Biomedical subjects
Publications and source records attributed to C Zhou.
N-Substituted nipecotic and iso-nipecotic amides of beta-methylTrpLys tert-butyl ester were found to be novel, selective and potent agonists of the somatostatin subtype-2 receptor in vitro. For example iso-nipecotic amide 8a showed high hsst2 binding affinity (Ki = 0.5 nM) and good selectivity (h5/h2 = 832).
Tumorigenesis is a complex process involving multiple genes. As a step toward understanding the complicated changes between normal and malignant cells, this report focused on gene expression profile variations among normal and abnormal esophageal epithelium tissues. The cDNA microarray approach was used to investigate gene expression profiles of 5 different stages during initiation and progression of esophageal cancer. According to pathological characteristics, these 5 stages were normal, dysplasia I (mild dysplasia), dysplasia II (moderate dysplasia), carcinoma in situ (CIS) and squamous cell carcinoma of esophagus (SCC). Comparing and analyzing those gene expression profiles, we observed that the expression levels of many genes changed in dysplasia I and some known tumor-related genes were over-expressed or under-expressed in all 4 abnormal stages. Using principle component analysis we identified a set of genes that may play an important role in tumor development. Hybridization data were confirmed by semi-quantitative reverse transcription-polymerase chain reaction and immunohistochemistry. These results suggest that cDNA microarray technology is a useful tool to discover genes frequently involved in esophageal neoplasia and provides novel clues to diagnosis, early detection and intervention of SCC.
We recently cloned a full-length cDNA of the rat ATP-binding cassette transporter 2 (ABC2, or ABCA2) protein, a member of the ABC1 (or ABCA) subfamily (-ABC1/ABCA1 is a causal gene for Tangier disease) and found it to be strongly expressed in the rat brain. In this study, we identified ABC2 as a lysosome-associated membrane protein that is being localized specifically in oligodendrocytes. The ABC2-immunolabeled cells were detected mainly in the white matter but were also scattered in gray matter throughout the whole brain. In addition, these cells were found to be colocalized with 2',3'-cyclic nucleotide-3'-phosphodiesterase (CNPase) immunoreactivity when the marker antibody for oligodendrocytes was used. However, no such colocalization was observed with markers for other kinds of glial cells. Unlike the CNP antibody, which also intensely stains myelin sheaths in the white matter, ABC2 immunoreactivity was detected only in the cell bodies of oligodendrocytes. At the ultrastructural level, ABC2 immunoreactivity was detected mostly around lysosome and partly in Golgi apparatus by electron microscopy. This was confirmed by immunocolocalization of ABC2 and lysosomal markers in a neuroblastoma cell line. Immunoblotting analysis of ABC2 from the whole brain and the ABC2-transfected cell line revealed bands at approximately 260 kDa. The result of in situ hybridization with a riboprobe for ABC2 matched the results obtained from immunostaining. These findings strongly suggest that ABC2 is a specific marker for oligodendrocytes but not for myelinsheaths and that it is as a novel mammalian lysosome-associated membrane protein involved in myelinization or other kinds of metabolism in the CNS.
We study synchronization regimes in a system of two coupled noisy excitable systems which exhibit excitability close to an Andronov bifurcation. The uncoupled system possesses three fixed points: a node, a saddle, and an unstable focus. We demonstrate that with an increase of coupling strength the system undergoes transitions from a desynchronous state to a train synchronization regime to a phase synchronization regime, and then to a complete synchronization regime. Train synchronization is a consequence of the existence of a saddle in the phase space. The mechanism of transitions in coupled noisy excitable systems is different from that in coupled phase-coherent chaotic systems.
The aim of this study was to explore the possibilities of non-surgical management for superficial carcinomas of the oesophagus and gastric cardia. Thirty-one patients with superficial oesophageal or gastric cardiac carcinomas, who refused or were unsuitable for surgery, received endoscopic Nd:YAG laser therapy combined with local injection of chemotherapeutic drugs 5-fluorouracil and mitomycin. After one to four sessions of treatment no cancer cells were detected by multiple biopsies and no complications such as bleeding or perforation occurred in any case. The 31 patients have been followed-up for 25-91 months (five cases for 91 months, eight cases for 79 months, four cases for 55 months, eight cases for 33 months and six cases for 25-31 months). All patients are surviving without sign of recurrence and no cancer cells were detected by endoscopic biopsies. Our findings indicate that this is an effective and safe therapeutic modality and may be considered as the first choice for those patients who refuse or are not suitable for surgery, and for those of older age and in poor condition.
