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Biomedical subjects

S Peng

Publications and source records attributed to S Peng.

At least 19 recordsLinked to original sources
PubMed2003

Neuron recognition by parallel Potts segmentation.

Identifying neurons and their spatial coordinates in images of the cerebral cortex is a necessary step in the quantitative analysis of spatial organization in the brain. This is especially important in the study of Alzheimer's disease (AD), in which spatial neuronal organization and relationships are highly disrupted because of neuronal loss. To automate neuron recognition by using high-resolution confocal microscope images from human brain tissue, we propose a recognition method based on statistical physics that consists of image preprocessing, parallel image segmentation, and cluster selection on the basis of shape, optical density, and size. We segment a preprocessed digital image into clusters by applying Monte Carlo simulations of a q-state inhomogeneous Potts model. We then select the range of Potts segmentation parameters to yield an ideal recognition of simplified objects in the test image. We apply our parallel segmentation method to control individuals and to AD patients and achieve recognition of 98% (for a control) and 93% (for an AD patient), with at most 3% false clusters.

Alzheimer Disease↗
PubMed2002

Claudin 5 is transiently expressed during the development of the retinal pigment epithelium.

During the development of chick retinal pigment epithelium (RPE), the permeability and selectivity of the epithelium's tight junctions are continuously modulated. Overall paracellular permeability decreases, but selectivity increases. Because the claudin family of transmembrane proteins appears to provide the structural basis for selectivity, we examined the expression of claudins as a function of development in chick RPE. Degenerate primers were used with the reverse transcriptase-polymerase chain reaction (RT-PCR) to obtain complete sequences of chick claudins 3 and 5. Northern blotting and semi-quantitative RT-PCR demonstrated that claudin 5 was expressed in RPE, but claudin 3 was expressed only in the choroid layer of the eye. Northern blotting, semiquantitative RT-PCR and immunoblotting demonstrated that the expression of claudin 5 was transient, with peak levels of expression between embryonic days 10 and 14. Primary cultures were used to demonstrate that factors secreted by the neural retina induced the expression of claudin 5 nearly 3-fold if RPE was isolated from embryonic day 7 embryos. There was little effect if RPE was isolated from embryonic day 14. The upregulation of claudin 5 correlates with permeability changes that occur during the intermediate stage of RPE development. Interestingly, claudin 5 must be replaced during the late stage of development when the number and complexity of tight junctional strands increases. This would imply more changes in selectivity.

Amino Acid Sequence↗
PubMed2001

Synthesis and analgesic effects of kyotorphin-steroid linkers.

Kyotorphin (KTP, H-Tyr-Arg-OH) was covalently bonded with hydrocortisone or estrone to form the corresponding hydrocortisone-21-O-yl-succinyl-Tyr-ArgOH or estrone-3-O-yl-acyl-Tyr-Arg-OH. Their analgesic activities were investigated using the tail flick test. The potency of the two linkers were significantly higher than that of KTP and the mixture of KTP and hydrocortisone or estrone in the CNS and/or the periphery administration.

Analgesics↗
PubMed2001

Formation of novel polymeric nanoparticles.

We have found that not only block copolymers but also ionomers can self-assemble in a selective solvent to form surfactant-free nanoparticles. The self-assembly can be induced by chemical reaction, polymer-polymer complexation, and microphase inversion in addition to the temperature. A recently developed microwave method for the preparation of uniform surfactant-free polymeric nanoparticles is also reviewed. Our results have revealed that for a given dispersion, the particle surface area occupied per stabilizer (surfactant, polymer chains, and ionic groups) is close to a constant.

Microspheres↗
PubMed2001

Melanocortin-1 receptor gene variants in four Chinese ethnic populations.

There is strong relationship between melanocortin-1 receptor (MC1R) gene variants and human hair color and skin type. Based on a sequencing study of MC1R gene in 50 individuals from the Uygur, Tibetan, Wa and Dai ethnic populations, we discuss the occurrence of 7 mc1r variants consisting of 5 nonsynonymous sites (Val60Leu, Arg67Gln, Val92Met, Arg163Gln and Ala299Val) and 2 synonymous sites (C414T and A942G), among which C414T and Ala299Val were reported for the first time. Confirmation and analysis were also made of 122 individuals at three common point mutations (Val92Met, Arg163Gln, A942G) using PCR-SSCP. The frequency of Arg163Gln variant varies in the four ethnic populations, with percentage of 40%, 85.0%, 66.2% and 72.7%, respectively, while those of Val92Met and A942G are roughly similar in these four populations. The different environments, migration and admixture of various ethnic groups in China might have impact on the observed frequency of Arg163Gln.

Alleles↗
PubMed2001

Indigenization and beyond: methodological relationalism in the study of personality across cultural traditions.

