Biomedical subjects
Publications and source records attributed to Y S Li.
The resting cells of a new isolate of Rhodococcus erythropolis FSD-2 were used to desulfurize diesel fuels. About 97% of the total sulfur content in the hydrodesulfurized diesel was removed by the two consecutive biodesulfurization (BDS) processes with the majority ( approximately 94%) being removed in the first treatment, resulting in diesel with a sulfur content of 5.7 microg ml(-1).
Hepatosplenic measurements among 550 Chinese subjects, aged 3-59 years from Yueyang city--a nonendemic area for schistosomiasis in Hunan province, China--were performed to define normal ranges of ultrasound organometry for assessing hepatosplenic morbidity in Schistosoma japonicum infection. Measurements included the size of the liver (left lobe and right lobe), the main portal vein stem, the peripheral periportal vein branches, and spleen length and thickness. The results document the significant relationship between body height and organometric parameters. The reference values stratified by body height improve the accuracy of assessment. Thus, height-based normal ranges established in this study can be applied in hospital routine and in field studies of patients infected with S. japonicum in Hunan province and in other endemic areas of China.
The rapid economic development in the Pearl River Delta (PRD) region in South China in the last three decades has had a significant impact on the local environment. Estuarine sediment is a major sink for contaminants and nutrients in the surrounding ecosystem. The accumulation of trace metals in sediments may cause serious environmental problems in the aquatic system. Thirty sediment cores were collected in the Pearl River Estuary (PRE) in 2000 for a study on trace metal pollution in this region. Heavy metal concentrations and Pb isotopic compositions in the four 210Pb-dated sediment cores were determined to assess the fluxes in metal deposits over the last one hundred years. The concentrations of Cu, Pb and Zn in the surface sediment layers were generally elevated when compared with the sub-surface layers. There has been a significant increase in inputs of Cu, Pb and Zn in the PRE since the 1970s. The results also showed that different sampling locations in the estuary received slightly different types of inputs. Pb isotopic composition data indicated that the increased Pb in the recent sediments was of anthropogenic origin. The results of trace metal influxes showed that about 30% of total Pb and 15% of total Zn in the sediments in the 1990s were from anthropogenic sources. The combination of trace metal analysis, Pb isotopic composition and 210Pb dating in an estuary can provide vital information on the long-term accumulation of metals in sediments.
The formation and dynamics of turbidity maxima (TM) in the Pearl River estuary (PRE) are not well understood but the existence of TM in the estuary have great potential engineering and environmental impacts. Based on the measurements of two large-scale field surveys conducted in the wet season of 1978 (July of 1978) and the dry season of 1979 (March of 1979), the existence and seasonal variations of TM in the PRE focusing on the two major natural navigation channels have been studied. The sediment transport fluxes over two consecutive tidal cycles have been analyzed in detail. The analysis results reveal that the formation mechanisms of TM in the estuary are rather complex. In general, gravitational circulation, tidal trapping, and sediment resuspension and deposition processes are the primary TM formation mechanisms in the PRE. The clockwise back flow pattern around Lingding Island also leads to the formation of TM in the West channel of the PRE. The occurrence of TM far upstream of the salt water wedge is the result of the complex hydrodynamic and sediment transport processes generated by the runoff of the major rivers.
This study evaluated the dissolution behavior of basic oxygen furnace slag (BOF slag) and the performance of H2O2 with BOF slag denoted as H2O2/BOF slag process to degrade polyethylene glycol (PEG) in the aqueous solution. The concentration of total organic carbon (TOC) was chosen as a mineralization index of the degradation of PEG by the H2O2/BOF slag process. A first-order kinetic model with respect to TOC was adopted to represent the mineralization of PEG by H2O2/BOF slag process. The experimental results in this study suggested that dosages with 3.98 x 10(-4) mole min(-1) l(-1) H2O2 and 15 g l(-1) BOF slag loading in the solution at pH 2 provided the optimal operation conditions for the mineralization of PEG yielding a 75.5% treatment efficiency at 100 min reaction time. The H2O2/Fe2+ ratio was then determined to be 13.5:1.
