Biomedical subjects

Jie Zhuang

Publications and source records attributed to Jie Zhuang.

11 recordsLinked to original sources

PubMed2006

Anti-CD146 monoclonal antibody AA98 inhibits angiogenesis via suppression of nuclear factor-kappaB activation.

Our previous study showed that an anti-CD146 monoclonal antibody (mAb), AA98, which was raised against the vascular endothelial cells stimulated by a conditioned medium from hepatocarcinoma SMMC 7721 cells (SMMC 7721-CM), inhibited cell migration, angiogenesis, and tumor growth. However, the underlying mechanism was not elucidated. The objective of this study was to understand the mechanism by which mAb AA98 inhibits the endothelial cell migration and angiogenesis that is induced by SMMC 7721-CM. Using confocal imaging and biochemical studies, we found that SMMC 7721-CM induced nuclear factor kappaB (NF-kappaB) activation through the upstream p38 mitogen-activated protein kinase pathway, leading to the up-regulation of matrix metalloproteinase 9 and intercellular adhesion molecule 1 expression. Interestingly, all these activities stimulated by SMMC 7721-CM could be effectively inhibited by mAb AA98 in a dose- and time-dependent manner. Our data showed that the engagement of mAb AA98 with membrane protein CD146 inhibited p38 mitogen-activated protein kinase phosphorylation, suppressed NF-kappaB activation, and down-regulated matrix metalloproteinase 9 and intercellular adhesion molecule 1 expression, suggesting that the suppression of NF-kappaB is a critical point for the inhibitory function of mAb AA98 on endothelial cell migration, angiogenesis, and tumor metastasis. These results will provide clues for a better understanding of the mechanisms underlying tumor angiogenesis as well as antiangiogenesis therapy.

Angiogenesis Inhibitors↗

PubMed2005

Retention and transport of amphiphilic colloids under unsaturated flow conditions: effect of particle size and surface property.

The purpose of this study was to examine the mechanisms responsible for deposition and transport of amphiphilic colloids with a wide range of particle sizes (20-420 nm) through porous media. A series of saturated and unsaturated column experiments were conducted using amphiphilic latex microspheres and a hydrophilic silica colloid. We found that the amphiphilic latex particles were retained to a greater extentthan the hydrophilic silica colloid in unsaturated media. This was attributed to colloidal attachment atthe air-water interface due mainly to hydrophobic interactions. We also found that dependence of colloid retention on particle size was nonlinear. There existed a fraction of colloids with greater mobility than other fractions, which we referred to as the most mobile colloids. As particle size increased from 20 to 420 nm, colloid deposition rate first decreased to reach a minimum value at --100 nm then increased, indicating that different retention mechanisms were involved. We showed that conducting saturated transport experiments and analysis using filtration theory may be an effective approach for determining the most mobile colloid size(s) in porous media, perhaps even for unsaturated flow conditions. This study highlights the importance of including size effect and surface properties when predicting concentrations and fluxes of amphiphilic colloids or colloid-bound amphiphilic and hydrophobic contaminants in the subsurface environment.

Colloids↗

PubMed2005

Prosody and lemma selection.

In three picture-naming experiments, we examined the effect of prosodic context on the synonyms people use to name pictures in Mandarin Chinese. This was done without time pressure. The results showed that when monosyllabic and bisyllabic synonyms (e.g., hen/chicken) were embedded in a context of pictures with either bisyllabic or trisyllabic names, participants gave bisyllabic responses to the synonyms more often than they did in a condition without such a context. The difference was very similar in magnitude in both the bisyllabic and trisyllabic contextual conditions. These results suggest that people are biased toward using synonyms that have numbers of syllables equal or similar to those of the prosodic context. If it is assumed that prosodic effects originate at a stage of processing beyond the lemma level, then this suggests either that multiple phonological forms of synonyms can be activated or that there is feedback from prosodic processing that influences lemma selection.

Humans↗

PubMed2004

Semantic processing of Chinese in left inferior prefrontal cortex studied with reversible words.

