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Biomedical subjects

X C Chen

Publications and source records attributed to X C Chen.

At least 19 recordsLinked to original sources
PubMed1998

Effect of taurine on human fetal neuron cells: proliferation and differentiation.

The purpose of this study was to investigate the effect of taurine on human fetal brain neuron cell proliferation and differentiation using a glial-free, pure cerebral neuronal culture grown in a serum-free environment. We found that taurine was necessary for neuronal survival and neurite extension. Taurine, on the other hand, has a trophic effect on the human fetal brain cell, promoting both proliferation and differentiation. Results showed that DNA synthesis of the neurons was increased in a dose-dependent manner when neurons were cultured in the medium containing taurine (100-6400 microM). The protein content of neuronal cells was also significantly increased in the neurons treated with taurine as compared to the control. At day 15, the expression of neuron-specific enolase (NSE) was only detected in the neurons cultured in the medium containing taurine. These results establish taurine as a putative human fetal brain neurontrophic factor in the process of human brain development.

Brain↗
PubMed1998

Effects of repletion with zinc and other micronutrients on neuropsychologic performance and growth of Chinese children.

The knowledge that zinc is essential for growth and neuropsychologic performance and a report of zinc-responsive stunting in Chinese children prompted this project. This article summarizes findings from a 10-wk, double-blind, controlled trial of zinc repletion in 740 urban, 6-9-y-old first graders from low-income families in Chongqing, Qingdao, and Shanghai, People's Republic of China. Treatments were 20 mg Zn alone (Z), 20 mg Zn with micronutrients (ZM), and micronutrients alone (M). The M mixture was based on National Research Council guidelines. Nutrients that might interfere with zinc retention were excluded or given in lower amounts. Main outcomes were changes in neuropsychologic performance and knee height. Hemoglobin, serum ferritin, plasma and hair zinc, and whole blood and hair lead were also measured. Anemia was not common, and serum ferritin concentrations were usually within the range of normal. Mean baseline plasma zinc concentrations were marginal in children from Chongqing and Qingdao and normal in children from Shanghai. After treatment with ZM or M plasma zinc increased. Hair zinc tended to decrease after all treatments. Mean baseline whole blood lead concentrations were slightly below the limit considered excessive for children by the US Centers for Disease Control and Prevention. Neuropsychologic performance and growth were most improved after treatment with ZM. These findings were consistent with the presence of zinc and other micronutrient deficiencies.

Brain↗
PubMed1997

A preliminary report: effects of zinc and micronutrient repletion on growth and neuropsychological function of urban Chinese children.

OBJECTIVE: Zinc is essential for growth and cognition of experimental animals. Past research found zinc repletion improved growth of stunted Chinese children. Therefore we measured effects of zinc repletion on growth and neuropsychological functions of children. DESIGN: Double-blind randomized controlled treatment trial. SETTING: Elementary schools in low income districts of Chongqing, Qingdao and Shanghai. SUBJECTS: Three hundred-seventy-two 6 to 9 year old first graders. INTERVENTIONS: Treatments were 20 mg zinc, 20 mg zinc with micronutrients, or micronutrients alone. The micronutrient mixture was based on guidelines of the US NAS/NRC. Treatments were assigned to classrooms of 40 or more children each, and administered by teachers 6 days per week for 10 weeks. MEASURES OF OUTCOME: Changes in knee height and neuropsychological functions. RESULTS: Zinc alone had the least effect on growth while zinc with micronutrients had the largest effect; micronutrients alone had an intermediate effect. Zinc-containing treatments improved neuropsychological functions, but micronutrients alone had little effect. CONCLUSIONS: The findings confirm the essentiality of zinc for growth of children, and show, for the first time, the essentiality of zinc for neuropsychological functions of children. In addition, the need for repletion of other potentially limiting nutrients in studies examining the effects of specific nutrients on growth and neuropsychological functions was confirmed.

Analysis of Variance↗
PubMed1996

Characterization of a recombinant chimeric plasminogen activator composed of Gly-Pro-Arg-Pro tetrapeptide and truncated urokinase-type plasminogen activator expressed in Escherichia coli.

