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Biomedical subjects

F Xu

Publications and source records attributed to F Xu.

339 records · Page 19Linked to original sources
PubMed1985

The effect of low osmotic potential on nitrite reduction in intact spinach chloroplasts.

The effect of water stress (reduced osmotic potential) on photosynthetic nitrite reduction was investigated using intact, isolated spinach (Spinacia oleracea) chloroplasts. Nitrite-dependent O(2) evolution was inhibited 39% at -29.5 bars osmotic potential, relative to a control at -11 bars. In the presence of an uncoupler of photophosphorylation this inhibition was not seen. Reduced osmotic potential did not inhibit either methyl viologen reduction or photosynthetic O(2) reduction. These results indicate that an inhibition of electron transport to ferredoxin cannot account for the observed inhibition of nitrite-dependent O(2) evolution. In vitro assay of nitrite reductase activity showed that the interaction of the enzyme with nitrite was not affected by changes in the concentrations of ions or molecules that might be caused by water stress conditions. These results indicate that the most likely site for the effect of water stress on chloroplastic nitrite reduction is the interaction of ferredoxin with nitrite reductase.

Journal Article↗
PubMedDate not supplied

Regulation and action of angiogenic factors in the primate ovary.

The ephemerality of the maturing follicle and subsequent corpus luteum as they perform their gametogenic and/or endocrine functions during the ovarian cycle is associated with remarkable changes in local vasculature. Studies on the angiogenic and angiolytic process in the ovary, rare in healthy adult tissues, complement recent efforts to understand vasculogenesis in embryonic tissues and to control angiogenesis in pathologic states such as cancer. Several reports indicate that the newly discovered vascular-specific angiogenic factors are expressed in the ovary, notably members of the vascular endothelial growth factor (VEGF) and angiopoietin (Ang) families plus their receptors (VEGF-Rs, neuropilins, Tie). Unlike in many other tissues, gonadotropic hormones (particularly luteinizing hormone, [LH]) are major stimulators of angiogenesis and VEGF/Ang expression in the ovary. However, local factors such as insulin-like growth factors or oxygen tension likely modulate the angiogenic processes. Recent studies employing systemic or local administration of anti-angiogenic drugs (TNP-470 or fumagillin) or specific VEGF antagonists (VEGF antibody or soluble VEGFR-1) demonstrate a vital role for normal angiogenesis and VEGF action in follicle development, ovulation, or corpus luteum function. Further studies discerning the various angiogenic factors and their roles in controlling the growth, maturation, function, and regression of the vasculature in ovarian compartments during the menstrual cycle could yield novel strategies for manipulating fertility or for alleviating infertility.

Angiogenesis Inhibitors↗
PubMedDate not supplied

Air pollution-type fluorosis in the region of Pingxiang, Jiangxi, Peoples' Republic of China.

This paper reports on the epidemiology, environmental factors, geological features, and total amount of fluoride intake by residents of the Pingxiang region in the Peoples' Republic of China where there is a high incidence of endemic fluorosis. The results demonstrate that the type of endemic fluorosis is related to air pollution, the major source of which comes from coal that is burned by the residents in their homes. Air pollution also originates from the small kilns that are used to make bricks and tile. The fluorine content in the coal and mud used to mix the coal is considerably high; the content in the mud used as adobe for tiles exceeds 10,000 mg/kg. During the process of burning coal or baking bricks or tiles, a large amount of nonsoluble fluorine is converted into water-soluble fluoride, which can have major human health effects.

Adolescent↗
PubMedDate not supplied

Influences of light-dark shifting on the immune system, tumor growth and life span of rats, mice and fruit flies as well as on the counteraction of melatonin.

Animal models were designed to study the changes in immune function, oncogenicity and life span of rats, mice and fruit flies following light-dark (LD) shift manipulations. Alternating the photoperiod of LD 14:10 and DL 10:14 every 3 days in rats disrupted the circadian immune rhythm pattern, decreased the blood leukocyte concentration by 48% and lowered the percentage of lymphocytes in the blood from 71% (control) to 49.2%. In mice, the phagocytosis of neutrophils was only reduced by 7%, but the level of serum hemolysin dropped significantly in the photoperiod-shifted group as compared with animals kept under a constant photoperiod of LD 12:12 or LD 14:10. In Ehrlich-carcinoma- or sarcoma-180-injected mice, a reduction of survival duration, acceleration of tumor growth and depression of the immune system were recorded in the LD-shifted animals. In addition, the life span of fruit flies was shortened by 9.6% by photoperiodic shifting. Melatonin treatment evidently counteracted the deleterious influences of photoperiodic shifting in the above animals. It is suggested that repeated inversion of the LD cycle results in a chronobiological abnormality that, in turn, induces dysfunctions. Reentrainment by exogenous melatonin may inhibit the harmful influences of photoperiodic shifting.

Animals↗
PubMedDate not supplied

Effects of melatonin on hypothalamic gamma-aminobutyric acid, aspartic acid, glutamic acid, beta-endorphin and serotonin levels in male mice.

