i.e., ASIA score of A through D) was associated with a prolonged hospital stay.

8.
BMC Pregnancy Childbirth ; 20(1): 754, 2020 Dec 02.
Article in English | MEDLINE | ID: mdl-33267785

ABSTRACT

BACKGROUND: The effect of SARS-CoV-2 infection in pregnant women and newborns is incompletely understood. Preliminary data shows a rather fluctuating course of the disease from asymptomatic or mild symptoms to maternal death. However, it is not clear whether the disease increases the risk of pregnancy-related complications. The aim of the study is to describe the maternal and neonatal clinical characteristics and outcome of pregnancies with SARS-CoV-2 infection. METHODS: In this retrospective national-based study, we analyzed the medical records of all pregnant women infected with SARS-CoV-2 and their neonates who were admitted to New-Jahra Hospital (NJH), Kuwait, between March 15th 2020 and May 31st 2020. During the study period and as part of the public health measures, a total of 185 pregnant women infected with SARS-CoV-2, regardless of symptoms, were hospitalized at NJH, and were included. Maternal and neonatal clinical manifestations, laboratory tests and treatments were collected. The outcomes of pregnancies included miscarriage, intrauterine fetal death (IUFD), preterm birth and live birth were assessed until the end date of the outcomes follow-up (November 10th 2020). RESULTS: A total of 185 pregnant women infected with SARS-CoV-2 were enrolled with a median age of 31 years (interquartile range, IQR: 27.5-34), and median gestational age at diagnosis of SARS-CoV2 infection was 29 weeks (IQR: 18-34). The majority (88%) of these women had mild symptoms, with fever (58%) being the most common presenting symptom followed by cough (50.6%). At the time of the analysis, out of the 185, 3 (1.6%) of the pregnant women had a miscarriage, 1 (0.54%) had IUFD which was not related to COVID-19, 16 (8.6%) had ongoing pregnancies and 165 (89%) had a live birth. Only 2 (1.1%) of these women developed severe pneumonia and required intensive care. A total of 167 neonates with two sets of twins were born with median gestational age at birth was 38 (IQR: 36-39) weeks. Most of the neonates were asymptomatic, and only 2 of them tested positive on day 5 by nasopharyngeal swab testing. CONCLUSIONS: In this national-based study, most of the pregnant women infected with SARS-CoV-2 showed mild symptoms. Although mother-to-child vertical transmission of SARS-CoV-2 is possible, COVID-19 infection during pregnancy may not lead to unfavorable maternal and neonatal outcomes.


Subject(s)
COVID-19/epidemiology , Infectious Disease Transmission, Vertical/statistics & numerical data , Pregnancy Complications, Infectious/epidemiology , Prenatal Diagnosis/statistics & numerical data , Adult , COVID-19/diagnosis , Female , Humans , Infant, Newborn , Kuwait , Maternal Welfare/statistics & numerical data , Pandemics/statistics & numerical data , Pregnancy , Pregnancy Complications, Infectious/diagnosis , Pregnancy Outcome , Retrospective Studies , Young Adult
9.
Article in English | MEDLINE | ID: mdl-31827548

ABSTRACT

BACKGROUND: Toxoplasmosis remains widely distributed globally and is one of the major neglected parasitic zoonotic infections. The infection is still endemic in most parts of the world due to poor control as well as challenges of the currently used medications which can be overcome by using natural products. This study evaluated the effect of ethanolic extract from the stem of Tinospora crispa (EETC) on host cell invasion and intracellular replication of Toxoplasma gondii. METHOD: The stem powder of T. crispa was soaked in absolute ethanol for 72 hours. The resulting ethanolic extract was screened for the presence of phytochemicals. Vero cells monolayer in 96-well plate was infected with RH strain of T. gondii and treated with concentrations of the EETC, Veratrine alkaloid, and clindamycin ranging from 1.56 to 200 µg/mL. MTT assay was conducted after 24 hours to evaluate the cytotoxicity and antiparasitic activities of the EETC. Four and 24 hours treatment models were adapted to assess the infection index and intracellular proliferation of T. RESULTS: The study revealed that the EETC had no cytotoxic effects on Vero cells with IC50 = 179 µg/mL, as compared to clindamycin (IC50 = 116.5 µg/mL) and Veratrine alkaloid (IC50 = 60.4 µg/mL). The EETC had good anti-toxoplasma activities with IC50 = 6.31 µg/mL in comparison with clindamycin (IC50 = 8.33 µg/mL) and Veratrine alkaloid (IC50 = 14.25 µg/mL). The EETC caused more than 70% and 80% reduction in infection index and intracellular proliferation in both treatment models, respectively. CONCLUSION: This in vitro study showed that the EETC contains promising phytochemicals effective against T. gondii and safe to the host cells.

