Human Cardiovascular Model and Applications

Cardiovascular diseases (CVDs) can be known as a class of diseases which affect different parts of the cardiovascular system such as the heart or blood vessels. Hemodynamic signals are an important tool used by doctors to diagnose the type of CVD occurred in a patient. Diagnosing the correct type of CVD in a patient early will allow the patient to have the suitable medical treatment. Some examples of CVDs include coronary heart disease, cerebrovascular disease and peripheral arterial disease. A human cardiovascular model is developed in order to simulate different hemodynamic signals of the cardiovascular system. The hemodynamic signals include the blood pressures, flow rates and volumes in various part of the cardiovascular system. This paper presents a model which is able to simulate hemodynamic signals and they are able to represent the human arterial blood pressure accurately. Hence this model can also be used to simulate hypertensive patients in order to design control systems for regulation of blood pressure. Signal verification has been performed and the stability of the model is being investigated. Applications of the human cardiovascular model are also presented.     

Barrett's esophagus and cancer risk: a more realistic estimate

The cancer risk in patients with Barrett's esophagus is important because it determines screening, surveillance, and treatment considerations. Previously, the risk of progression to esophageal adenocarcinoma in patients with Barrett's esophagus was thought to be approximately 1%. Recently, 2 very large population-based studies have significantly reduced this risk estimate of cancer. Paradoxically, esophageal adenocarcinoma continues to rise exponentially in the United States. Screening and surveillance programs based on endoscopic, histopathological, and molecular criteria need to be improved to identify a high-risk population of progressors.     

The Quorum-Sensing Molecule Farnesol Is a Modulator of Drug Efflux Mediated by ABC Multidrug Transporters and Synergizes with Drugs in Candida albicans

Overexpression of the CaCDR1-encoded multidrug efflux pump protein CaCdr1p (Candida drug resistance protein 1), belonging to the ATP binding cassette (ABC) superfamily of transporters, is one of the most prominent contributors of multidrug resistance (MDR) in Candida albicans. Thus, blocking or modulating the function of the drug efflux pumps represents an attractive approach in combating MDR. In the present study, we provide first evidence that the quorum-sensing molecule farnesol (FAR) is a specific modulator of efflux mediated by ABC multidrug transporters, such as CaCdr1p and CaCdr2p of C. albicans and ScPdr5p of Saccharomyces cerevisiae. Interestingly, FAR did not modulate the efflux mediated by the multidrug extrusion pump protein CaMdr1p, belonging to the major facilitator superfamily (MFS). Kinetic data revealed that FAR competitively inhibited rhodamine 6G efflux in CaCdr1p-overexpressing cells, with a simultaneous increase in an apparent K_m without affecting the V_max values and the ATPase activity. We also observed that when used in combination, FAR at a nontoxic concentration synergized with the drugs at their respective nonlethal concentrations, as was evident from their <0.5 fractional inhibitory concentration index (FICI) values and from the drop of 14- to 64-fold in the MIC₈₀ values in the wild-type strain and in azole-resistant clinical isolates of C. albicans. Our biochemical experiments revealed that the synergistic interaction of FAR with the drugs led to reactive oxygen species accumulation, which triggered early apoptosis, and that both could be partly reversed by the addition of an antioxidant. Collectively, FAR modulates drug extrusion mediated exclusively by ABC proteins and is synergistic to fluconazole (FLC), ketoconazole (KTC), miconazole (MCZ), and amphotericin (AMB).     

Antiplasmodial activity of artecyclopentyl mether a new artemisinin derivative and its effect on pathogenesis in <Emphasis Type="Italic">Plasmodium yoelii nigeriensis</Emphasis> infected mice

In an effort to evaluate novel derivatives from artemisinin, possessing potential antimalarial activity, a new derivative artecyclopentyl mether (CPM-1) was derivatized and evaluated for its dose-dependent efficacy in Plasmodium yoelii nigeriensis infected mice. The survivability of mice at 7.5 mg/kg was >28 days with negligible parasitaemia and recovered anemia (66.16–72.62%). Artecyclopentyl mether was also found to modulate the pro- and anti-inflammatory cytokines (IFN-γ, 39.64–56.92%; TNF, 49.10–74.31%; IL-4, 11.53–43.22%; IL-10, 37.60–53.52%) favourably besides optimizing the oxidative stress to the infected subjects as evident by the nitric oxide (88.76–95.43%), lipid peroxidation (59.30–76.05%) and glycaemic data (62.70–76.66%). The results indicate the potentiality of the new derivative as an antimalarial against asexual stages of the parasite.     

Spontaneous hip dislocation secondary to intraarticular neurofibroma: a case report

Spontaneous hip dislocation due to intraarticular neurofibroma in patients with neurofibromatosis type 1 is extremely rare. We describe the imaging features of spontaneous dislocation of hip due to histologically proven intraarticular neurofibroma in young woman with neurofibromatosis type 1, and review the literature.     

Toxicity characterization of environmental chemicals by the US National Toxicology Program: an overview

The US National Toxicology Program (NTP) is an interagency program whose mission is to evaluate agents of public health concern by developing and applying the tools of modern toxicology and molecular biology. Chemicals substances or physical agents selected for toxicology and carcinogenesis evaluations by the NTP are usually studied in a series of subacute (14-day exposure), subchronic (90-day exposure) and chronic (2-year exposure) studies in rodents. The NTP has published more than 500 reports of the findings and conclusions from its toxicology and carcinogenesis studies. In more specialized studies, the NTP also evaluates adverse effects on the structure and function of the immune, reproductive, nervous, and respiratory systems. The program attempts to evaluate and appropriately incorporate new technologies to improve the way we study the toxicity of chemicals. For example, the program has extensively evaluated several transgenic mouse models for their potential use as short-term cancer screens and has been a full participant in an international effort to examine their usefulness in pharmaceutical registration. Toxicogenomics, an emerging scientific field that examines the expression of thousands of genes simultaneously in response to chemical exposure, holds promise for future application to better understand the underlying mechanisms of chemical toxicity. A number of public health issues being addressed by the NTP are not only of national importance but also have global impact, such as the potential for endocrine disruptors to influence development and carcinogenesis and the safety of herbal medicines and dietary supplements. The program participates in the preparation of national and international toxicity testing guidelines and the findings from NTP studies are widely used for risk assessments by international organizations and federal agencies. The NTP maintains databases that contain toxicity, and health and safety information on a large number of chemicals. These databases are available from the NTP web site (http://ntp-server.niehs.nih.gov) and are accessed over 100000 times a month from around the world.