Body Systems (body + system)

Distribution by Scientific Domains
Distribution within Medical Sciences


Selected Abstracts


Vertical dynamic responses of a simply supported bridge subjected to a moving train with two-wheelset vehicles using modal analysis method

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2005
Ping Lou
Abstract The vertical dynamic responses of a simply supported bridge subjected to a moving train are investigated by means of the modal analysis method. Each vehicle of train is modelled as a four-degree-of-freedom mass,spring,damper multi-rigid body system with a car body and two wheelsets. The bridge, together with track, is modelled as a simply supported Bernoulli,Euler beam. The deflection of the beam is described by superimposing modes. The train and the beam are regarded as an entire dynamic system, in which the contact forces between wheelset and beam are considered as internal forces. The equations of vertical motion in matrix form with time-dependent coefficients for this system are directly derived from the Hamilton's principle. The equations of motion are solved by Wilson-, method to obtain the dynamic responses for both the support beam and the moving train. Compared with the results previous reported, good agreement between the proposed method and the finite element method is obtained. Finally, the effects of beam mode number, vehicle number, beam top surface, and train velocity on the dynamic responses of the entire train and bridge coupling system are studied, and the dynamic responses of beam are given under the train moving with resonant velocity. Copyright © 2005 John Wiley & Sons, Ltd. [source]


Formulation of dynamics, actuation, and inversion of a three-dimensional two-link rigid body system

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2005
Hooshang Hemami
In this paper, three issues related to three-dimensional multilink rigid body systems are considered: dynamics, actuation, and inversion. Based on the Newton-Euler equations, a state space formulation of the dynamics is discussed that renders itself to inclusion of actuators, and allows systematic ways of stabilization and construction of inverse systems. The development here is relevant to robotic systems, biological modeling, humanoid studies, and collaborating man-machine systems. The recursive dynamic formulation involves a method for sequential measurement and estimation of joint forces and couples for an open chain system. The sequence can start from top downwards or from the ground upwards. Three-dimensional actuators that produce couples at the joints are included in the dynamics. Inverse methods that allow estimation of these couples from the kinematic trajectories and physical parameters of the system are developed. The formulation and derivations are carried out for a two-link system. Digital computer simulations of a two-rigid body system are presented to demonstrate the feasibility and effectiveness of the methods. © 2005 Wiley Periodicals, Inc. [source]


The limitations of corticosteroid therapy in Crohn's disease

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 10 2001
P. J. Rutgeerts
Corticosteroids are highly effective in inducing clinical remission in patients with active Crohn's disease. However, the role of corticosteroids in the treatment of this disease is primarily ameliorative because they are ineffective in maintaining remission or healing mucosal lesions. Nearly half of the patients who initially respond to corticosteroid therapy develop a dependency on corticosteroids or have a relapse within 1 year. In addition, use of these agents is often limited by a relatively high risk of serious adverse effects that can involve nearly every major body system. These effects include: bone loss, which can develop with even short-term and low-dose corticosteroid therapy; metabolic complications such as glucose intolerance and diabetes mellitus; increased intraocular pressure and glaucoma; and potentially lethal infections. To minimize the risk of toxicity, corticosteroids are increasingly recommended for short-term use only at the lowest effective dose to induce remission in patients with moderately to severely active Crohn's disease. Corticosteroid formulations with low systemic bioavailability, such as controlled-release budesonide, may be associated with a lower rate of dermatologic adverse effects but appear to be somewhat less effective than conventional corticosteroids in inducing remission in patients with active Crohn's disease. Immunosuppressive agents such as azathioprine, 6-mercaptopurine, and methotrexate have demon- strated corticosteroid-sparing effects, facilitating the withdrawal of corticosteroids when initiated as maintenance therapy. Infliximab can be used as an alternative to corticosteroids. [source]


