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Biomedical subjects

S Chen

Publications and source records attributed to S Chen.

At least 1,297 records · Page 72Linked to original sources
PubMed1992

[Identification of morphology and inorganic elements of Eucommia ulmoides Oliv. produced in Sichuan by applying scanning electron microscope with energy dispersive X-ray analysis].

A research on the identification of morphology and inorganic elements of Eucommia ulmoides produced in Sichuan has been made by applying scanning electron microscope; energy dispersive X-ray analysis. Qualitative and semi-quantitative analyses of the inorganic elements in the observed areas have been obtained.

Calcium↗
PubMed1992

[Growth regularities of yujin (Curcuma longa L.)].

Based on the characteristics of leaf, root and tuber growth as well as dry matter accumulation, the ontogeny of Yujin is divided into 4 stages. The growth and correlation among the leaf, root and tuber as well as accumulation of essential oils and curcumins have also been studied.

Curcumin↗
PubMed1992

Significance of the 56th tyrosine on cytotoxic activity of tumor necrosis factor.

After using site-specific mutagenesis a conserved amino acid residue, the 56th tyrosine in human tumor necrosis was substituted by glutamine. The expression level of the mutant protein in E. coli did not changed significantly, however, its specific activity of the cytotoxicity on L929 cultural cells was decreased to 1/583 of that of the unmutant tumor necrosis factor. The results show that the 56th tyrosine residue or the region where tyrosine 56th located is important for the cytotoxic activity of tumor necrosis factor.

Base Sequence↗
PubMed1992

[Investigation on the incidence of high altitude polycythemia and its hemoglobin characteristics in a Tibetan population].

The incidences of high altitude polycythemia (HAPC) and its hemoglobin characteristics in natives and immigrants at 2 different altitudes in the Tibet Autonomous Region were investigated. The results were as follows: 1) The incidences of HAPC among residents in Lhasa (3650 meters above sea level) and in Naqu-Ando district (4500-4800 meters above sea-level) were 2.39% and 12.95%, respectively. The incidence of HAPC increased with increasing altitude. The incidences in immigrants and in men were higher than those in natives and in women. 2) The MetHb concentration in RBC from patients with HAPC was 10.14%, distinctly higher than that in healthy adults (6.35%) in the same area. This may be one of the causes leading to oxygen carrying malfunction in the RBCs of HAPC patients. 3) The Mossbauer spectra of RBCs from patients with HAPC had a third component "c" in addition to the two normal components, oxy-Hb "a" and deoxy-Hb "b." The third component "c" may be adenatured Hb in the RBCs of the patients. The question of whether it is related to oxygen carrying power requires further study.

Adolescent↗
PubMed1992

[Changes in the nasal mucosal microvascular with allergic rhinitis].

The nasal mucosal microvascular of 37 patients with allergic rhinitis had been studied by nasal mucosal microcirculation microscope. It was found that the nasal mucosal microvascular diameter was wider after the nasal challenge test than before, but both after and before the nasal challenge test, the nasal mucosal microvascular diameter in patients with allergic rhinitis was narrower than in normal persons. The number of the microvascular in patients was also less than that in normal persons. The results indicate that the nasal mucosal microvascular with allergic rhinitis are characterized by dilated capacitance vessels and exchange vessels and constricted resistance vessels after nasal allergen challenge.

Adolescent↗
PubMed1992

[Dopa-induced dyskinesia in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated hemiparkinsonian monkeys].

Infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) into the right common carotid artery of 5 rhesus monkeys produced hemiparkinsonian syndrome in the contralateral limbs which responded to madopa or apomorphine therapy. Moreover, these two drugs induced circling away from the MPTP-treated side, amphetamine induced rotation toward the MPTP-treated side. Long-term use of madopa developed a peak-dose dyskinesia of the face and the limbs contralateral to the MPTP-treated side. The ipsilateral toxic effects were confirmed biochemically by reduction of nigrostriatal DA and histologically by degeneration of nigral neurons of the MPTP-treated side. It is concluded that this hemiparkinsonian model of rhesus monkey will be of value in the elucidation of the neural mechanism underlying L-DOPA or DA agonist induced dyskinesia in Parkinson's disease and in the search for newer methods of treatment which would produce less dyskinesia and response fluctuations.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1992

Use of baseline data for estimation of treatment effects in the presence of regression to the mean.