A chimeric plasminogen activator, GPRP-u-PA (144-411), consisting of the Gly-Pro-Arg-Pro tetrapeptide fused to the N-terminal of a truncated urokinase-type plasminogen activator (comprising Leu 144 through Leu 411), was produced by expression of the corresponding chimeric cDNA in Escherichia coli cells. After renaturation, the chimera was purified to homogeneity with specific amidolytic activity of 100,000 IU/mg protein. The chimera showed 6-fold greater affinity for fibrin clots than native low molecular weight urokinase (LUK) and 1.5-fold greater affinity than a chemical conjugate, GPRP-LUK, generating via coupling Gly-Pro-Arg-Pro tetrapeptide to native low molecular weight urokinase. The chimera had 2 to 3 fold greater fibrinolytic potency than native LUK in vitro. Fibrinogen had no influence on fibrinolysis of the chimera. The chimera consumed much less fibrinogen than native LUK.

Base Sequence↗
PubMed1996

Chemical conjugation of Gly-Pro-Arg-Pro. Tetrapeptide to low molecular weight urokinase.

Two low molecular weight urokinase derivatives were obtained by covalent coupling of a synthetic Gly-Pro-Arg-Pro tetrapeptide to peptide A of low molecular weight urokinase and exchanging the native peptide A of low molecular weight urokinase with Gly-Pro-Arg-Pro-peptide A to obtain derivative I or direct conjugation of Gly-Pro-Arg-Pro tetrapeptide to low molecular weight urokinase to obtain derivative II. In caseinolytic assay, fibrin can stimulate the two derivatives to activate plasminogen. But the two derivatives showed different kinetic behaviors. The derivative I displayed immediate onset of lysis and derivative II displayed a lag phase.

Caseins↗
PubMed1996

A low molecular weight urokinase derivative with enhanced fibrin affinity.

A Gly-Pro-Arg-Pro tetrapeptide, homologous to amino-terminal segment of the human fibrin alpha chain after the release of the fibrinopeptide A, was covalently coupled to peptide A of low molecular weight urokinase. The resulting derivative gained increased affinity for fibrin. In caseinolytic assay, fibrin can stimulate the derivative to activate plasminogen. The derivative had two-fold greater fibrinolytic potency than native low molecular weight urokinase and its affinity for fibrin clot was 3.9-fold higher than that of low molecular weight urokinase.

Chromatography, Affinity↗
PubMed1994

Seasonal and geographical variations in the growth rate of infants in China receiving increasing dosages of vitamin D supplements.

In theory, sunshine exposure is sufficient to maintain normal vitamin D concentrations for the optimal growth of newborn infants. To determine whether season of birth, latitude (north v. south) and increasing dosages of vitamin D supplements would influence the growth rate for the first 6 months of life, 255 healthy fall-and spring-born infants from two northern and two southern cities in China were randomly assigned to receive either 100, 200, or 400 IU of vitamin D a day. The study showed that season of birth and dose of vitamin D did not affect the growth rate of infants born in the same latitude, but a significant difference was found in the gain in length over the 6-month period between infants from the north and infants from the south (P = 0.0001). Regional differences among the Chinese people, other than sunshine exposure, may have influenced the difference in length gain.

Anthropometry↗
PubMed1993

Prevalence and type of anaemia in female cotton mill workers in Beijing, China.

