MicroRNA-135a participates in the development of astrocytes derived from bacterial meningitis by downregulating HIF-1α.

Accumulating evidence has highlighted the potential of microRNAs (miRs) as biomarkers in various human diseases. However, the roles of miRs in bacterial meningitis (BM), a severe infectious condition, still remain unclear. Thus, the present study aimed to investigate the effects of miR-135a on proliferation and apoptosis of astrocytes in BM. Neonatal rats were injected with Streptococcus pneumoniae to establish the BM model. The expression of miR-135a and hypoxia-inducible factor 1α (HIF-1α) in the BM rat models were characterized, followed by determination of their interaction. Using gain- and loss-of-function approaches, the effects of miR-135a on proliferation, apoptosis, and expression of glial fibrillary acidic protein (GFAP), in addition to apoptosis-related factors in astrocytes were examined accordingly. The regulatory effect of HIF-1α was also determined along with the overexpression or knockdown of HIF-1α. The results obtained indicated that miR-135a was poorly expressed, whereas HIF-1α was highly expressed in the BM rat models. In addition, restored expression levels of miR-135a were determined to promote proliferation while inhibiting the apoptosis of astrocytes, along with downregulated Bax and Bad, as well as upregulated Bcl-2, Bcl-XL, and GFAP. As a target gene of miR-135a, HIF-1α expression was determined to be diminished by miR-135a. The upregulation of HIF-1α reversed the miR-135a-induced proliferation of astrocytes. Taken together, the key findings of the current study present evidence suggesting that miR-135a can downregulate HIF-1α and play a contributory role in the development of astrocytes derived from BM, providing a novel theoretical perspective for BM treatment approaches.

Effects of dexamethasone on aquaporin-4 expression in brain tissue of rat with bacterial meningitis.

Aquaporin-4 (AQP4) is the most popular water channel protein expressed in brain tissue and plays a very important role in regulating the water balance in and outside of brain parenchyma. To investigate the expression of aquaporin-4 in the rat brain tissue after dexamethasone therapy of meningitis induced by Streptococcus pneumonia, total 40 of 3-week old Sprague-Dawley rats were divided into infection group (n=30) and normal control group (n=10). The meningitis groups were infected with 1×10(7) cfu/ml of Streptococcus pneumoniae and then randomized into no treatment (untreated group, n=10), treatment with ceftriaxone (CTRX group, n=10) and treatment with dexamethasone combined ceftriaxone (CTRX+DEXA group, n=10). The normal control group was established by using saline. The rats were euthanized when they reached terminal illness or five days after infection, followed by detection of AQP4 through using immunohistochemistry and Western blot methods. Data has showed that expression of AQP4 in model group remained higher than the control and treatment group (P<0.05). AQP4 expression in CTRX+DEXA group was lower than that in CTRX group (P<0.05). There was no statistical difference between CTRX+DEXA group and the control group (P>0.05). These data suggested that Dexamethasone could down-regulate the expression of AQP4 in the brain tissue of rats with meningitis and provides evidence for the mechanism of protective effect of Dexamethasone on central neurosystem.

[NMDAR expression in the cochlear nucleus and hearing damage in neonatal rats with hyperbilirubinemia].

OBJECTIVE: To study the role of N-methyl-D-aspartate-receptor (NMDAR) expression in the development of hearing damage in neonatal rats with hyperbilirubinemia. METHODS: Sixty seven-day-old Sprague-Dawley rats were randomly injected with bilirubin of 100 microg/g (low-dose treatment group) or 200 microg/g (high-dose treatment group) or normal saline (control group). Auditory brainstem response (ABR) was examined. The concentrations of bilirubin in blood and brain were measured. NMDAR expression in the cochlear nucleus slices was examined by immunohistochemistry assay. RESULTS: ABR reflecting threshold obviously increased, and I, II and III wave latency as well as I-II, II-III and I-III interval were more prolonged in the two bilirubin treatment groups when compared with the control group. The NMDAR expression in the cochlear nucleuse in the two bilirubin treatment groups was obviously lower than that in the control group. The NMDAR expression in the cochlear nucleuse was negatively correlated with the brain bilirubin content and the ABR reflecting threshold in the two bilirubin treatment groups. CONCLUSIONS: An increased NMDAR activity may play an important role in hearing damage following hyperbilirubinemia.

[Miniature quadrupole mass spectrometer array and its applications in manned spaceflight].

This paper explained the working method of the quadrupole mass spectrometer array and its features of volume, weight, power, sensitivity to many kinds of gases as well as flexibility when used together with a miniature gas chromatograph (GC) and a thermal-conductivity detector (TCD). Three types of structure formed in its development are also described. Finally, the applications of the quadrupole mass spectrometer array in the field of manned spaceflight were summarized.