Methods for determination of absolute configuration of monosaccharides / 中草药·英文版

Monosaccharides are one of the most important structural components of biomolecules, such as polysaccharides, nucleic acids, glycolipids and glycoproteins. In structural analysis of polysaccharides and glycoconjugates, the absolute configurations (D or L) of the constituent monosaccharides are usually determined by measurement of the optical rotation, CD spectra or characteristic chromatographic retention behavior. However, each method has its unique advantages and limitations which should be considered while using them. In this review, an overview of the different methods for the determination of absolute configuration of monosaccharides and their underlying principles are summarized to serve as a reference for researchers.

Theoretical methods in configuration determinations for natural chiral products: Research advances / 国际药学研究杂志

Identification of natural products has been a big challenge because of their structural complexity and diversity. Recently, with the development of separation materials, more and more complex compounds have been found with small quantity, which causes difficulty in absolute configuration assignment. Now, the computational methods, such as to compute the 13C NMR data and compare them with experimental results, could be used for relative configuration study other methods, for example, to compute optical rotation (OR), or optical rotatory dispersion (ORD), electronic circular dichroism (ECD or CD) or vibrational circular dichroism VCD, could be efficiently used for absolute configuration determinations for chiral compounds, including the derminant computations for chiral acyclic compounds. Now, two or two more methods are applied for the absolute configuration study and exhibit very powerful reliability.

A major problem in strabismus and its possible solution / Um grande problema no estrabismo e suas possíveis soluções

Purpose: One of the challenges in strabismus is to guarantee stability of the surgical corrections. Re-surgeries are often required even after careful diagnosis, planning, and execution. Several factors contribute to this undesired outcome and the existing management strategies are ineffective. The present alternative is to compensate for their consequences. Ocular rotations are evoked by muscular contractions and relaxations (active forces). During eye movement, periocular tissues are stretched, storing part of the kinetic energy, which may be posteriorly recovered (passive forces), whereas the remaining part of the energy is lost via friction and inelastic deformations (dissipative forces). A method for measuring the forces that cause post-surgery eye drift has not been reported. However, this may be indirectly determined as a function of the respective mechanical variables. The estimated ratio between the kinetic energies of a post-surgery eye drift and a normal pursuit eye movement is ~10-15. Theoretically, it can be expected that the addition of continuously acting forces of such magnitudes to the oculomotor system might prevent the undesired post-surgery eye movement. Methods: Several methods for increasing the restraining, dissipative forces to ocular rotations may be conceived. One method is to increase the friction to ocular movements, as for instance, by periocular injection of viscous substances. Another possibility is to use the forces of a magnetic field, which may stabilize the eye in a desired position without avoiding the rotations caused by greater muscular forces acting on it. It has been demonstrated that these forces neutralize the nystagmic movements, whose intensities of mechanical variables are much higher than those of a post-surgery eye drift. Some models of application of this technique are then discussed. Small magnets fixed to the orbit and metallic ferromagnetic elements fixed to the sclera to cover a suitable ...

Objetivo: Um grande problema nos estrabismos é garantir um resultado bom e estável de suas correções cirúrgicas. A necessidade de reoperações é relativamente alta, apesar de cuidadosos procedimentos diagnósticos, planejamento cirúrgico e execução tenham sido tomados. O resultado indesejado é devido a muitos fatores que ainda não são apropriadamente controlados. A alternativa atual é, então, compensar as consequências correspondentes. Rotações oculares são evocadas por contrações e relaxamentos musculares (forças ativas). Nesses movimentos oculares, tecidos perioculares são distendidos, mantendo parte da energia cinética, que pode ser posteriormente recuperada (forças passivas), enquanto outra parte é definitivamente perdida em fricção e deformações inelásticas (forças dissipativas). Não é conhecida a medida das forças que causam um desvio ocular pós-operatório, mas ela pode ser indiretamente determinada como função das respectivas variáveis mecânicas. A relação entre as energias cinéticas de um desvio ocular pós-operatório e de um movimento ocular persecutório normal pode ser então estimada como de cerca 10-15. Teoricamente, pode-se esperar que a adição de forças dessas magnitudes ao sistema oculomotor, continuadamente atuantes, possam prevenir os movimentos pós-operatórios indesejados. Métodos: Podem ser concebidas várias possibilidades de aumento das forças dissipativas, restritivas de rotações oculares. Uma é a de aumentar a fricção aos movimentos oculares como, por exemplo, por injeções perioculares de substâncias viscoelásticas. Outra possibilidade é oferecida por forças de campos magnéticos ...