Polysiloxane/liquid crystal composite membrane was first suggested to be used as biomaterials. In this work, the polydimethyl-methylhydrosiloxane and polydimethyl-methylethylenesilosiane, as a substrate, were blended with cholesteryl oleyl carbonate (COC) in tetrahydrofuran, and then crosslinked into membranes on glass plates by means of the platinum catalyst at 110 degrees C for 20 min. The effects of the liquid-crystal content in composite membranes on the formation of liquid-crystal phase were verified by the observation of optical polarization microscopy. The relationship between the morphology of the composite membranes and blood compatibility was identified by the dynamic blood-clotting tests, haemolysis ratio measurement, platelet adhesion and SEM observation. The results show that the blood-compatibility of composite membranes with the concentration of liquid crystal 20, 30% (wt) is more excellent than that of other composite membranes.
To explore the possible involvement of glutamate (Glu) in modulation of inner hair cell (IHC) functions, the glutamate (Glu) induced changes in intracellular free Ca(2+) ([Ca(2+)]i) concentration in isolated IHCs and outer hair cells (OHCs) of the guinea pig cochlea were investigated with fluo-3, a fluorescent probe for intracellular Ca(2+). Their unique flask shape identified the IHCs with a distinct neck and spherical base with a large spherical nucleus. Normal cell shapes could be maintained for about 2 h. Fluorescence of fluo-3 was distributed in the whole isolated IHC with brighter staining nuclei. Static [Ca(2+)]i remained constant within the observation period in the absence of Glu. In the presence of a low concentration of Glu (3.85 microM), there was an increase of [Ca(2+)]i in IHCs, whereas no obvious [Ca(2+)]i change was found in OHCs. The increase of the fluorescence in IHCs reached peak level at 180 s and then gradually reduced at 400 s after the administration of Glu. The increases of [Ca(2+)]i were observed in nine of 10 IHCs, but one IHC did not show any change. For 10 of the observed OHCs, seven showed no [Ca(2+)]i change, and three showed minor reduction of [Ca(2+)]i. The increase of the Glu concentration resulted in a corresponding change of [Ca(2+)]i in the IHCs after three times administration of Glu. These results suggest that Glu acts on the IHCs presynaptic autoreceptor in a positive feedback manner.
The neuronal ceroid lipofuscinoses (NCLs) are lysosomal storage diseases with severe neurodegenerative pathology. An ovine model (OCL) has well defined parallels with the human disease at a biochemical and pathological level. The gene for OCL is located in the chromosomal region OAR 7q13-15. This region is syntenic with HSA 15q21-23 suggesting that OCL and CLN6 represent mutations in orthologous genes. New microsatellite markers were used for refinement of the OCL critical region. YAC clones that span the critical region have been isolated and comparative gene mapping confirms that the regions for CLN6 and OCL are equivalent.
Self-assembly and aggregation of guanine rich sequences can provide useful insights into DNA nanotechnology and telomeric structure and function. In this paper, we designed a guanine rich sequence d(GGCGTTTTGCGG). We found that it can form stable structure in appropriate condition and it exhibits an anomalous CD spectra. This structures can be imaged in ambient environment with a Nanoscope III AFM (Digital Instruments). We found it forms branch structure and long multistrand DNA nanowire after incubation at 37 degrees C for 6-12 hours in 25 mM TE (pH=8.0) + 5 mM Mg2+ + 50 mM K+. The ability to self-assemble into branches and long wires not only clearly demonstrate its potential as scaffold structures for nanotechnology, but also give aids to understand telomeric structure further. We have proposed a model to explain how these structures formed.
