[Fluorescence peak shift corresponding to high chlorophyll concentrations in inland water].

Hyperspectral remote sensing offers the potential to detect water quality variables such as Chl-a by using narrow spectral channels of less than 10 nm, which could otherwise be masked by broadband satellites such as Landsat TM. Fluorescence peak of the red region is very important for the remote sensing of inland and coastal waters, which is unique to phytoplankton Chl-a that takes place in this region. Based on in situ water sampling and field spectral measurement from 2004 to 2006 in Nanhu Lake, the features of the spectral reflectance were analyzed in detail with peak position shift. The results showed: An exponential fitting model, peak position = a(Chl-a)b, was developed between chlorophyll-a concentration and fluorescence peak shift, where a varies between 686.11 and 686.29, while b between 0.0062 and 0.0065. It was found that the better the spectral resolution, the higher the precision of the model. Except that, the average of peak shift showed a high correlation with the average of different Chl-a grades, and the determination coefficient (R2) was higher than 0.81. It contributed significantly to the increase in the accuracy of the derivation of chlorophyll values from remote sensing data in Nanhu Lake. There is satisfactory correspondence between hyperspectral models and chl-a concentration, therefore, it is possible to monitor the water quality of Nanhu lake throngh the hyperspetral remote sensing data.

[Bio-optical model of total suspended matter based on reflectance in the near infrared wave band for case-II waters].

From August to October, 2006, reflectance spectra were measured in a turbid Case-Il waters condition with an ASD FieldSpec spectrometer for a total of 58 samples. Based on the observation of reflectance curves, spectral analysis was carried out over 400-1200 nm. Showing the typical character of Case-II waters, the reflectance values were generally higher than those in other similar studies. Strong backscattering of high concentration total suspended matter (TSM) contributed considerably to the total reflectance spectra in water. Two obvious TSM reflectance peaks were observed in the near infrared wave bands, i.e., 808 and 1067 nm, especially the latter one that was never reported before. The highest correlation coefficient between reflectance and concentrations of TSM existed at 873 nm. Based on the simplification of water inherent optical parameters in the near-infrared wave band, including absorption of TSM, Chlorophyll-a (Chl-a) and chromophoric dissolved organic matter (CDOM), and backscattering of pure water, Chl-a and CDOM, three empirical equations of the bio-optical model using reflectance at 808, 873 and 1067 nm respectively were established to estimate the concentrations of TSM. Compared with linear and exponential models, the bio-optical model showed fairly good performance with comparatively high determination coefficient (r2) and low root mean squared error (RMSE), which confirmed the applicability of the bio-optical model to retrieve concentrations of TSM effectively in turbid Case-II waters.

Differentiation of isolated human umbilical cord mesenchymal stem cells into neural stem cells.

AIM: To investigate whether umbilical cord human mesenchymal stem cell (UC-MSC) was able to differentiate into neural stem cell and neuron in vitro. METHODS: The umbilical cords were obtained from pregnant women with their written consent and the approval of the Clinic Ethnics Committee. UC-MSC were isolated by adherent culture in the medium contains 20% fetal bovine serum (FBS), then they were maintained in the medium contain 10% FBS and induced to neural cells in neural differentiation medium. We investigated whether UC-MSC was able to differentiate into neural stem cell and neuron in vitro by using flow cytometry, reverse transcriptase-polymerase chain reaction (RT-PCR) and immunofluorescence (IF) analyzes. RESULTS: A substantial number of UC-MSC was harvested using the tissue explants adherent method at about 2wk. Flow cytometric study revealed that these cells expressed common markers of MSCs, such as CD105 (SH2), CD73 (SH3) and CD90. After induction of differentiation of neural stem cells, the cells began to form clusters; RT-PCR and IF showed that the neuron specific enolase (NSE) and neurogenic differentiation 1-positive cells reached 87.3%±14.7% and 72.6%±11.8%, respectively. Cells showed neuronal cell differentiation after induced, including neuron-like protrusions, plump cell body, obviously and stronger refraction. RT-PCR and IF analysis showed that microtubule-associated protein 2 (MAP2) and nuclear factor-M-positive cells reached 43.1%±10.3% and 69.4%±19.5%, respectively. CONCLUSION: Human umbilical cord derived MSCs can be cultured and proliferated in vitro and differentiate into neural stem cells, which may be a valuable source for cell therapy of neurodegenerative eye diseases.

Visual function and vision-related quality of life after vitrectomy for idiopathic macular hole: a 12mo follow-up study.

AIM: To investigate the visual function and the relationship with vision-related quality of life (VRQOL) after macular hole repair surgery. METHODS: Prospective case series. Thirty-six consecutive eyes in 36 patients who underwent pars plana vitrectomy (PPV) and internal limiting membrane (ILM) peeling were included. The 25-item National Eye Institute Visual Function Questionnaire (VFQ-25) was answered by the participants before and 3 and 12mo after operation. Follow-up visits examinations included best-corrected visual acuity (BCVA), clinical examination, and central macular thickness (CMT) measured by optical coherence tomography (OCT). RESULTS: Macular-hole closure was achieved in 35 of 36 eyes (97.2%). At baseline and months 3 and 12, the logMAR BCVAs (mean±SD) were 1.15±0.47, 0.68±0.53 (P<0.0001 versus baseline), and 0.55±0.49 (P<0.001 versus baseline, P =0.273 versus month 3), respectively; the CMTs (µm) were 330±81, 244±62 (P<0.001 versus baseline), and 225±58 (P<0.001 versus baseline, P=0.222 versus month 3), respectively; the median preoperative VFQ-25 composite score of 73.50 (63.92-81.13) increased postoperatively to 85.50 (80.04-89.63) at 3mo (P<0.001) and 86.73(82.50-89.63) at 12mo (P<0.001) respectively. The improved BCVA was correlated with improvements in five subscales (r=-0.605 to -0.336, P<0.001 to P=0.046) at 12mo. CONCLUSION: PPV with ILM peeling improved anatomic outcome, visual function, and VRQOL. The improved BCVA was an important factor related to the improved VRQOL.

