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Biomedical subjects

X Jia

Publications and source records attributed to X Jia.

At least 73 records · Page 4Linked to original sources
PubMed1998

Identification of a new all-trans-retinol metabolite produced through a new retinol metabolic pathway.

In vitro incubation of all-trans-retinol (atROL) with kidney homogenate from vitamin A-deficient and retinoic acid-supplemented (VAD-RAS) female rats produces a new retinol metabolite. Reverse-phase (RP) and normal-phase (NP) high-performance liquid chromatography (HPLC) analysis showed that this metabolite coelutes with the unknown all-trans-retinol (atROL) metabolite previously found in the day 10 conceptus and kidneys of vitamin A-deficient rats maintained on all-trans-retinoic acid (VAD-RA) and given 2 microg of [3H]atROL. Normal-phase (NP) HPLC purification of the metabolite collected from a RP HPLC column further separated the radiolabeled material into two components. The two isolated compounds have identical or very similar spectroscopic properties. Their nuclear magnetic resonance (1H NMR) and mass spectra (MS) indicated that they are isomers. Spectroscopic studies of the metabolites and their derivatives showed that they are nine-carbon fragments resulting from an oxidative cleavage of the side chain of atROL. The cleavage occurs at C-9, and the product is then oxidized to a keto group. The primary hydroxy group from atROL is preserved in the metabolite. A sulfide bridge is formed between C-11 and C-14, which interrupts the conjugation. The formation of the new metabolites, possessing a 2,5-dihydrothiophene ring, is catalyzed by an enzyme(s) located in the cytosolic fraction of kidneys. The process represents a new retinol metabolic pathway; however, its biological significance is unknown.

Administration, Oral↗
PubMed1998

Risk factors for glioma in adults: a case-control study in northeast China.

A case-control study of risk factors for glioma in adults was carried out in Heilongjiang province in northeast China. Between September 1989 and May 1995, 218 histologically confirmed cases of glioma requiring surgery for tumor removal (139 astrocytoma glioma and 79 other glioma) and 436 controls with non-neoplastic and non-neurological disease were recruited and personally interviewed in the wards of six major hospitals. Controls were matched by sex, age, and area of residence. Occupational, lifestyle, and medical information was obtained through a standardized questionnaire. Use of liquor was associated with cancer risk. Compared with males who never drank liquor, males with total lifetime liquor consumption of less than 1000 liters had an adjusted odds ratio (OR) of 1.60 (95% CI: 0.89-2.88) and for more than 1000 liters, 2.73 (95% CI: 1.06-7.08). Statistically significant associations were also found for diseases related to the brain (OR: 5.75; 95% CI: 1.08-30.47) and trauma to the head requiring medical attention (OR: 4.09; 95% CI: 2.51-10.31). Increased consumption of vegetables and of fruit were each associated with decreased glioma risk. Compared with lowest quartile intake, adjusted risks associated with highest quartile intake were 0.51 (95% CI: 0.29-0.89) for total vegetables and 0.28 (95% CI: 0.16-0.51) for total fruit.

Adult↗
PubMed1998

An extension of Satterthwaite's approximation applied to pharmacokinetics.

Satterthwaite's approximation for the degrees of freedom of a linear combination of independent mean squares is extended to the case that the mean squares are correlated. The mean squares are sample variances where some of the experimental units have been used in more than one sample. The motivation for such an extension comes from pharmacokinetics. The observations, taken at different time points from a set of animals, are blood drug concentrations. Some animals were sampled at more than one time point. A linear combination of sample means provides an estimate of the population mean area under the concentration-versus-time curve, which is an indicator of drug exposure. An associated linear combination of sample variances provides an estimate of the variance of the area estimator. The behavior of confidence intervals based on the approximation was studied by simulation. The confidence interval for the population mean, constructed by assuming that the variance estimator has a chi-square distribution with the computed degrees of freedom, achieved close to its nominal 95% coverage, justifying the extension of Satterthwaite's approximation.

Algorithms↗
PubMed1998

[Development of a recorder of environmental parameters for small biocabin].

A recorder for recording temperature in a small biocabin on board the recoverable satellite and the speed of a centrifuge incorporated in the cabin was developed. Using the internal timer and A/D converter of a microcomputer, it automatically measures the temperature in the biocabin and the speed of the centrifuge alternatively every 30 min, then writes the data to Flash Memory 28C64. It demonstrated that the recorder controlled by a low consumptive PIC microcomputer is suitable for use in the small biocabin.