The present study investigates the prevalence and type of anaemia in Chinese female cotton mill workers. The prevalence of anaemia is reported in 447 non-pregnant female workers aged between 19 and 45 years. The mean value for haemoglobin (Hb) was 123 (SD 15) g/l and 150 of the total 447 subjects had Hb values below 120 g/l; thus 34% of the population was anaemic according to World Health Organization (WHO, 1975) criteria. The mean value for free erythrocyte protoporphyrin (FEP) was 419 (SD 215) micrograms/l; 55% of the total population had FEP values higher than 350 micrograms/l and 72% among the anaemic subjects. Serum ferritin (SF) was tested in all the women with a Hb value less than 120 g/l and 71% of them had SF values below 12.0 micrograms/l. Eighty women diagnosed as either Fe deficient or with Fe-deficient anaemia were selected for a diagnostic supplementation trial. They were randomly assigned to FeSO4 (60 or 120 mg Fe/d) or placebo treatment for 12 weeks. Fe supplementation increased mean Hb values from 114 to 127 g/l (P < 0.001) and SF levels from 9.7 to 30.0 micrograms/l (P < 0.001), and decreased mean FEP values from 570 to 277 micrograms/l (P < 0.001). The response rate of Hb in the whole Fe-treated group or Fe-treated subjects with an Hb level less than 120 g/l was 90% or 92% respectively. These findings indicate that the type of anaemia in this population was mainly Fe deficiency. It was also found that in this population the severity of anaemia, not the prevalence, was significantly related to the use of intra-uterine devices (IUD).

Adult↗
PubMed1992

Reproducibility of head-up tilt-table testing for eliciting susceptibility to neurally mediated syncope in patients without structural heart disease.

Head-up tilt testing has gained acceptance as a tool for assessing susceptibility to neurally mediated syncopal syndromes (e.g., vasovagal syncope), and is currently being evaluated as a means of testing therapeutic interventions in these conditions. To assess reproducibility of head-up tilt testing and thereby assess the potential of such testing for immediate evaluation of a planned treatment, findings during 2 sequential 80 degrees head-up tilt tests were compared in 23 patients (age range 6.5 to 74 years) undergoing evaluation of syncope of unknown origin. Upright tilt was performed initially in the absence of drugs, and repeated if necessary during pharmacologic provocation by means of isoproterenol infusions of 1 and 3 micrograms/min (tilt 1). End points were syncope, maximal tolerated isoproterenol dose, or a tilt duration of 10 minutes. The second tilt test (tilt 2) was conducted after approximately 30 minutes of supine rest using the maximal provocative conditions used in tilt 1. Fifteen of 23 patients (65%) developed syncope in either tilt 1 or 2, while 8 of 23 (35%) remained asymptomatic. Tilt testing results were concordant (i.e., positive in both tests, or negative in both tests) in 20 of 23 (87%) patients. Concordance was, however, less among tilt-positive patients (12 of 15, 80%) since 3 patients were tilt-positive in tilt 1 only.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Prospective study of vitamin D supplementation and rickets in China.

To determine whether amounts of vitamin D lower than recommended doses are effective in preventing rickets, 256 term infants from two northern and two southern cities in China were studied in a randomized trial of vitamin D supplementation (100, 200, or 400 IU/day) during the first 6 months of life. Cord blood and 6-month blood samples were collected and radiographs were obtained at 3 to 5 days and at 6 months of age. Cord serum 25-hydroxyvitamin D concentrations were lower in the north than in the south (5 vs 14 ng/ml (12.5 vs 35.0 nmol/L); p less than 0.01). Wrist ossification centers were less likely to be present at birth in the northern children than in the southern children (p = 0.009) and were more likely to be present in infants born in the fall who had higher cord serum concentrations of 25-hydroxyvitamin D (p = 0.04). Serum 25-hydroxyvitamin D concentrations were lower in northern children 6 months of age than in southern children (p = 0.005) and were higher with an increasing supplemental dosage of vitamin D (p less than 0.001), particularly in infants in the north. None of the infants had rickets at 6 months of age. Because of the low serum 25-hydroxyvitamin D concentrations, especially among infants in the north, it may be prudent to supplement the diet with vitamin D at a dose of 400 IU/day.

China↗
PubMed1992

Monitoring of serum markers for fibrosis during CCl4-induced liver damage. Effects of anti-fibrotic agents.

