Dual-frequency fundamental-mode NPRO laser for low-noise microwave generation.

Monolithic nonplanar ring oscillators (NPROs) have achieved great success in industry, scientific applications and space missions due to their excellent narrow-linewidth, low-noise, high beam-quality, lightweight and compact performances. Here, we show that stable dual-frequency or multi-frequency fundamental-mode (DFFM or MFFM) laser can be stimulated directly by tunning pump divergence-angle and beam-waist injected to NPRO. The DFFM laser has a frequency deviation of one free spectral range of the resonator and thus can be utilized for pure microwave generation by common-mode-rejection. To demonstrate the purity of the microwave signal, a theoretical phase noise model is established, and the phase noise and the frequency tunability of the microwave signal are experimentally studied. Single sideband phase noise for a 5.7 GHz carrier is measured as low as -112 dBc/Hz at 10 kHz offset, and -150 dBc/Hz at 10 MHz offset in the free running condition of the laser, which outperforms its counterparts from dual-frequency Laguerre-Gaussian (LG) modes. The frequency of the microwave signal can be efficiently tunned through two channels, with frequency tunning coefficients of 15 Hz/V by piezo, and -60.5 kHz/K by temperature, respectively. We expect that such compact, tunable, low-cost and low-noise microwave sources can facilitate multiple applications including miniaturized atomic clocks, communication and radar, etc.

Unidirectional operation criterion in monolithic nonplanar ring oscillators.

Monolithic nonplanar ring oscillators (NPROs) under an applied magnetic field can operate unidirectional single-frequency lasing due to the loss differences among its four eigenpolarizations, where the minimum was empirically estimated to be 0.01%. However, this value has never been verified because the applied magnetic field is not uniformly distributed, making it hard to resolve both theoretically and experimentally. Here, we propose a method to resolve the applied magnetic field through an NPRO by combining finite-element analysis and experimental verification. By introducing the non-uniform magnetic field information to the eigenpolarization theory, the loss differences can be calculated by path integration along the optical path in the NPRO. The critical point, where the bidirectional lasing is emerging, is identified by the relative amplitude noise (RAN) of the laser and by the beating signal between the clockwise (CW) and counterclockwise (CCW) lasing. With this method, we determine that unidirectional operation is possible with loss differences as low as 0.0001% and 0.0003%, corresponding to two different NPRO designs with out-of-plane angles of 90° and 45°, respectively, which increases the precision of the loss differences for unidirectional single-frequency lasing by more than one order of magnitude. Our findings will greatly facilitate NPRO laser design with lowered magnetic field intensity requirements.

Dexmedetomidine protects against high mobility group box 1-induced cellular injury by inhibiting pyroptosis.

Dexmedetomidine (DEX) is a widely used clinical anesthetic with proven anti-inflammatory effects. Both high mobility group box 1 (HMGB1) and pyroptosis play an important role in the inflammatory response to infection and trauma. Thus far, there have been no studies published addressing the effect of DEX on HMGB1 and pyroptosis. In order to fill this gap in the literature, bone marrow-derived macrophages (BMDMs) were exposed to HMGB1 (4 µg/mL) with or without DEX (50 µM) pretreatment. The production of pro-inflammatory cytokines [such as tumor necrosis factor α (TNF-α), interleukin 1ß (IL-1ß), and IL-18], phosphorylation of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) and P38, and the activation of caspase-1 were measured by enzyme immunosorbent assay, western blot analysis, confocal microscope, and flow cytometry, respectively. We found that DEX protected against HMGB1-induced cell death of BMDMs. In addition, DEX suppressed the generation of TNF-α, IL-1ß, and IL-18 as well as the phosphorylation of ERK1/2 and P38. Moreover, DEX inhibited caspase-1 activation and decreased pyroptosis. Taken together, these findings demonstrate the protective effect of DEX in mediating HMGB1-induced cellular injury, thus indicating that DEX may be a potential therapeutic candidate for the management of infection and trauma-derived inflammation.

Ultrasensitive analysis of glucose in serum by capillary electrophoresis with LIF detection in combination with signal amplification strategies and on-column enzymatic assay.