Centrifugation↗
PubMed1998

[Chemical constituents of the root of Epimedium acumiantum Franch].

Four known flavonol glycosides, ikarisoside A(I), 2"-O-rhamnosyl-icariside II (II), 2"-O-rhamnosyl-ikarisoside A(III) and ikarisoside B(IV) were isolated from the ethyl acetate extract of the root of Epimedium acuminatum. Their structures were elucidated by spectroscopic and chemical methods. II, III and IV were isolated from this plant for the first time.

Drugs, Chinese Herbal↗
PubMed1998

[Effect of various methods of tissue storage on split-skin viability at 4 degrees C].

OBJECTIVE: To study various tissues and organs storage solutions (liver, kidney and corneal) at 4 degrees C for the storage of skin and the viability of skins stored in these solutions at correspondent condition. METHOD: Five experiment groups investigated for storing porcine split-skin at 4 degrees C were MEM, UW, MEM plus CS, UW-R and MEM-R. A new assay, WST-1, was applied to evaluate skin viability at 1, 3, 5, 7, 10 and 14 day during storage respectively. RESULT: Skin viability can all be protected by these three solutions. The effect of UW solution was superior to MEM. UW-R and MEM-R were superior to MEM and UW. CONCLUSION: The method of UW-R which replaces medium routinely may be an optimal method of storing skin at 4 degrees C.

Animals↗
PubMed1998

[Chemical constituents of Epimedium acuminatum Franch. (II)].

OBJECTIVE: To study the components of roots of Epimedium acuminatum. METHOD: Column chromatography was employed for the isolation. The isolated compounds were elucidated by UV, IR, FAB-MS, 1HNMR and 13CNMR analysis. RESULT: Four constituents were obtained and elucidated as epimedoside A(V), diphylloside B(VI), epimedin C(VII) and ikarisoside C(VIII). CONCLUSION: Four constituents are all flavonol glycosides, of which VI, VII and VIII were separated from this plant for the first time.

Disaccharides↗
PubMed1998

[Studies on fermentation conditions of cytokinin produced by rhizobia strain 4012a].

The conditions of cytokinin fermentation of the rhizobia strain 4012a were detected by the ELISA. The results indicated that the optimal medium for cytokinin production by strain 4012a was composed of glucose 10 g/L, (NH4)2SO4 1.0, K2HPO4.3H2O 0.6, MgSO4.7H2O 0.1, CaCl2.2H2O 0.4, FeCl3.6H2O 0.04, Na2MoO4.2H2O 0.1 mg/L, calcium pantothenate 100 micrograms/L, adenine 200 mg/L. When strain 4012a was grown in 250 ml flask containing 50 ml of the medium on the rotary shaker (150 r/min) at 27 degrees C for 96 h, the yield of CTK 908 micrograms/L culture solution was obtained. It displayed bioactivity kinetin equivalents (KE) 1 mg/L medium with the radish cotyledon expansion test.

Culture Media↗
PubMed1998

[The comparison on growth rate and photopigments of filaments of Spirulina platensis strain Z with different morphology].

The line-shaped filaments Sp-Z(L) were isolated and cultured from Spirulina platensis Sp-Z. The growth rate of Sp-Z(L) was only 64% as much as that of Sp-Z when the light intensity was 4000 Lux. The contents (x 10(-3) g/g dry weight) of chlorophylls, carotenoids and phycobilins of Sp-Z(L) and Sp-Z were 20.6, 0.343, 5.00 and 24.1 0.297, 4.46, respectively. Moreover, as to the absorption spectra of the three photopigments of Sp-Z(L), red shifts were observed. Therefore, after the spiral Sp-Z breeded or changed into Sp-Z(L), The contents of carotenoids and phycobilins raised 23% and 12%, respectively, but the contents of chlorophylls dropped 14.5%, and the growth rate dropped 36% too. The results probably showed that the decrease of chlorophylls was one of the main reasons that caused the remarkable decrease of the growth rate of Sp-Z(L).

Carotenoids↗
PubMed1997

Identification of determinants for inhibitor binding within the RNA active site of human telomerase using PNA scanning.