A comparative study on the transplantation of different concentrations of human umbilical mesenchymal cells into diabetic rats.

AIM: To observe the effects of intravitreal injections of different concentrations of human umbilical mesenchymal stem cells on retinopathy in rats with diabetes mellitus. METHODS: Healthy and adult male Sprague-Dawley (SD) rats were randomly assigned to a normal control group (group A), a diabetic retinopathy (DR) blank control group (group B), a high-concentration transplantation group (group C), a low-concentration transplantation group (group D) and a placebo transplantation group (group E). The expression of nerve growth factor (NGF) protein in the retinal layers was detected by immunohistochemical staining at 2, 4, 6 and 8wk. RESULTS: The expression of NGF was positive in group A and most positive in the retinal ganglion cell layer. In groups B and E, the expression of NGF was positive 2wk after transplantation and showed an increase in all layers. However, the level of expression had decreased in all layers at 4wk and was significantly reduced at 8wk. In groups C and D, the expression of NGF had increased at 2wk and continued to increase up to 8wk. The level of expression in group C was much higher than that in group D. CONCLUSION: DR can be improved by intravitreal injection of human umbilical mesenchymal stem cells. High concentrations of human umbilical mesenchymal stem cells confer a better protective effect on DR than low concentrations.

[Vertical distribution of water quality and its influence on underwater light field in Lake Chaohu].

There are few reports on the vertical distribution of water quality and its influence on underwater light field. In our study, we analyzed the vertical distribution of water quality based on the in situ data in Lake Chaohu, and studied their influence on diffuse attenuation coefficients of downwelling irradiance Kd via Hydrolight simulation. It was indicated that the suspended matter and colored dissolved organic matter (CDOM) were relatively vertical-uniform in Lake Chaohu; excluding algae scums at the surface, the vertical profiles of chlorophyll-a conformed to Gaussian distribution; the complex Kd in vertical was affected by chlorophyll-a and inorganic suspended matter. The analysis on vertical distributions of water quality and its influence on Kd could be the basis for further studying the influence of algae vertical heterogeneity on underwater light field in Case II waters.

[Estimation of DOC concentrations using CDOM absorption coefficients: a case study in Taihu Lake].

Dissolved organic carbon (DOC) is the largest organic carbon stock in water ecosystems, which plays an important role in the carbon cycle in water. Chromophoric dissolved organic matter (CDOM), an important water color variation, is the colored fraction of DOC and its absorption controls the instruction of light under water. The available linkage between DOC concentration and CDOM absorptions enables the determination of DOC accumulations using remote sensing reflectance or radiance in lake waters. The present study explored the multi-liner relationship between CDOM absorptions [a(g) (250) and a(g) (365)] and DOC concentrations in Taihu Lake, based on the available data in 4 cruises (201005, 201101, 201103, 201105) (totally 183 sampling sites). Meanwhile, the results were validated with the data of the experiment carried out from August 29 to September 2, 2011 in Taihu Lake (n = 27). Furthermore, a universal pattern of modeling from remote sensing was built for lake waters. The results demonstrated that this method provided more satisfying estimation of DOC concentrations in Taihu Lake. Except the data obtained in January 2011, the fitted results of which were not conductive to the winter dataset (201101) in Taihu Lake, due to the diverse sources and sinks of DOC and CDOM, the multi-liner relationship was robust for the data collected in the other three cruises (R2 = 0.64, RMSE = 14.31%, n = 164), which was validated using the 201108 sampling dataset (R2 = 0.67, RMSE = 10.58%, n = 27). In addition, the form of the statistic model is universal, to some extent, for other water areas, however, there is difference in the modeling coefficients. Further research should be focused on the parameterization using local data from different lakes, which provides effective methodology for the estimation of DOC concentrations in lakes and other water regions.

[Aerosol optical thickness of the atmospheric aerosol over Taihu Lake and its features: results of in-site measurements].

Based on the data measured in situ by an automatic sun tracking photometer (CE-318), the aerosol optical thickness (AOT) and the corresponding Angström coefficient alpha of the atmospheric aerosol over Taihu Lake from November 2005 to October 2010 were collected. The results showed that high values of AOT over Taihu Lake were measured in summer (June to July) whereas low values were detected in autumn and winter (October to January). However, the low and high values of a appeared in spring (March to April) and in autumn (September to November), respectively. The variations of AOT and a over Taihu Lake may be related to weather patterns in this region. Based on the frequency distribution, AOT (500 nm) had only one peak value, with a maximum frequency of 0.4-0.6 and a yearly average value of 0.80, accounting for 26% of the total sample. Calculated from the mean AOT (500 nm), the solar radiation reduction was reduced by at least 50% by the atmospheric aerosol, resulting in more turbid atmosphere in this region and consequently heavy fog and haze. There were two peak values of the Angström coefficient alpha, with the maximum frequency ranging from 1.1-1.3 and 1.3-1.5 and a yearly average value of 1.17, accounting for 30% of the total sample. Significant variations were also observed in the daily average values of AOT (500 nm) and a, indicating the coexistence of different types of aerosols over Taihu Lake. The mean value of AOT (500 nm) declined when a increased. To sum up, values of AOT (500 nm) over Taihu Lake changed greatly with time, and the aerosol should be classified as an urban-industrial aerosol.