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Biomedical subjects

Bin Chen

Publications and source records attributed to Bin Chen.

205 records · Page 12Linked to original sources
PubMed2002

Intraspecific hybridization of Anopheles minimus (Diptera: Culicidae) species A and C in Thailand.

Hybridization tests of laboratory-raised, isolines of Anopheles minimus, species A and C were conducted by induced copulation. The three isolines were established based on three morphological variants of wild-caught, fully engorged females and two distinct types of metaphase chromosomes. They were An. minimus species A: V form (X1,Y1), M form (X2,Y1); species C: P form (X3,Y2). The results of reciprocal and back crosses indicated that the two morphologically variant forms of species A were genetically compatible, providing viable progeny and completely synaptic salivary gland polytene chromosomes, whereas they were genetically incompatible with species C and/or the P form. Hybrid progeny was only obtained from both forms of species A females x species C males, but asynaptic salivary gland polytene chromosomes on 3L and partial development of ovarian follicles in females were seen. Back crosses of F1 hybrid males with parental species A females provided viable progeny, while back crosses of F1 hybrid females with parental species C males provided progeny of low viability and adult males with abnormal spermatozoa, suggesting the partial reproductive isolation of An. minimus species A and C.

Animals↗
PubMed1998

A clinical evaluation of serum concentrations of intercellular adhesion molecule-1 in patients with gastric cancer.

AIM:To investigate the correlation between the serum soluble intercellular adhesion molecule-1 (sICAM-1) and the clinicopathologic features and to evaluate the possible prognostic significance of sICAM-1 concentration in gastric cancer.METHODS: Thirty-four patients with gastric cancer were prospectively included and evaluated. Venous blood samples were collected before the surgery. Sera were obtained by centrifugation, and store at -30 degree until assay. The control group consisted of 20 healthy volunteers. Serum concentrations of ICAM-1 were measured with the quantitative sandwich enzyme immunoassay technic. Differences between the two groups were analyzed by Student's t test. x+2s of normal control sICAM-1 was taken as upper limit to calculate the positive rates.RESULTS:The mean value of serum ICAM-1 in patients with gastric cancer was 367.7&mgr;g/L plus minus 104.7&mgr;g/L and that of control group was 236.9&mgr;g/L plus minus 74.3&mgr;g/L, and the difference was significant (P < 0.001). The patients with tumor size of > = 5cm had significantly higher serum concentrations of sICAM-1 than those with smaller ones (406.7&mgr;g/L plus minus 90.2&mgr;g/L vs 319.9&mgr;g/L plus minus 105.3&mgr;g/L,P <0.01). Compared with stages I-II gastric cancer patients, patients with more advanced clinical stage (III-IIV) had higher levels of sICAM-1 (397.1&mgr;g/L plus minus 102.4&mgr;g/L vs 306.0&mgr;g/L plus minus 82.3&mgr;g/L,P <0.05).Difference was significant statistically in sICAM-1 levels between patients with positive lymph node status and those without lymph node involvement (403.6&mgr;g/L plus minus 99.7&mgr;g/L vs 302.7&mgr;g/L plus minus 81.4&mgr;g/L,P <0.01). No relation was observed between the level of sICAM-1 and grade of histological differentiation in the patients with gastric cancer.CONCLUSION:Serum sICAM-1 concentration may be a valuable parameter for predicting the prognosis and degree of the gastric cancer.

Journal Article↗
PubMedDate not supplied

Using the atomic force microscope to observe and study the ultrastructure of the living BIU-87 cells of the human bladder cancer.

In this study, the ultrastructure of living BIU-87 cells of human bladder cancer was mapped using atomic force microscopy to reveal the dynamic change of single cancerous cell division. Simultaneously, the feasibility and functional reliability of the atomic force microscope (AFM) were established and a laboratory model using AFM to study living cancerous cells was created. In this experiment, BIU-87 cells of human bladder cancer were cultured by conventional methods and grown in gelatin-treated dishes. A thermostat was used for preserving the cell's living temperature. Scanning of these cells using AFM was carried out in physiologic condition. The AFM images of the ultrastructure of living BIU-87 cells as well as those of the cell's membrane and cytoskeleton were very clear. The dynamic phenomenon of single cell division was observed. It was concluded that the AFM was able to observe and depict the ultrastructure of living cells of human bladder cancer directly and in real time. This experimental model is expected to play an important role in elucidating the cancerous mechanism of bladder normal cells at the atomic or nanometer level.

