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Search Results: 1 - 10 of 405178 matches for " The M. Nguyen "
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Donnan Electric Potential Dependence of Intraparticle Diffusion of Malachite Green in Single Cation Exchange Resin Particles: A Laser Trapping-Microspectroscopy Study  [PDF]
Nguyen M. Cuong, Shoji Ishizaka, Noboru Kitamura
American Journal of Analytical Chemistry (AJAC) , 2012, DOI: 10.4236/ajac.2012.33027
Abstract: A laser trapping-microspectroscopy technique combined with excitation energy transfer from a fluorescent cationic dye (Rhodamine B, RB+) to a non-fluorescent cationic dye (Malachite Green, MG+) was employed to study pH effects on the diffusion coefficients of MG+ (D(MG+)) in single cation-exchange resin microparticles with the diameters of 16 μm. When RB+-pre-adsorbed resin particles were soaked in an aqueous MG+ solution, the RB+ fluorescence was quenched gradually with the soaking time. The time course of the quenching efficiency of RB+ by MG+ was then used to evaluate the D(MG+) value in the particle. The D(MG+) value increased from 1.1 × 10-11 to 4.3 × 10-11 cm2.s–1 on going the solu- tion pH value from 9 to 4. The results were explained reasonably by a Donnan electric potential model.
Atypical Cutaneous Lymphoproliferative Disorder: A Fatal Mimic of Cutaneous T-Cell Lymphoma in a Patient with HIV Infection  [PDF]
Veronica Nguyen, Russell Dorer, David M. Aboulafia
World Journal of AIDS (WJA) , 2013, DOI: 10.4236/wja.2013.31002
Abstract:

Atypical cutaneous lymphoproliferative disorder (ACLD) is a rare condition that has been associated with HIV infection. Patients with ACLD present with diffuse, erythematous and pruritic skin lesions accompanied by generalized lymphadenopathy. The clinical characteristics of ACLD overlap most notably with several other conditions including Mycosis Fungoides/Sézary Syndrome (MF/SS), a cutaneous lymphoma of T-cell lineage. Unlike Mycosis Fungoides, the noxious infiltrates of ACLD are not monoclonal but polyclonal and consist of cytotoxic CD8+ T-cells instead of CD4+ T-cells or B-cells. Highly active antiretroviral therapy (HAART) has been reported to improve ACLD. We describe the case of a Caucasian man with longstanding HIV infection who presented with severe erythroderma. Skin and lymph node biopsies showed polyclonal CD8+ T-cell infiltrates. Gene rearrangement studies did not reveal an obvious clonal disorder. Hallmark peripheral blood findings consisting of a severe depletion of CD4+ T-lymphocytes and markedly elevated CD8+ cells provided an important diagnostic clue. Despite the purported benefits of HAART in ameliorating this disorder, erythroderma and extreme pruritus improved only after the patient began taking mycophenolate mofetil and hydroxyurea. Unfortunately, he succumbed to complications of methicillin-resistant Staphylococcus aureus septicemia. We alert readers to this rare HIV-associated condition which may mimic other benign and malignant skin conditions and briefly discuss diagnostic and therapeutic options.

The integral equations of Compton Scatter Tomography  [PDF]
M. K. Nguyen, T. T. Truong
Open Journal of Applied Sciences (OJAppS) , 2012, DOI: 10.4236/ojapps.2012.24B013
Abstract: Two new Compton Scatter Tomography modalities, which are aimed at imaging hidden structures in bulk matter for industrial non-destructive control (or testing) and for medical diagnostics are shown to be based on the solutions of a special class of Chebyshev integral transforms. Besides their remarkable analytic properties, they can be inverted by existing methods which lend themselves nicely to numerical treatment and provide convergent, stable and fast computation algorithms. The existence of explicit inversion formulas implies that viable new imaging techniques can be developed, which may take over the current ones in a near future.
Determination and comparison of vitamin C, calcium and potassium in four selected conventionally and organically grown fruits and vegetables
KG Masamba, M Nguyen
African Journal of Biotechnology , 2008,
Abstract: It is evident that the growing interest in organically grown produce has correspondingly necessitated the debate on the nutritional supremacy between organically and conventionally grown produce. A study was carried out to determine and compare vitamin C, calcium and potassium in organically and conventionally grown cabbage, carrots, Cos lettuce and Valencia oranges. Samples were purchased from local supermarkets within Central Coast, New South Wales in Australia from late March to early April 2007. Vitamin C content was determined by 2,6-dichloroindophenol titrimetric method while calcium and potassium were determined by atomic absorption spectroscopy. Results from the study showed inconsistent pattern with respect to vitamin C, calcium and potassium contents in the conventionally and organically grown samples. No significant differences were observed in vitamin C content in conventionally and organically grown cabbage, carrots and Cos lettuce while significant differences were observed in Valencia oranges which showed higher vitamin C content in organic Valencia oranges as compared to conventional ones (51.8 to 43.4 mg/100 g fresh weight). Results on calcium and potassium contents showed significant differences in all the samples with the trend of higher values for organically grown cabbage, carrots and Cos lettuce as opposed to their conventionally grown counterparts. However, for Valencia oranges, results showed that the calcium and potassium contents were significantly higher in conventional Valencia oranges compared to the organic Valencia orange (54.5 and192.0 mg to 51.8 and 189.5 mg/100 g, respectively).