A highly specific and sensitive method for glucose quantification in human serum samples based on on-column enzymatic assay is described. In this method, the head of the capillary was used as a nanoliter-microreactor, the diluted samples spiked with a novel fluorogenic reagent named 2-[6-(4'-amino) phenoxy-3H-xanthen-3-on-9-yl] benzoic acid (APF), and the mixed enzyme solutions of glucose oxidase (GOx) and horseradish peroxidase (HRP), were individually injected into the capillary. Hydrogen peroxide (H2 O2 ) generated in situ by catalytic reaction between GOx and glucose, activates APF in the presence of HRP to form a highly fluorescent product, which was electrophoretically separated from the unreacted APF and detected by the LIF detector. The proposed method allowed the determination of glucose down to 10 nM in real samples, with RSD values lower than 3.5%, which also has the potential for measurements of multicomponents in many other systems including measurement of α-glucosidase activity and screening for its inhibitors.

Copper(II)-catalyzed C5 and C7 halogenation of quinolines using sodium halides under mild conditions.

A simple and mild protocol for copper catalyzed halogenation of quinoline at C5 and C7 positions was developed, affording the desired remote C-H activation products in moderate to good yields. This reaction proceeds with low-cost sodium halides (NaX, X = Cl, Br, I) and features excellent substrate tolerance. A series of control experiments were carried out to illustrate a single-electron-transfer process which plays a vital role in the halogenation.

The effect of dexmedetomidine on inflammatory response of septic rats.

BACKGROUND: Some studies have demonstrated dexmedetomidine has anti-inflammatory effect on septic rats. However, the mechanism of how dexmedetomidine exerts these effects is still remained unknown. This study was designed to investigate the mechanism of how dexmedetomidine inhibits the production of inflammatory mediators in cecal ligation and puncturinduced septic rats. METHODS: 48 Sprague-Dawley rats were randomly divided into six groups: sham-operated (sham) group, cecal ligation and puncture (CLP) group, dexmedetomidine 5 µg/kg (DEX5) group, dexmedetomidine 10 µg/kg (DEX10) group,dexmedetomidine + yohimbine (DEX10 + Yoh) group and yohimibine group (Yoh). Blood, bronchoalveolarlavage fluid (BALF) and lung tissues in each group were collected at six hours after dexmedetomidine or yohimbine treatment,. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in BALF and plasma were measured by enzyme-linked immunosorbent assay (ELISA). Toll-like receptor-4(TLR4) and myeloid differerntiation factor(MyD88) expression were measuredby quantitative PCR, and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation were determined by western blott. RESULTS: Compared with CLP group, dexmedetomidine significantly decreased not only the production of TNF-α and IL-6 both in plasma and BALF, but also inhibited the expression of TLR4 and MyD88 in mRNA level and the activation of ERK1/2 and NF-κB in the lung tissues of CLP-induced septic rats. All these effects could not be reversed by yohimibine. CONCLUSIONS: Dexmedetomidine treatment can effectively reduce the generation of inflammatory mediators in the plasma and BALF of CLP-induced septic rats. These effects of dexmedetomidine rely on TLR4/MyD88/MAPK/ NF-κB signaling pathway and are independent of α2-adrenoceptor.

[Molecular mechanism underlying the inhibitory effect of propofol on lipopolysaccharide-induced pyroptosis of mouse bone marrow-derived macrophages].

OBJECTIVE: To investigate the molecular mechanism underlying the inhibitory effect of propofol on pyroptosis of macrophages. METHODS: Macrophages derived from bone marrow were extracted and divided into three groups: control group, LPS+ATP group and propofol+LPS+ATP group. The control group was not given any treatment; LPS+ATP group was given LPS 1 µg/mL stimulation for 4 h, then ATP 4 mM stimulation for 1 h; Propofol+LPS+ATP group was given propofol+LPS 1 µg/mL stimulation for 4 h, then ATP stimulation for 1 h. After treatment, the supernatant and cells of cell culture were collected. the cell activity was detected by CCK8 and flow cytometry. The inflammatory cytokines IL-1ßand IL-18 were detected by Elisa. Western blot was used to detect the expression of caspase-1 protein and TLR4 on cell membran Immunohistochemical fluorescence was used to detect apoptosis of cells. RESULTS: LPS+ATP significantly decreased the viability of the macrophages and increased the cellular production of IL-1ß and IL-18, activation of caspase-1 protein and the expression of TLR-4 on the cell membrane (P < 0.05). Treatment with propofol obviously reversed the changes induced by LPS+ATP. CONCLUSIONS: LPS+ATP can induce pyroptosis of mouse bone marrow-derived macrophages, and propofol effectively inhibits such cell death, suggesting that propofol anesthesia is beneficial during operation and helps to regulate the immune function of in patients with sepsis.