10.
Indian J Ophthalmol ; 67(1): 109-115, 2019 Jan.
Article in English | MEDLINE | ID: mdl-30574904

ABSTRACT

PURPOSE: To test the hypothesis that eye muscle surgery in treatment of patients with acquired downbeat nystagmus results in improvement measures of visual and ocular motor function. METHODS: This is a prospective, interventional case series analysis of clinical and electrophyisological data before and after eye muscle surgery in 17 patients with acquired downbeat nystagmus who did not respond to medical treatments. Outcome measures included: 1) routine demography and clinical characteristics, 2) subjective oscillopsia (SO), 3) binocular best-corrected visual acuity in the null position (BVA), 3) primary position strabismic deviation (SD), 5) anomalous head posture (AHP), 6) contrast sensitivity function (CS), and 7) nystagmus slow phase velocity (SPV). All patients were followed at least 12 months. Parametric and non-parametric statistical analysis of outcome measure data above pre- and post-treatment were perfomed using standard software on grouped data using computerized software. RESULTS: Patients' age ranged from 5 to 85 years (average 27 years). About 59% were male. Follow up ranged from 1-10 years (average 2.0 years). Around 70% had an associated central nervous systemic diagnosis, 100% had an AHP, oscillopsia and decreased CS, 53% had other eye disease, and 59% had strabismus. There were no complications from surgery. There were signficant post-treatment improvements in mean/median group BVA, SO, SD, AHP, CS, and SPV. CONCLUSION: This study supports the hypothesis that eye muscle surgery as treatments for patients with acquired downbeat nystagmus can result in improvements in multiple aspects of ocular motor and visual functions.


Subject(s)
Electrophysiological Phenomena/physiology , Eye Movements/physiology , Nystagmus, Pathologic/surgery , Oculomotor Muscles/surgery , Ophthalmologic Surgical Procedures/methods , Vision, Binocular/physiology , Visual Acuity , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Female , Follow-Up Studies , Humans , Male , Middle Aged , Nystagmus, Pathologic/diagnosis , Nystagmus, Pathologic/physiopathology , Oculomotor Muscles/physiopathology , Prospective Studies , Young Adult
11.
Innate Immun ; 24(3): 171-179, 2018 04.
Article in English | MEDLINE | ID: mdl-29635981

ABSTRACT

Childhood asthma represents a worldwide problem, involving genetic, immune defense and environmental components. MicroRNAs (miRs) are non-coding, single-stranded RNAs involved in immune regulation. The aim was to evaluate clinical potential of plasma miR-21 and miR-146a involved in T helper differentiation in childhood asthma and non-asthmatic controls. Group 1 consisted of 27 asthmatic children receiving inhaled corticosteroids (ICSs), which was compared to group 2 with 21 healthy control children. All patients were assessed by pulmonary function tests. miR-21 and miR-146a expression levels were determined by real-time quantitative PCR, and IL-13 was measured using ELISA. Group 1 showed significant up-regulation of plasma miR-21 and miR-146a levels with mean values 42.6-fold and 4.7-fold higher than average expression, respectively, in group 2. miR-21 levels positively correlated with IL-13 levels and eosinophil percentage, while miR-146a only correlated to eosinophil percentage. There was a linear association between each of miR-21 and miR-146a expression and FEV1 (forced expiratory volume in the first second), miR-21 and miR-146a are up-regulated in asthmatic children. miR-21 served as a better asthma biomarker. Association between both markers and FEV1 points to their role in determining asthma outcome following ICS treatment. miR-21 and miR-146a play a role in eosinophilic endotypic classification of asthma.


