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Biomedical subjects

X Fan

Publications and source records attributed to X Fan.

At least 217 records · Page 12Linked to original sources
PubMed1996

[Treatment of severe hump nose].

An improved operative method has been used to treat severe hump nose in 6 cases since 1989. During the one-stage operation, the shape of the nose was remodeled by correcting the hump deformity and trimming the large lateral cartilage, alar cartilage and septal cartilage. Five cases obtained satisfactory results. One case had second operation because of callus hyperplasia. The article describes the operative design and main points of the procedure. The advantages of the method are discussed.

Adult↗
PubMed1995

Characterization of recombinant human interleukin 4 receptor from CHO cells: role of N-linked oligosaccharides.

Interleukin 4 (IL-4) mediates its biological activities through interaction with its receptor on the cell surface. A recombinant extracellular domain of the alpha subunit of human interleukin 4 receptor was expressed in CHO cells and purified to homogeneity by a combination of ion exchange and immunoaffinity chromatography. Analysis of the purified protein by MALDI MS provided an average mass of 38,241 Da while microsequencing identified the site of the signal sequence processing to be Ser23-Gly24. The receptor was highly glycosylated, containing N-linked complex oligosaccharides with bi-, tri-, and tetraantennary structures. Five of the six potential glycosylation sites could be assigned to Asn residues 53, 98, 128, 134 and 176. N-deglycosylation increased aggregation and reduced solubility of the receptor but did not affect its IL-4 binding activity. These observations provide preliminary insights into the role of N-linked oligosaccharides in IL-4 receptor biosynthesis and function at the cell surface.

Amino Acid Sequence↗
PubMed1995

Characterization of MCSF-induced proliferation and subsequent osteoclast formation in murine marrow culture.

To clarify events involved in 1,25(OH)2D3-stimulated osteoclast-like cell (OCLC) formation in primary murine marrow culture, we have characterized kinetics of precursor proliferation and fusion and their dependence on macrophage colony-stimulating factor (MCSF). 3H-thymidine nuclear incorporation in tartrate-resistant acid phosphatase positive multinucleated cells (TRAP+ MNCs) was assessed: 3H-thymidine incorporation was greatest when tracer was added during day 4 or 5, with labeled nuclei in 81% (day 4) and 90% (day 5) of the TRAP+ MNCs counted at the end of day 7. The percentage of total nuclei labeled was highest when 3H-thymidine was dosed on day 4 (58%), decreasing to 2% by day 7. Final TRAP+ MNC numbers were depleted by 80% when treated for 24 h with hydroxyurea on either day 3 or 4; this inhibition dropped to 57% and 12% when hydroxyurea was pulsed during days 5 or 6, respectively. The absence of 1,25(OH)2D3 during days 1-4 caused 70% attenuation of TRAP+ MNC formation; however, exposure to 3H-thymidine during day 4 in this experiment resulted in subsequent labeling of 81% of the TRAP+ MNCs formed, indicating that precursor proliferation occurred in the absence of 1,25(OH)2D3. To demonstrate that proliferation required MCSF, cultures were exposed to a monoclonal anti-MCSF antibody during days 3, 4, 5, 6, or 7. Inhibition of TRAP+ MNC formation was 85% when antibody was added during day 3. Antibody treatment after day 5 had little effect on the OCLC number. Fusion of precursors showed steady progression with OCLCs containing 4.8 +/- 0.3 nuclei at the end of day 4, 8.3 +/- 0.5 nuclei after day 5, 12.0 +/- 1.3 after day 6, and 13.7 +/- 1.5 at the end of day 7. This steady accretion of nuclei was unaffected by doses of MCSF antibody which blocked proliferation. In conclusion, we have shown that OCLCs arise from an MCSF-dependent expansion of the precursor pool occurring during days 3 and 4. Fusion of these precursors, which begins as proliferation diminishes, is able to progress in the presence of anti-MCSF antibody. These results should help refine the analysis of factors affecting proliferation and fusion of osteoclasts in murine marrow culture.

Acid Phosphatase↗
PubMed1995

Photocycle of halorhodopsin from Halobacterium salinarium.

