[Activation of metabotropic glutamate receptor 1 inhibits chronic intermittent hypoxia-induced carotid body plasticity in rats].

The purpose of the present study was to explore the role of carotid body metabotropic glutamate receptor 1 (mGluR1) in chronic intermittent hypoxia (CIH)-induced carotid body plasticity. Sprague Dawley (SD) rats were exposed to CIH (6%-21% O2, 4 min/cycle, 8 h/day) for 4 weeks. The blood pressure of rats was monitored non-invasively by tail-cuff method under consciousness. RT-qPCR was used to examine the mRNA expression level of mGluR1 in rat carotid body. Western blot was used to detect the protein expression level of mGluR1 in rat carotid body. The role of mGluR1 in CIH-induced carotid body sensory long-term facilitation (sLTF) was investigated by ex vivo carotid sinus nerve discharge recording, and the carotid body sLTF was evoked by a 10-episode of repetitive acute intermittent hypoxia (AIH: 1 min of 5% O2 interspersed with 5 min of 95% O2). The results showed that: 1) CIH increased the systolic blood pressure (P < 0.001), diastolic blood pressure (P < 0.005) and mean arterial blood pressure (P < 0.001) of rats; 2) CIH decreased the mRNA and protein levels of mGluR1 in the rat carotid body (P < 0.01); 3) 4 weeks of CIH induced carotid body sLTF significantly, exhibiting as an increasing baseline sensory activity during post-AIH, which was inhibited by application of an agonist of group I metabotropic glutamate receptors, (S)-3,5-dihydroxyphenylglycine (DHPG), during sLTF induction (P < 0.005). In summary, these results suggest that activation of mGluR1 inhibits CIH-induced carotid body plasticity in rats.

[Role of group II and III mGluRs in carotid body plasticity induced by chronic intermittent hypoxia in rats].

The aim of the present study was to explore the role of group II and III metabotropic glutamate receptors (mGluRs) in carotid body plasticity induced by chronic intermittent hypoxia (CIH) in rats. Sprague Dawley (SD) rats were treated with CIH in Oxycycler A84 hypoxic chamber for 4 weeks, and the tail artery blood pressure was measured at the end of model preparation. RT-qPCR was performed to examine the mRNA expression levels of mGluR2/3/8 in rat carotid body. Carotid sinus nerve activity was detected by ex vivo carotid sinus nerve discharge recording technique, and acute intermittent hypoxia (AIH) was administered to induce carotid body sensory long-term facilitation (sLTF), in order to observe the role of group II and group III mGluRs in carotid body plasticity induced by CIH. The results showed that: 1) After 4 weeks of CIH exposure, the blood pressure of rats increased significantly; 2) CIH down-regulated the mRNA levels of mGluR2/3, and up-regulated the mRNA level of mGluR8 in the carotid body; 3) AIH induced sLTF in carotid body of CIH group. In the CIH group, activation of group II mGluRs had no effect on sLTF of carotid body, while activation of group III mGluRs completely inhibited sLTF. These results suggest that CIH increases blood pressure in rats, and group III mGluRs play an inhibitory role in CIH-induced carotid body plasticity in rats.

[Glutamate and its ionotropic receptor agonists inhibit the response to acute hypoxia in carotid body of rats].

The purpose of this study was to investigate the effect of glutamate and its ionotropic receptor agonists on the response to acute hypoxia in rat carotid body in vitro. Briefly, after SD rats were anesthetized and decapitated, the bilateral carotid bifurcations were rapidly isolated. Then bifurcation was placed into a recording chamber perfused with 95% O2-5% CO2 saturated Kreb's solution. The carotid body-sinus nerve complex was dissected, and the carotid sinus nerve discharge was recorded using a suction electrode. To detect the response of carotid body to acute hypoxia, the chamber was perfused with 5% O2-5% CO2-90% N2 saturated Kreb's solution for a period of 100 s at an interval of 15 min. To observe the effect of glutamate, ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor agonist AMPA or N-methyl-D-aspartate (NMDA) receptor agonist NMDA on the response to acute hypoxia in rat carotid body, the chamber was perfused with 5% O2-5% CO2-90% N2 saturated Kreb's solution containing the corresponding reagent. The results showed that glutamate (20 µmol/L), AMPA (5 µmol/L) or NMDA (10 µmol/L) inhibited the acute hypoxia-induced enhancement of carotid sinus nerve activity, and these inhibitory effects were dose-dependent. In summary, the activation of glutamate ionotropic receptors appears to exert an inhibitory effect on the response to acute hypoxia in carotid body of rats.

CRISPR/Cas9 from bench to bedside: what clinicians need to know before application?

In October 2020, Dr. Emmanuelle Charpentier and Dr. Jennifer Doudna won the Nobel Prize in Chemistry for their pioneering work in precise genome editing using the CRISPR technology. Although CRISPR technology has developed rapidly in the last decade, there are still many uncertainties before eventual use in clinical settings. In this mini review, we summarize the current efforts in addressing the limitations of CRISPR technology and future directions.

[Effect of dopamine on the sensitivity of carotid body to hypoxia induced by acute intermittent hypoxia in rats].

