ABSTRACT
The comparative structural modeling of djenkolic acid and its derivatives containing selenium and tellurium in chalcogen sites (Ch=Se, Te) has provided detailed information about the bond lengths and bond angles, filling the gap in what we know about the structural characteristics of these aminoacids. The investigation using the molecular mechanics technique with good approximation confirmed the available information on X-ray refinements for the related compounds methionine and selenomethionine, as well as for an estimate made earlier for telluromethionine. It was shown that the Ch-C(3) and Ch-C(4) bond lengths grow in parallel with the increasing anionic radii. Although the distances C-C, C-O, and C-N are very similar, the geometry of conformers is quite different owing to the possibility of rotation about four carbon atoms, hence the remarkable variability observed in dihedral angles. It was shown that the compounds contain a rigid block with two Ch atoms connected through a methylene group. The standard program Gaussian 03 with graphical interface Gaussview 4.1.2 has proved to be satisfactory tool for the structural description of less-common bioactive compositions when direct X-ray results are absent.
Subject(s)
Cysteine/analogs & derivatives , Selenium/chemistry , Sulfur/chemistry , Tellurium/chemistry , Crystallography, X-Ray , Cysteine/chemistry , Methionine/analogs & derivatives , Methionine/chemistry , Models, Molecular , Molecular Structure , Selenomethionine/chemistryABSTRACT
Computerized molecular models of adenosine triphosphate, adenosine tri-arsenate and adenosine trivanadate have been generated using the molecular mechanics technique. The analysis of structural parameters indicated that, at least theoretically, adenosine triarsenate is a realistic candidate for replacement of adenosine triphosphate in biochemical pathways. On the contrary, the structural arrangement of the inorganic segment of adenosine trivanadate does not seem to be capable of withstanding a swift hydrolytical splitting in aqueous milieu. It was shown that the universal force field as implemented in Gaussian software packages is an appropriate tool for the optimization of less-common bioactive compositions.
Subject(s)
Adenosine Triphosphate/chemistry , Adenosine/analogs & derivatives , Adenosine/chemistry , Arsenates/chemistry , Models, Molecular , Vanadates/chemistry , Computer Simulation , Hydrolysis , Models, ChemicalABSTRACT
Objetivos: verificar as alterações da função pulmonar: complacência dinâmica (Cdyn), volume corrente inspiratório (V Tinsp), pressão arterial de dióxido de carbono (PaCO2)' em recém-nasciâos pré-termo com síndrome do desconforto respiratório. Pacientes e métodos: estudo de caso controle, incluindo 11 pré-termos com idade gestacional < 35 semanas, e com peso de nascimento <2.500 gramas, todos com diagnóstico de sindrome do desconforto respiratório, tratados com 120 mg/kg de surfactante porcino. A PEEPinicial foi de 3cm H20. Para a avaliação da função pulmonar, foi utilizado um pneumotacógrafo com monitor gráfico. Após cada aumento da PEEP (4 e 6 cm de H20), aguardava-se 20 minutos para se aferir os dados da função pulmonar e gases arteriais.Resultados: dos 11 pacientes estudados com síndrome do desconforto respiratório, três eram do sexo masculino e oito do sexo feminino (1:2,7). A idade gestacional foi de 30,78 2,05 semanas, com umavariação de 26 a 34 semanas. O aumento da PEEP de 3 para 6cm de H20 ocasionou queda significativa do V Tinsp(6,46 3,43) para 4,20 2,35, p = 0,0262). Com o aumento da PEEP de 4 para 6 cmH20,também ocorreu queda do VTinsp (5,98 3,33 para 4,20 2,35, p=0,0044). Em relação à Cdyn, quando o aumento da PEEP foi de 3 para 6cm de H20, a diminuição foi estatisticamente significante (0,58 0,27 para 0,46 0,25, p = 0,0408), e quando foi de 4 para 6cm de H20, a diminuição da Cdyn também foi importante (0, 77 0,27 para 0,46 0,25, p= 0,0164). Aumentos da PEEP de 4 para 6cm de H20 provocaram aumentos nas PaCO2 (52,81 15,49 para 64,90 12,69, p = 0,0141). Um aumento mais acentuado foi observado quando a PEEP foi aumentada de 3 para 6cm de H20 (41,45 7,87 para 64,90 12,69, p = 0,0033). Conclusões: o estudo evidenciou que PEEP de 3 e 4 cmH20 produzem melhores resultados em termos de Cdyn e menores efeitos colaterais em termos de acidose respiratória e hiperinsuflação pulmonar, com diminuição da ventilação alveolar, evidenciados pelo aumento da PaCO2 e diminuição do V Tinsp
Subject(s)
Humans , Male , Female , Infant, Newborn , Positive-Pressure Respiration , Respiratory Distress Syndrome, NewbornABSTRACT
OBJECTIVE: To verify the alterations of pulmonary function in preterm newborn infants with respiratory distress syndrome (RDS). The parameters analyzed were Dynamic Compliance (Cdyn), Inspiratory Tidal Volume (TVinsp), partial arterial pressure of carbon dioxide (PaCO2). METHODS: Eleven preterm newborn infants, with gestational age <35 weeks, and birth weight <2,500 g, were include in a control case study. All infants presented RDS and were treated with 120 mg/Kg of porcine surfactant. The initial positive end expiratory pressure (PEEP) was 3 cm H2O. A pneumotachograph with a graphical monitor was used to assess the pulmonary function. After each increase in the PEEP (4 and 6 cm H2O), there was an interval of 20 minutes before measuring the arterial data of pulmonary function and arterial gases. RESULTS: There were three males and eight females (1:2.7) among the infants with RDS. The mean gestational age was 30.78. +/- 2.05 weeks, ranging from 26 to 34 weeks. The increase in the PEEP from 3 to 6 cm H2O caused significant decrease in the TVinsp (6.46 +/- 3.43 to 4.20 +/- 2.35, P=0.0262). With the increase in the PEEP from 4 to 6 cm H2O, there was also a decrease in the TVinsp (5.98 +/- 3.33 to 4.20 +/- 2.35), (P=0.0044). Regarding the Cdyn, when there was an increase in the PEEP from 3 to 6 cm H2O, the reduction was statistically significant (0.58 +/- 0.27 to 0.46 +/- 0.25, P=0.0408) and from 4 to 6 cm H2O, the reduction in the Cdyn was also important (0.77 +/- 0.27 to 0.46 +/- 0.25), (P=0.0164). Increases in the PEEP from 4 to 6 cm H2O caused increases in the PaCO2 (52.81 +/- 15.49 to 64.90 +/- 12.69), (P= 0.0141). A more significant increase was observed when the PEEP was elevated from 3 to 6 cm H2O (41.45 +/- 7.87 to 64.90 +/- 12.69, P=0.0033). CONCLUSIONS: The study showed that the PEEP from 3 to 4 cm H2O produces better results in terms of Cdyn and less collateral effects regarding respiratory acidosis and pulmonary hyperventilation with impairment of the alveolar ventilation, evidenced by the increase in the PaCO2 and the decrease in the TVinsp.