A practice of anesthesia scenario design for emergency cesarean section in patients with COVID-19 infection based on the role of standard patient.

The new coronavirus (COVID-19) has been characterized as a world pandemic by WHO since March 11, 2020. Although it is likely that COVID-19 transmission is primarily via droplets and close contact, airborne transmission and fecal-oral route remains a possibility. The medical staff working in the operating room, such as anesthesiologists, surgeons and nurses, are at high risk of exposure to virus due to closely contacting patients. The perioperative management is under great challenge while performing surgeries for patients suffering COVID-19, including emergency cesarean section, which is one of the most common surgeries under such circumstances. How to prevent medical staff from cross-infection is an issue of great concern. In this article, we give a practice of anesthesia scenario design for emergency cesarean section in a supposed standard patient suffering COVID-19, aimed to optimize the work flow and implement the protective details through simulation of a real operation scenario, which may be useful for training and clinical practice of anesthesia management for patients suffering COVID-19 or other fulminating infectious diseases.

[Postoperative low-dose sufentanil combined with transversus abdominis plane block promotes recovery following laparoscopic hysterectomy].

OBJECTIVE: To compare the efficacy and safety of postoperative analgesia with low-dose sufentanil combined with transversus abdominis plane (TAP) block and with sufentanil alone in promoting patients'recovery following laparoscopic hysterectomy. METHODS: Sixty patients undergoing laparoscopic hysterectomy in our hospital between September, 2016 and August, 2017 were randomly allocated into two equal groups. In group A, the patients were given postoperative analgesia with 1 µg/kg sufentanil, 9.96 mg tropisetronmesylate, and 200 mg flurbiprofen axetil (diluted with 0.9% NaCl solution to 100 mL, pumped at the rate of 2 mL/h) combined with TAP block; in group B, the patients received similar postoperative analgesia but at a higher dose of sufentanil (2 µg/kg) without TAP block. Visual analogue scale (VAS) was used to evaluate pain at 15 min and at 4, 8, 12, 24 and 48 h postoperatively, and the first off-bed time, the length of postoperative hospital stay and the incidence of postoperative nausea and vomiting (PONV) were recorded in all the patients. RESULTS: Compared with those in group B, the patients in group A had significantly lower VAS scores at 15 min, 4 h, 8 h, and 12 h postoperatively (P < 0.01) with also statistically shorter first off-bed time and postoperative hospital stay (P < 0.01). Two (6.7%) patients in group A had mild PONV, and 6 (20.0%) in group B had PONV (including 4 with mild and 2 with moderate PONV). CONCLUSIONS: Lowdose sufentanil combined with TAP block is effective for postoperative analgesia after laparoscopic hysterectomy and helps to reduce the incidence of PONV and shorten the first off-bed time and postoperative hospital stay to promote the recovery of the patients.

Simultaneous determination of pharmacologically active ingredients in Rhodiola by capillary chromatography with electrochemical detection.

Rhodiola, in which there are abundant pharmacologically active ingredients, is one of the functional adaptogenic agent that aid specific bodily functions to adapt to the changes and stress of life in addition to being tonic. In an attempt to qualitatively and quantitatively determine the pharmacologically active ingredients in Rhodiola, a new method based on capillary electrophoresis with electrochemical detection (CE-ED) has been developed. The effects of working electrode potential, pH and concentration of running buffer, separation voltage, applied potential and injection time on CE-ED were investigated. Under the optimum conditions, the analytes could be well separated within 24 min at the separation voltage of 18 kV in a 80 mmol L(-1) borax running buffer (pH 9.0). Good linear relationship was established between peak current and concentration of analytes over two orders of magnitude with detection limits (S/N=3) ranged from 3.16 x 10(-7) to 1.11 x 10(-7)g mL(-1) for all target ingredients. This proposed method has been successfully applied for the analysis of real samples, with satisfactory results.

[Protective effect of dexmedetomidine against perioperative inflammation and on pulmonary function in patients undergoing radical resection of lung cancer].

