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Biomedical subjects

J Si

Publications and source records attributed to J Si.

At least 37 records · Page 2Linked to original sources
PubMed1999

[Isolating, cloning, and sequencing of HPV16E6E7 gene from a cervical carcinoma biopsy in Shandong Province].

OBJECTIVE: In order to study the structure specificity of HPV16E6E7 gene of a Chinese patient of cervical carcinoma in Shandong province. METHODS: The tissue DNA were abstracted from cervical carcinoma biopsies and the type of HPV was identified by HPV multiple primers PCR. HPV16E6E7 gene was amplified by PCR from the cervical carcinoma tissue DNA with the infection of HPV16 type only, and then cloned the E6E7 gene into pALTERI vector. After sequencing the double strand, the gene was compared with the prototype E6E7 gene of HPV16. RESULTS: A new recombinant plasmid was constructed and named HPV16E6E7-SD. Sequencing results showed one mutation in HPV16E6E7-SD, the 557th neocleotide in the viral neocleotide sequence "T" was changed into "C", and caused the termination cordon TAA of E6 gene to convert into a Gln cordon CAA. CONCLUSIONS: There is a structure difference between HPV16E6E7-SD and the standard strain.

Base Sequence↗
PubMed1999

[A study on the relationship between tree age and bark quality in Magnolia officinalis].

Contents of magnolol and honokiol in 76 samples of Magnolia officinalis collected from 11 counties in Zhejiang, Fujian, Sichuan, Guangxi, Hunan, Jiangxi and Hubei are analyzed by means of HPLC. A study on the effect of tree age on effective ingredients in Magnolia offcinalis shows that the influence of tree age on the content of magnolol and honokiol is correlated with the varieties under cultivation, but a small effect on the content of the phenols with an indent at the tip of leaves. The content of magnolol in other types of leaves increases rapidly with increase in age, diameter of the trunk and thickness of the bark, with not many changes found at the age of 12 or up. Increase in age may be favorable to the full expression of oily characteristic. These results provide a scientific base for the determination of optimal time for harvesting bark from artificially established Magnolia officinalis stands.

Age Factors↗
PubMed1998

Weight-value convergence of the SOM algorithm for discrete input.

Some insights on the convergence of the weight values of the self-organizing map (SOM) to a stationary state in the case of discrete input are provided. The convergence result is obtained by applying the Robbins-Monro algorithm and is applicable to input-output maps of any dimension.

Algorithms↗
PubMed1998

A systematic and effective supervised learning mechanism based on Jacobian rank deficiency.

Most neural network applications rely on the fundamental approximation property of feedforward networks. Supervised learning is a means of implementing this approximate mapping. In a realistic problem setting, a mechanism is needed to devise this learning process based on available data, which encompasses choosing an appropriate set of parameters in order to avoid overfitting, using an efficient learning algorithm measured by computation and memory complexities, ensuring the accuracy of the training procedures as measured by the training error, and testing and cross-validation for generalization. We develop a comprehensive supervised learning algorithm to address these issues. The algorithm combines training and pruning into one procedure by utilizing a common observation of Jacobian rank deficiency in feedforward networks. The algorithm not only reduces the training time and overall complexity but also achieves training accuracy and generalization capabilities comparable to more standard approaches. Extensive simulation results are provided to demonstrate the effectiveness of the algorithm.

Algorithms↗
PubMed1998

Regulation by ARIA/neuregulin of acetylcholine receptor gene transcription at the neuromuscular junction.

Transcription of genes encoding nicotinic acetylcholine receptor (AChR) subunits (alpha, beta, gamma or epsilon, and delta) is highest in nuclei localized to the synaptic region of the muscle which contributes to maintain a high density of AChRs at the postjunctional membrane. ARIA (AChR inducing activity) is believed to be the trophic factor utilized by motor neurons to stimulate AChR synthesis in the subsynaptic area. ARIA stimulates tyrosine phosphorylation of the erbB proteins and activates the MAP kinase pathway which is required for the ARIA-mediated induction of AChR genes.

Animals↗
PubMed1998

[Cloning of human papillomavirus type 16 E7 gene and expression in E. coli].

OBJECTIVE: To study the biological activity of the E7 gene of human papillomavirus 16 (HPV16). METHODS: E7 gene from the cervical carcinoma of Chinese women was amplified by the PCR. The E7 DNA was sequenced and compared with the prototype E7 gene of HPV 16. RESULTS: It showed no mutations. However when E7 gene was inserted into the prokaryotic expression vector pGEX-2T and the fused E7 protein was efficiently expressed in E. Coli (DH5 alpha). The E7 antibody could combine specifically with this fused protein by Western blot technique. CONCLUSIONS: The result might aid for epidemiological investigation and preparation of the vaccine.

