[Comparison of nucleic acid detection methods in pharyngeal swabs of Mycoplasma pneumoniae infection in children]

Objective: To explore the value of nucleic acid detection methods in pharyngeal swabs in the etiological diagnosis of Mycoplasma pneumoniae (MP) infection in children. Methods: Four hundred and fifty-four (male 210, female 244) children with pneumonia in Department of Pulmonology, Children's Hospital of Zhejiang University School of Medicine were enrolled from July, 2018 to October, 2018. Pharyngeal swabs and venous blood were obtained on the first or the second day after hospitalization. Fluorescence detection quantitative amplification of DNA, thermostatic amplification of RNA, MP culture and MP-IgM were used to detect MP simultaneously. MP infection is diagnosed if MP culture is positive or the two of the other three methods are positive. Pharyngeal swabs were acquired and detected using fluorescence quantitative amplification of DNA, thermostatic amplification of RNA and MP culture again for children with confirmed MP infection before discharge. The detection rates and quantitative changes of the three methods were compared, and χ(2) test was used for comparison among groups. Results: A total of 454 hospitalized children with pneumonia were included in this study. The detection rates of fluorescence quantitative amplification of DNA, thermostatic amplification of RNA, MP culture and MP-IgM IgM were 43.6% (198/454), 43.2% (196/454), 40.0% (180/454) and 30.6% (139/454) respectively. The difference of detection rates of the four methods was statistically significant (χ(2)=20.8, P<0.05),but no significant difference between the detection rates of fluorescence quantitative amplification of DNA and thermostatic amplification of RNA was found (χ(2)=0.018, P=0.900). They both had higher detection rates than MP-IgM or MP culture. MP infection is diagnosed if MP culture is positive or the two of the other three methods are positive, and two hundred and nine children were diagnosed as MP infection. In the second test of MP infection in 209 children before discharge, the positive rate of MP culture was 67.5% (141/209), with 39.4% (13/33) changed from negative to positive, and 27.3% (48/176) changed from positive to negative. The positive rate of thermostatic amplification of RNA was 82.3% (172/209), with 16.2% (31/191) turned from positive to negative, and 66.7% (12/18) turned from negative to positive. The positive rate of fluorescence quantitative amplification of DNA was 67.0% (140/209), with 52.9% (18/34) cases changed from negative to positive, and 30.3% (53/175) cases changed from positive to negative. MP-DNA load decreased in 141 cases (67.5%) and increased in 68 cases (32.5%) in the second test among the positive samples tested by fluorescence quantitative amplification of DNA. The detection rates of the four methods in the non-severe group and the severe group were similar, and the differences among the groups were not statistically significant (all P>0.05). In the second test, the proportion of changing from negative to positive in the severe group was higher than that in the non-severe group, but only the difference in the thermostatic amplification of RNA was statistically significant (P=0.038) and the cases of changing from negative to positive of thermostatic amplification of RNA in the severe group and non-severe group are 7 and 5 respectively. Conclusions: The methods of pharyngeal swab nucleic acid detection have high sensitivity and application value in the etiological diagnosis of acute MP infection in children. The results of fluorescence quantitative amplification of DNA and thermostatic amplification of RNA are highly consistent, and they are both more advantageous than MP-IgM. Repeated testing in the acute phase is helpful to find MP infection children whose first test is negative. The load of MP-DNA did not decrease in some children in the acute stage after antibiotic treatment.

Aβ40 modulates GABA(A) receptor α6 subunit expression and rat cerebellar granule neuron maturation through the ERK/mTOR pathway

In addition to their neurotoxic role in Alzheimer's disease (AD), β-amyloid peptides (Aβs) are also known to play physiological roles. Here, we show that recombinant Aβ40 significantly increased the outward current of the GABA(A) receptor containing (GABA(A)α6) in rat cerebellar granule neurons (CGNs). The Aβ40-mediated increase in GABA(A)α6 current was mediated by an increase in GABA(A)α6 protein expression at the translational rather than the transcriptional level. The exposure of CGNs to Aβ40 markedly induced the phosphorylation of ERK (pERK) and mammalian target of rapamycin (pmTOR). The increase in GABA(A)α6 current and expression was attenuated by specific inhibitors of ERK or mTOR, suggesting that the ERK and mTOR signaling pathways are required for the effect of Aβ40 on GABA(A)α6 current and expression in CGNs. A pharmacological blockade of the p75 neurotrophin receptor (p75(NTR)), but not the insulin or α7-nAChR receptors, abrogated the effect of Aβ40 on GABA(A)α6 protein expression and current. Furthermore, the expression of GABA(A)α6 was lower in CGNs from APP(-/-) mice than in CGNs from wild-type mice. Moreover, the internal granule layer (IGL) in APP(-/-) mice was thinner than the IGL in wild-type mice. The injection of Aβ40 into the cerebellum reversed this effect, and the application of p75(NTR) blocking antibody abolished the effects of Aβ40 on cerebellum morphology in APP(-/-) mice. Our results suggest that low concentrations of Aβ40 play a role in regulating CGN maturation through p75(NTR).