OBJECTIVE: To study the protective effect of dexmedetomidine against perioperative inflammation and on pulmonary function in patients undergoing radical resection of lung cancer. METHODS: From May, 2014 to May, 2016, 124 patients with lung cancer receiving radical surgeries were randomized into experimental group (n=62) and control group (n=62). The patients in the control group received a single anesthetic agent for anesthesia, and additional dexmedetomidine was given in the experimental group. The levels of serum interleukin-1ß (IL-1ß), IL-10, and tumor necrosis factor-alpha (TNF-α) were measured before the operation (T0), at 30 min (T1) and 60 min (T2) during one lung ventilation (OLV) and at the end of operation (T3). Enzyme-linked immunosorbent assay (ELISA) was used to determine the levels of malondialdehyde (MDA), myeloperoxidase (MPO) and xanthine oxidase (XOD), and the arterial oxygen partial pressure (PaO2), oxygenation index (OI), airway plateau pressure (APP) and airway resistance (AR) were also recorded. RESULTS: At the time points of T1 and T2, IL-1ß, IL-10, MDA, MPO, TNF-α, and XOD levels were significantly increased in both of the groups, but the levels of IL-1, IL-10, TNF-α and MDA were significantly lower and MPO and XOD levels significantly higher in the experimental group than in the control group (P<0.05). In both groups, PaO2 and OI decreased and APP and AR increased significantly at T1 and T2, but APP and AR were significantly lower and PaO2 and OI significantly higher in the experimental group than in the control group (P<0.05). CONCLUSION: Anesthesia with dexmedetomidine in lung cancer patients undergoing radical surgery can effectively reduce the inflammatory response of the lungs and protect the lung function of the patients.

[Application of dexmedetomidine combined with propofol in patients undergoing painless colonoscopy for colonic polyps resection under Narcotrend monitoring].

OBJECTIVE: This clinical study was conducted to investigate the effects of dexmedetomidine (DEX) combined with propofol on vital signs and anaesthetic depth in patients. METHODS: Ninety patients with ASA 1-2 requiring painless colonoscopy for colonic polyps resection were randomized to receive DEX 0.3 micro;g/kg (group D, n=45) followed by propofol 1 mg/kg or propofol 2 mg/kg (group C, n=45), and according to the body activity and operation time, additional doses of propofol (0.2-0.5 mg/kg) were given. The full recovery time, operation time, consumed dose of propofol, mean arterial pressure (MAP), heart rate (HR), hemoglobin oxygen saturation levels(SPO2) and NTI were recorded. RESULTS: The SPO2recover time and the consumed dose of propofol in group D were decreased compared to those in group C (P<0.01). The rate of the body activity in group D was lower than that in group C (P<0.05). The NTI in group C was lower than that in group D (P<0.05). The HR and MAP were similar in both groups. CONCLUSION: Under Narcotrend monitoring, the value of DEX combined with low dose of propofol in colonoscopy for colonic polyps resection is to reach more reasonable depth of anesthesia to reduce adverse responses and the dose of propofol.

[Changes of endoplasmic reticulum stress- and apoptosis-related factors in rat cerebral cortex following controlled hypotension].

OBJECTIVE: To investigate the changes of endoplasmic reticulum stress (ERS)- and apoptosis-related factors in rat cerebral cortex following controlled hypotension. METHODS: Twenty-four healthy male SD rats were randomly divided into 4 equal groups, including a sham hypotension group (group A) and 3 hypotension groups with the mean arterial pressure maintained for 60 min at 70 mmHg (group B), 50 mmHg (group) and 30 mmHg (group D) with sodium nitroprusside and esmolol. All the rats received an equal volume of fluid infusion. Twelve hours after controlled hypotension, the rats were sacrificed to examine the protein expressions of Bax, Bcl-2, glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP) and caspase-12 in the cortex with Western blotting. GRP78 mRNA expression was measured by RT-PCR, and the cell apoptosis was evaluated by TUNEL staining. RESULTS: Compared with those in group A, GRP78 mRNA and protein expressions of GRP78, CHOP, caspase-12 related with ERS increased significantly in groups C and D (P<0.05), especially in group D (P<0.05), but not in group B (P>0.05). Apoptotic cells and Bax expression increased and Bcl-2 expression decreased significantly in groups C and D (P<0.05), but not in group B (P>0.05); such changes were more prominent in group D than in group C (P<0.05). CONCLUSION: Mild controlled hypotension (70 mmHg) does not induce neuronal injury in rat cerebral cortex, but severe hypertension (lower than 50 mmHg) can cause neuronal ERS and apoptosis.

[Changes of platelet mitochondria in rats with tourniquet-induced limb ischemia- reperfusion injury].