Base Sequence↗
PubMed1998

[Chemical constituents of the leaves of Crataegus scabrifolia (Franch.) Rehd].

OBJECTIVE: To explore the medicinal resources of Crataegus and seek compounds with pharmaceutical effects. METHOD: Column chromatography was employed for the isolation and purification of constituents and the structures were elucidated by spectral analysis and chemical evidence. RESULT: Six compounds were obtained and identified as rutin, hyperoside, vitexin, ursolic acid, daucosterol, and nonacosanol. CONCLUSION: The main constituents of the leaves of Crataegus scabrifolia are flavonoids.

Crataegus↗
PubMed1998

[Human interleukin-13 cDNA cloning and expression].

OBJECTIVE: To construct an efficient expression system for HIL-13 in prokaryotic cells. METHODS: After Amplified by RT-PCR, The cDNA fragment encoding HIL-13 was inserted into pGEX-2T plasmid and expressed under induced condition. RESULTS: HIL-13 cDNA was obtained. Recombinant plasmid pGEX-2T HIL-13 was constructed and sequenced, the inserted fragment of the recombinant plasmid was confirmed to be HIL-13 cDNA. HIL-13 was expressed as a fusion protein with glutathione-s-transferase (GST-HIL-13, MW = 39,000). CONCLUSIONS: (1) HIL-13 cDNA has been obtained from T lymphocytes. (2) The rate of expression of HIL-13 in prokaryotic cells is about 37%.

Amino Acid Sequence↗
PubMed1998

[Study on the relationship between provenance, leaf type and quality in Magnolia officinalis].

An analysis of effective ingredients in 20 to 29 year old Magnolia officinalis of three different leaf types coming from various sources shows that the content of phenols differ extremely significantly in various leaf types which are a key to determination of quality of Magnolia officinalis also varies significantly among different sources which only have a significant effect on the content of magnolol. Varieties and types cultivated in different places are responsible for the variation in content of magnolol. The conclusions obtained from this study coincide with the traditional insight into quality of Magnolia officinalis.

Biphenyl Compounds↗
PubMed1997

Identification of an element required for acetylcholine receptor-inducing activity (ARIA)-induced expression of the acetylcholine receptor epsilon subunit gene.

Acetylcholine Receptor (AChR)-inducing activity (ARIA) is believed to be the trophic factor utilized by motoneurons to stimulate AChR synthesis in the subsynaptic area. Among the four AChR subunit genes, the epsilon subunit gene is strictly expressed in nuclei localized to the synaptic region of the muscle. To understand mechanisms of the regulation of synapse-specific transcription, we studied the promoter activity of the 5'-flanking region of the AChR epsilon subunit gene in response to ARIA. Transgenes containing the wild type or mutant 5'-flanking regions upstream of a luciferase gene were transfected in C2C12 muscle cells. The promoter activity of these transgenes was determined by assaying activity of expressed luciferase. Analyzing a combination of 5' deletion and site-directed mutants, we identified a 10-nucleotide element (position -55/-46), which was crucial for ARIA-induced expression from the epsilon subunit promoter. This element was named ARE for ARIA-responsive element. Mutation of ARE greatly diminished ARIA-induced transgene expression and deletion of ARE abolished completely the ARIA response. Electrophoretic mobility shift analyses revealed a DNA binding activity in muscle nuclear extract that interacted with ARE. Such interaction was enhanced by ARIA stimulation of muscle cells and appeared to be dependent on nuclear protein phosphorylation.

Animals↗
PubMed1997

Self-organization of firing activities in monkey's motor cortex: trajectory computation from spike signals.

The population vector method has been developed to combine the simultaneous direction-related activities of a population of motor cortical neurons to predict the trajectory of the arm movement. In this article, we consider a self-organizing model of a neural representation of the arm trajectory based on neuronal discharge rates. As self-organizing feature map (SOFM) is used to select the optimal set of weights in the model to determine the contribution of an individual neuron to an overall movement representation. The correspondence between movement directions and discharge patterns of the motor cortical neurons is established in the output map. The topology-preserving property of the SOFM is used to analyze the recorded data of a behaving monkey. The data used in this analysis were taken while the monkey was tracing spirals and doing center-->out movements. The arm trajectory could be well predicted using such a statistical model based on the motor cortex neuronal firing information. The SOFM method is compared with the population vector method, which extracts information related to trajectory by assuming that each cell has a fixed preferred direction during the task. This implies that these cells are acting along lines labeled only for direction. However, extradirectional information is carried in these cell responses. The SOFM has the capability of extracting not only direction-related information but also other parameters that are consistently represented in the activity of the recorded population of cells.

