The discovery of the nerve growth factor(NGF),a specific protein material,by Rita Levi-Montalcini and her colleagues(1954)led to the observation that ifNGF is added to the culture medium,sympathetic and sensory neurons grow well inculture,for it is a potent and specific maintenance factor for these two types of neu-rons.Therefore,we chose the superior cervical ganglion(SCG)as a model systemfor nerve tissue culture in order to study the development,differentiation and rege-neration of nervous tissue in vitro.This report presents what we have observed onthe cultures of SCG that have been successfully established in our laboratory bymeans of explant technique.SCG from newborn rats were explanted onto collagen or plasma-coated coverslipsand maintained in Maximow depression slide assemblies at 37℃.The fluid me-dium was replaced twice a week and consisted of 1/3 calf serum,1/3 synthetic medium199 and 1/3 Hanks' BSS,or of equal parts of calf serum and Hanks' BSS,supplementedwith 600 mg% glucose.NGF(a crude extract of mouse salivary gland)was added tothe medium in a proportion of 1:20;for control,no NGF was added to the medium in some cultures.The cultures were examined microscopically every day,Nissl's stai-ned,Bodian's protargol and ammonium silver impregnated preparations were madeperiodically.Time lapse microcinematographic records were also made.We have planted altogether 209 SCG from newborn rats.All of them grew suc-cessfully in culture with NGF or without NGF,but the SCG with NGF grew muchmore rapidly than those without NGF.NGF strongly stimulates the outgrowth ofneurites and maintains the survival of the sympathetic neurons.Neurites grew outindividually or,more frequently,as bundles extending radially toward the peripheryor forming a meshwork.The tips of elongating neurites expanded to form growthcones from which are projected long slender microspikes(filopodia).These microspi-kes continually waved about,extending,and retracting as the growth cone movedover a substratum.The behavior of the growing tip of neurite is best analyzed bytime lapse microcinematography.The Schwann cells emerged from the explant andproliferate to accompany the neurites.These cells,fusiform or filiform in shape,were usually arranged in alignment along the neurites.They could be easily distingui-shed from fihroblasts.Mitosis of Schwann cells had been observed and recorded bytime lapse microcinematography.The bodies of the sympathetic neurons did not mig-rate away from the explant.

Objective To investigate the effects of benazepril on urinary excretion of endothelin 1(Et 1) and the level of plasmic Et 1 (PEt) in patients with diabetes mellitus (DM) and diabetic nephropathy(DN).Methods PEt and 24 hours urinary excretion of Et 1 (UEtV) in 54 patients with DM and 39 patients with DN before and after taking benazepril (7.5～12.5mg/d) for two months were measured using radioimmunoassay method.Results PEt and UEtV in patients with DM were significantly higher than in normal control group ( P

[Summary] The HK-2 cells with different culture media were divided into normal glucose group (NG group,5.5 mmol/L D-glucose) ; high glucose group (HG group,30 mmol/L D-glucose) ; mannitol group (MG group,5.5mmol/L D-glucose+24.5 mmol/L mannitol) ; 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] groups (V1-V3 group)which were exposed to medium containing 30 mmol/L D-glucose and different concentrations of 1,25-(OH)2D3 ;Nethyl-cysteim control group (NAC group,30 mmoL/L D-glucose + 1.0 mmol/L N-Nethyl-cysteim) ; and ethanol control group(SG group,30 mmol/L D-glucose+6.86 × 10-2 mol/L ethanol).The level of intracellular reactive oxygen species,mitochondrial membrane potential,activity of total-superoxide dismutase (T-SOD),level of malondialdehyde,expression of UCP2 mRNA and protein in HK-2 cells were detected.Compared with NG group,the mitochondrial membrane potential significantly decreased in HG group (P＜0.01),and the mitochondrial membrane potential in V group was lower than that in HG group(P＜0.01).The activity ofT-SOD in HG group was significantly lower than that in NG group(P＜0.01),while its level of malondialdehyde was significantly higher than that in NG group(P＜0.01).Compared with HG group,the activity of T-SOD in V groups was significantly increased (P＜0.05)and the level of malondialdehyde in these groups significantly decreased (P＜0.01).The mRNA expression of UCP2 in HG group was increased significantly in comparison with NG group (P ＜ 0.05) and the expression in V groups was significantly decreased in comparison with HG group (P＜0.01).The results suggest that 1,25-(OH)2D3 could reduce the mitochondrial membrane potential,the production of reactive oxygen species,and regulate the expression of UCP2 in order to suppress the oxidative stress induced by high glucose.

