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Biomedical subjects

Lin Zhu

Publications and source records attributed to Lin Zhu.

At least 19 recordsLinked to original sources
PubMed2024

Cohort Studies and Multi-omics Approaches to Low-Dose Ionizing Radiation-Induced Cardiovascular Disease: A Comprehensive Review.

The effect of low-dose ionizing radiation exposure on the risk of cardiovascular disease (CVD) represents a significant concern in the field of radiation protection. The prevailing approach to mitigating the adverse effects of low-dose or low-dose-rate radiation does not currently incorporate the potential risk of CVD, despite the possibility that such risk may be a substantial contributor to overall health hazards. Current evidence suggests a potential association between radiation exposure and CVD; however, the overall findings remain inconclusive. This is particularly due to the uncertainty surrounding the influence of significant non-radiation risk factors on the associations reported in epidemiological studies. It is difficult to discern the underlying connection in observational epidemiology when there is substantial variation in baseline risk factors. The paucity of epidemiological research in this domain is being partially offset by the advancement of multi-omics approaches. These methods assist in identifying radiosensitive targets, comprehending underlying biological processes, and pinpointing biomarkers. This, in turn, fortifies the evidence gleaned from epidemiological studies. In this review, we delve into the body of epidemiological research pertaining to CVD induced by low-dose ionizing radiation and the application of multi-omics techniques. The integration of these two methodologies holds the promise of identifying specific molecules or biological pathways that can be employed to validate endpoints related to radiation risk assessment.

Humans↗
PubMed2006

The inflammation in the gut after experimental subarachnoid hemorrhage.

BACKGROUND: Gastrointestinal dysfunction could be frequently observed in the patients suffering from SAH. This study test the hypothesis that experimental SAH could induce histopathological changes and inflammatory response associating with NF-kappaB activation pathway in the gut. MATERIALS AND METHODS: A total of 17 rabbits were randomly divided into two groups: control group (n = 8) and SAH group (n = 9). In the SAH group, the animals were subjected to experimental SAH according to the "two-hemorrhage" method. The histopathological study was performed to detect the intestinal mucosal morphological changes and immunohistochemical study was used to detect the TNF-alpha and ICAM-1 expressions. NF-kappaB binding activity was measured using the electrophoretic mobility shift assay. RESULTS: It was demonstrated that some damage changes and leukocytes infiltration occurred in the intestinal mucosa after SAH. More positive cells for TNF-alpha and ICAM-1 were observed in the SAH group. The NF-kappaB binding activity in the intestines was significantly increased in the SAH group (P < 0.01). CONCLUSIONS: The results of the present study suggest that SAH in the rabbits could induce NF-kappaB and proinflammatory cytokines activation in the intestine, which is associated with morphological changes.

Animals↗
PubMed2006

Inhibition of STAT3 activity with AG490 decreases the invasion of human pancreatic cancer cells in vitro.

Signal transducer and activator of transcription 3 (STAT3) is a central cytoplasmic transcription factor. Abnormal activation of STAT3 plays a critical role in oncogenesis and has been found frequently in a wide variety of human tumors including pancreatic cancer. In this study, we elucidated the significance of the STAT3 signaling pathway on metastatic potentials of pancreatic cancer. We found that phosphorylated STAT3 (p-STAT3) protein levels were significantly higher in highly metastatic SW1990 cells compared to the poorly metastatic CaPan-2 cells, which expressed weak levels of this protein. Furthermore, a Janus kinase (JAK) specific inhibitor, AG490, significantly inhibited the expression of p-STAT3, and subsequently reduced invasion and adhesion potential of SW1990 cells compared to the cells treated with vehicle only. Finally, inhibition of the STAT3 signaling pathway by AG490 also led to a decrease in matrix metalloproteinase-2 and vascular endothelial growth factor expression at the protein and mRNA levels. These results demonstrate that activation of the STAT3 signaling pathway plays an important role in the progression of pancreatic cancer and that inhibition of this pathway may be useful for an anti-invasive therapeutic option in pancreatic cancer.