Exposure to extremely low-frequency electromagnetic fields modulates Na+ currents in rat cerebellar granule cells through increase of AA/PGE2 and EP receptor-mediated cAMP/PKA pathway

Although the modulation of Ca²⁺ channel activity by extremely low-frequency electromagnetic fields (ELF-EMF) has been studied previously, few reports have addressed the effects of such fields on the activity of voltage-activated Na⁺ channels (Na_v). Here, we investigated the effects of ELF-EMF on Na_v activity in rat cerebellar granule cells (GCs). Our results reveal that exposing cerebellar GCs to ELF-EMF for 10–60 min significantly increased Na_v currents (I_Na) by 30–125% in a time- and intensity-dependent manner. The Na_v channel steady-state activation curve, but not the steady-state inactivation curve, was significantly shifted (by 5.2 mV) towards hyperpolarization by ELF-EMF stimulation. This phenomenon is similar to the effect of intracellular application of arachidonic acid (AA) and prostaglandin E₂ (PGE₂) on I_Na in cerebellar GCs. Increases in intracellular AA, PGE₂ and phosphorylated PKA levels in cerebellar GCs were observed following ELF-EMF exposure. Western blottings indicated that the Na_V 1.2 protein on the cerebellar GCs membrane was increased, the total expression levels of Na_V 1.2 protein were not affected after exposure to ELF-EMF. Cyclooxygenase inhibitors and PGE₂ receptor (EP) antagonists were able to eliminate this ELF-EMF-induced increase in phosphorylated PKA and I_Na. In addition, ELF-EMF exposure significantly enhanced the activity of PLA₂ in cerebellar GCs but did not affect COX-1 or COX-2 activity. Together, these data demonstrate for the first time that neuronal I_Na is significantly increased by ELF-EMF exposure via a cPLA2 AA PGE₂ EP receptors PKA signaling pathway.

Neuritin activates insulin receptor pathway to up-regulate Kv4.2-mediated transient outward K+ current in rat cerebellar granule neurons

Neuritin is a new neurotrophic factor discovered in a screen to identify genes involved in activity-dependent synaptic plasticity. Neuritin also plays multiple roles in the process of neural development and synaptic plasticity. The receptors for binding neuritin and its downstream signaling effectors, however, remain unclear. Here, we report that neuritin specifically increases the densities of transient outward K(+) currents (I(A)) in rat cerebellar granule neurons (CGNs) in a time- and concentration-dependent manner. Neuritin-induced amplification of I(A) is mediated by increased mRNA and protein expression of Kv4.2, the main α-subunit of I(A). Exposure of CGNs to neuritin markedly induces phosphorylation of ERK (pERK), Akt (pAkt), and mammalian target of rapamycin (pmTOR). Neuritin-induced I(A) and increased expression of Kv4.2 are attenuated by ERK, Akt, or mTOR inhibitors. Unexpectedly, pharmacological blockade of insulin receptor, but not the insulin-like growth factor 1 receptor, abrogates the effect of neuritin on I(A) amplification and Kv4.2 induction. Indeed, neuritin activates downstream signaling effectors of the insulin receptor in CGNs and HeLa. Our data reveal, for the first time, an unanticipated role of the insulin receptor in previously unrecognized neuritin-mediated signaling.

Amoxapine inhibits the delayed rectifier outward K+ current in mouse cortical neurons via cAMP/protein kinase A pathways

Ion channels are known to be modulated by antidepressant drugs, but the molecular mechanisms are not known. We have shown that the antidepressant drug amoxapine suppresses rectifier outward K(+) (I(K)) currents in mouse cortical neurons. At a concentration of 10 to 500 muM, amoxapine reversibly inhibited I(K) in a dose-dependent manner and modulated both steady-state activation and inactivation properties. The application of forskolin or dibutyryl cAMP mimicked the inhibitory effect of amoxapine on I(K) and abolished further inhibition by amoxapine. N-[2-(p-Bromocinnamylamino)ethyl]-5-iso-quinolinesulphonamide (H-89), a protein kinase A (PKA) inhibitor, augmented I(K) amplitudes and completely eliminated amoxapine inhibition of I(K). Amoxapine was also found to significantly increase intracellular cAMP levels. The effects of amoxapine on I(K) were abolished by preincubation with 5-hydroxytryptamine (5-HT) and the antagonists of 5-HT(2) receptor. Moreover, intracellular application of guanosine 5'-[gammathio]-triphosphate increased I(K) amplitudes and prevented amoxapine-induced inhibition. The selective Kv2.1 subunit blocker Jingzhaotoxin-III reduced I(K) amplitudes by 30% and also significantly abolished the inhibitory effect of amoxapine. Together these results suggest that amoxapine inhibits I(K) in mouse cortical neurons by cAMP/PKA-dependent pathway associated with the 5-HT receptor, and suggest that the Kv2.1 alpha-subunit may be the target for this inhibition.