The light-driven chloride pump, halorhodopsin, is a mixture containing all-trans and 13-cis retinal chromophores under both light and dark-adapted conditions and can exist in chloride-free and chloride-binding forms. To describe the photochemical cycle of the all-trans, chloride-binding state that is associated with the transport, and thereby initiate study of the chloride translocation mechanism, one must first dissect the contributions of these species to the measured spectral changes. We resolved the multiple photochemical reactions by determining flash-induced difference spectra and photocycle kinetics in halorhodopsin-containing membranes prepared from Halobacterium salinarium, with light- and dark-adapted samples at various chloride concentrations. The high expression of cloned halorhodopsin made it possible to do these measurements with unfractionated cell envelope membranes in which the chromophore is photostable not only in the presence of NaCl but also in the Na2SO4 solution used for reference. Careful examination of the flash-induced changes at selected wavelengths allowed separating the spectral changes into components and assigning them to the individual photocycles. According to the results, a substantial revision of the photocycle model for H. salinarium halorhodopsin, and its dependence on chloride, is required. The cycle of the all-trans chloride-binding form is described by the scheme, HR-hv-->K<==>L1<==>L2<==>N-->HR, where HR, K, L, and N designate halorhodopsin and its photointermediates. Unlike the earlier models, this is very similar to the photoreaction of bacteriorhodopsin when deprotonation of the Schiff base is prevented (e.g., at low pH or in the D85N mutant). Also unlike in the earlier models, no step in this photocycle was noticeably affected when the chloride concentration was varied between 20 mM and 2 M in an attempt to identify a chloride-binding reaction.

Bacteriorhodopsins↗
PubMed1995

Control of the necrosed tissue volume during noninvasive ultrasound surgery using a 16-element phased array.

Focused high-power ultrasound beams are well suited for noninvasive local destruction of deep target volumes. In order to avoid cavitation and to utilize only thermal tissue damage, high frequencies (1-5 MHz) are used in ultrasonic surgery. However, the focal spots generated by sharply focused transducers become so small that only small tumors can be treated in a reasonable time. Phased array ultrasound transducers can be employed to electronically scan a focal spot or to produce multiple foci in the desired region to increase the treated volume. In this article, theoretical and experimental studies of spherically curved square-element phased arrays for use in ultrasonic surgery were performed. The simulation results were compared with experimental results from a 16-element array. It was shown that the phased array could control the necrosed tissue volume by using closely spaced multiple foci. The phased array can also be used to enlarge a necrosed tissue volume in only one direction at a time, i.e., lateral or longitudinal. The spherically curved 16 square-element phased array can produce useful results by varying the phase and amplitude setting. Four focal points can be easily generated with a distance of two or four wavelengths between the two closest peaks. The maximum necrosed tissue volume generated by the array can be up to sixteen times the volume induced by a similar spherical transducer. Therefore the treatment time could be reduced compared with single transducer treatment.

Biophysical Phenomena↗
PubMed1995

Differential regulation of epidermal growth factor and transforming growth factor-alpha messenger ribonucleic acid in the rat anterior pituitary and hypothalamus induced by stresses.

Evidence has shown that epidermal growth factor (EGF) and transforming growth factor-alpha (TGF alpha) are present in the anterior pituitary as well as the hypothalamus, and that EGF can influence the function of pituitary cells, particularly corticotropes in vivo and in vitro. However, little is known about their exact functional roles and how they are regulated in these two areas. The present study was designed to determine if EGF and TGF alpha messenger RNA (mRNA) are expressed in the rat anterior pituitary and hypothalamus and how stress conditions such as cold, ether, or restraint affect their local expression. A sensitive mRNA detection method, the ribonuclease protection assay, detected both EGF and TGF alpha mRNA in the rat anterior pituitary and hypothalamus. Reverse transcription-polymerase chain reaction (RT-PCR) further showed the presence of EGF and TGF alpha mRNA in these two areas and several other rat tissues (submandibular gland, liver, kidney, lung cerebral cortex, and testis). No TGF alpha mRNA was found in the kidney, however. EGF mRNA was up-regulated in the anterior pituitary after 30 min acute cold stress (CS) and restrainer-restraint stress (RS) but not 30 min after ether stress (2 min, ES), novelty stress (NS), or tape-restraint stress (TS). Further analysis showed that EGF mRNA expression decreased after 1 h CS (1C) and then increased after 3 h CS (3C). In contrast, TGF alpha mRNA in the anterior pituitary and hypothalamus and hypothalamic EGF mRNA did not show significant changes in response to either acute stresses (CS, ES, RS, TS, NS) or longer CS (1C, 3C). Our results suggest that 1) EGF, is up-regulated after some stresses; 2) increased pituitary EGF mRNA in response to stresses varies with the type of stress; and 3) pituitary TGF alpha and hypothalamic EGF and TGF alpha may be not involved in the stress response.

Adrenocorticotropic Hormone↗
PubMed1995

Epidermal growth factor and transforming growth factor-alpha messenger ribonucleic acids and their receptors in the rat anterior pituitary: localization and regulation.