Caenorhabditis elegans proteomics comes of age

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 4 2010
Yhong-Hee Shim
Abstract Caenorhabditis elegans, a free-living soil nematode, is an ideal model system for studying various physiological problems relevant to human diseases. Despite its short history, C. elegans proteomics is receiving great attention in multiple research areas, including the genome annotation, major signaling pathways (e.g. TGF-, and insulin/IGF-1 signaling), verification of RNA interference-mediated gene targeting, aging, disease models, as well as peptidomic analysis of neuropeptides involved in behavior and locomotion. For example, a proteome-wide profiling of developmental and aging processes not only provides basic information necessary for constructing a molecular network, but also identifies important target proteins for chemical modulation. Although C. elegans has a simple body system and neural circuitry, it exhibits very complicated functions ranging from feeding to locomotion. Investigation of these functions through proteomic analysis of various C. elegans neuropeptides, some of which are not found in the predicted genome sequence, would open a new field of peptidomics. Given the importance of nematode infection in plants and mammalian pathogenesis pathways, proteomics could be applied to investigate the molecular mechanisms underlying plant, or animal,nematode pathogenesis and to identify novel antinematodal drugs. Thus, C. elegans proteomics, in combination of other molecular, biological and genetic techniques, would provide a versatile new tool box for the systematic analysis of gene functions throughout the entire life cycle of this nematode. [source]


Accounting for Multiplicities in Assessing Drug Safety: A Three-Level Hierarchical Mixture Model

BIOMETRICS, Issue 2 2004
Scott M. Berry
Summary. Multiple comparisons and other multiplicities are among the most difficult of problems that face statisticians, frequentists, and Bayesians alike. An example is the analysis of the many types of adverse events (AEs) that are recorded in drug clinical trials. We propose a three-level hierarchical mixed model. The most basic level is type of AE. The second level is body system, each of which contains a number of types of possibly related AEs. The highest level is the collection of all body systems. Our analysis allows for borrowing across body systems, but there is greater potential,depending on the actual data,for borrowing within each body system. The probability that a drug has caused a type of AE is greater if its rate is elevated for several types of AEs within the same body system than if the AEs with elevated rates were in different body systems. We give examples to illustrate our method and we describe its application to other types of problems. [source]


Expression and Purification of ZNF191(243,368) in Three Expression Systems

CHINESE JOURNAL OF CHEMISTRY, Issue 11 2007
Dong-Xin ZHAO
Abstract ZNF191(243,368), a new human zinc finger protein, probably relates to some hereditary diseases and cancers. To obtain adequate amount of ZNF191(243,368) for the study of its property, structure and function, three different expression systems of inclusion-body, glutathione S-transferase (GST), and hexahistidine (6×His) were used and compared. Among these systems, the expression level of ZNF191(243,368) was increased in inclusion body system under a higher isopropylthio- , - D -galactoside (IPTG) concentration, but the non-target proteins were also increased more, which made its purification more difficult and the yield lower. The expression of His-tag fusion protein was almost not affected by IPTG concentration, temperature and inducing time. At a high IPTG concentration the highest expression yield for GST fusion protein was obtained. And the fusion proteins can be partially purified by a single affinity chromatography step. The fusion protein systems show advantages for expression of these proteins. [source]