Considering the narrow therapeutic index of digoxin and the low range between the safe and toxic serum concentrations of this drug, to evaluate the relative bioavailability of tablets and oral solution is necessary. The pharmacokinetic properties of digoxin after oral administration of its hydroxypropyl-beta-cyclodextrin (HPCD) inclusion complex to rabbits and human volunteers were investigated in comparison with those of commercially available tablets. The aqueous solubility of digoxin was enhanced by HPCD for about 2000 times at HPCD concentration of 50% (w/v). But in a human bioavailability study no significant difference was observed in the extent of absorption (AUC(0-t)) and Cmax between the two formulations. Time to reach peak was significantly shorter for the solution than for the tablets (p < 0.01). The pharmacokinetic results from the rabbit study were similar to human studies and no significant difference was observed for AUC, Cmax and Tmax. As the bioavailability of both tablets and solution is equivalent HPCD based oral digoxin solution could serve as an alternative to tablets.
The hydrolyzed product of a mixture of tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTEOS) was used to produce organic-inorganic hybrid silica by sol-gel processing. The product was a kind of composite with vinyl groups incorporated into the structure of the final particles through C-Si bonds. These hybrid silica particles were spherical and the average diameter was about 350 nm as measured by scanning electron microscopy (SEM). The particles were non-porous as proved by BET method. The hybrid silica particles were subsequently encapsulated with a layer of PS-DVB, a polymeric mixture of styrene and divinylbenzene, with the vinyl groups on the particle surface as anchors of the polymer chains. The encapsulated packing was used as stationary phases in CEC, and the chromatographic behaviors were studied. Experimental results showed that, as expected, the smaller diameter stationary phase resulted in higher column efficiencies. In comparison with the columns packed with 5 microm diameter encapsulated-silica stationary phases of the same kind and other sub-micron stationary phases reported, it can be concluded that the EOF velocity is independent of the particle diameter when using 350 nm phase, but determined by the surface nature of the stationary phase.
The concentrations and chemical partitioning of heavy metals in the sediment cores of the Pearl River Estuary were studied. Based on Pearson correlation coefficients and principal component analysis results, Al was selected as the concentration normalizer for Pb, while Fe was used as the normalizing element for Co, Cu, Ni and Zn. In each profile, sections with metal concentrations exceeding the upper 95% prediction interval of the linear regression model were regarded as metal enrichment layers. The heavy metal accumulation mainly occurred at sites in the western shallow water areas and east channel, which reflected the hydraulic conditions and influence from riparian anthropogenic activities. Heavy metals in the enrichment sections were evaluated by a sequential extraction method for possible chemical forms in sediments. Since the residual, Fe/Mn oxides and organic/sulfide fractions were dominant geochemical phases in the enriched sections, the bioavailability of heavy metals in sediments was generally low. The 206Pb/207Pb ratios in the metal-enriched sediment sections also revealed the influence of anthropogenic sources. The spatial distribution of cumulative heavy metals in the sediments suggested that the Zn and Cu mainly originated from point sources, while the Pb probably came from non-point sources in the estuary.
We have shown previously that anti-fecundity immunity can be induced experimentally against recombinant 26 kDa glutathione S-transferase (reSjc26GST) in Chinese water buffaloes (Bos buffelus), important reservoir hosts for Schistosoma japonicum in China. In the field study described here, we immunized buffaloes with reSjc26GST to induce protective immunity against S. japonicum and to evaluate its effectiveness in controlling schistosomiasis japonica. We selected two villages as test and control groups in inside-embankment areas endemic for schistosomiasis japonica. The buffaloes in the test village were vaccinated with reSjc26GST, whereas those in the control village were not. The indicators of the effect of the vaccine included the generation of specific IgG antibodies in the vaccinated buffaloes, changes in the prevalence and infection intensity in buffaloes and village children, changes in the density of infected snails, and changes in the infectivity of water bodies (assessed by sentinel mice) in transmission areas adjacent to both villages. Twenty months after vaccination, the infection rate of buffaloes in the test village was decreased by 60.4% (from an initial prevalence of 13.5% to 5.4%), and 67.9% when compared with that in the control village (initial prevalence of 16.7%). However, the infection rate in village children remained unchanged. The density of infected snails decreased by 71.4%, from 0.0049/0.11 m2 to 0.0014/0.11m2 in the high transmission area outside the embankment in the test village. There was no change in the infectivity of the water body transmission areas between the test and control villages. The levels of specific antibodies to reSjc26GST showed a continuous increase after vaccination. These results indicate that protective immunity was induced and maintained in buffaloes after vaccination with reSjc26GST. The vaccine could thus play a significant role in reducing S. japonicum transmission caused by water buffaloes in the Lake region of China.