Lithium Associated Hyperparathyroidism: An Evidence Based Surgical Approach  [PDF]
Umashankar K Ballehaninna, Steven M. Nguyen, Ronald S. Chamberlain
Surgical Science (SS) , 2011, DOI: 10.4236/ss.2011.210103
Abstract: Background: Long-term lithium use in psychiatric patients may lead to lithium associated hyperparathyroidism (LAH). Although anecdotal case reports have appeared, an evidence based algorithm for management of LAH is lacking. Methods: A comprehensive literature search was performed (1973-2010) using PubMed with keywords; “lithium” “hypercalcemia” “hyperparathyroidism” “sestamibi” “intra-operative parathyroid hormone (IOPTH) monitoring” “parathyroidectomy” and “medical management”. All English language publications addressing etiology and clinical management issues concerning LAH were critically analyzed. Results: Lithium associated hyperparathyroidism occurs in 4.3% - 6.3% of chronic lithium users compared to the general population which has an incidence of 0.5% - 1%. 194 cases of LAH have been reported which includes 10 patients (5%) treated medically and 170 patients (88%) who underwent parathyroidectomy. No details were available for 14 patients (7%). Among parathyroidectomy patients, 104 (59%) had adenomatous disease and 66 (39%) had multiglandular hyperplasia. Preoperative localization studies were utilized in only 22 patients (13%) and IOPTH monitoring was reported in only 3 studies (32 patients, 19%). Among surgical patients, bilateral neck exploration (BNE) was the most common approach performed in 162 patients (95%); focused neck exploration was utilized in only 8 patients (5%). Parathyroidectomy normalized LAH biochemical changes in nearly all patients (90% - 97%) in the early post-operative period, but recurrent hyperparathyroidism occurred in 8% - 42% of patients. Conclusion: LAH is an under appreciated and poorly understood endocrine disorder. LAH has a higher incidence of multiglandular disease and bilateral neck exploration is mandatory in majority for disease control. Nonsurgical approaches may be useful in select patients on short-term lithium therapy.
Reporting cervical effacement as a percentage: How accurate is it?  [PDF]
Radha Malapati, Yen N. Vuong, Tuan M. Nguyen
Open Journal of Obstetrics and Gynecology (OJOG) , 2013, DOI: 10.4236/ojog.2013.37102
Abstract:

Objective: To evaluate the accuracy of cervical effacement reported as a percentage by digital cervical exams using cervical length determined by transvaginal ultrasonography as a standard. Methods: Records of pregnant women who had a digital cervical exam and subsequent transvaginal ultrasound scan for cervical length between January 2005 and December 2008 were reviewed. Digital cervical exams were performed by different examiners. Transvaginal ultrasound was performed by one examiner who did not perform any of the digital exams. Cervical effacements were recorded as a percentage and cervical lengths were measured in centimeters. Results: A total of 173 women met the study criteria. Average cervical length for 0% effacement was 3.3 ± 1.1 cm (0.8 - 5.0 cm); 20% effacement, 1.6 ± 1.0 cm (0.9 - 3.0 cm); 25% effacement, 2.2 ± 0.2 cm (2.0 - 2.3 cm); 30% effacement, 2.6 ± 0.4 cm (2.1 - 3.0 cm); 40% effacement, 3.0 ± 0.4 cm (2.6 - 3.4 cm); 50% effacement, 2.4 ± 1.1 cm (0.6 - 4.6 cm); 60% effacement, 2.3 ± 1.4 cm (0.7 - 4.3 cm); 70% effacement, 2.2 ± 0.8 cm (1.1 - 3.3 cm); 75% effacement, 1.7 ± 1.4 cm (0.7 - 2.7 cm); 80% effacement, 2.0 ± 0.9 cm (0.6 - 4.4 cm); 90% effacement, 0.7 ± 0.4 cm (0.4 - 0.9 cm); 100% effacement, 1.2 ± 1.5 cm (0.3 - 3.0 cm). The coefficient of variation ranges from 10% - 124%. Conclusion: The traditional method of reporting cervical effacement as a percentage is unacceptably inaccurate compared to the actual cervical length determined by vaginal probe ultrasound.