This study utilized fast event-related fMRI with reversible words to examine the role of left inferior prefrontal cortex (PFC) in semantic processing of Chinese. As a special linguistic phenomenon in Chinese, a reversible word is a two-character word (AB) that, when read from right to left (BA), opposite to the normal left to right reading direction, is also a real word. The two words, AB and BA, can have very different meanings. Fourteen native Chinese saw a reversible word (BA) and were asked to read it backward silently to obtain the meaning of AB, defined as the target meaning. They then saw two test words and decided which of the two was semantically related to the target meaning. Activity in a subregion of BA47 was found to be modulated by the extent to which irrelevant semantic activation of the distractor word BA interfered with semantic retrieval of the target word AB. This finding demonstrated the involvement of the left inferior PFC in the control processes of semantic retrieval in Chinese. In addition, comparing conditions using reversible with that using nonreversible words, we found evidence suggesting a semantic/phonological functional subdivision in left inferior PFC, consistent with that in English.

Adult↗

PubMed2004

Modeling the water use efficiency of soybean and maize plants under environmental stresses: application of a synthetic model of photosynthesis-transpiration based on stomatal behavior.

Understanding the variability of plant WUE and its control mechanism can promote the comprehension to the coupling relationship of water and carbon cycle in terrestrial ecosystem, which is the foundation for developing water-carbon coupling cycle model. In this paper, we made clear the differences of net assimilation rate, transpiration rate, and WUE between the two species by comparing the experiment data of soybean (Glycine max Merr.) and maize (Zea mays L.) plants under water and soil nutrient stresses. WUE of maize was about two and a half times more than that of soybean in the same weather conditions. Enhancement of water stresses led to the marked decrease of Am and Em of two species, but water stresses of some degree could improve WUE, and this effect was more obvious for soybean. WUE of the two species changed with psiL in a second-order curve relation, and the WUE at high fertilization was higher than that at low fertilization, this effect was especially obvious for maize. Moreover, according to the synthetic model of photosynthesis-transpiration based on stomatal behavior (SMPTSB) presented by Yu et al. (2001), the WUE model and its applicability were discussed with the data measured in this experiment. The WUE estimated by means of the model accorded well with the measured values. However, this model underestimated the WUE for maize slightly, thus further improvement on the original model was made in this study. Finally, by discussing some physiological factors controlling Am and WUE, we made clear the physiological explanation for differences of the relative contributions of stomata- and mesophyll processes to control of Am and WUE, and the applicability of WUE model between the two species. Because the requirement to stomatal conductance by unit change of net assimilation rate is different, the responses of opening-closing activity of stomata to environmental stresses are different between the two species. To obtain the same level of net assimilation rate, soybean has to open its stomata more widely to keep small stomatal resistance, as compared with maize.

Ecosystem↗

PubMed2003

Colloid-facilitated Cs transport through water-saturated Hanford sediment and Ottawa sand.

In this study, a series of saturated column experiments were conducted to investigate effects of colloids on Cs transport in two types of porous media (Hanford sediment characteristic of 2:1 clay minerals and silica Ottawa sand). The colloids used were obtained by reacting Hanford sediment with simulated tank waste solutions. Because of the highly nonlinear nature of Cs sorption found in batch experiments, we used two different concentrations of Cs (7.5 x 10(-5) M and 1.4 x 10(-8) M) for the transport experiments. The presence of colloids facilitated the transport of Cs through both Hanford sediment and Ottawa sand via association of Cs with mobile colloidal particles. Due to the nonlinearity of the Cs sorption, the colloid-facilitated Cs transportwas more pronounced atthe low Cs concentration (1.4 x 10(-8) M) than at the high concentration (7.5 x 10(-5) M) when expressed relative to the inflow Cs concentration. In the absence of colloids, no Cs moved through the 10-cm long columns during the experiment within about 20 pore volumes, exceptfor the high Cs concentration in the Ottawa sand where a complete Cs breakthrough was obtained. Also, it was found that colloid-associated Cs could be partially stripped off from colloids during the transport. The stripping effect was controlled by both Cs concentration and sorption capacity of the transport matrix.

Cesium↗

PubMed2003

Virus retention and transport through Al-oxide coated sand columns: effects of ionic strength and composition.