In Saccharomyces cerevisiae, phospholipase D (PLD), encoded by the SPO14 gene, catalyzes the hydrolysis of phosphatidylcholine, producing choline and phosphatidic acid. SPO14 is essential for cellular differentiation during meiosis and is required for Golgi function when the normal secretory apparatus is perturbed (Sec14-independent secretion). We isolated specific alleles of SPO14 that support Sec14-independent secretion but not sporulation. Identification of these separation-of-function alleles indicates that the role of PLD in these two physiological processes is distinct. Analyses of the mutants reveal that the corresponding proteins are stable, phosphorylated, catalytically active in vitro, and can localize properly within the cell during meiosis. Surprisingly, the separation-of-function mutations map to the conserved catalytic region of the PLD protein. Choline and phosphatidic acid molecular species profiles during Sec14-independent secretion and meiosis reveal that while strains harboring one of these alleles, spo14S-11, hydrolyze phosphatidylcholine in Sec14-independent secretion, they fail to do so during sporulation or normal vegetative growth. These results demonstrate that Spo14 PLD catalytic activity and cellular function can be differentially regulated at the level of phosphatidylcholine hydrolysis.
An automated image analysis tool is being developed for the estimation of mammographic breast density. This tool may be useful for risk estimation or for monitoring breast density change in prevention or intervention programs. In this preliminary study, a data set of 4-view mammograms from 65 patients was used to evaluate our approach. Breast density analysis was performed on the digitized mammograms in three stages. First, the breast region was segmented from the surrounding background by an automated breast boundary-tracking algorithm. Second, an adaptive dynamic range compression technique was applied to the breast image to reduce the range of the gray level distribution in the low frequency background and to enhance the differences in the characteristic features of the gray level histogram for breasts of different densities. Third, rule-based classification was used to classify the breast images into four classes according to the characteristic features of their gray level histogram. For each image, a gray level threshold was automatically determined to segment the dense tissue from the breast region. The area of segmented dense tissue as a percentage of the breast area was then estimated. To evaluate the performance of the algorithm, the computer segmentation results were compared to manual segmentation with interactive thresholding by five radiologists. A "true" percent dense area for each mammogram was obtained by averaging the manually segmented areas of the radiologists. We found that the histograms of 6% (8 CC and 8 MLO views) of the breast regions were misclassified by the computer, resulting in poor segmentation of the dense region. For the images with correct classification, the correlation between the computer-estimated percent dense area and the "truth" was 0.94 and 0.91, respectively, for CC and MLO views, with a mean bias of less than 2%. The mean biases of the five radiologists' visual estimates for the same images ranged from 0.1% to 11%. The results demonstrate the feasibility of estimating mammographic breast density using computer vision techniques and its potential to improve the accuracy and reproducibility of breast density estimation in comparison with the subjective visual assessment by radiologists.
Studies of transient wave propagation in a single plate, a two-layer plate structure, and a two-layer-on-a-half-space structure are reported. Experimental results are used to verify the accuracy of a new model for wave propagation in layered solids. The experiments are performed using point load excitation and point detection at the surface of the layered structure. The basis of the new wave propagation model is first introduced. Then, experiments performed on a single plate are described. Results from different wave sources, plate materials, and wave sensors are compared with each other and with computed results from the model. The transient source function for a pencil-lead-break wave source is obtained. Next, the results of experiments performed on a two-layer plate structure (aluminum bonded to stainless steel) are reported. The cases of stainless steel atop aluminum and aluminum atop stainless steel are considered. The effects of the second layer on the transient displacement at the top surface are discussed. Finally, a two-layer-on-a-half-space structure consisting of a stainless steel plate as the top layer, an aluminum plate as the second layer and a thick acrylic resin block as the half-space is studied. The obtained experimental transient measurements agree with the computed results for all cases, thus verifying the accuracy of the model.
The number of phase levels in a Talbot array illuminator (TAIL) is an important factor for estimation of practical fabrication complexity and cost. We show that the number of phase levels in a two-dimensional TAIL (2D-TAIL) has a simple relation to the prime number. When the output array is alternatively pi phase modulated, there are similar simple relations. These simple relations should be highly interesting for practical use. An experiment with the 2D-TAIL based on the joint-Talbot effect is given as well.