We consider a regression to the mean problem with a very large sample for the first measurement and relatively small subsample for the second measurement, selected on the basis of the initial measurement. This is a situation that often occurs in screening trials. We propose to estimate the unselected population mean and variance from the first measurement in the larger sample. Using these estimates, the correlation between the two measurements, as well as an effect of treatment, can be estimated in simple and explicit form. Under the condition that the size of the subsample is of a smaller order, the new estimators for all the four parameters are as asymptotically efficient as the usual maximum likelihood estimators. Tests based on this new approach are also discussed. An illustration from a cholesterol screening study is included.

Analysis of Variance↗
PubMed1992

The acute effect of topical epinephrine on macular blood flow in humans.

The acute effect of topical epinephrine HCl 2% on macular capillary blood flow was studied in 18 healthy human volunteers using the blue-field simulation technique. This technique provides a method for quantifying the velocity of leukocytes flowing in macular capillaries. Subjects adjusted the velocity of simulated leukocytes on a computer screen to match that of their own entoptically perceived leukocytes before instilling the drug and 2 hr thereafter. An artificial tear solution was instilled into the fellow eye for a control. Epinephrine instillation resulted in a 8% increase in macular leukocyte velocity and presumably blood flow (P less than 0.03, paired student t-test).

Administration, Topical↗
PubMed1992

Detection of intratumoral aromatase in breast carcinomas. An immunohistochemical study with clinicopathologic correlation.

The expression of aromatase was evaluated in 38 breast carcinomas by an immunohistochemical method (ABC) using an specific polyclonal antibody against human placental aromatase. Fifteen tumors (40%) showed significant immunoreactivity, as defined by cytoplasmic positivity of moderate intensity present in at least 15% of the cells. The results were correlated with the estrogen and progesterone hormone receptor status and several clinicopathologic parameters such as age, tumor size, lymph node status, and stage of the disease. There was a significant, but inverse, correlation between the aromatase activity and the estrogen receptor status (P = 0.04), indicating the likelihood of negative estrogen if substantial aromatase activity was present. No statistically significant correlation was found between the presence of intratumoral aromatase and the rest of the parameters studied (P greater than 0.7). Nor was there a correlation between the aromatase content of the tumors and the menopausal status. The degree of intratumoral heterogeneity of the aromatase content was minimal in six cases where multiple samples from each tumor were analyzed. This is the first study reporting the detection of aromatase in archival material from breast carcinomas using immunohistochemical techniques. The lack of biologic significance of its presence in breast cancer reported here and by others using biochemical assays should be validated in larger series with longer follow-up. The method described can be readily used for that objective.

Aromatase↗
PubMed1991

Liquid chromatographic method for the determination of calcium cyanamide using pre-column derivatization.

A specific and stability-indicating high-performance liquid chromatographic (HPLC) method has been developed for the analysis of calcium cyanamide in bulk material and dosage form. Calcium cyanamide in samples was converted into dansyl cyanamide. A muBondapak C18 column was employed for HPLC with 0.01 M sodium phosphate (pH 6.3)-acetonitrile (75:25, v/v) as the mobile phase. The proposed HPLC method was validated for linearity, specificity, accuracy and reproducibility.

Chromatography, High Pressure Liquid↗
PubMed1991

Localization of P-type calcium channels in the central nervous system.

The distribution of the P-type calcium channel in the mammalian central nervous system has been demonstrated immunohistochemically by using a polyclonal specific antibody. This antibody was generated after P-channel isolation via a fraction from funnel-web spider toxin (FTX) that blocks the voltage-gated P channels in cerebellar Purkinje cells. In the cerebellar cortex, immunolabeling to the antibody appeared throughout the molecular layer, while all the other regions were negative. Intensely labeled patches of reactivity were seen on Purkinje cell dendrites, especially at bifurcations; much weaker reactivity was present in the soma and stem segment. Electron microscopic localization revealed labeled patches of plasma membrane on the soma, main dendrites, spiny branchlets, and spines; portions of the smooth endoplasmic reticulum were also labeled. Strong labeling was present in the periglomerular cells of the olfactory bulb and scattered neurons in the deep layer of the entorhinal and pyriform cortices. Neurons in the brainstem, habenula, nucleus of the trapezoid body and inferior olive and along the floor of the fourth ventricle were also labeled intensely. Medium-intensity reactions were observed in layer II pyramidal cells of the frontal cortex, the CA1 cells of the hippocampus, the lateral nucleus of the substantia nigra, lateral reticular nucleus, and spinal fifth nucleus. Light labeling was seen in the neocortex, striatum, and in some brainstem neurons.

Animals↗