Knowledge of the factors that influence the fate and transport of viruses in porous media is very important for accurately determining groundwater vulnerability and for developing protective regulations. In this study, six saturated sand column experiments were performed to examine the effects of a positively charged Al-oxide, which was coated on sand particles, on the retention and transport of viruses (phiX174 and MS-2) in background solutions of different ionic strength and composition. We found that the Al-oxide coating on sand significantly removed viruses during their transport in a phosphate buffered saline (PBS) solution. Mass balance calculations showed that 34% of the input MS-2 was inactivated/irreversibly sorbed on the surface of Al-oxide coated sand whereas 100% of phiX174 was recovered. Results from this study also indicated that higher ionic strength facilitated the transport of both phiX174 and MS-2 through the Al-oxide coated sand. This was attributed to the effect of ion shielding, which at higher ionic strength decreased the electrostatic attraction between the viral particles and the sand surface and consequently decreased virus sorption. Strong effect of the ionic strength indicates that an outer-sphere complexation mechanism was responsible for the virus sorption on the Al-oxide coated sand. Ion composition of the background solutions was also found to be a significant factor in influencing virus retention and transport. Virus transport was enhanced in the presence of phosphate (HPO(4)(2-)) as compared to bicarbonate (HCO(3)(-)), and the effect of HPO(4)(2-) was more significant on MS-2 than on phiX174. The presence of bivalent cations (Ca(2+) and Mg(2+)) increased virus transport because the cations partially screened the negative charges on the viruses therefore decreased the electrostatic attraction between the positively charged sand surface and the negatively charged viruses. Mass recovery data indicated that bivalent cations gave rise to a certain degree of inactivation/irreversibly sorption of phiX174 on the surface of Al-oxide coated sand. On the contrary, the bivalent cations appeared to have protected MS-2 from inactivation/irreversibly sorption. This study provides some insights into the mechanisms responsible for virus retention and transport in porous media.

Aluminum Oxide↗

PubMed2002

Effects of surface coatings on electrochemical properties and contaminant sorption of clay minerals.

Surface charges play a major role in determining the interactions of contaminants with soils. The most important sources of soil charges are clay mineral colloids, whose electrochemical properties are usually modified by metal-oxides and organic matter in natural environments. In this study, effects of coatings of organic matter and Fe- and Al-oxides on a series of electrochemical properties and heavy metal sorption of three clay minerals (kaolinite, montmorillonite and illite) predominant in natural soils were investigated using batch techniques. The results indicate that the coatings increased the specific surface area of the clay minerals, except for the Al-oxide coated montmorillonite and organic matter coated 2:1 clay minerals. The sesquioxide coatings increased amount of positive charges but decreased negative charges. This causes great reduction of the negative potential on the clay surfaces, shift of the zero point of charge to a higher pH, and promotion of fluoride sorption due to presence of more OH- and OH2 on the oxide surfaces than on the clay surfaces. In contrast, the organic coating significantly increased the negativity of surface charges, and thus the zero point of charge and zeta-potential of the clays dropped down. The organic coating also induced a reduction of fluoride sorption on the clays. With respect to the sorption of lead and cadmium, the sesquioxide coatings produced insignificant effects. The experiments of lead/cadmium competitive sorption show that on both the oxide-coated surface and the original clay surface there exist different types of sites, each of which preferentially binds with a heavy metal.

Adsorption↗

PubMed2002

[Disseminated Penicillium marneffei infection associated with AIDS, report of a case].

