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Biomedical subjects

X Shen

Publications and source records attributed to X Shen.

234 records · Page 13Linked to original sources
PubMed1991

[A clinical trial of treating asthma of moderate severity with beclomethasone dipropionate aerosol].

In order to investigate the efficacy of steroid inhalation in treating asthma of moderate severity, a single-blind, randomized short-term (3-4 weeks) trial was performed in 25 asthmatics uncontrolled by salbutamol inhalation, oral aminophylline and beta 2-agonist. 22 patients finished the trial. Among them, twelve received beclomethasone dipropionate 300 mcg/day and ten received placebo. There was significant improvement in asthmatic symptoms and pulmonary function (FEV1.0, V50, V25) in the group treated with steroid inhalation at the end of this trial, whereas no significant changes were observed in the placebo group. The results demonstrated that steroid inhalation could effectively control asthma of moderate severity.

Administration, Inhalation↗
PubMed1990

Copper catalyzed oxidation of ascorbate: chemical and ESR studies.

Cu-catalyzed oxidation of ascorbate has been studied in the absence and the presence of superoxide dismutase, catalase, mannitol, glycerol, ethanol, formate, and thiourea. None of these agents except thiourea inhibited the reaction. Therefore, the role of the Haber-Weiss reaction in the ascorbate oxidation could not be demonstrated. Electron spin resonance studies demonstrated that the preventive effect of the thiol is primarily due to the chelation of the reduced copper ions with the sulphur atom. The oxidation was also prevented by the chelation of copper with physiological levels of bovine serum albumin. These observations are consistent with the concept that a metal-oxygen complex is perhaps directly involved in the oxidative process. Measurements of the peroxide produced during oxidation indicated that significant amounts of this compound accumulates only at lower levels of ascorbate and in the absence of a protein or other chelating agents. At higher ascorbate levels no peroxide accumulation takes place. These results are, thus, useful in predicting the conditions under which the nutrient may act as a pro-oxidant or as an anti-oxidant. The observations suggest that under normal conditions low levels of ascorbate may act as a pro-oxidant through H2O2 production if the system has transition metal ions devoid of chelating agents. At higher concentrations ascorbate acts predominantly as an antioxidant.

Ascorbic Acid↗
PubMed1989

NMR study on the major components in hematoporphyrin derivative YHPD.

The hematoporphyrin derivative YHPD, a China-made product, has been clinically used in photodynamic therapy of tumors as a good photosensitizing drug. The NMR study on the structure of its major components is reported here. In terms of high performance liquid chromatography (HPLC) four major components A, B, C and D were isolated. The NMR results showed that the component A is O-acetylhematoporphyrin, B and C are two isomers of vinyldeuteroporphyrin. The spectra of 2-dimensional homonuclear correlation NMR, 2-dimensional NOE (nuclear overhauser enhancement), 13C-NMR and off-resonance as well as FAB (fast atom bombarding) mass spectrum of component D indicate that it is a protoporphyrin dimer linked by carbon-carbon bond. This finding may provide a chemical basis for understanding the difference in biological activity between YHPD and other foreign commercial HPD, as well as the composition of clinically used alkali-treated HPD and its effective component.

Chromatography, High Pressure Liquid↗
PubMed1989

Tumor size-dependent elevations of serum gangliosides in patients with head and neck carcinomas.

Serum gangliosides were studied in 100 patients with benign or tumoral head and neck lesions. Whereas very few changes over the normal level were noticed in benign cases, 78% of patients with head and neck carcinomas had a significant elevation of serum gangliosides, mostly accounted for by GM3 and GD3. Such an increase was correlated with the observed tumor size, and the level of serum gangliosides returned to normal within one month after surgery. Follow-up of patients showed that further elevations of serum gangliosides were associated with relapses.

Biomarkers, Tumor↗
PubMed1984

Flash photolysis study of insulin.

The transient absorption spectra of the initial UV-photolysis products of insulin and des-pentapeptide (B26-30)-insulin (DPI) were determined and compared with that of free tyrosine. The far-UV band of the spectra (less than 300 nm) has not been reported before. Their main initial photoproducts are p-alanylphenoxyl radical (lambda max = 410,390 nm) and an unidentified radical (lambda max = 270 nm). The photolysis yields are closely correlative with the dissociation rate of hydroxyl group on phenol ring of tyrosine residues, which in turn depends on the exposed degree of these residues. The quantum yields of the phenoxyl radicals formed in photolysis of insulin and DPI were determined and compared with that of free tyrosine. Based on the comparison, the number of light accessible tyrosine residue in insulin and DPI can be calculated, which provides more quantitative information on the exposed degree of tyrosine residues in these two proteins.

Hydrogen-Ion Concentration↗
PubMed1982

Isolation of genome-enzyme complex from cytoplasmic polyhedrosis virus of silkworm Bombyx mori.

The genome-enzyme complex is isolated from the silkworm cytoplasmic polyhedrosis virus with DEAE-Sephadex column chromatography after ultraviolet irradiation. The genome-enzyme complex shows both RNA-polymerase and methyltransferase activities while using 3H-UTP and [3H-methyl]-S-adenosyle-L-methionine as substrates. Like the double-stranded RNA genome of CPV, the genome-enzyme complex could be separated into nine segments on polyacrylamide gel electrophoresis. It is demonstrated that the RNA polymerase and methyl-transferase are tightly bound to the double-stranded RNA genome and that the individual segments of the genome-enzyme complex all possess RNA-polymerase and methyltransferase activities. It appears that each segment of the double-stranded RNA genome is transcribed independently.

