BCAA-BCKA axis regulates WAT browning through acetylation of PRDM16

The link between branched-chain amino acids (BCAAs) and obesity has been known for decades but the functional role of BCAA metabolism in white adipose tissue (WAT) of obese individuals remains vague. Here, we show that mice with adipose tissue knockout of Bcat2, which converts BCAAs to branched-chain keto acids (BCKAs), are resistant to high-fat diet-induced obesity due to increased inguinal WAT browning and thermogenesis. Mechanistically, acetyl-CoA derived from BCKA suppresses WAT browning by acetylation of PR domain-containing protein 16 (PRDM16) at K915, disrupting the interaction between PRDM16 and peroxisome proliferator-activated receptor-γ (PPARγ) to maintain WAT characteristics. Depletion of BCKA-derived acetyl-CoA robustly prompts WAT browning and energy expenditure. In contrast, BCKA supplementation re-establishes high-fat diet-induced obesity in Bcat2 knockout mice. Moreover, telmisartan, an anti-hypertension drug, significantly represses Bcat2 activity via direct binding, resulting in enhanced WAT browning and reduced adiposity. Strikingly, BCKA supplementation reverses the lean phenotype conferred by telmisartan. Thus, we uncover the critical role of the BCAA-BCKA axis in WAT browning.

Dynamical study of Νaν channel excitability under mechanical stress

Alteration of [Formula: see text] channel functions (channelopathies) has been encountered in various hereditary muscle diseases. [Formula: see text] channel mutations lead to aberrant excitability in skeletal muscle myotonia and paralysis. In general, these mutations disable inactivation of the [Formula: see text] channel, producing either repetitive action potential firing (myotonia) or electrical dormancy (flaccid paralysis) in skeletal muscles. These "sick-excitable" cell conditions were shown to correlate with a mechanical stretch-driven left shift of the conductance factors of the two gating mechanisms of a fraction of [Formula: see text] channels, which make them firing at inappropriate hyperpolarised (left-shifted) voltages. Here we elaborate on a variant of the Hodgkin-Huxley model that includes a stretch elasticity energy component in the activation and inactivation gate kinetic rates. We show that this model reproduces fairly well sick-excitable cell behaviour and can be used to predict the parameter domains where aberrant excitability or paralysis may occur. By allowing us to separate the incidences of activation and inactivation gate impairments in [Formula: see text] channel excitability, this model could be a strong asset for diagnosing the origin of excitable cell disorders.

[Biotransformation of benzene to cis-1,2-dihydroxycyclohexa-3,5-diene using recombinant Escherichia coli JM109 (pKST11)]

Cis-1,2-dihydroxycyclohexa-3,5-diene (DHCD) can be used as a valuable chiral intermediates for applications in pharmaceuticals, aerospace, electrical and fine chemical industries. By on-line detection of toluene dioxygenase (TDO) activity in whole recombinant Escherichia coli JM109 (pKST11) cells that harbored TDO gene under a tac promoter, effects of IPTG and various benzene addition strategies on bioransformation of benzene to DHCD were investigated. When IPTG was used at the beginning of fermentation, the growth of cells was inhibited and TDO activity only maintained for 4 hours while same experiments with addition of IPTG at 6h or 8h generated TDO activity for 18 hours. Suitable induction time for IPTG was in the cell logarithmic growth phase and 0.5 mmol/L IPTG was sufficient for inducing maximum TDO activities. Benzene strongly inhibited the activity of TDO which catalyses the conversion of benzene to DHCD. It was found that both cell growth and TDO activity was remarkably inhibited by feeding of benzene vapor, only 7.5 g/L DHCD was obtained. While the benzene inhibition effect was ameliorated by two-liquid phase culture fermentation in which liquid paraffin was used as second phase in the broth. Using different initial ratios of paraffin to benzene in fed-batch culture, DHCD contents were increased to 22.6 g/L, which was 3-fold more compared with that in benzene vapor culture. A further improvement of DHCD production was achieved when the mixture of liquid paraffin and benzene was added continuously by peristaltic pump, the DHCD contents were increased to a final concentration of 36.8 g/L. It was proven that the key to improving DHCD production by recombinants is to prolong TDO activity in cells, which can be achieved by using suitable addition benzene strategies.

[Observation of deaf-mute students' audition examine and otacoustic effect]

OBJECTIVE

To explore the state of the remnant hearing of deaf-mute students and to check the effect of hearing aids to them.

METHOD

38 cases of deaf and dumb students were examined with the pure tone auditometry, acoustic immitance test, auditory brainstem response, and the environmental sound discrimination test.

RESULT

In 17 cases, the average threshold of air conduction of speech frequency is below 89 dB HL; In 18 cases, it is between 90 dB and 110 dB; In 3 cases, it is above 110 dB. 33 cases have model A curve and 5 cases have model B curve. When 123 dB peSPL was presented, 24 cases generated the waveform but the others didn't. 16 cases could discriminate the environmental sound and the other 22 cases could not, but if the patients weared the hearing aids, the number of the persons who could discriminate the environmental sound increased to 24, only 14 cases had no effect by this means.

CONCLUSION

Examination of deaf-mutes audition can find persons with residual audition. If they wear the hearing aids and go into hearing rehabilitation training at the same time as early as possible, it will improve the environmental sound discrimination rate.