Cell Division↗
PubMedDate not supplied

Analysis of sampling volume and tissue heterogeneity on the in vivo detection of fluorescence.

The effect of sampling region size and tissue heterogeneity is examined using fluorescence histogram assessment in a rat prostate tumor model with benzoporphyrin derivative fluorophore. Spatial heterogeneity in the fluorescence signal occurs on both macroscopic and microscopic scales. The periphery of the tumor is more fluorescent than the center. Fluorescence is also highest nearest the blood vessels immediately after injection, but over time this fluorescence becomes uniform through the tumor tissue. Using microscopy analysis, the fluorescence intensity histogram distributions follow a normal distribution, yet as the sampling area is increased from the micron scale to the millimeter scale, the variance of the distribution decreases. The mean fluorescence intensity is accurately measured with a millimeter size scale, but this cannot provide accurate measurements of the microscopic variance of drug in tissue. Fiber probe measurements taken in vivo are used to confirm that the variance observed is smaller than would be expected with microscopic sampling, but that the average fluorescence can be measured with fibers. Sampling tissue with fibers smaller than the intercapillary spacing could provide a way to estimate the spatial variance more accurately. In summary, sampling fiber size affects the fluorescence intensities detected and use of multiple region microscopic sampling could provide better information about the distribution of values that occur.

Algorithms↗
PubMedDate not supplied

Purification process for vertically aligned carbon nanofibers.

Individual, free-standing, vertically aligned multiwall carbon nanotubes or nanofibers are ideal for sensor and electrode applications. Our plasma-enhanced chemical vapor deposition techniques for producing free-standing and vertically aligned carbon nanofibers use catalyst particles at the tip of the fiber. Here we present a simple purification process for the removal of iron catalyst particles at the tip of vertically aligned carbon nanofibers derived by plasma-enhanced chemical vapor deposition. The first step involves thermal oxidation in air, at temperatures of 200-400 degrees C, resulting in the physical swelling of the iron particles from the formation of iron oxide. Subsequently, the complete removal of the iron oxide particles is achieved with diluted acid (12% HCl). The purification process appears to be very efficient at removing all of the iron catalyst particles. Electron microscopy images and Raman spectroscopy data indicate that the purification process does not damage the graphitic structure of the nanotubes.

Catalysis↗
PubMedDate not supplied

Protoporphyrin IX level correlates with number of mitochondria, but increase in production correlates with tumor cell size.

Protoporphyrin IX (PpIX) is produced in cells via the heme synthesis pathway, from the substrate aminolevulinic acid (ALA), and can be used for tumor detection, monitoring or photodynamic therapy. PpIX production varies considerably between tumor cell types, and determining the cell types and methods to optimize production is a central issue in properly utilizing this drug. A panel of eight cancer cell types was examined for PpIX production capacity, including breast, prostate, and brain cancer tumors, and the production varied up to 10-fold among cell types. A positive correlation was seen between mitochondrial content and naturally occurring PpIX prior to ALA administration, but mitochondrial content did not correlate to the yield of PpIX resulting from the addition of ALA. Interestingly, total cell size was positively correlated to the yield of PpIX from ALA administration. Addition of an iron chelator, 1,2-dimethyl-3-hydroxy-4-pyridone (L1) in combination with ALA allows the final step in the heme synthesis pathway, conversion of PpIX to heme, to be delayed, thereby further increasing the yield of PpIX. Those cell types that had the lowest ALA to PpIX production without L1 showed the largest percentage increase in production with L1. The study indicates that use of L1 in tumors with a lower innate production of PpIX with ALA alone may be the most productive approach to this combined delivery.

Aminolevulinic Acid↗