Formulation Optimization Utilizing D-Optimal Experimental Design of Oral Capsules Containing Enteric-Coated Pellets of Lansoprazole and in vivo Bioequivalence  [PDF]
Anh Quang Luong, 0 0, Thang Ngoc Vu, Dang Hoa Nguyen, Sultan M. Alshahrani, John Mark Christensen, Chien Ngoc Nguyen
Pharmacology & Pharmacy (PP) , 2017, DOI: 10.4236/pp.2017.85011
Abstract: An optimized formulation of capsules containing Lansoprazole enteric-coated pellets using D-Optimal design with a polynomial statistical model were prepared by using Eudragit?L100 as an enteric coated polymer to provide resistance to simulated gastric acid dissolution in buffer media. D-Optimal experimental design was used to determine the optimal level for three coating layers that were applied to formulate the enteric-coated pellets including a drug loading layer, a sub-coating, and an outer enteric coating. Dissolution studies were performed on the prepared Lansoprazole capsules. Less than 5 percent of Lansoprazole was released in 60 minutes in an acidic dissolution medium (pH 1.2) and greater than 90 percent of active ingredient was released in the next 60 minutes in a buffer dissolution medium (pH 6.8). The Lansoprazole capsules were stable with no observable change in physico-chemical properties in accelerated and normal storage conditions for 6 and 18 months, respectively. The pharmacokinetic parameters Cmax, Tmax, AUC0-t, and AUC0-∞ were determined after administration of the D-Optimal design optimized capsules of LPZ to healthy beagle dogs and were statistically compared to Gastevin? capsules as a reference (KRKA, Slovenia) using the non-compartmental method with the aid of WinNonlin 5.2 software. The analysis of variance showed that the two formulations did not demonstrate bioequivalence using a 90% confidence interval range (80% - 120%) of Cmax, AUC0-t, and AUC0-∞. No significant difference in Tmax was found at the 0.95 significance level using the Wilcoxon signed-rank test. D-Optimal Experimental Design provided definitive direction for an optimal formulation of capsules containing enteric-coated pellets of lansoprazole loaded within the coating of pellets that provided similar bioequivalence to Gastevin.
Composition of Essential Oils from Litsea acutivena Hayata  [PDF]
Do N. Dai, Nguyen T. T. Lam, Nguyen A. Dung, Le T. Huong, Dao T. M. Chau, Isiaka A. Ogunwande
American Journal of Plant Sciences (AJPS) , 2019, DOI: 10.4236/ajps.2019.104044
Abstract: The chemical components of the leaf oil of Litsea acutivena Hayata collected from Pù Huong Natural Reserve, Nghe An Province, Vietnam, were identified by co-chromatography with authentic samples, gas chromatography/mass spectrometry (GC/MS) and linear retention indices. The significant compounds of L. acutivena were α-phellandrene (30.4%) and α-pinene (14.2%). The constituents of essential oil of L. acutivena from Vietnam are being reported for the first time.
Application of Artificial Immune System Algorithm to Electromagnetics Problems
Ozlem Kilic;Q. M. Nguyen
PIER B , 2010, DOI: 10.2528/PIERB10010701
Abstract: This paper investigates the use of clonal selection principles based on our immune system for optimization applications in electromagnetics. This concept is based on our immune system's ability to respond to an antigen and produce a pool of anti-body secreting cells. In addition to the common implementations of this algorithm where the affinity maturation and cloning principles of clonal selection principles are used, we utilize memory and the cross-over concepts that are common to other bio-inspired methods. The performance of the algorithm is investigated for well known mathematical test functions and its potential is demonstrated in the context of the design of a radar absorbing material and a planar phased array antenna with specific radiation and null characteristics.
Influenza Mortality in the United States, 2009 Pandemic: Burden, Timing and Age Distribution
Ann M. Nguyen, Andrew Noymer
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0064198
Abstract: Background In April 2009, the most recent pandemic of influenza A began. We present the first estimates of pandemic mortality based on the newly-released final data on deaths in 2009 and 2010 in the United States. Methods We obtained data on influenza and pneumonia deaths from the National Center for Health Statistics (NCHS). Age- and sex-specific death rates, and age-standardized death rates, were calculated. Using negative binomial Serfling-type methods, excess mortality was calculated separately by sex and age groups. Results In many age groups, observed pneumonia and influenza cause-specific mortality rates in October and November 2009 broke month-specific records since 1959 when the current series of detailed US mortality data began. Compared to the typical pattern of seasonal flu deaths, the 2009 pandemic age-specific mortality, as well as influenza-attributable (excess) mortality, skewed much younger. We estimate 2,634 excess pneumonia and influenza deaths in 2009–10; the excess death rate in 2009 was 0.79 per 100,000. Conclusions Pandemic influenza mortality skews younger than seasonal influenza. This can be explained by a protective effect due to antigenic cycling. When older cohorts have been previously exposed to a similar antigen, immune memory results in lower death rates at older ages. Age-targeted vaccination of younger people should be considered in future pandemics.
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