Cyclotorsion measurement in laser refractive surgery / Medida da ciclotorção em cirurgia refrativa a laser

PURPOSE: The aim of this study was to verify the presence of cyclotorsion in eyes that underwent laser refractive surgery. METHODS: This was a comparative observational study, which analyzed the medical records of 61 patients (104 eyes) who underwent laser refractive surgery and compared the axis of astigmatism of the sitting and the supine positions. Regarding the gender, 37.5% were male and 62.5% were female. The age ranged from 20 to 54 years old, with the median of 29 years. The lowest degree of astigmatism was -0.75 cylinder diopters (DC) and the highest was -6.50 DC, with a mean of -3.06 ± 1.16 DC. First, the axis of astigmatism of the seated patient was captured by the Schwind's ORK-CAM. In a second moment, inside the operating room, the axis of astigmatism of the patient in supine position was captured by the laser equipment's own camera (Schwind Amaris®), which was then compared with the previous measure. The incyclotorsion was defined by a minus sign (-) and the excyclotorsion, by a plus sign (+). RESULTS: The maximum excyclotorsion was +7.7 and the maximum incyclotorsion was -11.0 degrees. The mean torsion (excyclo or incyclo) was 2.74 (56.7%), with a standard deviation of 2.30 degrees. There was no statistically significant change (p=0.985) in the axis of astigmatism between patients sitting versus supine. CONCLUSION: There was clinically significant cyclotorsion in 36.5% of the eyes submitted to laser correction.

OBJETIVO: Verificar a presença de ciclotorção em olhos submetidos à cirurgia refrativa a laser. MÉTODOS: Realizou-se um estudo observacional comparativo, feito pela avaliação dos prontuários de 61 indivíduos (104 olhos) submetidos à cirurgia refrativa a laser, para comparar a orientação do astigmatismo ocular na posição sentada e em decúbito dorsal. Foram computados 37,5% de homens com idade variando de 20 a 54 anos, com mediana de 29 anos. O menor grau de astigmatismo avaliado foi de -0,75 e o maior de -6,50, com média de -3,06 ± 1,16 dioptrias cilíndricas (DC). A captação da orientação (eixo) do astigmatismo foi feita no primeiro momento (sentado) pelo aparelho ORK-CAM da empresa Schwind. Em um segundo momento (decúbito dorsal), na sala de cirurgia, o eixo foi captado pela câmera do próprio laser (Schwind Amaris®) para então comparar o eixo nos dois momentos. A inciclotorção foi identificada por um sinal negativo (-) e a exciclotorção por um sinal positivo (+). RESULTADOS: A exciclotorção máxima foi de +7,7 e a inciclotorção máxima de -11,0 graus. A média de torção (exciclo ou inciclo) foi de 2,74 (56,7%), com desvio padrão de 2,30 graus. Não houve variação estatisticamente significativa (p=0,985) no eixo do astigmatismo entre os indivíduos sentados versus decúbito dorsal. CONCLUSÃO: Houve ciclotorção clinicamente significativa em 36,5% dos olhos submetidos à cirurgia refrativa a laser.

Chiral Separation and Enantiomerization of Triazole Pesticides / 分析化学

The chiral separation of three triazole pesticides, i.e. diniconazole, triadimefon and triadimenol was studied on a Chiralcel OJ-H and a Chiralcel OD-H HPLC chiral columns. The optical rotation quality of diniconazole and triadimefon enantiomers was measured and the absolute configurations of individual enan-)tiomers) were further concluded. On this basis, the absolute configurations of the four triadimenol stereoisomers were deduced via the reductive experiment of triadimefon to triadimenol. Furthermore, the chiral stability of the three triazole pesticides in organic solvents and buffer solutions was investigated. The results showed the obvious enantiomerization was observed as for triadimefon in methanol, ethanol and water, whereas dinicona-)zole) and triadimefon were chiral stable in organic solvents and water. The enantiomerization of triadimefon would be accelerated at higher temperature and in alkaline media.