Liver fibrosis was induced in rats by repeated peritoneal injections of carbon tetrachloride (CCl4) over a period of 2-11 weeks. Serum procollagen III peptide (SPIIINP), prolidase (SP) and alanine aminotransferase (SALT) levels were monitored during the period of induction. The extent of fibrosis was semi-quantitatively estimated after collagen staining, and the anti-fibrotic effects of 16,16-dimethyl prostaglandin E2 (DMPGE2), colchicine, and zinc sulphate were studied. SPIIINP and SP were increased the first 2 weeks after CCl4 administration and peaked at 6 weeks. Alterations in SPIIINP and SP correlated well to the semi-quantitative histological score of liver sections during the first 6 weeks, and SP was positively related to SPIIINP throughout the whole induction period. DMPGE2 decreased SPIIINP, SP and SALT significantly in addition to a markedly decreased formation of liver collagens. Colchicine had a similar but less dramatic effect, whereas zinc sulphate only reduced SPIIINP without influencing liver damage. In conclusion SPIIINP seems to be a valuable indicator of liver fibrogenesis, and SP may play a limited role in indicating accelerated collagen metabolism in the liver. DMPGE2 obviously inhibited the production of collagens induced by CCl4. Colchicine also had an apparent effect on liver fibrosis, whereas zinc sulphate merely seemed to postpone it.

16,16-Dimethylprostaglandin E2↗
PubMed1990

Dietary standards and goals for the People's Republic of China with special emphasis on nutritional requirements of Chinese infants.

A recent dietary survey shows that protein, energy and the majority of the mineral and vitamin intakes of the people in China are sufficient to meet their physiologic requirements. However, the dietary energy derived from cereals appear to be high and the dietary protein derived from animal foods is low. Thus, to improve the nutritional status of the Chinese people, a greater consumption of animal food is encouraged. The goal of an adequate adult diet is to maintain optimal health through a balanced intake of energy and all the essential nutrients. This can be achieved in China by the increase in food production through agriculture, fishery and animal husbandry, and by national planning utilizing the Recommended Dietary Allowances as the standard. Children are the future of our country. Hence, research on child nutrition should receive priority, particularly in the area of protein and energy requirements of pre-school children.

Adult↗
PubMed1989

Provocation of bradycardia and hypotension by isoproterenol and upright posture in patients with unexplained syncope.

Neurally mediated hypotension and bradycardia are believed to be common causes of syncope. We used the "upright-tilt test" (duration, less than or equal to 10 minutes) with or without an infusion of exogenous catecholamine (isoproterenol [1 to 5 micrograms per minute], given intravenously) to elicit bradycardia, hypotension, or both in 24 patients with recurrent syncope and in 18 control subjects. A conventional electrophysiologic test performed before the tilt test was positive in 9 of the 24 patients, revealing arrhythmias that may have caused recurrent syncope, but was negative and thus nondiagnostic in 15 patients. The tilt test alone (i.e., without isoproterenol) induced symptomatic bradycardia or hypotension in 1 of the 9 patients with positive electrophysiologic tests (11 percent), 4 of the 15 patients with negative electrophysiologic tests (27 percent), and none of the controls. When the isoproterenol infusion was administered during the tilt test, 9 of the 11 patients with negative electrophysiologic and tilt tests had syncope, marked slowing of the heart rate, and hypotension. In contrast, isoproterenol was associated with tachycardia and only a slight decline in arterial pressure in the 8 remaining patients with positive electrophysiologic tests and the 18 control subjects, and syncope developed in only 1 of the 8 patients with positive electrophysiologic tests and negative tilt tests (13 percent) and 2 of the 18 control subjects (11 percent). We conclude that an isoproterenol infusion administered in conjunction with the upright-tilt test may be useful for identifying susceptibility to neurally mediated recurrent syncope.

Adolescent↗
PubMed1987

Surgical treatment of arteriovenous malformations of the striatothalamocapsular region.

Sixteen patients with arteriovenous malformations (AVM's) located in the striatothalamocapsular region were treated microsurgically at the Hau Shan Hospital, Shanghai. These AVM's had a tendency to bleed intracerebrally and typically presented with hemiplegia, hemianesthesia, and hemianopsia. Angiographically the lesions were primarily located in the triangle of Reil. Postoperative outcome was not as good as that of AVM's in other locations, but the operation may have prevented the risk of further hemorrhage. This report details the operative technique used and the clinical course in this group of patients.

Adolescent↗