Telomerase is a ribonucleoprotein that participates in the maintenance of telomere length. Its activity is up-regulated in many tumor types, suggesting that it may be a novel target for chemotherapy. The RNA component of telomerase contains an active site that plays at least two roles&sbd;binding telomere ends and templating their replication [Greider, C. W., & Blackburn, E. H. (1989) Nature 337, 331-337]. The accessibility of RNA nucleotides for inhibitor binding cannot be assumed because of the potential for RNA secondary structure and RNA-protein interactions. Here we use high-affinity recognition by overlapping peptide nucleic acids (PNAs) [Nielsen, P. E., et al. (1991) Science 254, 1497-1500] to identify nucleotides within the RNA active site of telomerase that are determinants for inhibitor recognition. The IC50 for inhibition decreases from 30 microM to 10 nM as cytidines 50-52 (C50-52) at the boundary between the alignment and elongation domains are recognized by PNAs overlapping from the 5' direction. As C50-52 are uncovered in the 3' direction, IC50 increases from 10 nM to 300 nM. As cytidine 56 at the extreme 3' end of the active site is uncovered, IC50 values increase from 0.5 microM to 10 microM. This analysis demonstrates that C50-C52 and C56 are important for PNA recognition and are physically accessible for inhibitor binding. We use identification of these key determinants to minimize the size of PNA inhibitors, and knowledge of these determinants should facilitate design of other small molecules capable of targeting telomerase. The striking differences in IC50 values for inhibition of telomerase activity by related PNAs emphasize the potential of PNAs to be sensitive probes for mapping complex nucleic acids. We also find that PNA hybridization is sensitive to nearest-neighbor interactions, and that consecutive guanine bases within a PNA strand increase binding to complementary DNA and RNA sequences.

Binding Sites↗
PubMed1997

B7-2 requirement for helminth-induced granuloma formation and CD4 type 2 T helper cell cytokine expression.

B7 ligands on APCs engage CD28/CTLA4 counter-receptors on T cells critical for T lymphocyte activation and functional differentiation of T helper subsets. To examine whether the ligands B7-1 (CD80) and B7-2 (CD86) affect gene expression of Th2 cytokines and development of Th2-mediated pathologic tissue reactions, mice were treated with anti-B7-1 or anti-B7-2 at the time of sensitization to footpad inoculation of Schistosoma mansoni eggs or induction of pulmonary granuloma by i.v. injected eggs. Anti-B7-2 treatment inhibited pulmonary granuloma formation by 74% and decreased levels of lung IL-5 and IL-13 transcripts compared with those in animals given control Ig by 20- and 5-fold, respectively, while anti-B7-1 administration has no effect. Anti-B7-2 treatment blocked CD4 cell gene expression of IL-4, IL-5, and IL-13, but had no effect on IFN-gamma or IL-10 in animals inoculated with S. mansoni ova, larvae from the filarial helminth Brugia malayi, or CFA. Anti-B7-1 administration had no effect on CD4 cell transcript levels of IL-4 and IL-5, but inhibited IFN-gamma in mice inoculated with ova. Similar effects of anti-B7-2 on CD4 cell cytokine expression were observed in IL-4 knockout mice, indicating the existence of an alternative pathway for induction and/or expression of these cytokine genes. These findings suggest a possible role for anti-B7-2 in the therapy of infectious and atopic diseases in which immunopathologic reactions are mediated by selected Th2 cytokines.

Animals↗
PubMed1997

The pH dependence of silicon-iron interaction in rats.

A 2 x 2 x 3 factorial experiment was conducted to study the pH dependence of a silicon-iron interaction in vivo. The dietary treatments used in the factorial design were the following (mg/kg of diet): silicon, 0 and 500; iron, 35 and 187; acid-base, ammonium chloride as 0.5% of total diet (acidic), sodium bicarbonate as 1.0% of total diet (basic), or no supplementation of acid or base (control). The supplementation of 500 mg silicon/kg of diet increased plasma-iron concentration in rats fed the acidic or control diets, but not in rats fed the basic diet. A high dietary-iron level suppressed copper absorption and utilization and subsequently imposed a negative effect on its own utilization. An increase in the plasma total-cholesterol concentration caused by high dietary-iron level was likely a consequence of the antagonistic effect of iron on copper absorption and utilization. The use of cupric sulfate pentahydrate as the dietary-copper source in this study resulted in plasma copper concentrations that were approximately twice those obtained in a related study using cupric carbonate. Also, a 42% coefficient of variation (C.V.) for plasma-copper concentrations of rats fed cupric sulfate in this study was greatly reduced from the C.V. = 108% previously associated with the dietary cupric carbonate.