Subject(s)
Asthma/genetics , Interleukin-13/genetics , MicroRNAs/genetics , Adrenal Cortex Hormones/therapeutic use , Age Factors , Anti-Asthmatic Agents/therapeutic use , Asthma/metabolism , Asthma/physiopathology , Biomarkers , Case-Control Studies , Cell Differentiation/genetics , Child , Eosinophils , Female , Forced Expiratory Volume , Humans , Interleukin-13/biosynthesis , Male , MicroRNAs/biosynthesis , Sex Factors , T-Lymphocytes, Helper-Inducer , Th2 Cells , Up-Regulation/drug effects
13.
Anal Chem ; 82(14): 6090-7, 2010 Jul 15.
Article in English | MEDLINE | ID: mdl-20552987

ABSTRACT

We present a novel nonenzymatic carbon nanotube sensor integrated in a microfluidic channel for the detection of sugars. The sensor is assembled as a liquid-gated field-effect transistor, with the transistor channel composed of 1 to 10 nanotubes, which are controllably functionalized with boronic acid receptors. The devices show sensitivity to glucose in a concentration range of 5 to 30 mM. Furthermore, by controlling the type of nanotube-receptor coupling (as covalent or noncovalent) and by deploying a sensitive impedance-based detection technique, we corroborate in detail the transduction mechanism of our affinity-based sensor. In the case of covalent coupling, charge carrier scattering along the nanotubes is the dominant mechanism. While in the noncovalent case, surface charge effects dominate. The identification of the mechanism along with the tunability of the chemical coupling and the cost-effective integration in microchannels constitute a solid basis for the entry of nanotube-based sensors in lab-on-a-chip applications.


Subject(s)
Biosensing Techniques/methods , Glucose/analysis , Microfluidic Analytical Techniques/methods , Nanotubes, Carbon/chemistry , Boronic Acids/chemistry , Enzymes/chemistry , Microscopy, Atomic Force
14.
Afr J Paediatr Surg ; 6(2): 120-1, 2009.
Article in English | MEDLINE | ID: mdl-19661647

ABSTRACT

According to the current understanding, duodenal atresia is considered to be a primary malformation resulting from the errors in recanalisation in early gestation. We report a rare case of duodenal atresia with apple-peel configuration of remaining small bowel with absent superior mesenteric artery in a preterm child, which indicates that in rare circumstances vascular accidents may be the underlying cause for duodenal atresia, and jejuno-ileal atresia; only second such case to be reported in the English literature.


Subject(s)
Duodenal Obstruction/diagnostic imaging , Duodenal Obstruction/surgery , Intestinal Atresia/surgery , Mesenteric Artery, Superior/abnormalities , Duodenal Obstruction/congenital , Humans , Infant, Newborn , Intestinal Atresia/diagnostic imaging , Male , Radiography
15.
Afr J Paediatr Surg ; 6(2): 122-3, 2009.
Article in English | MEDLINE | ID: mdl-19661648

ABSTRACT

An eight-year old male was admitted with complaints of right scrotal swelling, dysuria and intermittent retention of urine for 10 days. On per-rectal examination, a hard mass was palpable in the posterior urethra. An X-ray (KUB) of the abdomen revealed a double dumb-bell calculus at the base of bladder, extending into the posterior urethra. A cystolithotomy via the suprapubic approach was successfully curative.


Subject(s)
Urinary Bladder Calculi/surgery , Child , Dysuria , Humans , Male , Urologic Surgical Procedures/methods
17.
Chemphyschem ; 10(13): 2251-5, 2009 Sep 14.
Article in English | MEDLINE | ID: mdl-19630055

ABSTRACT

We report here on the interaction of the fluorescent dye rhodamine B (RB) with single-walled carbon nanotubes (SWCNTs). We observe that SWCNTs statically quench the fluorescence of RB by forming a stable ground state complex. Careful spectroscopic analysis indicates that the complex formation is efficient mainly with certain chiral forms. We propose three different applications utilizing this quenching mechanism and the associated complexation. Firstly, the quenching efficiency can be utilized as a measure for the characterization and quantification of nanotube dispersions. Secondly, we demonstrate that the specific complexation of RB can be deployed to enrich certain chiral forms in suspension. Finally, we show that RB can be effectively used to visualize nanotubes deposited on substrates.