Objective: To investigate the sensitivity of carotid body to hypoxia and the effect of dopamine on the sensitivity of carotid body to hypoxia after acute intermittent hypoxia stimulation in rats. Methods: The isolated carotid body-sinus nerve in rat was transferred to incubator, and then the isolated sinus nerve was inhaled into the recorded glass electrode for recording electrical signals. The baseline buffer was bubbled with 95% O 2 + 5% CO 2 mixture gas, and the hypoxic stress was treated with 5% O 2 + 5% CO 2 + 90% N2 mixture gas, hypoxic stimulation was given for 30 seconds, 95% O 2 + 5% CO 2 for 90 seconds, a total of 10 cycles. No less than 5 rats in each group. Results: In this experiment, the electrical activity of sinus nerve isolated from rats was enhanced by hypoxia stimulation after acute intermittent hypoxia, but the response of sinus nerve to hypoxia was inhibited by dopamine. Before acute intermittent hypoxic stress, dopamine also inhibited the firing activity of sinus nerve, but after acute intermittent hypoxic cycle, the inhibition of dopamine on the firing activity of sinus nerve was strengthened. Conclusion: Acute intermittent hypoxia enhances the response of sinus nerve isolated from rats to hypoxia, dopamine inhibits the enhancement of carotid body sensitivity to hypoxia induced by acute intermittent hypoxic.

Interaction of malachite green with bovine serum albumin: determination of the binding mechanism and binding site by spectroscopic methods.

The interaction between malachite green (MG) and bovine serum albumin (BSA) under simulative physiological conditions was investigated by the methods of fluorescence spectroscopy, UV-vis absorption and circular dichroism (CD) spectroscopy. Fluorescence data showed that the fluorescence quenching of BSA by MG was the result of the formation of the MG-BSA complex. According to the modified Stern-Volmer equation, the effective quenching constants (K(a)) between MG and BSA at four different temperatures were obtained to be 3.734 x 10(4), 3.264 x 10(4), 2.718 x 10(4), and 2.164 x 10(4)L mol(-1), respectively. The enthalpy change (Delta H) and entropy change (DeltaS) were calculated to be -27.25 kJ mol(-1) and -11.23 J mol(-1)K(-1), indicating that van der Waals force and hydrogen bonds were the dominant intermolecular force in stabilizing the complex. Site marker competitive experiments indicated that the binding of MG to BSA primarily took place in sub-domain IIA. The binding distance (r) between MG and the tryptophan residue of BSA was obtained to be 4.79 nm according to Förster theory of non-radioactive energy transfer. The conformational investigation showed that the presence of MG decreased the alpha-helical content of BSA (from 62.6% to 55.6%) and induced the slight unfolding of the polypeptides of protein, which confirmed some micro-environmental and conformational changes of BSA molecules.

Study of antibacterial activity of ZnZnbisporphyrin complexes and its free components on Staphylococcus aureus by microcalorimetry.

The antibacterial effect of Zn(II), tetraphenyl porphyrin (TPP), propdioxyl bridged tetraphenyl bisporphyrin 1, and its metallobisporphyrin complexes (ZnMnbisporphyrin 2 and ZnZnbisporphyrin 3) towards Staphylococcus aureus growth was investigated by microcalorimetry at 37 degrees C. Differences in their capacities to inhibit the growth metabolism of S. aureus were observed. By analyzing the power-time curves, crucial parameters such as the rate constant of bacterial growth (k), inhibitory ratio (I), and generation time (t (G)) were determined. The growth rate constant (k) of S. aureus (in the log phase) in the presence of the drugs decreased linearly with increasing concentrations of the complexes. The sequence of the antibacterial activities of these compounds tested was 3 > 2 > 1 > Zn(II) > TPP. ZnZnbisporphyrin 3 is proposed to benefit from the synergetic effects of Zn(II) and 1.

[Study on control of graft-versus-host disease by blocking CD137-CD137L ligand costimulatory pathway in mice].

OBJECTIVE: To explore the in vitro effect on control of graft-versus-host disease (GVHD) and its mechanism in mice by blockade of CD137-CD137L pathway. METHODS: Responder spleen cells from BALB/c donor mice (H-2(d)) were incubated with stimulator spleen cells from C57BL/6 ( H-2(b)) recipient mice, with or without anti-CD137L mAb. Lethally irradiated C57BL/6 mice were transplanted with donor bone marrow cells plus primary MLC spleen T cells. Group A (Allo-BMT control group): allo-BMT mice not receiving any prevention measures for GVHD. Group B (CsA + MTX control group): CsA and MTX given to C57BL/6 mice after transplantation. Group C (experimental group): donor spleen cells from BALB/c mice treated with anti-CD137L mAb. The percentages of CD3+ CD8+ T and CD3+ CD4+ T cells in the three groups were detected by flow cytometry, and the level of cytokines (IFN-gamma, IL-2, IL-10, IL-4) by RT-PCR. RESULTS: The incidence of GVHD in group C was 70%, while in group A and group B were 100%. The survival rate was higher and the median survival time was longer of group C than that of group A and B (P < 0.01). All mice in group A died of aGVHD within 15 ds, while 30% of mice in group C survived more than 30 ds. Symptoms and histological signs of GVHD in group C were the mildest among the three groups. The percentage of CD3+ CD8+ T cells and the levels of IFN-gamma were significantly lower (P < 0.01), and the levels of IL-10 were significantly higher in group C than those in group A and B (P < 0.01). CONCLUSION: Treatment of donor T cells with anti-CD137L mAb in vitro may relieve GVHD, thereby improve the survival time and survival rate, which maybe related to increasing Th1 cytokine (IFN-gamma) and decreasing Th2 cytokine (IL-10) as well as reducing CD3+ CD8+ T cells.