A brief intellectual history of the indigenization movement in Asia leads to the thesis that the generation of psychological knowledge is culture dependent. Indigenous psychologies go further and insist on viewing a target group from the natives' own standpoint. Psychological decentering underlies conceptions of human existence rooted in Asian intellectual traditions, in particular, relatedness between persons predominates in Confucianism. These conceptions demand new approaches to knowledge generation that signify a paradigmatic shift from methodological individualism to methodological relationalism. An implication is that relationships precede situations in the study of personality and social behavior. We define personality as the sum total of common attributes manifest in, and abstracted from, a person's behavior directly or indirectly observed across interpersonal relationships and situations over time. We rely on the notion that there are identifiable levels of cognition to develop a metatheoretical framework for reconstructing selfhood. Confronting the subject-object dichotomy opens the door to investigations of transcendent consciousness; confronting the self-other demarcation underlying Western theories leads to the construction of self-in-relations.

Cross-Cultural Comparison↗
PubMed2001

[The development of multi-lead EEG telemetry and tele-monitoring system].

This paper introduces a kind of EEG Telemetry and Tele-monitoring system. With the use of the public telephone network to transport signals and the portable EEG recording system as the sender of system, the EEG data of 20 standard leads can be transmitted to the receiver of system (monitoring center) synchronously. And at the monitoring center, the waves can be displayed real-time, freezing, stored, reviewed, analyzed and printed, thus providing aid in remote diagnosis and treatment consultations.

Computer Communication Networks↗
PubMed2001

[Association of apolipoprotein E gene polymorphism with early-onset coronary heart disease and its effect on plasma lipid levels].

OBJECTIVE: To detect the association of apolipoprotein E(apoE) gene polymorphism with early-onset coronary heart disease(CHD) and to evaluate the effect of apoE gene polymorphism on plasma lipid levels. METHODS: The apoE genotypes of 52 early-onset CHD patients (aged 38-55 years), 161 aged CHD patients and 180 controls were determined by PCR-RFLP. Plasma lipid levels were measured by using routine methods. RESULTS: Five genotypes of apoE, E3/3, E4/4, E3/2, E4/3 and E4/2 were detected in this study. Statistically differences in apoE4/3 and epsilon4 frequencies between early-onset and aged CHD patients and controls were seen (P<0.05). The frequency of epsilon4 in the early-onset CHD patients was higher than that in the aged CHD patients. epsilon4 and epsilon2 alleles also differently affected the plasma total cholesterol and low density lipoprotein cholesterol levels. CONCLUSION: These results suggest that apoE gene polymorphism is in association with the occurrence and development of early-onset CHD and it affects the plasma lipid levels.

Adult↗
PubMed2001

[Influence of elevated atmospheric CO2 concentration on photosynthesis and leaf nitrogen partition in process of photosynthetic carbon cycle in Musa paradisiaca].

The photosynthetic rate (Pn) in leaves of Musa paradisiaca grown under elevated CO2 concentration (700 +/- 56 microliters.L-1) for one week was 5.14 +/- 0.32 mumol.m-2.s-1, 22.1% higher than that under ambient CO2 concentration, while under elevated CO2 concentration for 8 week, the Pn decreased by 18.1%. It can be inferred that the photosynthetic acclimation to elevated CO2 concentration and the Pn inhibition occurred in leaves of M. paradisiaca. The respiration rate in light (Rd) was lower in leaves under higher CO2 concentration, compared with that under ambient CO2 concentration. If the respiration in light was not included, the difference in CO2 compensation point for the leaves of both plants was not significant. Under higher CO2 concentration for 8 weeks, the maximum carboxylation rate(Vcmax) and electron transportation rate (J) in leaves decreased respectively by 30.5% and 14.8%, compared with that under ambient CO2 concentration. The calculated apparent quantum yield (alpha) in leaves under elevated CO2 concentration according to the initial slope of Pn/PAR was reduced to 0.014 +/- 0.010 molCO2.mol-1 quanta, compared with the value of 0.025 +/- 0.005 molCO2.mol-1 quanta in the control. The efficiency of light energy conversion also decreased from 0.203 to 0.136 electrons.quanta-1 in plants under elevated CO2 concentration. A lower partitioning coefficient for leaf nitrogen in Rubisco, bioenergetics and thylakoid light-harvesting components was observed in plants under higher CO2 concentration. The results indicated that the multi-process of photosynthesis was suppressed significantly by a long-term (8 weeks) higher CO2 concentration incubation.

Carbon Dioxide↗
PubMed2001

[Species and species diversity in relation with restoration and persistence of degraded ecosystem functions].