Blotting, Western↗
PubMed2006

Cell density- and ComE-dependent expression of a group of mutacin and mutacin-like genes in Streptococcus mutans.

Streptococcus mutans is a major cariogenic inhabitant of the high cell density oral biofilm (dental plaque). In previous studies, we showed that production of one of its virulence factors, the bacteriocin mutacin IV, was regulated by high cell density as well as the competence regulatory system ComED. In this study, we utilized luciferase fusions and real-time reverse transcriptase polymerase chain reaction (RT-PCR), to demonstrate that high cell density and ComED also regulate an uncharacterized group of mutacin and mutacin-like genes. Under high cell density or in the presence of externally added competence-stimulating peptide (CSP), gene expression increased 10- to 30-fold. Interestingly, high cell density was able to bypass the requirement for CSP addition. However, both cell density and CSP-dependent gene expression had a strict requirement for the ComE response regulator.

Bacterial Proteins↗
PubMed2006

Corrosion test, cell behavior test, and in vivo study of gradient TiO2 layers produced by compound electrochemical oxidation.

This paper describes efforts to improve implant biocompatibility and durability by applying a hybrid technique using composite oxidation. Pure titanium was used as the substrate material. A porous oxide film as the outer layer was produced by micro-arc oxidation and a dense oxide film as the inner layer was produced by pre-anodic oxidation. In this study, physicochemical characteristics, corrosion test, cell attachment behavior, and in vivo studies were used to compare this gradient layer with untreated titanium. The results revealed that the gradient layer was composed of two layers of oxide films which were made up of rutile and anatase and the surface was porous with calcium and phosphor. The corrosion resistance of the gradient layer was improved remarkably, which was about three times the values for titanium and two times the value for the dense layer. The cell-material interaction study indicated that L929 cells seeded and cultured on the gradient layer appeared to attach well and the rate of proliferation was the greatest. The study in vivo showed that the gradient layer had good biocompatibility. This gradient layer provides a material with high corrosion resistance, bioactivity, and biological properties suitable for tissue engineering applications.

Animals↗
PubMed2006

Electrically pumped two-dimensional Bragg grating lasers.

We demonstrate electrically pumped InGaAsP two-dimensional Bragg grating (2DBG) lasers with two line defects. The 2DBG structure uses a weak 2D index perturbation surface grating to control the optical modes in the plane of the wafer. Measurements of the 2DBG lasers show that modal control in both the longitudinal and transverse directions is due to the gratings and defects. The 2DBG lasers are promising candidates for single-mode, high power, and high efficiency large-area lasers.

Journal Article↗
PubMed2006

Transmission and group delay of microring coupled-resonator optical waveguides.

We measured the transmission and group delay of microring coupled-resonator optical waveguides (CROWs). The CROWs consisted of 12 weakly coupled, microring resonators fabricated in optical polymers (PMMA on Cytop). The intrinsic quality factor of the resonators was 18,000 and the interresonator coupling was 1%, resulting in a delay of 110-140 ps and a slowing factor of 23-29 over a 17 GHz bandwidth.

Journal Article↗
PubMed2006

Functional characterization of cell-wall-associated protein WapA in Streptococcus mutans.

Streptococcus mutans is known as a primary pathogen responsible for dental caries. One of the virulence factors of S. mutans in cariogenicity is its ability to attach to the tooth surface and form a biofilm. Several surface proteins have been shown to be involved in this process. A 29 kDa surface protein named wall-associated protein A (WapA, antigen A or antigen III), was previously used as a vaccine in animal studies for immunization against dental caries. However, the function of WapA in S. mutans is still not clear. This study characterized the function of WapA in cell surface structure and biofilm formation. Compared to the wild-type, the wapA mutant had much-reduced cell chain length, diminished cell-cell aggregation, altered cell surface ultrastructure, and unstructured biofilm architecture. Furthermore, in vivo force spectroscopy revealed that the cell surface of the wapA mutant was less sticky than that of the wild-type cells. More interestingly, these phenotypic differences diminished as sucrose concentration in the medium was increased to 0.5 %. Real-time RT-PCR analysis demonstrated that sucrose strongly repressed wapA gene expression in both planktonic and biofilm cells. These results suggest that the WapA protein plays an important structural role on the cell surface, which ultimately affects sucrose-independent cell-cell aggregation and biofilm architecture.

