RESUMO OBJETIVO: Investigar o efeito protetor e o mecanismo da dexmedetomidina (Dex) na lesão perioperativa do miocárdio em doentes com dissecação aórtica Tipo A de Stanford (AD). MÉTODOS: Oitenta e seis pacientes com o Tipo A de Stanford foram aleatoriamente divididos em Dex e grupos de controle, 43 casos em cada grupo. Durante a cirurgia, o grupo de controle recebeu a anestesia de rotina, e o grupo Dex recebeu tratamento Dex baseado na anestesia de rotina. A frequência cardíaca (AR) e a pressão arterial média (MAP) foram registradas no momento anterior ao Dex carregar (t0), 10 minutos após o Dex carregar (t1), incisão cutânea (t2), serragem de esterno (t3), antes do bypass cardiopulmonar (t4), extubação (t5) e fim da cirurgia (t6). Os índices de sangue foram determinados no momento antes da indução da anestesia (T0) e no pós-operatório 12 horas (T1), 24 horas (T2), 48 horas (T3) e 72 horas (T4). RESULTADOS: Em T2 e t3, o RH e o MAP do grupo Dex foram inferiores ao grupo de controle (p<0,05). Em comparação com o grupo de controle, no grupo Dex em T1, T2 e T3, os níveis séricos de creatina quinase-MB, troponina-I, proteína C-reativa e necrose do fator-α do tumor diminuíram, o nível interleucina-10 aumentou, o desalinhamento total do superóxido sérico e a capacidade antioxidante total aumentaram e os níveis de mielopeperóxido e malondialdeído diminuíram (todos p<0,05). CONCLUSÃO: O tratamento com Dex pode aliviar a lesão do miocárdio perioperativo em doentes com o Tipo A de Stanford por resistência à resposta inflamatória e ao estresse oxidativo.

SUMMARY OBJECTIVE: To investigate the protective effect and mechanism of dexmedetomidine (Dex) on perioperative myocardial injury in patients with Stanford type-A aortic dissection (AD). METHODS: Eighty-six patients with Stanford type-A AD were randomly divided into Dex and control groups, with 43 cases in each group. During the surgery, the control group received the routine anesthesia, and the Dex group received Dex treatment based on routine anesthesia. The heart rate (HR) and mean arterial pressure (MAP) were recorded before Dex loading (t0), 10 min after Dex loading (t1), at the skin incision (t2), sternum sawing (t3), before cardiopulmonary bypass (t4), at the extubation (t5), and at end of surgery (t6). The blood indexes were determined before anesthesia induction (T0) and postoperatively after 12h (T1), 24h (T2), 48h (T3), and 72h (T4). RESULTS: At t2 and t3, the HR and MAP in the Dex group were lower than in the control group (P < 0.05). Compared with the control group, in the Dex group at T1, T2, and T3, the serum creatine kinase-MB, cardiac troponin-I, C-reactive protein, and tumor necrosis factor-α levels were decreased, and the interleukin-10 level, the serum total superoxide dismutase, and total anti-oxidant capability increased, while the myeloperoxidase and malondialdehyde levels decreased (all P < 0.05). CONCLUSIONS: Dex treatment may alleviate perioperative myocardial injury in patients with Stanford type-A AD by resisting inflammatory response and oxidative stress.

L-lactate is one of main byproducts excreted in to the fermentation medium. To improve L-glutamate production and reduce L-lactate accumulation, L-lactate dehydrogenase-encoding gene ldhA was knocked out from L-glutamate producing strain Corynebacterium glutamicum GDK-9, designated GDK-9ΔldhA. GDK-9ΔldhA produced approximately 10.1% more L-glutamate than the GDK-9, and yielded lower levels of such by-products as α-ketoglutarate, L-lactate and L-alanine. Since dissolved oxygen (DO) is one of main factors affecting L-lactate formation during L-glutamate fermentation, we investigated the effect of ldhA deletion from GDK-9 under different DO conditions. Under both oxygen-deficient and high oxygen conditions, L-glutamate production by GDK-9ΔldhA was not higher than that of the GDK-9. However, under micro-aerobic conditions, GDK-9ΔldhA exhibited 11.61% higher L-glutamate and 58.50% lower L-alanine production than GDK-9. Taken together, it is demonstrated that deletion of ldhA can enhance L-glutamate production and lower the unwanted by-products concentration, especially under micro-aerobic conditions.