Effects of melatonin on hypothalamic neurotransmitters in male mice were studied. Exogenous melatonin administered intraperitoneally significantly increased (p < 0.05) hypothalamic concentrations of aspartic acid and gamma-aminobutyric acid by over 29 and 50% respectively. Conversely, hypothalamic beta-endorphin concentration was significantly decreased (p < 0.05) 30 min after melatonin administration with doses between 5- and 100 micrograms/kg. Similarly, melatonin, at a concentration of 100 micrograms/kg, decreased (p < 0.05) the serotonin level in mouse hypothalamus by 46%. Melatonin, however, did not affect the concentration of hypothalamic glutamic acid over a dose range of 0.5-300 micrograms melatonin/kg. Our findings suggested that actions of pineal melatonin in animals such as inhibition on serum corticosterone levels might be mediated by the potentiation of activities of hypothalamic neurons containing gamma-aminobutyric acid and aspartic acid or by the inhibition of the beta-endorphin and serotonin hypothalamic neurons. The neurons containing glutamic acid in the hypothalamus were, however, not influenced by melatonin. Our results are in line with the suggestion that melatonin actions on adrenal corticosterone release or other endocrine secretions may be mediated by way of its actions on hypothalamic neurotransmitter activities.

Animals↗
PubMedDate not supplied

Prediction of soil organic partition coefficients by a soil leaching column chromatographic method.

The soil organic partition coefficient (Koc) is one of the most important parameters to depict the transfer and fate of a chemical in the soil-water system. Predicting Koc by using a chromatographic technique has been developing into a convenient and low-cost method. In this paper, a soil leaching column chromatograpy (SLCC) method employing the soil column packed with reference soil GSE 17201 (obtained from Bayer Landwirtschaftszentrum, Monheim, Germany) and methanol-water eluents was developed to predict the Koc of hydrophobic organic chemicals (HOCs), over a log Koc range of 4.8 orders of magnitude, from their capacity factors. The capacity factor with water as an eluent (k'w) could be obtained by linearly extrapolating capacity factors in methanol-water eluents (k'w) with various volume fractions of methanol (symbol in text). The important effects of solute activity coefficients in water on k'w and Koc were illustrated. Hence, the correlation between log Koc and log k'w (and log k') exists in the soil. The correlation coefficient (r) of the log Koc vs. log k'w correlation for 58 apolar and polar compounds could reach 0.987, while the correlation coefficients of the log Koc -log k' correlations were no less than 0.968, with (symbol in text)ranging from 0 to 0.50. The smaller the (symbol in text), the higher the r. Therefore, it is recommended that the eluent of smaller (symbol in text), such as water, be used for accurately estimating Koc. Correspondingly, the r value of the log Koc -log k'w correlation on a reversed-phase Hypersil ODS (Thermo Hypersil, Kleinostheim, Germany) column was less than 0.940 for the same solutes. The SLCC method could provide a more reliable route to predict Koc indirectly from a correlation with k'w than the reversed-phase liquid chromatographic (RPLC) one.

Chromatography, Liquid↗
PubMedDate not supplied

Molecular cloning and characterization of FX3, a novel zinc-finger protein.

In a screen for cyclin G1 interacting proteins using the yeast two-hybrid system, we identified a cDNA clone encoding a novel zinc-finger protein. In addition to a C-terminal zinc-finger domain, the 18 kDa protein, designated FX3, contains a bipartite nuclear targeting sequence and a number of putative protein kinase phosphorylation sites. The physical interaction of FX3 with cyclin G1 was confirmed in vitro by co-immunoprecipitation. Further studies demonstrated that the zinc-finger domain is not required for the observed interaction between FX3 and cyclin G1. FX3 is an essential gene expressed in numerous human tissues, with the highest levels observed in the liver.

Amino Acid Sequence↗
PubMedDate not supplied

Spectral differences between epitopes in the cronomes of salivary CA130 and CA125.

Ovarian tumor markers CA125 and CA130 are here investigated in the search for harbingers of an elevated cancer risk or pre-cancer. A circadian rhythm of large amplitude is demonstrated for salivary CA125 and CA130 of a clinically healthy 28-year-old woman (AP). The circadian rhythms of both markers found in AP have a pattern similar to that of a patient (EH) with a müllerian cancer involving the ovary, with high values in the early morning and low values in the afternoon. Whereas acrophases occur approximately at the same circadian stage in both AP and EH, the MESOR and circadian amplitude are higher in EH as compared to AP. The circadian rhythm of salivary CA130 of AP is similar to that of other clinically healthy women. CA130 concentrations are lower than CA125 concentrations in unstimulated saliva (before rinsing of the mouth) in this clinically healthy woman (AP), and in other women studied herein. This difference between CA130 and CA125 concentrations is observed irrespective of circadian stage and irrespective of the concentration range of CA125 at the outset. After rinsing of the mouth, a statistically significant decrease in both CA130 and CA125 concentration is observed in AP and in another healty woman (GC) who collected saliva both before and after rinsing of the mouth.

Adult↗
PubMedDate not supplied

Toward salivary-urinary chronosensitivity testing: chronomes of OVX1, M-CSF and CA130.

Several rhythmic components were previously mapped for salivary and/or urinary CA125 and CA130. On the background of such reference standards, OVX1 and M-CSF were assayed on 242 urine samples and 160 saliva samples provided by a 71-year-old patient with a Müllerian/ovarian adenocarcinoma. Serum OVX1 correlates with serum CA125 (P = 0.002); when circulating CA125 concentrations decreased (from 122 to 14 U/ml), the urinary excretion rate of OVX1 decreased (P = 0.005), whereas the urinary excretion rate of CA125 increased (P < 0.001). Salivary OVX1 and urinary M-CSF show ultradian variations (with a frequency of one cycle in 14-17 hours), which could be utilized to guide treatment timing targeted first to optimize treatment efficacy and as a second consideration to minimize treatment toxicity.

Aged↗