Species diversity is an important character of an ecosystem, and keeps it to function. Species diversity and their communities provide human with essential ecosystem services, including nutrient cycling, biological productivity, trophic function, etc. Species diversity is tightly related with the ecosystem's ability to withstand stress and disturbance. Increasing biodiversity could enhance system stability. Compared to individual species and species number, functional group and functional diversity impose larger impact on system functioning, and are good approaches used to measure stability and to predict community change. Several forms with which the species act on ecosystem functioning were proposed and discussed in this paper. Understanding the relationship between species diversity and ecosystem function could guide the practice of restoring degraded ecosystem and maintaining its functions. Particularly, it provides basic ecological theories for "species assemblage" at initial stage of restoration.

Ecosystem↗
PubMed2001

[Antimetastatic effects of arginine-aspartate on salivary adenoid cystic carcinoma in vitro].

OBJECTIVE: To test the effects of arginine-aspartate (RD) on metastasis of salivary cystic carcinoma (SACC). METHODS: Highly metastatic SACC cell line SACC-LM was used in the study. The effect of RD on tumor cell-ECM adhesion was assayed by MTT technique. The effect of RD on invasion and migration of SACC-LM were evaluated using modified boyden chamber. RESULTS: RD inhibited tumor cell fibronectin adhesion at 5 mg/L concentration, but no effects on tumor cell laminin and tumor cell type IV collagen adhesion. RD inhibited the invasion at 1, 5, 25 mg/L, and inhibited the migration only at 25 mg/L. CONCLUSIONS: The result shows that the RD has an antimetastatic effect on SACC-LM cells in vitro.

Antineoplastic Agents↗
PubMed2001

[The development of computerized cardiac programmable stimulator].

This paper introduces a fully computerized cardiac programmable stimulator. With the visual interface of computer, the configuration and control of stimulation will be realized conveniently. Meanwhile, the current status and the waves during stimulation will be displayed in window real-time, which improved the visualization and availability in medical application. It has been proved that this system is simpler in operation and more functional than traditional cardiac programmable stimulators, and therefore it is valuable in medical applications.

Electric Stimulation↗
PubMed2001

[The development of an all-purpose medical electronic teaching instrument].

This paper introduces a kind of all-purpose medical electronic teaching instrument. According to the modularization design rule, a medical electronic teaching instrument integrated with information transfer, signal processing, keyboard monitoring and signal sampling, etc, can be realized. On the other hand, A/D, D/A, self-detecting of computer, collecting and testing of biological potentials, driving electromotor and generating functional signals, etc can also be realized by the related software based on the system. It has been proved that, by using single-chip processor and computer, the system can implement full-scale test and processing of biomedical signals so that operators can understand the principles and the construction of medical instruments more easily and deeply. Therefore, it is valuable in application of medical electronic coursesteaching, research and etc.

Computer-Assisted Instruction↗
PubMed2001

[Study of chemical constituents of essential oil from flowers of Mikania micrantha H.B.K].

The essential oil from flowers of Mikania micrantha H.B.K were extracted and its chemical constituents were analyzed by GC/MS. Forty-two compounds were identified and the main compounds with high contents were beta-cubebene (12.95%), allo-aromadendrene (11.67%), beta-caryophyllene (9.17%), 1H-inden-1-one, 5-(1, 1-dimethylethyl)-2, 3-(6.23%), beta-himaohalene (4.56%), trans-alpha-bergamotene (4.09%), limonene (3.68%), beta-ocimene (2.53%).

Azulenes↗
PubMed2001

[Determination of 10 elements in the 12 kinds of Chinese traditional medicines by AAS].

The 10 kinds of inorganic elements were determined in 12 kinds of Chinese traditional medicines. The relation showed that there were numerous inorganic elements in the traditional chinese medicines. The relation between these inorganic elements and the efficacies of these medicines was studied and the efficacies of these Chinese traditional medicines were discussed. The efficacies of these traditional medicines were greatly influenced by the content of inorganic elements. To guarantee the efficacies of these traditional medicines, the reasonable control lines concerned with the content of inorganic elements shall be established and the lines will be discussed in the future.

Calcium↗
PubMed2000

Abnormal chloride and potassium conductances in cultured embryonic tongue muscle from trisomy 16 mouse.

Trisomy 16 (Ts16) mouse is considered an animal model of Down syndrome (human trisomy 21). Whole-cell patch-clamp was used to evaluate potassium and chloride currents of cultured tongue muscle cells from fetal Ts16 and diploid mice. No difference was found in membrane capacitance between the two groups. K(+) and Cl(-) currents were pharmacologically isolated. K(+) conductance was reduced by 31% in Ts16 cells (373 pS/pF) compared with diploid cells (539 pS/pF). Cl(-) conductance was 51% larger in Ts16 cells (103 pS/pF) compared with diploid cells (68 pS/pF). However kinetics for K(+) and Cl(-) currents did not differ between the cell types. An increase in Cl(-) conductance and a decrease in K(+) conductance in Ts16 muscle cells, if present in muscle of Down syndrome subjects, might account for the observed hypotonia in these subjects.

Animals↗