Recent trends in the treatment of testosterone deficiency syndrome

INTERNATIONAL JOURNAL OF UROLOGY, Issue 11 2007
Bum Sik Hong
Abstract: Testosterone deficiency syndrome (TDS) is defined as a clinical and biochemical syndrome associated with advancing age and is characterized by typical symptoms and deficiency in serum testosterone levels. TDS is a result of the interaction of hypothalamo-pituitary and testicular factors. Now, treatment of TDS with testosterone is still controversial due to a lack of large, controlled clinical trials on efficacy. The risks of treatment with testosterone appear to be minimal, although long-term studies on the safety of testosterone therapy are lacking. The aim of the therapy is to establish a physiological concentration of serum testosterone in order to correct the androgen deficiency, relieve its symptoms and prevent long-term sequelae. All of the available products, despite their varying pharmacodynamic and pharmacokinetic profiles, are able to reach this goal. Newer testosterone patches seem not to cause severe skin irritation. Testosterone gels minimize the skin irritation while providing flexibility in dosing and a low discontinuation rate. Oral testosterone undecanoate (TU) is free of liver toxicity. Recent formulation of oral TU markedly increased shelf-live, a major drawback in the older preparation. Producing swings in testosterone levels rising rapidly to the supraphysiological range is not the case with the new injectable long-acting preparation of TU. To be able to rapidly react and stop treatment in cases where side-effects and contraindications are detected, the short-acting transdermal and oral delivery modes have certain advantages. However, there is no evidence that the use of an injectable long-acting TU in men with TDS has limitations in clinical application for this reason. The use of dehydroepiandrosterone is still controversial because of a lack of well designed long-term trials, although some recent studies suggest positive effects on various body systems. Only a few studies have been carried out to investigate the effect of hCG (human chorionic gonadotropin) in TDS with some positive results on various body systems. [source]


Formulation of dynamics, actuation, and inversion of a three-dimensional two-link rigid body system

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2005
Hooshang Hemami
In this paper, three issues related to three-dimensional multilink rigid body systems are considered: dynamics, actuation, and inversion. Based on the Newton-Euler equations, a state space formulation of the dynamics is discussed that renders itself to inclusion of actuators, and allows systematic ways of stabilization and construction of inverse systems. The development here is relevant to robotic systems, biological modeling, humanoid studies, and collaborating man-machine systems. The recursive dynamic formulation involves a method for sequential measurement and estimation of joint forces and couples for an open chain system. The sequence can start from top downwards or from the ground upwards. Three-dimensional actuators that produce couples at the joints are included in the dynamics. Inverse methods that allow estimation of these couples from the kinematic trajectories and physical parameters of the system are developed. The formulation and derivations are carried out for a two-link system. Digital computer simulations of a two-rigid body system are presented to demonstrate the feasibility and effectiveness of the methods. © 2005 Wiley Periodicals, Inc. [source]


Coagulation dynamics and platelet functions in obstructive jaundiced patients

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 5 2009
Tebessüm Çak
Abstract Background:, All of the body systems are affected by increased levels of bilirubin. The aim of this study is to investigate the function of platelets and clotting dynamics in patients with obstructive jaundice. Methods:, Liver function tests, serum CRP, PT, PTT and hemogram were measured in 23 patients with obstructive jaundice. Thromboelastography (TEG) was done for the evaluation of coagulation dynamics, while platelet function assay (PFA 100) was used to evaluate platelet functions. Blood samples were obtained at two occasions, before the drainage and 3 weeks after the relief of the obstruction. Results:, Hypercoagulation was detected in 80% of patients. Maximum strength, elasticity, coagulation indices of the clot were correlated with increased concentrations of direct bilirubin. Although maximum strength of coagulum usually represents increased activity of platelet function, membrane closure times with PFA 100 were found to be prolonged in 30% of patients, reduced values were determined in 17% of patients. No demonstrable effect on coagulation parameters and platelet function were detected after drainage procedures regardless of modality. Conclusions:, Even though there is a general assumption about the increased bleeding tendency in obstructive jaundiced patients, we could not demonstrate reduced clotting activity by measuring with either PFA or TEG. On the contrary we observed tendency for hypercoagulation independent of increased prothrombin times. The most probable cause of this effect is the increased activity of fibrin polymers on platelet membrane. [source]


