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Search Results: 1 - 10 of 21273 matches for " Wai-Tao Chan "
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Meckel’s Diverticulum: Factors Associated with Clinical Manifestations
Jeng-Jung Chen,Hung-Chang Lee,Chun-Yan Yeung,Wai-Tao Chan,Chuen-Bin Jiang,Jin-Cherng Sheu,Nein-Lu Wang
ISRN Gastroenterology , 2014, DOI: 10.1155/2014/390869
Abstract: Objectives. The purpose of this study was to investigate the clinical features of Meckel’s diverticula at different ages, genders, and pathology in order to serve as a reminder to clinicians when evaluating potential cases and to help obtain an early diagnosis. Methods. We collected information of patients with Meckel’s diverticulum diagnosed at Mackay Memorial Hospital in Taiwan from 1984 to 2009. After performing a thorough review of their charts, the clinical features of the Meckel’s diverticula were analyzed according to age groups, gender, and pathology. Result. A total of 126 patients, with 90 males and 36 females, were enrolled in this study. Seventy-five patients were symptomatic and 51 Meckel’s diverticula were found incidentally during surgery for other diseases. Among symptomatic patients, 39% of pediatric patients and 5% of adult patients had intestinal hemorrhage. Twenty-eight percent of pediatric patients and 67% of adult patients had inflammation of Meckel’s diverticulum. Forty-six percent of males and 16% of females had inflammation. Conversely, 27% of males and 58% percent of females had intestinal obstruction. When Meckel’s diverticulum had ectopic gastric mucosa, it tended to cause intestinal hemorrhage when the patient is young. Conclusions. Age, gender, and pathology affect the clinical presentations of Meckel’s diverticula. 1. Introduction Meckel’s diverticulum (MD) is the most common congenital anomaly of the gastrointestinal tract. It was first described in 1809 [1]. MD is a remnant of the omphalomesenteric or vitelline duct [2, 3]. The prevalence ranges from 2 to 4%. Anatomically, MD is a true diverticulum containing all layers of the small intestine, arising from the antimesenteric border of the ileum and receiving its blood supply from a remnant of the vitelline artery [4]. MD involves a variety of complications, including intestinal obstruction, intussusceptions, ulceration, hemorrhage, vesico-diverticular fistulae, and tumors [4–8]. The incidence of complications differed between different articles, which analyzed only adults or pediatric populations [2, 8–11]. The purpose of this study was to investigate the clinical features of MD at different ages and genders in order to serve as a reminder to clinicians when evaluating potential cases and to help obtain an early diagnosis. 2. Methods 2.1. Patients and Medical Records We retrospectively reviewed the charts of all patients with MD who were managed at Mackay Memorial Hospital in Taiwan from 1984 to 2009. The diagnosis of MD was made according to surgical and pathologic
In Vitro Prevention of Salmonella Lipopolysaccharide-Induced Damages in Epithelial Barrier Function by Various Lactobacillus Strains
Chun-Yan Yeung,Jen-Shiu Chiang Chiau,Wai-Tao Chan,Chun-Bin Jiang,Mei-Lien Cheng,Hsuan-Liang Liu,Hung-Chang Lee
Gastroenterology Research and Practice , 2013, DOI: 10.1155/2013/973209
Abstract: Background. Lactobacillus shows beneficial anti-inflammatory effects on Salmonella infection. The maintenance of the tight junction (TJ) integrity plays an importance role in avoiding bacterial invasion. Whether Lactobacillus could be used to regulate the TJ protein expression and distribution in inflamed intestinal epithelial cells was determined. Methods. Using the transwell coculture model, Salmonella lipopolysaccharide (LPS) was apically added to polarized Caco-2 cells cocultured with peripheral blood mononuclear cells in the basolateral compartment. LPS-stimulated Caco-2 cells were incubated with various Lactobacillus strains. TJ integrity was determined by measuring transepithelial electrical resistance across Caco-2 