HK-2 cells cultured in vitro were divided into three groups: normal glucose group ( NG ), high glucose group( HG), and mannitol group(MG). The expression of angiotensin-converting enzyme( ACE ) and ACE2 mRNA in HK-2 cells was detected. The concentration of angiotensin Ⅱ ( Ang Ⅱ ) in the culture medium was detected. The mRNA and protein expression of ACE and ACE2 existed in normal cultured HK-2 ( NG group ). In comparison with NG group, the mRNA and protein expressions of ACE in HG group increased significantly ( P＜0. 01 ), and the expression of ACE2 mRNA decreased significantly( P＜0. 01 ). The level of Ang Ⅱ in HG group was significantly higher than in NG group( P＜0. 05 ). The result show that high glucose may induce ACE expression and inhibit ACE2 expression, then promote synthesis of Ang Ⅱ in proximal tubular cells.

The superior cervical ganglia (SCG) were dissected from neonatal rats.Dissoci-ated cell cultures were grown in Eagle's MEM supplemented with 20% calf serumwhich contain nerve growth factor (NGF).The cultures were divided into two groups:laser irradiation group and control.The former was exposed to lower dose of Helium-Neon laser (power:4 milliwatt)5 minutes every two hours.Two groups cultured for 20,22,24 and 28 hoursrespectively.Then the length of neurites of neurons were measured.At 22 hours,RNA and DNA synthesis of neurons labeled by ~3H-uridine and ~3H-thymidine wereobserved.The results showed that lower dose of Helium-Neon laser irradiation not onlypromotes growth of neurite but also enhances RNA synthesis of neurons in culture.However DNA synthesis in neurons does not promote in this experiment.

AIM: To investigate the effect of interleukin-13 (IL-13) on cell proliferation and interleukin-6 (IL-6) production in mesangial cells. METHODS: Cell proliferation was tested by MTT method. The protein synthesis of IL-6 in mesangial cells was measured by ELISA. The expression of IL-6 mRNA in mesangial cells was evaluated by RT-PCR. RESULTS: IL-13(1 ?g/L-100 ?g/L) inhibited the proliferation of mesangial cell in a dose-dependent manner. Both mRNA and protein of IL-6 in mesangial cells were increased significantly in the presence of LPS and this increase could be reversed by IL-13 (1?g/L-100?g/L). However, this increase could not be reversed by IL-13 if the dose was lower than 0.1?g/L and if the mesangial cells were cultured in 5% FCS RPMI1640. CONCLUSION: IL-13 could inhibit IL-6 expression induced by LPS in mesangial cells . We suggested that IL-13 may be an inhibitory cytokine in the regulation of the mesangial cell proliferaltion and inflammatory reaction in glomerulonephritis.

Objective:To explore the relationship between the binaural high-frequency mean hearing threshold and the hypertension of female workers exposed to noise, and to understand the application significance of the binaural high-frequency mean hearing threshold as an internal effect indicator of the risk of hypertension in female workers exposed to noise.Methods:From January to December 2018, a total of 20882 female workers exposed to noise in Guangzhou were selected by cluster sampling. Pure tone audiometry, blood pressure, age and length of service were collected. Trend test was used to evaluate the effects of exposure to noise and binaural high-frequency mean hearing threshold on blood pressure. Binary logistic regression model was used to evaluate the risk of hypertension associated with exposure to noise and binaural high-frequency mean hearing threshold.Results:The detection rate of normal hearing threshold, mild hearing loss and severe hearing loss was 80.73% (16858/20882) , 16.21% (3384/20882) and 3.06% (640/20882) respectively. The prevalence of hypertension was 6.04% (1018/16858) in normal hearing group, 10.28% (348/3384) in patients with high frequency mild hearing loss, and 11.25% (72/640) in patients with high frequency severe hearing loss. There was a linear relationship between the increase of working age and high-frequency mean hearing threshold and the increase of systolic and diastolic blood pressure ( P< 0.05) . Compared with those exposed to noise for less than 1 year, the risk of hypertension in female workers with 7-9 years and more than 9 years was decreased ( OR= 0.79, 0.75, P<0.05) . Compared with normal hearing group, the risk of hypertension in high frequency mild hearing loss group was increased ( OR=1.31, P<0.05) . Conclusion:The increase in the binaural high-frequency mean hearing threshold of female workers exposed to noise can increase the blood pressure level and the risk of hypertension, and attention should be paid to female workers with high-frequency mild hearing loss.