OBJECTIVE: To investigate the changes of platelet mitochondria in rats with tourniquet-induced limb ischemia-reperfusion (IR) injury. METHODS: Thirty SD rats were randomized equally into 5 groups including a control group and 4 limb IR injury groups for blood sampling at 2, 6, 12, or 24 h following IR injury induced by tourniquet on the thighs for 4 h. Platelet was separated from the blood samples for measurement of ATP content, mitochondrial membrane potentials, plasma cytochrome C level, and hydroperoxides. RESULTS: Compared with the control group, the rats with tourniquet-induced limb IR injury showed significantly decreased ATP content, lowered mitochondrial membrane potential, and increased plasma cytochrome C and hydroperoxide levels in the platelets at 2 and 6 h following the injury (P<0.05 or 0.01). These alterations recovered partially but remained significantly different from the control levels at 12 h (P<0.05 or 0.01) until full recovery at 24 h. Limb IR injury did not cause significant variations of the platelet counts. CONCLUSION: Tourniquet-induced limb IR injury can cause mitochondrial damage in the platelets, which occurs mainly in the early stage (6 h) and recovers gradually afterwards without significant impact on platelet counts.

Inhibition of S100A9 expression by propofol in monocytes of rats with endotoxemia.

The inflammatory response is a non-specific autoimmune response. Monocytes are the most important effector cells in the systemic inflammatory response. In recent years, the function of the intravenous anesthetic, propofol, in the inhibition of the inflammatory response has attracted much attention. However, the specific signal transduction mechanism related to the anti-inflammatory effect of propofol remains unclear. In this study, monocyte protein expression in rats with endotoxemia was detected using proteomic techniques before and after propofol intervention. By two-dimensional electrophoresis and mass spectrometric identification, we found that S100A9 protein expression was significantly reduced after propofol treatment. In addition, we used western blot analysis to confirm the results of two-dimensional electrophoresis. The S100A9 protein, a member of the S100A calcium-binding protein family, is closely related to the occurrence and development of inflammation. The results of this study suggest that the anti-inflammatory effect of propofol may be related to the inhibition of S100A9 protein expression.

[Analgesic effect of COX inhibitors and its mechanism in a rat model of neuropathic pain].

OBJECTIVE: To investigate the effect of COX inhibitors on pain threshold and spinal N-methyl-D-aspartate (NMDA) receptor subunit 2B (NR2B) expression in a rat model of neuropathic pain. METHODS: Thirty-six male SD rats were randomly divided into sham-operated group, chronic constriction injury (CCI) of the sciatic nerve group, indomethacin+CCI group, and parecoxib+CCI group with corresponding treatments. All the rats were tested for mechanical withdrawal threshold, and at day 13 after the surgery, the rats were decapitated for detection of NR2B expression in the spinal cord at the L4-6 levels. RESULTS: The mechanical withdrawal threshold were lowered significantly after the operation in CCI, indomethacin+CCI and parecoxib+CCI groups (P<0.05). Parecoxib alleviated the hypersensitivity of CCI model rats but not affected spinal NR2B expressions (P>0.05). No significant differences were found in the mechanical withdrawal threshold or spinal NR2B expression between CCI group and indomethacin+CCI group (P>0.05). CONCLUSION: Parecoxib can alleviate neuropathic hypersensitivity in rats, but this effect may not be associated with NR2B expression in the spinal cord.

[Effect of electroacupuncture on pain threshold and spinal NR2B subunit expression in a rat model of neuropathic pain].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on pain threshold and spinal NR2B subunit expression in a rat model of neuropathic pain due to chronic compression injury (CCI) of the sciatic nerve and explore the analgesic mechanism of EA. METHODS: Male SD rats weighing 200-280 g were randomly divided into 4 groups (n=10), namely the sham-operated group, CCI group, EA+CCI group, and sham EA+CCI group. All the rats underwent tests of the mechanical withdrawal threshold and thermal threshold. On day 13 after the surgery, all the rats were decapitated to collect the L4-6 segments of the spinal cord to examine NR2B expression using Western blotting. RESULTS: The postoperative mechanical withdrawal threshold and thermal threshold were significantly lowered in CCI, EA+CCI and sham EA+CCI groups as compared to those before the surgery (P<0.05). EA obviously alleviated the hypersensitivity in the rats with CCI and inhibited spinal NR2B expressions (P<0.05). No significant differences were found in the mechanical withdrawal threshold, thermal threshold or spinal NR2B subunit expression between CCI group and sham EA+CCI group (P>0.05). CONCLUSION: EA may alleviate neuropathic hypersensitivity partially by inhibiting NR2B expression in the spinal cord of rats with neuropathic pain resulting from CCI of the sciatic nerve.