3.1.2 Regression QSAR modeling
QSAR models were developed to predict the toxicity (-log EC50 mmol/L) of chemicals using the EL based modeling methods (DTB, DTF). Distribution of the selected descriptors for regression modeling is shown in the radar chart (Fig. 1). A 10-fold CV was adopted to determine the optimal architecture and the model parameters, using the criterion of minimum MSE in training and validation set. The average values (10 runs) of MSEs and in internal validation and training data for the proposed QSAR models were 0.56, 0.11 and 0.709 0.941 (DTB) and 0.70, 0.14, and 0.661, 0.940 (DTF). These values are comparable to the results obtained when establishing the models in the training (DTB 0.11, 0.946; DTF 0.16, 0.940) and test (DTB 0.31, 0.793; DTF 0.41, 0.753) phase. A model is considered acceptable90 when the value of exceeds 0.5. The results indicate that both the models herein investigated are robust. Further, the results of the external validation of these models (Table 3) suggest that in all the cases, values were above its threshold (0.6).65 Consonni et al.66 demonstrated that results obtained by are independent of the prediction set distribution and sample size, hence independent of the samples chemical space. Moreover, according to the criteria proposed by Eriksson et al.91 the difference between R2 (training) and R2 (validation) should not exceed 0.3. As our models fulfill these criteria and also positively pass internal and external validation, these were applied to predict the toxicity of new, untested chemicals.
Table 3
The regression QSAR models were based on topological (chi simple path descriptor of order 1, SP-1; molecular distance edge between all secondary and tertiary carbons, MDEC-23...
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...M. H., and Ghorbannezhad, Z. (2011) Estimation of the volume of distribution of some pharmacologically important compounds from their structural descriptors. J. Serb. Chem. Soc. 76, 1003-1014.
(94) Todeschini, R., and Consonni, V. (2000) Hand book of molecular descriptors. Wiley-VCH, 11, pp.1-668.
(95) Singh, K. P., Ojha, P., Malik, A., and Jain, G. (2009) Partial least squares and artificial neural networks modeling for predicting chlorophenol removal from aqueous solution. Chemom. Intell. Lab. Syst. 99, 150-160.
(96) Franks, N., and Lieb, W. (1990) Mechanisms of General Anesthesia. Environ. Health Perspect. 87, 199-205.
(97) Cronin, M. T. D., Netzeva, T. I., Dearden, J. C., Edwards, R., and Worgan, A. D. P. (2004) Assessment and Modeling of the Toxicity of Organic Chemicals to Chlorella vulgaris: Development of a Novel Database. Chem. Res. Toxicol. 17, 545-554.
Zhang X., Tang H., Ye C. and Liu M. (2006). Structure-based drug design: NMR-based approach for ligand-protein interactions. Drug Discovery Today: Technologies. 3 (3), pp. 241-245.
Anesthesia was not used in surgeries until 1846, so prior to that the patient was completely conscious when they operated on him or her, unless the patient passed out from pain. Patients were unwilling to be cut into while they were awake: “Dragged unwillingly or carried from the ward to the operating theatre by a couple of hospital attendants (in Edinburgh a large wicker basker was used for this purpose) the patient was laid on the operating table and if necessary strapped down” (Youngson 27). The tools used in surgeries can be seen here. Anesthetics Anesthetics were not used in surgery until October 16, 1846, at Massachusetts General Hospital (Youngson 51). Anesthesia is an inhaled gas known as ether.
Disinfection is applied in water as well as wastewater treatment as a finishing step so as to destroy pathogens but the cause of concern regarding the disinfection process is the formation of disinfection byproducts (DBPs). Natural organic matter (NOM) in water has been considered as the predominant DBP precursors. Disinfectants are powerful oxidants that oxidize the organic matter present in water forming DBPs. Chlorine, ozone, chlorine dioxide, and chloramines are the most common disinfectants used nowadays and each produces its own suite of chemical DBPs in finished drinking water (Richardson, 2003). DBPs so formed pose a threat to human health because of their potential to cause cancer and reproductive/developmental effects. Most developed nations have regulated concentration of DBPs so as to minimize exposure to potentially harmful DBPs while maintaining adequate disinfection and control of targeted
Volles, D. F. (2011, April 11). University of Virginia Health System Adult and Geriatric Sedation/Analgesia for Diagnostic and Therapeutic Procedures. Retrieved May 12, 2011, from University of Virgina Health System: University of Virginia Health System Adult and Geriatric Sedation/Analgesia for Diagnostic and Therapeutic Procedures
American Association of Nurse Anesthetists. Professional Aspects of Nurse Anesthesia Practice. Philadelphia: F. A. Davis Company, 1994. Print.
Pesticides are grouped into what they call “families”. This is because they share similar ...
There are many things that enter our waterways that we have to clean out. One of the worst things is pesticides. They not only contaminate our water, but they are harmful to animals. It enters our water sources by seeping through the soil to groundwater or entering streams as surface run-off. Farmers and other workers try to keep our water safe from pesticides, but it is a very hard and stressful job. Let’s take a look at the ways that pesticides enter our water and also some possible solutions for this problem.
Hemmings H.C.and Hopkins P.M., (2006) Foundations of Anesthesia 2sd ed. Elsevier. Hudspith M.J., Siddall P.J. and Munglani R. Physiology of Pain.
Anesthesia is used in almost every single surgery. It is a numbing medicine that numbs the nerves and makes the body go unconscious. You can’t feel anything or move while under the sedative and are often delusional after being taken off of the anesthetic. Believe it or not, about roughly two hundred years ago doctors didn’t use anesthesia during surgery. It was rarely ever practiced. Patients could feel everything and were physically held down while being operated on. 2It wasn’t until 1846 that a dentist first used an anesthetic on a patient going into surgery and the practice spread and became popular (Anesthesia). To this day, advancements are still being made in anesthesiology. 7The more scientists learn about molecules and anesthetic side effects, the better ability to design agents that are more targeted, more effective and safer, with fewer side effects for the patients (Anesthesia). Technological advancements will make it easier to read vital life signs in a person and help better decide the specific dosages a person needs.
Webster CS, Merry AF, Larsson L, McGrath KA, Weller J. The frequency and nature of drug administration error during anaesthesia. Anaesth Intensive Care 2001; 29: 494-500.
Hilgenkamp, K. (2006). Environmental Toxins and Toxicology. In Environmental health: Ecological perspectives (pp. 89-90). Princeton, N.J: Recording for the Blind & Dyslexic.
2- Using the available data to predict the physical and chemical properties of various chemical compounds.
Molecular pharmacology deals with the biochemical and biophysical characteristics of interactions between molecules of different substances and those of the cell. In other words, it is molecular biology applied to pharmacologic and toxicologic questions. The methods of molecular pharmacology include precise mathematical, physical, chemical and molecular biological techniques to understand how cells respond to hormones or pharmacologic agents, and how chemical structure correlates with biological activity of various
Professional audience: Toxicology is a multidisciplinary, scientific field, which studies the hazards and adverse effects of xenobiotic agents on biotic components of the ecosystem. These biotic components include, but are not limited to the following: humans, animals, and plants. More importantly, the field of toxicology is also used to construct preventative measures, treatment, and other amelioration strategies relative to the adverse health effects and the agent(s) being analyzed. The field of toxicology has evolved from a science focused on poisons