Antigens, Bacterial↗
PubMed2006

[Effects of nitrogen source and aeration mode on algae growth in freshwater].

Aquarium microcosms were used to study the effects of nitrogen source and aeration mode on the growth and species changes of algae in freshwater. Nitrate nitrogen(NO3(-) -N) and ammonia nitrogen(NH4(+) -N) were used as nitrogen sources. For each nitrogen source, four modes of aeration were selected, including control, continuous aeration, aeration during the day, and aeration at night. In the early stage of the experiment, algae in the NH4(+) -N treatment experiment grew well. In the later stage, algae in the NO3(-) -N treatment experiment grew better. For different aeration modes, continuous aeration show varied effects on algae growth in the two nitrogen source treatments. Day-only aeration had little effect on algae growth. Night-only aeration inhibited algae growth considerably. In NH(+) -N treatments, cyanophyta became dominant species easily. In contrast, chlorophyta dominated in NO3(-) -N treatments.

Ammonia↗
PubMed2006

[Changes of algal communities in water body with different proportions of nitrogen and phosphorus].

A simulation test was conducted in aquaria to study the responses of algal communities to different N/P ratios in urban water body. The water sample was taken from a small artificial lake in Tianjin, and its initial N/P ratio was adjusted to 0. 5:1,7.2:1, 25:1 and 50:1, respectively. The results showed that in high N/P ratio groups, the numbers of Chlorophyta species decreased, while those of Cyanophyta species didn' t change very much. The numbers of these two species were both decreased in low N/P ratio group. Algal biomass, cell density and chlorophyll a content in medium and high N groups were higher than those in control and high P groups. The mean value of chlorophyll a reached the highest (69.7 microg x L(-1)) in high N group, and was 54.3, 30.3 and 29.7 microg x L(-1) in medium N, control, and high P groups, respectively. At the mid-late stages of culture, green algae Dictyosphaerium pulchellum was dominant in high P group, while blue algae Phormidium tenue, P. corium, Lyngbya limnetica and Microcystis aeruginosa were dominated in high N/P ratio groups. Control group had the highest species richness, while medium and high N groups had the highest and lowest ecological species dominance, respectively.

Chlorophyta↗
PubMed2006

[Flow injection biosensor based on the immobilized AChE].

A biosensor based on the flow injection system was constructed with the immobilized AChE from Scomberomorus niphonius (Curier) as identification element and a pH electrode as transducer. When phosphate buffer was used as carrier liquid, a good reproducibility (RSD = 1.427% , n=10) of the biosensor response was obtained after the substrate was injected repetitively. After an incubation time of 20 min, the calibration graph to methyl-parathion is linear (r = 0.9986) when its concentration ranges from 4.29 x 10(-10) mol x L(-1) to 4.29 x 10(-8) mol x L(-1) , and the detection limit is 1.3 x 10(-10) mol x L(-1). However, the sensitivity of this biosensor to methyl-parathion when using clean seawater as carrier liquid is not as good as that using phosphate buffer. But after preoxidation of methyl-parathion with NaClO as oxidant, the detection limit of the biosensor to methyl-parathion in seawater can be improve to 2.16 x 10(-7) mol x L(-1).

Acetylcholinesterase↗
PubMed2006

[Effect of complete Freund's adjuvant on islet beta cell apoptosis and its mechanism in non-obese diabetic mice].