18.
Chemphyschem ; 10(6): 905-9, 2009 Apr 14.
Article in English | MEDLINE | ID: mdl-19308969

ABSTRACT

Highly selective: Enhancement of the photoluminescence (PL) emission efficiency of selected chiral forms of semiconducting single-walled carbon nanotubes (SWCNTs) is presented (see figure). Excitation of Nile blue A in the presence of SWCNTs results in the quenching of its fluorescence. The energy is resonantly transferred to the (7,5) SWCNT whereas the (8,7) tube is not in resonance; hence, its PL remains unaffected.We report on a simple method for enhancing the efficiency of photoluminescence (PL) emission from selected chiral forms of semiconducting single-wall carbon nanotubes (SWCNTs). The method is based on the use of a fluorescent dye (Nile blue A) that shows the capability of resonant energy transfer on to nanotubes. The excitation of Nile blue A in the presence of SWCNTs results in the quenching of its fluorescence and the energy is resonantly transferred to certain chiral forms. The PL emission from these chiral forms shows a marked increase in efficiency signifying the occurrence of Förster type resonant energy transfer (FRET). Due to its simplicity, this procedure has widespread implications for the detection of carbon nanotubes as well as for their use as fluorophores in FRET-based in vivo and in vitro biological applications.

19.
Biosci Biotechnol Biochem ; 71(8): 1970-8, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17690445

ABSTRACT

Real-time PCR is a potent technique for nucleic acid quantification for research and diagnostic purposes, the wide dynamic range being one of the advantages over other techniques like the microarray. Several additives and enhancers have been studied to expand the PCR dynamic range in order to be more efficient in quantifying low quantities of nucleic acids, increase the yield and improve reaction efficiency. Shown here is that a combination of new buffers with the regularly used Tris buffer makes it possible to expand the real-time PCR dynamic range and to improve the efficiency and correlation coefficient. Mixing HEPES, TEA or MOPS with Tris was more efficient than Tris alone. It was also found that, if the pH value of the Tris buffer was calibrated with phosphoric acid instead of hydrochloric acid, then the dynamic range was significantly improved and low quantities could be detected and quantified more efficiently. Mixing more than one compound with the Tris buffer was also effective for expanding the dynamic range and increasing the efficiency and correlation coefficient in quantitative real-time PCR.


Subject(s)
Buffers , Polymerase Chain Reaction/methods , HEPES , Hydrogen-Ion Concentration , Morpholines , Polymerase Chain Reaction/standards , Tromethamine
20.
Anal Bioanal Chem ; 389(3): 983-8, 2007 Oct.
Article in English | MEDLINE | ID: mdl-17673983

ABSTRACT

Asymmetric cyanine dyes bind to the minor groove of double stranded DNA (dsDNA) owing to their crescent configuration; therefore, these dyes are widely used as a dsDNA probes. BOXTO-MEE is derived from BOXTO by adding the polar methoxyethoxyethyl tail in order to increase solubility, dissociation rate kinetics, and stability. As a result, BOXTO-MEE showed significant reduction in nonspecific amplification (primer dimers) without significant effect on target sequence amplification, PCR efficiency, and standard curve correlation coefficient. BETIBO is another example of an asymmetric cyanine dye that can binds to dsDNA but is less efficient than BOXTO-MEE for use in real-time PCR. Statistical analysis of reproducibility results shows that BETIBO is not strong enough to be used for quantifying low nucleic acid quantities. Statistical analysis for BOXTO-MEE results shows that there is no significant difference between the efficiency and correlation coefficient achieved by BOXTO-MEE and SYBR Green I, but a significant difference in the dynamic range is observed because BOXTO-MEE has a wider dynamic range. BOXTO-MEE stock solution was stable at -20 degrees C for more than 1 year and 40 microM solution was stable for 45 days (at least) at 4 degrees C.


Subject(s)
Carbocyanines/chemistry , DNA/chemistry , Fluorescent Dyes/chemistry , Organic Chemicals/chemistry , Benzothiazoles , Binding Sites , Carbocyanines/metabolism , DNA/metabolism , DNA Primers , DNA Probes , Diamines , Fluorescent Dyes/metabolism , Kinetics , Nucleic Acid Amplification Techniques/methods , Organic Chemicals/metabolism , Polymerase Chain Reaction/methods , Quinolines , Reproducibility of Results , Solubility , Temperature
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