PubMed Health⌕ Search

Biomedical subjects

X Fu

Publications and source records attributed to X Fu.

At least 73 records · Page 4Linked to original sources
PubMed2000

[Raman and infrared spectroscopic investigation of SO4(2-)/TiO2 solid acids].

The structure, crystal phase transition and surface acid centers of SO4(2-)/TiO2 solid acids calcined at different temperatures were studied by IR and Raman spectroscopy. The results showed that SO4(2-) is combined with metal ions of TiO2 in a chelating bidentate mode. When the calcination temperature is below 500 degrees C, the samples possess stable structure with anatase as the main crystal phase, and there are two types of acid sites (Lewis and Bronsted acid) on the samples, the amount of B acid is about twice as that of L acid. When the temperature is above 500 degrees C, surface SO4(2-) desorb gradually with increasing calcination temperature, leading to crystal phase transition from anatase to rutile and the surface B acid sites fade away.

Acids↗
PubMed2000

[Comparative studies on the spectral behavior between SO4(2-)/TiO2 and TiO2 photocatalysts].

The differences of spectral behavior between SO4(2-)/TiO2 and TiO2 photocatalysts were studied by using IR, Raman as well as UV-Vis diffuse reflectance spectroscopy(DRS). The results showed that both L and B acid sites exist on SO4(2-)/TiO2 photocatalyst while only L acid sites on TiO2 photocatalyst. As compared with unmodified TiO2, the sulfated TiO2 (SO4(2-)/TiO2) exhibits higher resistance to crystal phase transition from anatase to rutile, higher resistance to growth of crystal grain. As the results of sulfation, SO4(2-)/TiO2 samples possess higher anatase content, smaller crystal grain, and the blue-shifted band edge of adsorption spectra, which increases the optical absorption threshold value and yield larger redox potential.

Adsorption↗
PubMed2000

[FT-Raman spectroscopic investigation on stomach cancer].

FT-Raman spectroscopy was used to investigate 40 normal and malignant tissues from stomach. Statistic analysis shows that the bands related to OH, NH, C=O stretching and H-O-H bending are stronger in malignant tissues. This phenomenon suggests that the hydrogen bonding systems among water and protein vary in malignant tissues.

Humans↗
PubMed1999

Fibroblast growth factor protects the kidney against ischemia-reperfusion injury.

Ischemia-reperfusion injury, a common source of renal dysfunction in adults, is associated with tubular epithelial cell damage. Since fibroblast growth factors (FGF) attenuated tissue injury after transient myocardial ischemia, we hypothesized that acidic fibroblast growth factor (aFGF; FGF-1) would attenuate renal ischemia-reperfusion injury. We studied the effects of FGF-1 in a rat model of acute renal failure induced by bilateral renal ischemia (60 min) and 1, 2 or 7 days reperfusion. After FGF-1 administration at the onset of renal reperfusion, there was less functional impairment of the kidneys. The histological changes were not as severe as in controls. Increases in serum creatinine and blood urea nitrogen 24 h after reperfusion were attenuated by 35% (p< 0.01) and by 53% (p< 0.001), respectively, in FGF-1-treated animals compared to vehicle-treated rats. The ischemia/reperfusion-induced increase in tissue myeloperoxidase, a marker of neutrophil infiltration, was mitigated (67% reduction, p< 0.05) with FGF-1 treatment. As shown by histology, neutrophil infiltration and tubular cell necrosis in medulla were less pronounced (p< 0.0001 and p< 0.05, respectively) in animals receiving FGF-1. Furthermore, ischemia-induced apoptosis, prevalent in tubular cells of the cortex, was also attenuated by FGF-1-treatment (83% reduction, p< 0.0001). Pretreatment of animals with Nw-nitro-L-arginine (L-NNA), an inhibitor of nitric oxide synthase, abolished the attenuating effects of FGF-1 on neutrophil infiltration, suggesting that nitric oxide might participate in the anti-inflammatory effects of FGF-1 in this experimental design. Our data support a role for FGF-1 in attenuation of renal damage or failure after ischemia-reperfusion injury of the kidney, in part at least by inhibition of neutrophil infiltration.

Animals↗
PubMed1999

EB-1, a tyrosine kinase signal transduction gene, is transcriptionally activated in the t(1;19) subset of pre-B ALL, which express oncoprotein E2a-Pbx1.