OBJECTIVE: To explore the clinical and laboratory features of disseminated Penicillium marneffei infection in patients with AIDS. METHODS: The HIV antibody in serum was assayed by both enzyme immunoassay (EIA) and Western immunoblot (WIB) methods. Morphology of the pathogenic fungus in smear and biopsy specimens of bone marrow was observed. The fungus was isolated from the patient's skin lesion and inoculated into the abdominal cavities of 2 rats and 2 mice. Twenty days later the rats and mice were killed and their viscera were taken out. Blood from the organs were cultured in Sabourand glucose agar at 25 degrees C and 37 degrees C. The colonies were observed. The morphology of the fungus was observed by microscopy and scanning electron microscopy. RESULTS: The most common clinical manifestations of Penicilium marneffei infection were fever, weight loss, anemia, papular skin lesion, hepatosplenomegaly, and lymphadenectasis. Yeast-like cells were found in the culture at 37 degrees C or in tissues. The fungi outside the host cells were elongated, often curved, sausage-like and with clear central septi. When cultured at 25 degrees C, the fungus was mycelia-like and produced a characteristic red pigment, diffusing into the medium. CONCLUSION: Disseminated Penicilliosis marneffei is one of the most important opportunistic infections in patients with AIDS in Southeast Asia and the southern part of China. Since there is no specific clinical manifestation for Penicillium marneffei infection, it is often misdiagnosed. Definite diagnosis requires culture of the pathogenic fungus from clinical specimens. The fungus is thermally dimorphic, produces red pigment, and is sausage-form with clear central septum outside the host cell. Amphotericin B and itraconazole are effective in treating Penicilliosis marneffei.

AIDS-Related Opportunistic Infections↗

PubMedDate not supplied

Sorption of MS2 bacteriophage to layered double hydroxides: effects of reaction time, pH, and competing anions.

Batch sorption and column breakthrough studies were conducted to investigate the potential of layered double hydroxides (LDHs) to remove bacteriophage MS2 from contaminated waters. All four of the LDHs evaluated in this study had very high retention capacities for MS2. Sorption results showed that MS2 could be completely removed from 5.2 x 10(2) plaque-forming units (pfu)/mL solution by Mg-Al LDH 2 (i.e., 2:1 Mg to Al ratio LDH), with the highest sorption capacity observed in this study of 1.51 x 10(10) pfu/g. Attachment of MS2 to LDHs was a rapid process and reached quasi-equilibrium after a 1-h reaction time. Within the pH range studied (pH 4-9), Mg-Al LDH 2 showed high sorption potential for MS2 at all pH values but sorption decreased slightly with increasing solution pH. Background solution anions influenced virus sorption, with SO4(2-) and HPO4(2-) decreasing sorption significantly whereas the presence of NO3- had little effect on the attachment of MS2 to Mg-Al LDH 2. The addition of another virus (phiX174) only caused a slight decrease in the retention of MS2 by Mg-Al LDH 2, suggesting that there was insignificant competitive sorption between MS2 and phiX174 on LDH surfaces. Results from column experiments indicate that there was no MS2 breakthrough from columns packed with Mg-Al LDH 2-coated sand, suggesting complete MS2 retention at the virus concentration tested. The high mass recovery by beef extract solution revealed that the removal of viruses by the LDH was due to sorption of MS2 to LDH surfaces, rather than inactivation.

Adsorption↗

PubMedDate not supplied

Virus retention and transport as influenced by different forms of soil organic matter.

Organic materials are widespread in natural soil and aquatic environments. Their effect on virus transport is very important in assessing the risk for contamination of ground water by viruses. This study aimed to determine how different forms (mineral-associated and dissolved) of natural organic matter influence the retention and transport of two bacteriophages (MS-2 and phiX174) in two porous media (a sand and a soil). We found that mineral-associated organic matter significantly promoted the transport of one virus (MS-2) but not the other (phiX174) in a phosphate-buffered saline solution. Similarly, MS-2 was retained less in sand columns with increasing concentrations of dissolved humic acid, while little effect was observed for phiX174 under the same conditions. The two viruses have different surface properties and thus exhibited different reactivity to the metal oxides present on sand particles and were affected differently by organic matter. Because the organic matter used in the study was negatively charged and hydrophilic, blocking of virus sorption sites and increasing of virus-medium electrostatic repulsion arising from modification of the sand and virus surface by organic matter are probably responsible for the facilitated transport. For dissolved humic acid, its competition for sorption sites with viruses was an additional mechanism involved. This study suggests that the effect of organic matter varied depending on the organic material properties and the type of viruses involved. As a general trend, the effect of organic matter was dominated by electrostatic rather than hydrophobic interactions.

Adsorption↗