Objective To investigate the effects of the fibrin scaffold on the differentiation and the proliferation of neural stem cells and astrocytes. Methods Neural stem cells and the gliocytes derived from spinal cord were cultured in vitro respectively. The purified neural stem cells or gliocytes were seeded separately onto the fibrin scaffolds as experimental group and the glass slides modified with poly-L-lysine(PLL)as control group. At different time in culture the neural stem cells were immunofluorescence stained with antibodies against the marker of neurons I.e. Neurofilament(NF).The length of NF-positive neuritis was masured and the average value was calculated in the culture well (n=4). The gliocytes were immunofluorescence stained with antibodies against the marker of astrocytes I.e. Glial fibrillary acidic protein (GFAP ). The total number of the cells and the GFAP-positive cells were counted from 5 different fields of vision in the culture well (n=4), then the average ratio of GFAP-positive cells was calculated. The differentiation of neural stem cells, the extension of neurites and the proliferation of astrocytes on the fibrin scaffolds were compared with those on the slides. The protein of GFAP was detected by Western blotting to analyse the mature degree of astrocytes. All above experiments were repeated 3 times respectively. Results Immunofluorescence staining showed that the NF-positive neurites in the fibrin scaffold group were longer than those in the control group, whereas GFAP-positive cells were fewer than those in the control group. The expression of GFAP in the cells on the scaffold was lower than that in the control group.Conclusion The fibrin scaffold could promote differentiation of the neural stem cells to neurons and extension of the neurites. Meanwhile, the scaffold could inhibit proliferation and mature of the astrocytes.

OBJECTIVETo identify the tyrosinase inhibitory constituent quickly from Potentilla bifurca.

METHODThe active constituent was found through fraction collecting and tyrosinase inhibitory activity by bioassay-linked HPLC method.

RESULTThe methanol extracts and BuOH fraction of Potentilla bifurca showed strong tyrosinase inhibitory activities. From BuOH fraction of Potentilla bifurca, the tyrosinase inhibitory constituent was isolated and identified as flavonoid, quercetin-4'-O-beta-D-glucoside. It express stronger tyrosinase inhibition than the known tyrosinase inhibitor, kojic acid (IC50 = 0.28 mmol x L(-1)) with IC50 value of 0.001 9 mmol x L(-1).

CONCLUSIONBioassay-linked HPLC fractionation method was provided for determination the active constituents quickly from herbal medicines.

Enzyme Inhibitors ; chemistry ; isolation & purification ; Kinetics ; Peptides ; chemistry ; isolation & purification ; Plant Extracts ; chemistry ; isolation & purification ; Potentilla ; chemistry

Background The current increasing trend of new cases of occupational noise-induced deafness indicates that the hearing loss of occupational population has not been effectively controlled in China. It is of great significance to study the characteristics of hearing loss among noise-exposed workers and its related factors. Objective To investigate characteristics and influencing factors of hearing loss among occupational noise-exposed workers in a large machinery maintenance enterprise, and to provide a scientific basis to prevent and control noise-induced hearing loss. Methods A cross-sectional survey was conducted to investigate male Han occupational noise-exposed workers in a large mechanical maintenance enterprise. We acquired demographic characteristics, occupational exposure history, and individual life behavior characteristics of the workers through questionnaires, collected occupational exposure level data from annual occupational disease hazard factor surveillance reports, obtained pure tone hearing threshold test data through occupational health examinations, and estimated individual noise exposure levels using cumulative noise exposure (CNE). According to the results of pure tone air conduction hearing threshold test, the workers were divided into a hearing loss group and a normal hearing group. The chi-square test was employed to compare the occupational exposure characteristics and individual life behavior characteristics between the two groups. Additionally, the trend chi-square test was utilized to analyze the changing trends of age, length of service, CNE, and hearing loss rate within the two groups. The relationship between high-frequency hearing loss in both ears and its related influencing factors was assessed by a multiple logistic regression model. Results The M (P₂₅, P₇₅) of CNE for the 2531 occupational noise-exposed workers was 97.51 (95.39, 99.96) dB(A)·year. The incidence of hearing anomaly, binaural high-frequency hearing anomaly, random ear high-frequency hearing anomaly, binaural low-frequency hearing anomaly, and random ear low-frequency hearing anomaly were 22.48%, 16.59%, 22.13%, 2.77%, and 3.52%, respectively. High-frequency hearing threshold increase was the main reason for hearing anomaly (98.42%). In comparison to the CNE ≤ 97 dB(A)·year group, the 97 dB(A)·year100 dB(A)·year group experienced a 36.4% and 52.3% increase in the risk of bilateral high-frequency hearing loss, respectively. The smoking group exhibited a 43.5% elevated risk of bilateral high-frequency hearing loss when compared to the non-smoking group. Conversely, the group frequently wearing hearing protection equipment demonstrated a 23.6% lower risk of bilateral high-frequency hearing loss in comparison to the group occasionally wearing protective equipment. The data suggested that CNE＞97 dB(A)·year and smoking might be independent risk factors for bilateral high-frequency hearing loss, and frequently wearing hearing protection equipment might be an important protective factor. Conclusion Increased CNE and smoking can elevate the risk of high-frequency hearing loss, while personal hearing protection can effectively reduce the risk of hearing loss.