Ischemia,reperfusion injury pathophysiology, part I

JOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 4 2004
DACVECC, Maureen McMichael DVM
Abstract Objective: To review the current scientific literature on ischemia,reperfusion (IR) injury in both human and veterinary medicine. To describe the normal antioxidant defense mechanisms, the pathophysiology of IR injury, and the role of neutrophils in IR injury. Data sources: Data sources include scientific reviews and original research publications in both human and veterinary medicine. Summary: IR injury is a complex pathophysiological process involving numerous pathways and body systems. Normal antioxidant defense mechanisms function to limit oxidative injury during times of health. Ischemia is the period that occurs before oxygenated blood is re-introduced and the severity of injury has been shown to correlate with the magnitude and length of ischemia in dogs. During ischemia, there is a buildup of substances (i.e., xanthine oxidase, hypoxanthine, etc.) that, upon re-introduction of oxygen, form reactive oxygen species (ROS). ROS, produced in large part upon reperfusion, can cause extensive damage to DNA, proteins, carbohydrates, and lipids. Although mammalian systems are endowed with abundant antioxidant defenses, the generation of large amounts of ROS can overwhelm these mechanisms leading to cell dysfunction and death. Neutrophils play a critical role in IR injury and may mediate the majority of mucosal and microvascular injury that occurs by releasing ROS and proteolytic enzymes. Although experimental studies have been carried out on cats, dogs, and horses there are few clinical studies on companion animals. Conclusions: The pathophysiology of IR injury is complex and involves damage by ROS to all biological membranes. Neutrophils play a major role in IR injury and initiate and propogate much of the damage. This article is intended as a review of the pathophysiology of IR injury. [source]


Congenital Cardiac Defects in Neonatal Foals: 18 Cases (1992,2007)

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2010
T.L. Hall
Background: Literature available regarding congenital cardiac defects in foals is limited to reports of individual cases or small case series. Objective: To describe the clinical, echocardiographic, and necropsy findings and breed predilection of congenital cardiac defects in neonatal foals. Animals: Eighteen foals <15 days of age with 1 or more congenital cardiac defects. Methods: Medical records of foals diagnosed with congenital cardiac defects at the William R. Pritchard Veterinary Medical Teaching Hospital were reviewed. Data collected included history, signalment, clinical signs, laboratory data, diagnostic and necropsy results, and outcome. Results: Arabian foals represented 39% of cases with congenital cardiac defects and were significantly (P= .004) overrepresented (OR = 4.7 [CI: 1.8,12.4]) compared with the general hospital population. Ventricular septal defect (VSD) (14/18), tetralogy of Fallot (5/18), and tricuspid valve atresia (4/18) were the most common defects identified. A ,3/6 heart murmur (14/14) accompanied by tachycardia (14/17), tachypnea (17/17), and cyanosis of mucous membranes (7/16) were the most common clinical signs. Concurrent congenital defects were common (9/18). Two foals, both with VSD, survived for , 8 years after diagnosis and 1 was a successful performance horse. Conclusions and Clinical Relevance: Arabian horses appear to have a predisposition for cardiac defects. The presence of a loud murmur (, 3/6), cyanotic membranes, and tachycardia or tachypnea in a neonatal foal should warrant thorough evaluation of the heart for congenital defects. Foals with cardiac defects should be closely evaluated for concurrent congenital defects in other body systems. [source]


On the clustering phase transition in self-gravitating N -body systems

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2001
Monica Cerruti-Sola
The thermodynamic behaviour of self-gravitating N -body systems has been worked out by borrowing a standard method from molecular dynamics. The link between dynamics and thermodynamics is made in the microcanonical ensemble of statistical mechanics. Through the computation of basic thermodynamic observables and of the equation of state in the plane, the clustering phase transition appears to be of the second-order type. The dynamical,microcanonical averages are compared with their corresponding canonical ensemble averages, obtained through standard Monte Carlo computations. The latter seem to have completely lost any information about the phase transition. Finally, our results , obtained in a ,microscopic' framework , are compared with some existing theoretical predictions , obtained in a ,macroscopic' (thermodynamic) framework: qualitative and quantitative agreement is found, with an interesting exception. [source]