monolayer. Expression and localization of TJ proteins (zonula-occludens- (ZO-) 1) were determined by Western blot and immunofluorescence microscopy. Results. Various strains of Lactobacillus were responsible for the different modulations of cell layer integrity. LPS was specifically able to disrupt epithelial barrier and change the location of ZO-1. Our data demonstrate that Lactobacillus could attenuate the barrier disruption of intestinal epithelial cells caused by Salmonella LPS administration. We showed that Lactobacillus strains are associated with the maintenance of the tight junction integrity and appearance. Conclusion. In this study we provide insight that live probiotics could improve epithelial barrier properties and this may explain the potential mechanism behind their beneficial effect in vivo. 1. Introduction Salmonella infection is a common cause of human food poisoning worldwide and can induce a broad spectrum of diseases from mild diarrhea to typhoid. All Salmonella serotypes share the ability to gain entry to the host through oral ingestion of contaminated food or water. They induce their own uptake into intestinal epithelial by Salmonella pathogenicity island-1 (SPI-1) type 3 secretion system. This epithelial barrier function can be further weakened by infection with bacteria, including S. typhimurium effectors [1, 2]. Salmonella enterica serovar Typhimurium has developed means of breaching the mucosal epithelial barrier by usurping signaling mechanisms within host cells [3]. It is likely that Salmonella induces localized effects on tight junction permeability during intestinal infections. These effects may act synergistically with other conditions, such as inflammatory responses, to promote tight junction (TJ) dysfunction [4]. At present, S. typhimurium overcoming the intestinal barrier is the most widely accepted
Determination of Backscatter-Extinction Coefficient Ratio for LIDAR-Retrieved Aerosol Optical Depth Based on Sunphotometer Data
Pak Wai Chan
Remote Sensing , 2010, DOI: 10.3390/rs2092127
Abstract: Backscattered power data from the Doppler LIght Detection And Ranging (LIDAR) systems at the Hong Kong International Airport (HKIA) could be used to obtain the extinction coefficient of the troposphere by combining with the meteorological optical range (MOR) data from the nearby forward scatter sensor. The Range-height Indicator (RHI) scan of the LIDAR is then utilized to derive the vertical profile of extinction coefficient, which is integrated with height to obtain the aerosol optical depth (AOD). In the retrieval of extinction coefficient profile, there is a power exponent of unknown value relating the backscattered power and the extinction coefficient. This exponent (called the backscatter-extinction coefficient ratio) depends on the optical properties of the aerosol in the air, and is normally assumed to be 1. In the present study, the value of this ratio is established by comparing the AOD measurements by a hand-held sunphotometer and the LIDAR-based AOD estimate in one winter (October 2008 to January 2009), which is the season with the largest number of haze episodes, and one summer-winter-spring period of the following year (July 2009 to May 2010) at HKIA. It is found to be about 1.4. The sensitivity of extinction coefficient profile to the value of the ratio is also examined for two cases in the study period, one good visibility day and one hazy day.
促黄体激素受体突变导致的性器官发育异常
wai-yee,chan
北京大学学报(医学版) , 2005,
Abstract:
Simultaneous Quenching for Semilinear Parabolic System with Localized Sources in a Square Domain  [PDF]
Wai Yuen Chan
Journal of Applied Mathematics and Physics (JAMP) , 2019, DOI: 10.4236/jamp.2019.77099
Abstract: This paper studies quenching properties of solutions of a semilinear parabolic system with localized reaction sources in a square domain. The system has the homogeneous Dirichlet boundary condition and null initial condition. We prove that solutions quench simultaneously, and compute approximated critical values of the system using a numerical method.