Evidence has shown that epidermal growth factor (EGF), transforming growth factor-alpha (TGF alpha) and their receptors (EGF receptors) are present in the anterior pituitary, indicating that the growth factors are synthesized in situ and act locally. Studies have demonstrated that EGF could stimulate the hypothalamus-pituitary-adrenal (HPA) cortex axis, particularly at the pituitary level in vivo and in vitro, and also stimulate TGF alpha messenger RNA (mRNA) expression in cultured bovine pituitary cells. Recently, our studies have demonstrated that some stresses up-regulated EGF mRNA expression in the anterior pituitary, as detected by ribonuclease protection assay, further indicating the possible roles of EGF in the stress response. However, little is yet known about the sources and targets (sites of EGF receptors) of the growth factors in the pituitary. Therefore, this study was designed to localize EGF and TGF alpha mRNA and their receptors as well as to assess the effects of cold stress (CS) on their expression in the subsets of pituitary cells. In situ hybridization immunocytochemistry coupled with immunocytochemistry and dual immunocytochemistry studies revealed the presence of 1) EGF mRNA in somatotropes and gonadotropes; 2) TGF alpha mRNA in somatotropes, gonadotropes, and lactotropes; and 3) EGF receptors in all subsets of pituitary cells. CS (30 min) induced the expression of EGF mRNA in corticotropes and thyrotropes. EGF expression was not altered in somatotropes and gonadotropes. No significant changes were detected in TGF alpha mRNA expression in the pituitary cells after 30 min of CS. Expression of EGF receptors was also increased after 30 min of CS. This resulted from increases in EGF receptor-labeled cells among thyrotropes and gonadotropes. The cold stress-induced expression of EGF mRNA in corticotropes and thyrotropes fits with their overall activation after this type of stress. The increase in EGF receptor-labeled cells among thyrotropes may point to an important autocrine role for EGF in maintaining TSH responses to cold. On the other hand, the significance of EGF receptor up-regulation in gonadotropes (FSH-containing cells) caused by CS remains unknown.

Adrenocorticotropic Hormone↗
PubMed1995

Adhesion molecule expression on gastric intra-epithelial lymphocytes of patients with Helicobacter pylori infection.

OBJECTIVE: To examine the expression of adhesion molecules on gastric intra-epithelial lymphocytes (IELs) from patients infected with Helicobacter pylori. DESIGN: The expression of adhesion molecules and T-cell activation markers by gastric IELs from patients with gastritis or duodenal ulceration was examined using two-colour flow cytometry. Ten of the patients were H. pylori positive and eight were H. pylori negative. RESULTS: Expression of lymphocyte function-associated antigen-1 (LFA-1) on IELs was significantly lower (P < 0.05) in patients with H. pylori infection than in patients negative for H. pylori. There were no significant differences in the expression on IELs of intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), human mucosal lymphocyte (antigen)-1 (HML-1), very late antigen-4 (VLA-4) or CD43 between H. pylori-positive and H. pylori-negative individuals. In addition, the transferrin receptor, a maker associated with proliferation and activation, was found on a small population of IELs from H. pylori-positive individuals. CONCLUSION: A reduction in the expression of LFA-1 has previously been reported on activation of IELs. The finding of reduced LFA-1 expression and increased transferrin receptor expression on IELs from H. pylori-positive individuals suggests that activation of these cells is associated with H. pylori infection.

Case-Control Studies↗
PubMed1995

[Clinical use of the C-shaped cross finger flap].

The C-shaped cross finger flap is an axial flap based on the digital vascular bundle either distally or proximally. We have successfully used this flap to repair different defects of the finger in 12 cases. The flap can be made rather big and the operation is easy. The surgical technique and the advantages and disadvantages are described.

Adolescent↗
PubMed1994

The effects of curved tissue layers on the power deposition patterns of therapeutic ultrasound beams.

A numerical model for calculating the ultrasonic power deposition in layered media was developed and experimentally tested. The new model takes into account the ultrasound wave reflection and refraction occurring at tissue interfaces. In order to study the effects of soft tissue interfaces on the resulting ultrasonic power deposition patterns, the tested model was applied to simulate four different treatments situations in ultrasound therapy (such as hyperthermia). It was found that in most cases the effect of soft tissue interfaces could be ignored during ultrasound treatments. However, strongly curved tissue interfaces such as those encountered during brain treatments could have significant effects on the location of the focus and the magnitude of local power deposition if sharply focused ultrasound beams are used. The maximum lateral displacement of the focus in a brain treatment was 3 mm. This is too large to be ignored during therapy and thus the effect of tissue interfaces should be taken into account when certain ultrasound treatments are planned and executed.

Acoustics↗
PubMed1994

Increased tumour necrosis factor alpha production by neutrophils in patients with hepatitis B.