The t(1;19) translocation of pre-B cell acute lymphocytic leukemia (ALL) produces E2a-Pbx1, a chimeric oncoprotein containing the transactivation domains of E2a joined to the homeodomain protein, Pbx1. E2a-Pbx1 causes T cell and myeloid leukemia in mice, blocks differentiation of cultured myeloid progenitors, and transforms fibroblasts through a mechanism accompanied by aberrant expression of tissue-specific and developmentally-regulated genes. Here we investigate whether aberrant gene expression also occurs specifically in the t(1;19)-containing subset of pre-B cell ALL in man. Two new genes, EB-1 and EB-2, as well as Caldesmon were transcriptionally activated in each of seven t(1;19) cell lines. EB-1 expression was extremely low in marrow from patients having pre-B ALL not associated with the t(1;19), and elevated more than 100-fold in marrow from patients with pre-B ALL associated with the t(1;19). Normal EB-1 expression was strong in brain and testis, the same tissues exhibiting the highest levels of PBX1 expression. EB-1 encodes a signaling protein containing a phosphotyrosine binding domain homologous to that of dNumb developmental regulators and two SAM domains homologous to those in the C-terminal tail of Eph receptor tyrosine kinases. We conclude that aberrant expression of tissue-specific genes is a characteristic of t(1;19) pre-B ALL, as was previously found in fibroblasts transformed by E2a-Pbx1. Potentially, EB-1 overexpression could interfere with normal signaling controlling proliferation or differentiation.

Adenomatous Polyposis Coli Protein↗
PubMed1999

A pathway for conformational diversity in proteins mediated by intramolecular chaperones.

Conformational diversity within unique amino acid sequences is observed in diseases like scrapie and Alzheimer's disease. The molecular basis of such diversity is unknown. Similar phenomena occur in subtilisin, a serine protease homologous with eukaryotic pro-hormone convertases. The subtilisin propeptide functions as an intramolecular chaperone (IMC) that imparts steric information during folding but is not required for enzymatic activity. Point mutations within IMCs alter folding, resulting in structural conformers that specifically interact with their cognate IMCs in a process termed "protein memory." Here, we show a mechanism that mediates conformational diversity in subtilisin. During maturation, while the IMC is autocleaved and subsequently degraded by the active site of subtilisin, enzymatic properties of this site differ significantly before and after cleavage. Although subtilisin folded by Ile-48 --> Thr IMC (IMCI-48T) acquires an "altered" enzymatically active conformation (SubI-48T) significantly different from wild-type subtilisin (SubWT), both precursors undergo autocleavage at similar rates. IMC cleavage initiates conformational changes during which the IMC continues its chaperoning function subsequent to its cleavage from subtilisin. Structural imprinting resulting in conformational diversity originates during this reorganization stage and is a late folding event catalyzed by autocleavage of the IMC.

Amino Acid Sequence↗
PubMed1999

Abuse of guaifenesin-containing medications generates an excess of a carboxylate salt of beta-(2-methoxyphenoxy)-lactic acid, a guaifenesin metabolite, and results in urolithiasis.

OBJECTIVES: Several urinary calculi were submitted to our institution for compositional analysis. The typical techniques of analysis, polarized light microscopy, electron microprobe analysis, and infrared spectroscopy proved inadequate for a definitive identification. As a result, a more detailed organic analysis was conducted to determine the exact chemical structure of the material. METHODS: Infrared spectroscopy and mass spectrometric analysis were carried out on the solid material, providing information concerning the functional groups and the molecular mass of the organic constituent and its components. The stone was solubilized in deuterated solvents and analyzed by nuclear magnetic resonance spectroscopy, which resulted in a definitive chemical structure. RESULTS: The spectroscopic analysis indicated that the stones were composed of a calcium salt of beta-(2-methoxyphenoxy)-lactic acid, a metabolite of the pharmaceutical guaifenesin, which is used as an expectorant. CONCLUSIONS: Guaifenesin, an expectorant common in over-the-counter cold and allergy remedies, can cause urolithiasis if taken in excess. Discussions with physicians and their patients confirmed that most patients admitted to taking large doses of guaifenesin-containing medications.