Osteoblast growth and differentiation are critical processes for bone development and maintenance, and are regulated by both humoral and mechanical factors. Humoral (hormonal) factors can affect gene transcription via MAPkinases, e.g., extracellular signal-regulated kinase (ERK). We studied whether the ERK pathway is also involved in processing mechanical inputs in human bone cells. Exposing MG63 cells to physiologically relevant levels of fluid flow resulted in ERK phosphorylation. Genistein blocked this response, indicating that it is dependent on tyrosine phosphorylation. Furthermore, alpha v beta 3 integrins were activated in response to fluid flow, as shown by recruitment of adaptor molecule Shc and clustering of alpha v beta 3 in focal adhesion-like structures. Antibodies blocking formation of beta 1 or beta 3 integrin-matrix interactions or RGD peptides could not inhibit fluid flow-induced ERK phosphorylation, suggesting that formation of new integrin-matrix interactions is not essential for this response and that other upstream mechanosensors regulate induction of ERK phosphorylation in response to fluid flow in human bone cells.
The recently developed DNA microarray technology provides a powerful and efficient tool to rapidly compare the differential expression of a large number of genes. Using the DNA microarray approach, we investigated gene expression profiles in cultured human aortic endothelial cells (HAECs) in response to 24 h of laminar shear stress at 12 dyn/cm(2). This relatively long-term shearing of cultured HAECs led to the modulation of the expression of a number of genes. Several genes related to inflammation and EC proliferation were downregulated, suggesting that 24-h shearing may keep ECs in a relatively noninflammatory and nonproliferative state compared with static cells. Some genes were significantly upregulated by the 24-h shear stress; these includes genes involved in EC survival and angiogenesis (Tie2 and Flk-1) and vascular remodeling (matrix metalloproteinase 1). These results provide information on the profile of gene expression in shear-adapted ECs, which is the case for the native ECs in the straight part of the aorta in vivo.
Vascular endothelial cells (ECs) in vivo are subject to different flow conditions due to the variation in vessel geometry. The aim of this study is to elucidate the effects of different flow conditions on EC monolayer migration into a mechanically denuded zone and their underlying mechanisms. Both laminar and disturbed flows significantly enhanced EC migration. EC migration speed was the fastest under laminar flow, which preferentially promoted directional EC migration from the upstream side of the wounded monolayer. C3 exoenzyme (a Rho inhibitor) inhibited EC migration under static and flow conditions, and markedly reduced the effects of flow on EC migration. These results indicate that flow promotes EC migration through the Rho signaling pathway. Genistein (a tyrosine kinase inhibitor) selectively retarded EC migration under disturbed flow, suggesting that tyrosine phosphorylation may play a role in EC migration under disturbed flow. This study has demonstrated that different flow patterns differentially affect EC monolayer migration into the denuded zone involving multiple mechanisms.
To identify possible associations between host genetic factors and the onset of liver fibrosis following Schistosoma japonicum infection, the major histocompatibility class II alleles of 84 individuals living on an island (Jishan) endemic for schistosomiasis japonica in the Poyang Lake Region of Southern China were determined. Forty patients exhibiting advanced schistosomiasis, characterised by extensive liver fibrosis, and 44 age and sex-matched control subjects were assessed for the class II haplotypes HLA-DRB1 and HLA-DQB1. Two HLA-DRB1 alleles, HLA-DRB1*0901 (P=0.012) and *1302 (P=0.039), and two HLA-DQB1 alleles, HLA-DQB1*0303 (P=0.012) and *0609 (P=0.037), were found to be significantly associated with susceptibility to fibrosis. These associated DRB1 and DQB1 alleles are in very strong linkage disequilibrium, with DRB1*0901-DQB1*0303 and DRB1*1302-DQB1*0609 found as common haplotypes in this population. In contrast, the alleles HLA-DRB1*1501 (P=0.025) and HLA-DQB1*0601 (P=0.022) were found to be associated with resistance to hepatosplenic disease. Moreover, the alleles DQB1*0303 and DRB1*0901 did not increase susceptibility in the presence of DQB1*0601, indicating that DQB1*0601 is dominant over DQB1*0303 and DRB1*0901. The study has thus identified both positive and negative associations between HLA class II alleles and the risk of individuals developing moderate to severe liver fibrosis following schistosome infection.
Explore the source record for details and available documents.