Animals↗
PubMed1997

Biochemical interactions among silicon, iron and ascorbic acid in the rat.

A 2 x 2 x 2 factorial experiment was conducted using two dietary levels each (mg/kg of diet) of silicon, 0 and 500; iron, 35 and 187; and ascorbic acid, 0 and 900, to identify biochemical interactions occurring among these nutrients. Supplemental silicon, in conjunction with the higher dietary-iron level, prevented the plasma-iron decreasing effect observed for the higher level of iron in the absence of silicon. In the absence of ascorbic acid, silicon also increased iron concentration in the liver. Lower growth of the silicon and iron-supplemented rats is believed to be a response to a subsequent iron-imposed aberration of copper or zinc metabolism. This is supported by decreased intestinal metallothionein, increased weights (g/100 g body weight) of liver, heart, and testes, and decreased packed-cell volume and hemoglobin concentration. The lower plasma-iron level associated with the higher level of dietary iron appeared to be an expression of the iron-imposed reduction of liver copper stores. Ascorbic acid decreased plasma-iron concentration and prevented the silicon-related increase in liver iron.

Animals↗
PubMed1997

Developmental changes in chemoreceptive control of gill ventilation in larval bullfrogs (Rana catesbeiana). I. Reflex ventilatory responses to ambient hyperoxia, hypoxia and NaCN

The time course of reflex changes in gill ventilation frequency, buccal pressure, branchial stroke volume and minute ventilation caused by a step-wise change in PO2 of inspired water and by the introduction of NaCN into the inspired water was measured in unanesthetized larval bullfrogs (Rana catesbeiana) at developmental stages TK V&shy;VII, IX&shy;XI and XVII&shy;XIX. The inspiration of hypoxic or hyperoxic water caused significant increases in gill ventilation within 7 s, while hyperoxic water had the opposite effect. Introduction of NaCN into the inspired water stream caused nearly instantaneous respiratory responses (<3 s). Early and middle stage larvae showed a significantly faster and more pronounced reflex response than the older group in all experiments. The rapid changes in gill ventilation indicate the presence of a population of branchial receptors monitoring inspired water O2 levels or possibly blood O2 levels in the efferent branchial circulation. The progressive decrease in both the amplitude and rapidity of onset of the responses with development are consistent with the progressive degeneration of the gills and a reduction in the importance of branchial gas exchange in late larval stages.

Journal Article↗
PubMed1997

Developmental changes in chemoreceptive control of gill ventilation in larval bullfrogs (Rana catesbeiana). II. Sites of O2-sensitive chemoreceptors

The time course of reflex changes in gill ventilation variables caused by a step-wise change in PO2 of inspired water and by the introduction of NaCN into inspired water was measured in two populations of unanesthetized larval bullfrogs (Rana catesbeiana) &shy; one with intact gill arches and a second with bilateral ablation of the first gill arch. Developmental stages TK V&shy;VII, IX&shy;XI and XVII&shy;XIX were examined. Inspiring hypoxic water or a pulse of NaCN significantly increased gill ventilation within 7 s in control larvae. Ablation of the first gill arches in larval R. catesbeiana eliminated the initial, quick response of gill ventilation to changes in the PO2 of inspired water and to the presence of NaCN in all three developmental groups. These data suggest that O2-sensitive chemoreceptors are located on the first gill arch and are responsible for the initial rapid ventilatory response. However, a slow response (>15 s) to changes in PO2 of inspired water persisted even after removal of the first gill arch. This response is far slower than the minimum blood circulation time (approximately 5&shy;8 s as measured in all three groups), indicating that a second population of receptors is not directly monitoring arterial or venous blood. Instead, this second population of receptors is likely to be located 'behind' a significant diffusion barrier, possibly monitoring cerebrospinal fluid.

Journal Article↗
PubMed1997

[The injury of human lung cultured vascular endothelial cells in vitro added to burned skin extracts].

Human lung cultured vascular endothelial cells model was established in vitro. Two kinds of skin extracts (human burned skin extracts, HBSE, and human natural skin extracts, HNSE) were added to cultured endothelial cells. The results showed that HBSE exerted toxic effect on endothelial cells in vitro. There were significantly higher contents of ET-1, NO, TNF-alpha, and abnormal structural changes in EC in the HBSE group.

Burns↗