Adolescent↗
PubMed1999

Malayenolides A-D, novel diterpenes from the indonesian sea pen veretillum malayense

Malayenolides A-D (1-4), four new briarane diterpenes, were isolated from the sea pen Veretillum malayense collected in Indonesia. The new diterpenes possess benzoate and senecioate substitutents, both of which are rare among marine natural products. The structures of the new compounds were determined from spectral data. Compounds 1-4 are toxic to brine shrimp.

Journal Article↗
PubMed1999

Longithorols A and B, novel prenylated paracyclophane- and metacyclophane-type hydroquinones from the tunicate Aplidium longithorax.

The tunicate Aplidium longithorax collected from Palau contained two novel prenylated paracyclophane- and metacyclophane-type hydroquinones, longithorols A (1) and B (2), in addition to longithorones A-I. Longithorols A and B were very unstable and were therefore isolated as their more stable pentaacetate forms, 3 and 4, respectively. The structures of 3 and 4 were determined by spectral data, especially 2D NMR data.

Animals↗
PubMed1999

mAngiogenin-3, a target gene of oncoprotein E2a-Pbx1, encodes a new angiogenic member of the angiogenin family.

Angiogenins are proteins in the pancreatic ribonuclease superfamily that utilize their ribonuclease activity to induce formation of new blood vessels. Recently we identified a new member of the angiogenin gene family, mouse angiogenin-3, by virtue of its transcriptional activation in NIH3T3 fibroblasts coincident with transformation by the chimeric leukemia oncogene, E2a-Pbx1. Here we have isolated the cDNA encoding mouse angiogenin-3 and used it to produce the protein in E. coli. We demonstrate that mouse angiogenin-3 is a ribonuclease whose activity and specificity towards tRNA and dinucleotide substrates differ from those of mouse angiogenin or of mouse angiogenin-related protein, a non-angiogenic factor. Mouse angiogenin-3 induced angiogenesis in both the chicken embryo chorioallantoic membrane assay and the rat cremaster muscle. Electron microscopy revealed that endothelial cells within vessels induced by both mouse angiogenin-3 and mouse angiogenin contain fenestrations similar to those observed in endothelial cells from neovasculature induced by vascular endothelial growth factor and basic fibroblast growth factor. Mouse angiogenin-3 also induced other molecular events typical of rapidly proliferating endothelial cells, such as increases in rough endoplasmic reticulum, polysomes, and mitochondria.

3T3 Cells↗
PubMed1999

A double blind observation for therapeutic effects of the tong luo kai bi tablets on rheumatoid arthritis.

The therapeutic effects of the Tong Luo Kai Bi Tablets [symbol: see text] in 120 patients with rheumatoid arthritis were observed in this clinical trial by the randomized double blind method. Both the observed group and the control group each had 60 patients. In the observed group treated with the Tong Luo Kai Bi Tablets, 1 case (1.7%) was cured clinically, 27 cases (45.0%) improved markedly, 26 cases (43.3%) improved, with a total effective rate of 90.0%. In the control group treated with Rheumatic Semen Strychni Tablets [symbol: see text], no case was cured, 16 cases (26.7%) improved markedly, 33 cases (55.0%) improved, with a total effective rate of 81.7%. Statistical data showed the Tong Luo Kai Bi Tablets had much better therapeutic effectiveness clinically than the Rheumatic Semen Strychni Tablets (P < 0.05).

Adult↗
PubMed1999

[The changes in endogenous growth factors and their relation with wound healing].

OBJECTIVE: To explore the effects of endogenous growth factors on the formation of scars and ulcers after trauma or burn. METHODS: The amounts of endogenous epidermal growth factor (EGF), tumor necrosis factor(TNF) and nitric oxide (NO) in scar and the developing granulation tissues after trauma or burn were determined and their relation with the wound healing were studied. RESULTS: The results showed that EGF, TNF and NO could be found in all scars and the granulation tissues, but their concentration varied with different tissues, sex and age of patients. In male patients or youngsters, the amounts of EGF, TNF and NO in scars were much greater than those in granulation tissues. CONCLUSIONS: The results indicated that the growth factors are necessary for wound healing, but insufficiency or overproduction of the endogenous growth factors may lead to the development of chronic ulcers or scar formation after trauma or burn.

Adult↗