Objective:To investigate the epidemiological characteristics and late diagnosis of suspected occupational diseases in Guangzhou from 2006 to 2018.Methods:The cases of suspected occupational diseases reported in Guangzhou from January 1, 2006 to December 31, 2018 were collected and followed up to the end of 2018. The cases of suspected occupational diseases were analyzed statistically.Results:A total of 1502 suspected occupational cases were reported in Guangzhou from 2006 to 2018, including suspected occupational otorhinolaryngological and oral diseases (58.59%, 880/1502) , suspected occupational chronic poisoning (25.03%, 376/1502) and suspected occupational pneumoconiosis (11.72%, 176/1502) . The key reporting areas were Huangpu District (27.50%, 413/1502) and Panyu District (20.91%, 314/1502) . The key reporting industries were manufacturing industry (80.36%, 1207/1502) , among which railway, ship, aerospace and other transportation equipment manufacturing industry (13.26%, 160/1207) , automobile manufacturing industry (12.51%, 151/1207) and general equipment manufacturing industry (10.19%, 123/1207) were the main industries. The main type of reported economy was private economy (39.95%, 600/1502) . The scale of the key reporting enterprises was medium and small-sized enterprises (31.09%, 467/1502 and 34.62%, 520/1502) . As of December 31, 2018, 263 cases were diagnosed with occupational diseases, and the diagnosis rate was 17.51%.Conclusion:The number of suspected occupational diseases reported in Guangzhou from 2006 to 2018 is large, and the overall diagnosis rate of suspected occupational diseases is low. It is necessary to strengthen the supervision and management of key diseases, key regions, and key industries of suspected occupational diseases. It is suggested that the reporting system of suspected occupational diseases should be standardized as soon as possible.

Objective:To investigate the epidemiological characteristics and late diagnosis of suspected occupational diseases in Guangzhou from 2006 to 2018.Methods:The cases of suspected occupational diseases reported in Guangzhou from January 1, 2006 to December 31, 2018 were collected and followed up to the end of 2018. The cases of suspected occupational diseases were analyzed statistically.Results:A total of 1502 suspected occupational cases were reported in Guangzhou from 2006 to 2018, including suspected occupational otorhinolaryngological and oral diseases (58.59%, 880/1502) , suspected occupational chronic poisoning (25.03%, 376/1502) and suspected occupational pneumoconiosis (11.72%, 176/1502) . The key reporting areas were Huangpu District (27.50%, 413/1502) and Panyu District (20.91%, 314/1502) . The key reporting industries were manufacturing industry (80.36%, 1207/1502) , among which railway, ship, aerospace and other transportation equipment manufacturing industry (13.26%, 160/1207) , automobile manufacturing industry (12.51%, 151/1207) and general equipment manufacturing industry (10.19%, 123/1207) were the main industries. The main type of reported economy was private economy (39.95%, 600/1502) . The scale of the key reporting enterprises was medium and small-sized enterprises (31.09%, 467/1502 and 34.62%, 520/1502) . As of December 31, 2018, 263 cases were diagnosed with occupational diseases, and the diagnosis rate was 17.51%.Conclusion:The number of suspected occupational diseases reported in Guangzhou from 2006 to 2018 is large, and the overall diagnosis rate of suspected occupational diseases is low. It is necessary to strengthen the supervision and management of key diseases, key regions, and key industries of suspected occupational diseases. It is suggested that the reporting system of suspected occupational diseases should be standardized as soon as possible.

Objective:To explore the relationship between the binaural high-frequency mean hearing threshold and the hypertension of female workers exposed to noise, and to understand the application significance of the binaural high-frequency mean hearing threshold as an internal effect indicator of the risk of hypertension in female workers exposed to noise.Methods:From January to December 2018, a total of 20882 female workers exposed to noise in Guangzhou were selected by cluster sampling. Pure tone audiometry, blood pressure, age and length of service were collected. Trend test was used to evaluate the effects of exposure to noise and binaural high-frequency mean hearing threshold on blood pressure. Binary logistic regression model was used to evaluate the risk of hypertension associated with exposure to noise and binaural high-frequency mean hearing threshold.Results:The detection rate of normal hearing threshold, mild hearing loss and severe hearing loss was 80.73% (16858/20882) , 16.21% (3384/20882) and 3.06% (640/20882) respectively. The prevalence of hypertension was 6.04% (1018/16858) in normal hearing group, 10.28% (348/3384) in patients with high frequency mild hearing loss, and 11.25% (72/640) in patients with high frequency severe hearing loss. There was a linear relationship between the increase of working age and high-frequency mean hearing threshold and the increase of systolic and diastolic blood pressure ( P< 0.05) . Compared with those exposed to noise for less than 1 year, the risk of hypertension in female workers with 7-9 years and more than 9 years was decreased ( OR= 0.79, 0.75, P<0.05) . Compared with normal hearing group, the risk of hypertension in high frequency mild hearing loss group was increased ( OR=1.31, P<0.05) . Conclusion:The increase in the binaural high-frequency mean hearing threshold of female workers exposed to noise can increase the blood pressure level and the risk of hypertension, and attention should be paid to female workers with high-frequency mild hearing loss.