OBJECTIVE: To investigate the effect of complete Freund's adjuvant (CFA) on islet beta cell apoptosis in preventing diabetes in non-obese diabetic (NOD) mice, and the influence on apoptotic related-gene expression. METHODS: Four-week-old female NOD mice were randomly divided into Group CFA (n=5) and Group saline (NS) control (n=5). Mice in Group CFA were injected in the hind footpad with 50 microL CFA and mice in Group NS with 50 microL NS. Blood sugar was monitored and diabetes was diagnosed if blood sugar was higher than 11.1 mmol/L for 2 continuous days in the NOD mice. The mice were sacrificed when diagnosed as diabetes or at 30 weeks of age. Pancreatic sections were made for: evaluation of insulitis severity with HE staining; counting of apoptotic beta cells with the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labeling (TUNEL) method, and ABC immunohistochemical double labeling; counting of Fas, FasL and Bcl-x positive cells respectively with ABC immunohistochemical method. RESULTS: By 30 weeks of age, none of the 5 CFA-treated mice, compared with 3 of the 5 control mice, had developed diabetes. The insulitis score was lower (1.820+/-0.962 vs. 3.020+/-1.040, P<0.05), the rates of apoptotic beta cells, Fas positive cells and FasL positive cells were lower [(10.2+/-2.8)% vs. (15.9+/-6.5)%, (54.9+/-14.5)% vs. (75.7+/-12.9)%, (20.3+/-10.4)% vs. (27.9+/-12.0)%, P<0.05), and the Bcl-x positive cell rate was higher [(74.9+/-10.7)% vs. (66.0+/-18.3)%, P<0.05] in the CFA-treated group than those in the NS-treated group respectively. CONCLUSION: CFA may inhibit beta cell apoptosis in NOD mice by regulating Fas, FasL and Bcl-x expression on cells within islets.

Animals↗
PubMed2005

Spectroscopic studies on 2,3,4,5-tetraphenylpyrylium salts with and without silver (I)-bridged structures.

Two novel phenylated pyrylium compounds, silver (I)-bridged 2,3,4,5-tetraphenylpyrylium perchlorate (P1) and its silver (I)-free pyrylium ligand (P2) were prepared from 1,2,3,4-tetraphenylcyclopentadiene to examine their spectroscopic behaviors. The UV/vis absorption and fluorescent emission spectra of P1 and P2, measured in three solvents (acetonitrile, dichloromethane and toluene), reveal that the photophysical behaviors are closely related to silver (I) fragment, and strongly dependent on solvent polarity. In polar acetonitrile, P1 displays longer absorption wavelength and much lower fluorescent emission intensity than P2, although they exhibit much similarity in shape. In contrast, in nonpolar toluene, while P2 shows an apparent absorption band at 338 nm, P1 displays a tail-like line without absorption band observed. All the spectra obtained indicate a better coplanarity and a stronger intra-molecular charge transfer in P1 due to the effect of silver (I) fragment. Additionally, the 1H NMR spectra of P1 and P2, which were recorded under the same conditions, indicate that the silver (I) fragment reinforces pyrylium ring's capacity to localize the formal positive charge within the heterocyclic ring.

Heterocyclic Compounds, 3-Ring↗
PubMed2005

Simultaneous determination of methylephedrine and noscapine in human plasma by liquid chromatography-tandem mass spectrometry.

A selective and sensitive method has been developed and validated for simultaneous quantification of methylephedrine and noscapine in human plasma. Analytes were extracted from human plasma samples by liquid-liquid extraction, separated on a Diamonsil C18 column and detected by tandem mass spectrometer with an atmospheric pressure chemical ionization (APCI) interface. Diphenhydramine was used as the internal standard (I.S.). The method was found to be precise and accurate within the linear range 0.1-100 ng/ml for each analyte. The intra- and inter-day relative standard deviations (R.S.D.s) were below 5.2% for methylephedrine and 6.7% for noscapine. The inter-day relative error (RE) as determined from quality control samples (QCs) was less than 3.0% for each analyte. The assay was successfully employed in a pharmacokinetic study after an oral administration of a multicomponent formulation containing 20 mg DL-methylephedrine hydrochloride, 16 mg noscapine, 300 mg paracetamol and 1mg of chlorpheniramine maleate.

Atmospheric Pressure↗
PubMed2005

Development and validation of a liquid chromatography/tandem mass spectrometry procedure for the quantification of adefovir in human plasma.