Algorithms↗
PubMed1996

Induction of acetylcholine receptor gene expression by ARIA requires activation of mitogen-activated protein kinase.

Transcription of genes encoding nicotinic acetylcholine receptor (AChR) subunits (alpha, beta, gamma or epsilon, and delta) is highest in nuclei localized to the synaptic region of the muscle, which contributes to maintain a high density of AChRs at the postjunctional membrane. ARIA (AChR inducing activity) is believed to be the trophic factor utilized by motor neurons to stimulate AChR synthesis in the subsynaptic area. To elucidate the signaling mechanism initiated by ARIA, we established stable C2C12 cell lines carrying the nuclear lacZ gene under the control of the mouse epsilon subunit promoter or chicken alpha subunit promoter. ARIA stimulated tyrosine phosphorylation of erbB proteins in these C2C12 cells within 15 s with a peak at 5 min. Immediately following tyrosine phosphorylation of erbB proteins, mitogen-activated protein (MAP) kinase was activated which occurred within 30 s and peaked at 8 min after ARIA stimulation. Concomitantly, expression of AChR genes was induced by ARIA. ARIA-induced AChR subunit transgene expression was observed only in differentiated myotubes and not in myoblasts, suggesting that downstream signaling component(s) are regulated in a manner dependent on the myogenic program. Inhibition of the MAP kinase activity by using a specific MAP kinase kinase inhibitor or by overexpressing dominant negative mutants of Raf or MAP kinase kinase attenuated or abolished the ARIA-induced activation of AChR alpha and epsilon subunit gene expression. These results indicate that regulation of AChR gene expression by ARIA in C2C12 cells requires activation of the MAP kinase signaling pathway.

Androstadienes↗
PubMed1996

Differentiation of pseudocondyloma of vulva and condyloma acuminata by dot blot hybridization and polymerase chain reaction.

This study differentiated pseudocondyloma of vulva from condyloma acuminata using dot blot hybridization and polymerase chain reaction (PCR). A total of 27 cases of pseudocondyloma of vulva and 65 cases of condyloma acuminata were selected for the study. The genital lesions were examined clinically and were biopsied. Each biopsy was subjected to histological examination and HPV DNA analysis by dot blot hybridization and PCR. Dot blot analysis detected HPV DNA in 19(82.6%) out of 23 cases of condyloma acuminata and 2(25%) out of 8 cases pseudocondyloma of vulvae (P < 0.05). PCR detected HPV DNA in 51(92.7%) out of 55 cases of condyloma acuminata, compared with none in 23 cases of pseudocondyloma (P < 0.001). HPV DNA was present in the majority of condyloma acuminata specimens, HPV 6 and 11 were the predominant types. Peudocondyloma is probably not associated with HPV. PCR was the most sensitive and useful technique for HPV DNA detection.

Adolescent↗
PubMed1995

A computationally efficient method for solving the redundant problem in biomechanics.

Determining the optimal set of musculotendon forces with which to produce a forward dynamic simulation of movement typically involves a huge investment of time and computational resources. A new, computationally efficient method is proposed that simultaneously achieves the desired trajectory and the dynamically optimized set of muscle stresses, and hence forces, according to the maximal endurance criterion function of Crowninshield and Brand (1981). Muscle-induced accelerations of the system resulting from unit stress contractions of individual muscles are superposed via the new pseudoinverse method to yield the desired motion trajectory. The method is tested on a control problem involving a five degree-of-freedom (DOF), 30 muscle, upper extremity model, which incorporates a dual rigid-body forearm to represent pronation and supination more adequately. The pseudoinverse method delivered the desired motion to within 0.25 degrees for each DOF during a three-second simulation. It is anticipated that the methodology can be easily and accurately applied to other highly redundant optimal control problems in biomechanics.

Acceleration↗
PubMed1995

Tyrosine phosphorylation and synapse formation at the neuromuscular junction.

Protein tyrosine phosphorylation is prevalent throughout the nervous system. It has been implicated to play an important role in the development and maintenance of neuronal functions. In the past few years significant advances have been made in our understanding of the molecular mechanisms of synapse formation and synaptic plasticity. Protein tyrosine phosphorylation appears to be important in the neuron-induced synthesis of the nicotinic acetylcholine receptor and aggregation of synaptic proteins at the neuromuscular junction during development. In addition, protein tyrosine phosphorylation may regulate the ion channel activity of the nicotinic acetylcholine receptor.

Animals↗