Finite Element Analysis of Contact Pressures between Seat Cushion and Human Buttock-Thigh Tissue  [PDF]
Chak Yin Tang, Wai Chan, Chi Pong Tsui
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.29093
Abstract: Unrelieved pressure on load-bearing muscle tissues of humans can produce pressure ulcers. In a seated upright posture, the highest pressures occur inferior to the ischial tuberosities (ITs). Moreover, the vibration can initiate the development of pressure ulcer. Therefore, the seat cushion is not only used to lower the maximum seating pressure on buttocks but also minimize the transmission of vibration to human body. The purpose of this study was to investigate the effects of varying vertical vibration frequencies on seat-interface contact pressure during sitting on three different seat cushions by using a finite element modeling approach. A simplified two-dimensional human buttock-thigh model was developed to simulate the mechanical response of the muscle of buttocks and thigh under vertical vibration. Static and vibrational loads with five different frequencies of 0.1, 1, 10, 30 and 50 Hz and the same amplitude of 3 mm were applied to different seat cushions. The result showed that the “SAF 6060” seat cushion with both hyperelastic and viscoelastic behaviors could be effective in reducing the amplitude of varying maximum contact pressure, especially for the frequency of 10-20 Hz. This method could help in design of seat cushions with appropriate material properties and shape so as to reduce vibrations transmitted to human body at a certain frequency range.
Ternary Sums of Squares and Triangular Numbers
Wai Kiu Chan,Anna Haensch
Mathematics , 2010,
Abstract: For any integer $x$, let $T_x$ denote the triangular number $\frac{x(x+1)}{2}$. In this paper we give a complete characterization of all the triples of positive integers $(\alpha, \beta, \gamma)$ for which the ternary sums $\alpha x^2 +\beta T_y + \gamma T_z$ represent all but finitely many positive integers. This resolves a conjecture of Kane and Sun \cite[Conjecture 1.19(i)]{KS08} and complete the characterization of all almost universal ternary mixed sums of squares and triangular numbers.
Small zeros of hermitian forms over a quaternion algebra
Wai Kiu Chan,Lenny Fukshansky
Mathematics , 2009,
Abstract: Let $D$ be a positive definite quaternion algebra over a totally real number field $K$, $F(X,Y)$ a hermitian form in 2N variables over $D$, and $Z$ a right $D$-vector space which is isotropic with respect to $F$. We prove the existence of a small-height basis for $Z$ over $D$, such that $F(X,X)$ vanishes at each of the basis vectors. This constitutes a non-commutative analogue of a theorem of Vaaler, and presents an extension of the classical theorem of Cassels on small zeros of rational quadratic forms to the context of quaternion algebras.
The representation of integers by positive ternary quadratic polynomials
Wai Kiu Chan,James Ricci
Mathematics , 2015,
Abstract: An integral quadratic polynomial is called regular if it represents every integer that is represented by the polynomial itself over the reals and over the $p$-adic integers for every prime $p$. It is called complete if it is of the form $Q({\mathbf x} + {\mathbf v})$, where $Q$ is an integral quadratic form in the variables ${\mathbf x} = (x_1, \ldots, x_n)$ and ${\mathbf v}$ is a vector in ${\mathbb Q}^n$. Its conductor is defined to be the smallest positive integer $c$ such that $c{\mathbf v} \in {\mathbb Z}^n$. We prove that for a fixed positive integer $c$, there are only finitely many equivalence classes of positive primitive ternary regular complete quadratic polynomials with conductor $c$. This generalizes the analogous finiteness results for positive definite regular ternary quadratic forms by Watson and for ternary triangular forms by Chan and Oh.
SOME RESULTS ON MATCHING AND TOTAL DOMINATION IN GRAPHS
Wai Chee Shiu,Xue-gang Chen,Wai Hong Chan
Applicable Analysis and Discrete Mathematics , 2010, DOI: 10.2298/aadm100219017s
Abstract: Let $G$ be a graph. A set $S$ of vertices of $G$ is called a totaldominating set of $G$ if every vertex of $G$ is adjacent to at leastone vertex in $S.$ The total domination number $gamma_t(G)$ and thematching number $alpha'(G)$ of $G$ are the cardinalities of theminimum total dominating set and the maximum matching of $G,$respectively. In this paper, we introduce an upper bound of thedifference between $gamma_t(G)$ and $alpha'(G).$ We alsocharacterize every tree $T$ with $gamma_t(T)leq alpha'(T),$ andgive a family of graphs with $gamma_t(G)leq alpha'(G).$
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