Bombyx↗
PubMedDate not supplied

Chemical composition and microstructure of uroliths and urinary sediment crystals associated with the feeding of high-level cottonseed meal diet to water buffalo calves.

The chemical composition and microstructure of seven uroliths and four urinary sediment samples associated with the feeding of high-level cottonseed meal diet to buffalo calves were examined by chemical qualitative analyses, scanning electron microscopy (SEM), X-ray diffraction, and X-ray energy dispersive spectrometry (EDS). Struvite was a major component of kidney stones and of some bladder stones. The kidney stone sample appeared cracked under low power under SEM, aggregated into tiny balls under high power, and as a blade-like structure under even higher power. The bladder stone samples appeared finely granular or granular with various forms of prismatic crystals. The urinary sediments were prismatic crystals, with granules. The newly found prismatic crystals, which were rich in potassium and similar to struvite in crystal structure, were identified as potassium magnesium phosphate (KMgPO4.6H2O) in some bladder stones and urinary sediments. However, crystals which contained Mg and P only, which had been used for struvite identification, were not found by EDS examination in urinary sediments from fresh urine samples of buffalo calves fed the high-level cottonseed meal diet.

Animals↗
PubMedDate not supplied

Validation of rat endometriosis model by using raloxifene as a positive control for the evaluation of novel SERM compounds.

Approximately 10% of women of reproductive age suffer from endometriosis, a potentially painful disease process and important cause of female infertility. Raloxifene, a commercially available SERM (selective estrogen receptor modulator) compound, used for the treatment of postmenopausal osteoporosis, has preclinically demonstrated its estrogen antagonist effect on uterine tissue in rats. There is potential that SERM compounds may become a viable treatment option for human endometriosis, although more investigation is needed. In this study, raloxifene was administered at various doses to determine the efficacy and an appropriate dose level for use as a positive control in a rat model of endometriosis. Prior to dose administration, all rats underwent a bilateral ovariectomy, autologous transplantation of uterine tissue onto the peritoneal surface of the abdominal wall, and implantation of a subcutaneous estrogen pellet (E2). Two separate postsurgical experiments were performed. In experiment 1, following a 4-wk recovery, the rats bearing implants were assigned to three groups: (1) removal of the E2 pellet and dosing vehicle only (n = 7); (2) E2 and vehicle (n = 6); and (3) E2 and raloxifene at 10.0 mg/kg (n = 6). In experiment 2, also following a 4-week recovery, the rats bearing implants were assigned to five groups (n = 8/group): (1) E2 and vehicle only; (2) E2 and raloxifene, 0.3 mg/kg/d; (3) E2 and raloxifene, 1.0 mg/kg/d; (4) E2 and raloxifene, 3.0 mg/kg/d; (5) E2 and raloxifene, 10.0 mg/kg/d. All rats were dosed orally BID for 14 d. At the end of the study, the implanted endometrium was remeasured and compared to the pretreatment measurement. The results from both studies demonstrated that Raloxifene at only one dose (10.0 mg/kg) displayed significant implant regression (p < .05). Subsequently, our rat endometriosis experimental model consistently uses the exogenous E2 pellet and raloxifene at 10 mg/kg, BID, as a positive control to help screen and compare novel SERM compounds.

Animals↗
PubMedDate not supplied

Genomic instability in scleroderma.

Scleroderma is an enigmatic rheumatic disorder of uncertain etio-pathogenesis. Cancer has an approximately two-fold higher incidence in scleroderma patients than in the general population. There are preliminary data of acquired genetic damage in scleroderma but the significance of these observations are uncertain. To determine somatic mutation frequency at the glycophorin-A (GPA) locus in patients with limited and diffuse cutaneous scleroderma. The GPA assay measures the total somatic mutation frequency (Vf), composed of gene inactivating mutations (NO) and mutations arising from mitotic recombination (NN) in individuals heterozygous for the GPA MN blood group. Mutation frequency was determined using a validated GPA flow cytometric assay using fluorescent labeled monoclonal antibodies specific for the GPA blood groups M and N. This assay detects and enumerates progeny of red blood cell (rbc) precursor cells which have acquired genetic damage resulting in a loss of expression of one of the GPA alleles. It was found that patients with scleroderma (n = 23) had significantly elevated Vf as compared with young healthy controls (p < 0.001) and elderly controls (p = 0.03). Patients with diffuse scleroderma had higher mean Vf as compared with limited scleroderma (p = 0.055). In comparison with controls, patients with scleroderma exhibit a higher proportion of mitotic recombinant mutations than inactivating mutations (p < 0.002). There was no correlation between Vf and disease duration, age at onset or autoantibody status. We have documented evidence of acquired genetic damage at the GPA locus in scleroderma. Evidence of acquired genetic damage in this disorder may be importance in explaining both the etio-pathogenesis of scleroderma and the association of scleroderma with cancer.

Adolescent↗