INTRODUCTION: The Mini-Mental State Examination (MMSE) and Cognitive Capacity Screening Examination (CCSE) are easily and rapidly administered tests for quantifying the general cognitive status of young as well as geriatric subjects. Likewise, the Hamilton Depression Rating Scale (HDRS) is a brief instrument for quantifying depression that may confound cognitive test performances. Testing by means of all three scales concurrently provides useful information for longitudinal research among the elderly. OBJECTIVES: To validate the combined longitudinal use of MMSE, CCSE and HDRS among a specific cohort of normal subjects with vascular headaches characterized by known well-established temporary cognitive decline occurring only during temporary intervals with headache. METHODS: The MMSE, CCSE and HDRS were serially tested at 3-12 monthly intervals among 196 healthy subjects attending our out-patient headache clinic who suffered from migraine or cluster headaches. Stability and specificity of MMSE, CCSE and HDRS were evaluated by comparing consecutive normative scores during headache-free intervals. Sensitivity of MMSE and CCSE for detecting temporary cognitive decline were evaluated by comparing scores during headache and headache-free intervals. RESULTS: CCSE, MMSE and HDRS gave stable headache-free normative values over intervals of 3-10 years among 182 subjects. Among 77 subjects during headache intervals, temporary cognitive decline were confirmed by both CCSE and MMSE (p < 0.0001). When cutoff points for both CCSE and MMSE normal scores were placed at >/= 27, specificity for detecting cognitively normal values for CCSE and MMSE when headache-free were 92.2 and 89.6%, respectively (p > 0.05), while sensitivity for detecting cognitively decline during headache intervals were 83.7 and 49%, respectively (p < 0.001). Compared with scoring by a single rater, reliability estimates for all three rating scales were slightly lower when tested by different raters, but these differences were not significant. CONCLUSIONS: CCSE is reliable and more sensitive than MMSE for detecting cognitive decline.
OBJECTIVES: This prospectively designed longitudinal study assesses prevalence, incidence and prognosis of depressive symptoms among cognitively normal elderly volunteers compared with patients with mild cognitive impairment (MCI), dementia of Alzheimer type (DAT), and vascular dementia (VAD). Possible relationships between depressive symptoms, cognitive performance, disease types, and effects of antidepressant treatment were analyzed. METHODS: Two hundred and ninety four subjects exhibiting different levels of cognitive performance were admitted to this study. Demographics, cardiovascular and neurodegenerative risk factors, together with measures of neuropsychological test performance, were obtained at sequential visits. Depressive symptoms were selectively treated with antidepressant medications. RESULTS: One hundred and forty six subjects with normal cognition, 19 subjects with MCI, 42 patients with DAT, and 32 patients with VAD were followed for a mean of 3.5 years. With the passage of time, there were trends showing prevalence of depressive symptoms to decrease among DAT and to increase among VAD patients. VAD patients exhibited the highest incidences of new-onset depressive symptoms, followed in incidence by DAT and MCI groups. Depressive symptoms among VAD and MCI patients were more persistent and refractory to antidepressant medications than for DAT patients. Trends suggested that antidepressant treatment might benefit MCI and VAD subjects more than DAT patients. Motivationally related depressive symptoms accounted for major components of elevated Hamilton depression rating scale scores. CONCLUSIONS: Depressive symptoms among DAT patients have higher rates of spontaneous resolution, without requiring intensive drug treatment, than among VAD patients in whom depressive symptoms are more persistent and refractory to drug treatment. Early depressive symptoms among subjects with MCI may represent a preclinical sign and should be considered as a risk factor for impending DAT or VAD among the elderly.
Explore the source record for details and available documents.
The chemical forms of heavy metals (Pb, Zn and Cu) in sediment cores of the Pearl River Estuary were studied using a sequential chemical extraction method. The isotope ratios of 206Pb/207Pb in various chemical fractions were also measured to assess the potential Pb sources. Zinc and Cu were mainly associated with the residual fraction. The Fe-Mn oxide and organic/sulphide fractions were the next important phases for Zn and Cu, respectively. For Pb, different chemical partitioning patterns were found among different sediment cores. Most Pb was associated with the residual fraction in the sediments. In some sediment profiles, the major phase of Pb in the top layers was the Fe-Mn oxide fraction. The proportion of Pb in the Fe-Mn oxide fraction decreased significantly with increasing depth. Among the different depths, the 206Pb/207Pb isotope ratios in the residual fraction remained fairly stable, with a mean value of 1.202, which may represent the natural background value. The 206Pb/207Pb ratios in the exchangeable fraction were the lowest among the five fractions, particularly in top sediments, showing the anthropogenic inputs of heavy metals from recent rapid industrial development in the surrounding region. For the other three non-residual fractions, there was a similar trend of increasing 206Pb/207Pb ratios down the profile. Results from this study are useful in assessing both the chemical changes for heavy metals in marine sediments and the potential of heavy metal release into the water environment of an estuary area.