[Therapeutic effects of aerosolized signal transducer and activator of transcription 1 antisense oligonucleotide administered at different time points on bleomycin-induced pulmonary fibrosis: experiment with rats]

OBJECTIVE

To investigate the curative effects of inhaling signal transducer and activator of transcription 1 (STAT1) antisense oligonucleotide (ASON) on alveolitis and pulmonary fibrosis and the best administration time.

METHODS

Twenty-five adult female Wistar rats were randomly divided into 5 equal groups: BLM group, undergoing intra-tracheal perfusion of BLM so as to establish animal models of alveolitis and pulmonary fibrosis and then inhaling aerosolized normal saline (NS); NS group undergoing intra-tracheal perfusion of NS and then inhaling aerosolized NS; ASON 0 d group, undergoing intra-tracheal perfusion of BLM and then inhaling aerosolized STAT1 ASON 3 ml immediately; ASON 7 d group, undergoing intra-tracheal perfusion of BLM and then inhaling STAT1 ASON 3 ml 7 days later; and ASON 14 d group undergoing intra-tracheal perfusion of BLM and then inhaling aerosolized STAT1 ASON 3 ml 14 days later. Aerosolized inhalation was repeated once every other day for 4 times. Twenty-eight days after intra-tracheal perfusion the rats were sacrificed with their lungs taken out to undergo pathological examination. NS was infused into the right lungs to get bronchoalveolar lavage fluid (BALF). ELISA was used to examine the concentrations of transforming growth factor-beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha) in the BALF.

RESULTS

The pathology result of the lung tissues showed that compared with the BLM and ASON 14 d groups, the alveolitis and pulmonary fibrosis of the ASON 0 d group were obviously milder. The scores of alveolitis and pulmonary fibrosis of the ASON 0 d group were (1.80 +/- 0.84) and (2.60 +/- 0.55) respectively, both significantly lower than those of the BLM group [(2.40 +/- 0.55) and (4.40 +/- 0.55) respectively] and those of the ASON 7 d group [(2.20 +/- 0.45) and (3.00 +/- 0.71) respectively] (all P < 0.05). The scores of pulmonary fibrosis of the ASON 7 d group was significantly lower than those of the BLM and ASON 14 d groups (both P < 0.05). The concentrations of TGF-beta and TNF-alpha in BALF of the ASON 0 d group were (48.11 +/- 3.46) pg/ml and (1.93 +/- 0.14) ng/ml respectively, both significantly lower than those of the BLM group [(57.67 +/- 2.46) pg/ml and (2.45 +/- 0.25) ng/ml respectively, both P < 0.05]. The concentration of TGF-beta in BALF of the ASON 0 d group was significantly lower than those of the ASON 7 d and ASON 14 d groups [(51.42 +/- 3.57) pg/ml and (55.8 3 +/- 1.79) pg/ml respectively, both P < 0.05]. The concentration of TGF-beta in BALF of the ASON7 d group was significantly lower than those of the BLM and ASON 14 d groups (both P < 0.05).

CONCLUSIONS

STAT1 ASON administered in the early stage helps depress the pulmonary fibrosis procedure, and the earlier the drug is administrated the better effect would be obtained. Aerosolized STAT1 ASON can be used as a therapeutic method for pulmonary fibrosis.

Sensitive fluorimetric determination of formaldehyde by the co-quenching effect of formaldehyde and sulfite on the fluorescence of tetra-substituted amino aluminium phthalocyanine

A novel and sensitive fluorimetric method was developed for the determination of formaldehyde based on the co-quenching effect of formaldehyde and sulfite on the fluorescence of tetra-substituted amino aluminium phthalocyanine. Formaldehyde in the concentration range 0.040-1.19 micrograms ml-1 can be determined with a limit of detection of 7.5 ng ml-1. The relative standard deviation for nine replicate measurements of 80.0 ng ml-1 formaldehyde is 1.8%. The method was applied to the analysis of real samples with satisfactory results.