Poisson's ratio of simple planar ,isotropic' solids in two dimensions

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2007
Konstantin V. Tretiakov
Abstract The influence of molecular geometry on the Poisson's ratio has been investigated for a few two-dimensional (2D) hard body systems (hard discs, hard dimers, hard cyclic trimers, and hard cyclic hexamers) forming elastically isotropic solid phases. The Poisson's ratio of the studied periodic and aperiodic solids was determined by Monte Carlo simulations using the analysis of the box fluctuations in the constant pressure ensemble (NpT) with variable box shape. The results obtained for all the studied systems showed that the Poisson's ratio grows when the density is decreased. It has been also found that the Poisson's ratio decreases with increasing number of discs in the molecule and its value for hard trimers is negative near close packing. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Energy consistent time integration of planar multibody systems

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2006
Stefan Uhlar
The planar motion of rigid bodies and multibody systems can be easily described by coordinates belonging to a linear vector space. This is due to the fact that in the planar case finite rotations commute. Accordingly, using this type of generalized coordinates can be considered as canonical description of planar multibody systems. However, the extension to the three-dimensional case is not straightforward. In contrast to that, employing the elements of the direction cosine matrix as redundant coordinates makes possible a straightforward treatment of both planar and three-dimensional multibody systems. This alternative approach leads in general to differential-algebraic equations (DAEs) governing the dynamics of rigid body systems. The main purpose of the present paper is to present a comparison of the two alternative descriptions. In both cases energy-consistent time integration schemes are applied. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Accounting for Multiplicities in Assessing Drug Safety: A Three-Level Hierarchical Mixture Model

BIOMETRICS, Issue 2 2004
Scott M. Berry
Summary. Multiple comparisons and other multiplicities are among the most difficult of problems that face statisticians, frequentists, and Bayesians alike. An example is the analysis of the many types of adverse events (AEs) that are recorded in drug clinical trials. We propose a three-level hierarchical mixed model. The most basic level is type of AE. The second level is body system, each of which contains a number of types of possibly related AEs. The highest level is the collection of all body systems. Our analysis allows for borrowing across body systems, but there is greater potential,depending on the actual data,for borrowing within each body system. The probability that a drug has caused a type of AE is greater if its rate is elevated for several types of AEs within the same body system than if the AEs with elevated rates were in different body systems. We give examples to illustrate our method and we describe its application to other types of problems. [source]


First-year survival of infants born with congenital heart defects in Arkansas (1993-1998): A survival analysis using registry data

BIRTH DEFECTS RESEARCH, Issue 9 2003
Mario A. Cleves
BACKGROUND In the United States and other developed nations, birth defects are the leading cause of infant mortality. Congenital heart defects (CHDs) are among the most prevalent and fatal of all birth defects. Here we report the survival probability of infants born with CHDs in Arkansas and examine the impact of multiple malformations on survival. METHODS Birth and death certificate records were linked to birth defects registry data for infants born with CHDs from January 1993 through December 1998 in Arkansas. Both neonatal and first-year survival probabilities were estimated. These were computed non-parametrically using Kaplan-Meier's product limit method. A Cox proportional-hazards model was used to evaluate the relative importance of additional malformations on survival. RESULTS A total of 1,983 infants with CHDs were included in this study. The neonatal survival probability for this cohort was 94.0% (95% CI: 93.0%, 95.1%), and the first-year survival probability was 88.2% (95% CI: 86.8%, 89.6%). The presence of hypoplastic left heart syndrome conferred the greatest reduction in survival, whereas infants with pulmonic valve stenosis and infants with ventricular septal defects had the highest first-year survival. Infants with multiple CHDs had decreased survival compared to those with isolated heart defects. Survival was also adversely affected by the presence of congenital abnormalities in other body systems. CONCLUSIONS Neonatal and first-year survival of infants with CHDs varies by both the type of cardiac malformation and the presence of additional cardiac and non-cardiac malformations. Further work will focus on the effects of maternal and infant characteristics on survival. Birth Defects Research (Part A) 67:662,668, 2003. © 2003 Wiley-Liss, Inc. [source]