AIMS: To investigate the role of serum and neutrophil tumour necrosis factor alpha (TNF alpha) in patients with viral hepatitis. METHODS: The activities of serum and neutrophil TNF alpha were measured using a bioassay of in vitro cytotoxicity against L929 cells in 57 patients with viral hepatitis and 20 healthy blood donors. RESULTS: Both serum and neutrophil TNF alpha in patients with chronic active hepatitis (CAH) and subacute fulminant hepatitis (SAFH) increased compared with those in normal controls (p < 0.01). No such differences were seen in patients with acute hepatitis. Serum and neutrophil TNF alpha were obviously reduced in patients with CAH and SAFH during convalescence compared with the active period (p < 0.05; p < 0.01). Furthermore, serum TNF alpha was significantly increased in patients with SAFH and complications compared with those without (p < 0.01), and in patients with SAFH who died compared with those who survived (p < 0.01). Neutrophil TNF alpha was significantly higher in patients with SAFH and secondary bacterial infections (p < 0.05). CONCLUSIONS: Production of serum and neutrophil TNF alpha is increased in patients with CAH and SAFH, suggesting that neutrophil TNF alpha causes liver injury in these patients.

Adult↗
PubMed1994

[Chemical constituents of roots, rhizomes and stems of Amomum villosum Lour].

Ethyl octacosate, docosyl hexylate, a new compound stigmast-4-ene-1,3-dione, beta-sitosterol and daucosterol were isolated and identified from the roots and rhizomes of Amomum villosum cultivated in Xishuangbanna, Yunnan. Two compounds daucosterol and emodin monoglycoside were isolated and identified from the stems of A. villosum.

Drugs, Chinese Herbal↗
PubMed1994

[Repair of heel defect with a free medial plantar flap].

The results of reconstruction of plantar heel defects with a local random flap or an island medial plantar flap have in a majority of cases been satisfactory. However, in cases of extensive plantar defects, local tissue transfers are almost impossible. Since 1988, 8 cases with extensive plantar defects have been treated using free medial plantar cutaneous or musculocutaneous flaps. All flaps survived. Six weeks postoperatively, full weight-bearing was obtained and normal activities were resumed. No ulceration in the flaps has been noted in the follow up period between 6 and 24 months, and the two point discrimination was from 20 to 24 mm. The paper particularly points out the importance of nerve repair in the reconstruction, because recovery of the protective sensation is the most important factor to prevent plantar ulceration, and is the basis for good operative results.

Adolescent↗
PubMed1993

Biochemical and immunological characterization of X-linked ichthyosis.

An immunoquantification protocol based on an enzyme-linked immunosorbent assay was developed to measure the abundance of the microsomal enzyme steroid sulphatase (STS). The two-step sandwich immunoassay is sufficiently sensitive to detect 100-200 pg purified steroid sulphatase in a 50-microliters sample. The steroid sulphatase content in fibroblast, leukocyte and placental extracts correlates with the steroid sulphatase activity in these extracts. No steroid sulphatase protein was found in approximately 350 micrograms plasma proteins from a normal person. In three of four X-linked ichthyosis patients a complete gene deletion was found by Southern hybridization with the full-length STS cDNA as probe. Neither steroid sulphatase protein nor enzymatic activity was found in fibroblast extracts of these three patients. In a fibroblast extract of another X-linked ichthyosis patient, which had a normal Southern blotting pattern, no immunoreactive protein was detected. Residual activity of steroid sulphatase was also not found after prolonged incubation of this fibroblast extract with the natural substrate oestrone sulphate.

Arylsulfatases↗
PubMed1993

Biocompatibilities of organic solvents with Lactobacillus delbrueckii.

In the search for biocompatible extractants for extractive fermentation of lactic acid, the effect of twelve organic solvents on the activity of L. delbrueckii were studied at different concentration levels. On this basis, the compatibilities of twelve solvents with L. delbrueckii were summarized into four classes: completely compatible, compatible at molecular level, partially compatible and non-compatible. The characteristics were described qualitatively for each class in terms of relative values between the solubility of organic solvent in water (Cs) and the toxicity of organic solvent, which is indicated by a newly defined concentration parameter (Cm). The classification was helpful for the selection of extractant in extractive fermentation.

Fermentation↗
PubMed1993

Expression of a fusion protein containing calf prochymosin B(1-161) and human proinsulin.

The plasmid pJG202 containing Tac promoter, calf prochymosin B(1-161) gene and human proinsulin gene was constructed and transformed into E. coli JM105. The expression of the fusion protein consisting of 249 amino acids was controlled by IPTG and temperature, and the expressed protein was estimated to be 20-35% of the total cellular proteins by scanning of the SDS-PAGE gel stained with Coomassie brilliant blue R250. After CNBr cleavage, sulfitolysis, partial separation of the S-sulfonated human proinsulin and recombination of the disulfide bonds, human proinsulin with native properties, as evidenced by amino acid composition analysis, receptor binding and radioimmunoassays, could be obtained.

Animals↗