To investigate the pharmacokinetics of adefovir as an anti-hepatitis B virus drug, a sensitive and specific liquid chromatography/tandem mass spectrometry method was developed and validated. After a simple protein precipitation using methanol, the post-treatment samples were analyzed on a C(18) column interfaced with a triple-quadrupole tandem mass spectrometer using positive electrospray ionization. A structural analogue, PMPA, was used as the internal standard. The method was linear in the concentration range 0.25-100 ng/mL. The lower limit of quantification was 0.25 ng/mL. The intra- and inter-day relative standard deviation over the entire concentration range was 5.7% or less. The accuracy determined at three concentrations (0.75, 10 and 80 ng/mL for adefovir) was within +/-2.5% relative error. The method described here was successfully applied for the evaluation of pharmacokinetic profiles of adefovir after single oral administration doses of 5, 10 and 20 mg adefovir dipivoxil to ten healthy volunteers.

Adenine↗
PubMed2005

[Immuno-modulatory effect of somatostatin combined with traditional Chinese medicine on severe acute pancreatitis at early stage: a randomized control trial].

OBJECTIVE: To evaluate the immuno-modulatory effect of short course administration of somatostatin (stilamin) continuously at early stage in patients with severe acute pancreatitis (SAP). METHODS: Thirty-nine patients with SAP (22 men, 17 women; the middle age was 49 years)were randomly allocated into control group (20 patients treated with non-surgical integrated traditional Chinese and Western medicine) and treatment group (19 patients treated with somatostatin administered intravenously at a dosage of 250 mug/h for consecutive 72 hours as well as the treatment for the control group). Laboratory parameters, including the expressions of CD(3), CD(4) and CD(8) in lymphocytes (tested by flow cytometry) and C reactive protein (CRP), and indexes of therapeutic effect, including the occurrence of organic dysfunction, local complication and mortality between the two groups were compared. Another group of 30 healthy volunteers (19 men, 11 women; the middle age was 47 years) were recruited for testing the normal levels of CD(3), CD(4) and CD(8). RESULTS: (1) The levels of CD(3), CD(4) and CD(4)/CD(8) in lymphocytes before treatment in both groups were significantly lower than those in the healthy subjects (P<0.05), but there were no statistical differences between the two groups. At the 4th day, CD(3), CD(4) and CD(4)/CD(8) increased significantly in the treatment group (P<0.05) while no changes in the control group; the levels of CD(4) and CD(4)/CD(8) in the treatment group were also higher than those in the control group (P<0.05). (2) The CRP levels of the 2 groups showed no statistical difference before and 4 days after the treatment, but the CRP level in the treatment group was significantly lower than that in the control group at the 7th day (P<0.05). WBC count, serum levels of amylase, lipase, lactate dehydrogenase, aspartate aminotransferase, as well as the score of APACHE II in the treatment group recovered more quickly than those in the control group (P<0.05). (3) The occurrences of organic dysfunctions, local complications and mortality in both groups were not statistically different. CONCLUSION: The short course administration of somatostatin continuously at early stage can reduce the inflammatory response, up-regulate the cell immune function and improve the conditions of the patients with SAP, but its effect on mortality and morbidity needs further study.

Aged↗
PubMed2005

[Expression and significance of CD44v6 and MMP-9 in laryngeal squamous cell carcinoma].

OBJECTIVE: To investigate the clinical implication and the expression of CD44v6 and MMP-9 protein in laryngeal squamous cell carcinoma (LSCC). METHOD: Twenty-seven samples of LSCC and eight biopsies of adjacent non-cancerous tissue were detected with immunohistochemical technique (SABC method). The relationship between positive expression of CD44v6 or MMP-9 in LSCC and invasion or metastasis was analyzed. RESULT: Both CD44v6 and MMP-9 overexpressed in LSCC. The positive expression of CD44v6 was correlated with LSCC pathologic grade, cervical lymph node metastasis and postoperation survival rate (P < 0.05). The expression of MMP-9 was positively correlated with clinical staging and cervical lymph node metastasis (P < 0.05). There was a significant positive correlation between the expression of CD44v6 and MMP-9 (P < 0.01). CONCLUSION: There is a relationship between the expression of CD44 and MMP-9. CD44v6 and MMP-9 might be served as an objective indicator for lymph nodal metastatic potency, tumor invasion and prognosis in LSCC.

Adult↗