The central importance of quantum chemistry is to obtain solutions of the Schr?dinger equation for the accurate determination of the properties of atomic and molecular systems that occurred from the calculation of wav...The central importance of quantum chemistry is to obtain solutions of the Schr?dinger equation for the accurate determination of the properties of atomic and molecular systems that occurred from the calculation of wave functions accurate for many diatomic and polyatomic molecules, using Self Consistent Field method (SCF). The application of quantum chemical methods in the study and planning of bioactive compounds has become a common practice nowadays. From the point of view of planning it is important to note, when it comes to the use of molecular modeling, a collective term that refers to methods and theoretical modeling and computational techniques to mimic the behavior of molecules, not intend to reach a bioactive molecule simply through the use of computer programs. The choice of method for energy minimization depends on factors related to the size of the molecule, parameters of availability, stored data and computational resources. Molecular models generated by the computer are the result of mathematical equations that estimate the positions and properties of the electrons and nuclei, the calculations exploit experimentally, the characteristics of a structure, providing a new perspective on the molecule. In this work we show that studies of Highest Occupied Molecular Orbital Energy (HOMO), Low Unoccupied Molecular Orbital Energy (LUMO) and Map of molecular electrostatic potential (MEP) using Hatree-Fock method with different basis sets (HF/3-21G*, HF/3-21G**, HF/6-31G, HF/6-31G*, HF/6-31G** and HF/6-311G), that are of great importance in modern chemistry, biochemistry, molecular biology, and other fields of knowledge of health sciences. In order to obtain a significant correlation, it is essential that the descriptors are used appropriately. Thus, the quantum chemical calculations are an attractive source of new molecular descriptors that can, in principle, express all the geometrical and electronic properties of molecules and their interactions with biological receptor.展开更多
Objectives: To improve the diagnosis of damaged spinal motor pathways in incomplete spinal cord injury (iSCI) by assessing the facilitation of lower limbs motor evoked potentials (MEP). Methods: Control subjects (n = ...Objectives: To improve the diagnosis of damaged spinal motor pathways in incomplete spinal cord injury (iSCI) by assessing the facilitation of lower limbs motor evoked potentials (MEP). Methods: Control subjects (n = 12) and iSCI patients (n = 21) performed static and dynamic isometric foot dorsiflexions. MEPs induced by transcranial magnetic stimulation and EMG background of tibialis anterior muscle (TA) were analyzed. Static and dynamic muscle activation was performed at comparable levels of maximal voluntary contraction (MVC). The influence of the motor tasks on the excitability and facilitation of MEPs was compared between controls and iSCI patients. Results: In the controls an increased facilitation of TA MEP at lower levels of dynamic compared with static activation (10-20 % MVC) could be shown. At matched EMG background level the MEP responses were significantly increased. In the iSCI patients at a comparable level of TA activation the MEP responses were significantly reduced and 3 different patterns of MEP responses could be distinguished: i) preserved increment of TA MEP in the dynamic motor task, ii) unchanged MEP size in the dynamic and static motor task, and iii) elicitable MEPs in the dynamic motor task, which were abolished in the static motor task. Conclusions: Static and dynamic motor tasks have different effects on TA MEP facilitation. The task-dependent modulation of TA MEPs is comparable to that described for upper limb muscles. Complementary to the MEP delay this approach allows for an estimation of the severity of spinal tract damage. The task-dependent modulation of TA MEPs is an additional diagnostic tool to improve the assessment and monitoring of motor function in iSCI.展开更多
文摘The central importance of quantum chemistry is to obtain solutions of the Schr?dinger equation for the accurate determination of the properties of atomic and molecular systems that occurred from the calculation of wave functions accurate for many diatomic and polyatomic molecules, using Self Consistent Field method (SCF). The application of quantum chemical methods in the study and planning of bioactive compounds has become a common practice nowadays. From the point of view of planning it is important to note, when it comes to the use of molecular modeling, a collective term that refers to methods and theoretical modeling and computational techniques to mimic the behavior of molecules, not intend to reach a bioactive molecule simply through the use of computer programs. The choice of method for energy minimization depends on factors related to the size of the molecule, parameters of availability, stored data and computational resources. Molecular models generated by the computer are the result of mathematical equations that estimate the positions and properties of the electrons and nuclei, the calculations exploit experimentally, the characteristics of a structure, providing a new perspective on the molecule. In this work we show that studies of Highest Occupied Molecular Orbital Energy (HOMO), Low Unoccupied Molecular Orbital Energy (LUMO) and Map of molecular electrostatic potential (MEP) using Hatree-Fock method with different basis sets (HF/3-21G*, HF/3-21G**, HF/6-31G, HF/6-31G*, HF/6-31G** and HF/6-311G), that are of great importance in modern chemistry, biochemistry, molecular biology, and other fields of knowledge of health sciences. In order to obtain a significant correlation, it is essential that the descriptors are used appropriately. Thus, the quantum chemical calculations are an attractive source of new molecular descriptors that can, in principle, express all the geometrical and electronic properties of molecules and their interactions with biological receptor.
文摘Objectives: To improve the diagnosis of damaged spinal motor pathways in incomplete spinal cord injury (iSCI) by assessing the facilitation of lower limbs motor evoked potentials (MEP). Methods: Control subjects (n = 12) and iSCI patients (n = 21) performed static and dynamic isometric foot dorsiflexions. MEPs induced by transcranial magnetic stimulation and EMG background of tibialis anterior muscle (TA) were analyzed. Static and dynamic muscle activation was performed at comparable levels of maximal voluntary contraction (MVC). The influence of the motor tasks on the excitability and facilitation of MEPs was compared between controls and iSCI patients. Results: In the controls an increased facilitation of TA MEP at lower levels of dynamic compared with static activation (10-20 % MVC) could be shown. At matched EMG background level the MEP responses were significantly increased. In the iSCI patients at a comparable level of TA activation the MEP responses were significantly reduced and 3 different patterns of MEP responses could be distinguished: i) preserved increment of TA MEP in the dynamic motor task, ii) unchanged MEP size in the dynamic and static motor task, and iii) elicitable MEPs in the dynamic motor task, which were abolished in the static motor task. Conclusions: Static and dynamic motor tasks have different effects on TA MEP facilitation. The task-dependent modulation of TA MEPs is comparable to that described for upper limb muscles. Complementary to the MEP delay this approach allows for an estimation of the severity of spinal tract damage. The task-dependent modulation of TA MEPs is an additional diagnostic tool to improve the assessment and monitoring of motor function in iSCI.