Differential use of Chinese and western drugs, and combination of traditional theory of materia medica with the results of modern pharmacological research can be regarded as a general principle in the treatment of a disease, while combination of lowering blood pressure with preventing and treating complications is a specific method in the treatment of hypertension. As to the use of drugs based on differentiation of diseases and/or symptoms, drugs which have the action of relieving symptoms but also reducing blood pressure should be used as the first choice. For those drugs which have the action of relieving symptoms but can not lower blood pressure should not be used or should be used as less as possible. Drugs with action of raising blood pressure are contraindicated. When patients have the symptoms of hyperactivity of yang resulting from yin deficiency, Huang Bo ([symbol: see text] Cortex Phellodendri) and Zhi Mu ([symbol: see text] Rhizoma Anemarrhenae) are used together to enhance the effects of both nourishing yin to reduce pathogenic fire, and reducing blood pressure. This practice conforms to the TCM theory and also to the modern pharmacological research.
OBJECTIVE: To clarify the possible mechanisms which control p35(nck5a) neural-specific expression. METHODS: Thirteen luciferase expression vectors which contain different parts of 5'flanking sequence were constructed. Transient expression assay, DNase 1 hypersensitive site(DHSS) assay and primer extension assay were made to reveal the possible mechanisms of p35(nck5a) expression control. RESULTS: It was found that 5'flanking sequence of p35(nck5a) contained 5455bp and there were a few possible promoters in the fragment. The result of transient expression assay in primary cerebrum cortex cell of rat (Neuron) and established non-neuron cell such as HeLa showed the loss of neural-specific expression of all the luciferase expression vectors. The result of DNase 1 hypersensitive site assay revealed a DHSS located at the -400bp upstream of p35(nck5a) in brain but not in liver. The primer extension assay found the putative transcription initiation site near the position of DHSS. CONCLUSION: The results above suggest that there is no cis-element to control the neural-specific expression in the 5'flanking sequence, and the control on the chromosome level may be critical to the neural-specific expression of p35(nck5a).
The trace elements and heavy metals in the different growth stages of Ganoderma lucidum were analyzed by ICP-MS, AFS and AAS. The fermented mycelia, fruiting bodies and spore contained all kinds of detected trace elements and heavy metals, the contents of which were higher in spore. The content of Se was same in different growth stages. Ganoderma lucidum had the ability of bio-enrichment of Ge.
OBJECTIVE: To study the incidence, risk factors and clinical manifestation for ectopic pregnancy (EP) after in vitro fertilization and embryo transfer (IVF-ET). METHODS: A retrospective study of IVF and intracytoplasmic sperm injection (ICSI) pregnancies was performed between March 1998 and December 1999. RESULTS: A total of 432 woman conceived after IVF or ICSI were studied. The rate of EP was 3.9%, corresponding with 17 EPs, of which 4 (82.4%) were heterotopic pregnancy (HP). There were 14 EPs in tubal factor group, and 3(17.6%) in nontubal factor group. There appear to be no relationship between d 2 ET and d 3 ET, ovulation induction and age. The number of embryo transferred is 3.5 in EP and 4.1 in HP. CONCLUSIONS: Tubal pathology is associated with increased risk of EP. Close hormonal and ultrasonographic follow-up in pregnancies achieved in IVF treatments are recommended for early diagnosis and avoidance of further undesired consequences.
The effect of temperature(t) and soil water content(theta) on soil nitrogen mineralization under coniferous-broadleaved and spruce-fir coniferous forests was evaluated by using laboratory incubation method. Based on the analysis of inorganic nitrogen in soil extracts before and after incubation, it was showed that the net mineralization rate of soil nitrogen was positively related to t(alpha < 0.001) from 5 degrees C to 35 degrees C, and to water content when water contents was low, but there was a decrease in net mineralization rate when the water content was above an optimum value. The result suggested the interactive effect of temperature and moisture on the mineralization of soil nitrogen. Two dimensional (t, theta) equations to describe the effect were drawn up.