Biomedical subjects

G Yang

Publications and source records attributed to G Yang.

508 records · Page 29Linked to original sources

PubMedDate not supplied

Calculation of dose distribution near an innovative concentric balloon catheter for endovascular brachytherapy.

PURPOSE: Using a radioactive solution-filled catheter for intravascular irradiation has the potential problem of chemical and radiological toxicity in the case of a balloon rupture. In order to reduce this risk, an innovative concentric balloon catheter was developed. METHODS AND MATERIALS: The concentric balloon was made by inner and outer balloons filled with saline and radioactive solution, respectively. The optimal inner radius was determined by comparing the dose rate reduction vs. the volume reduction for various inner and outer radii for 188Re, 32P, and 90Y solutions. RESULTS: For a balloon with an outer radius of 1.5 mm, there was no advantage of a concentric balloon. For balloons with outer radii of 3.0 and 5 mm, the optimal inner radius was 1.5 and 3 mm, respectively. CONCLUSIONS: With the newly designed concentric balloon, the risk of toxicity can be reduced while keeping the dose rate high enough so that the treatment times within tolerable limits are still maintained.

Brachytherapy↗

PubMedDate not supplied

Differential expression of CCAAT/enhancer-binding protein-delta (c/EBPdelta) in rat androgen-dependent tissues and human prostate cancer.

CCAAT/enhancer-binding protein delta (C/EBPdelta) is a nuclear transcription factor that regulates cellular growth and differentiation. In this study we demonstrate that C/EBPdelta gene expression is differentially regulated in rat androgen-dependent tissues and human prostate cancer. C/EBPdelta messenger RNA (mRNA) levels were very low in adult rat ventral prostate, epididymis, and testis. In ventral prostate and epididymis, expression of C/EBPdelta mRNA increased more than sixfold when testicular testosterone was eliminated by surgical castration or treatment with ethane-1,2-dimethanesulfonate (EDS). Testosterone replacement reduced C/EBPdelta mRNA levels to near control values in both tissues. CWR22 is a human prostate cancer xenograft that mimics biological characteristics of androgen-dependent and androgen-independent human prostate cancer. In androgen-dependent CWR22 tumors, expression of C/EBPdelta mRNA declined in response to castration. Both C/EBPdelta mRNA and protein levels increased following testosterone administration. However, C/EBPdelta mRNA and protein levels were variable in recurrent CWR22 tumors growing in the absence of testicular androgen for approximately 5 months. C/EBPdelta expression was also variable in androgen-independent human prostate carcinomas (n = 3), although mRNA levels were substantially lower than those in androgen-dependent tumors (n = 3). These studies demonstrate that androgen down-regulates C/EBPdelta levels in androgen-dependent rat tissues, but induces C/EBPdelta expression in androgen-dependent human prostate cancer. Deregulation of C/EBPdelta occurs when prostate cancer progresses to the androgen-independent state.

Androgens↗

PubMedDate not supplied

Median nerve somatosensory evoked potentials and upper limb motor function in hemiparesis.

The purpose of this study is to describe the relationship between median nerve somatosensory evoked potential (SEP) parameters and clinical measures of motor impairment and physical disability in the affected upper limb of patients with hemiparesis. SEP assessments were carried out in 28 long-term survivors of stroke. Stroke survivors with preserved SEPs over the affected hemisphere exhibited significantly lower motor impairment and physical disability than those with absent waveforms. Among those with preserved waveforms, SEP amplitude exhibited a weak correlation with degree of upper limb motor impairment. The correlation between SEP amplitude and physical disability was not statistically significant. Contrary to prior reports, median nerve SEP appears to have a weak correlational relationship with clinical measures of upper limb function in hemiparesis.

Adult↗

PubMedDate not supplied

Enzyme-linked immunosorbent assay for screening aflatoxin B1 in cottonseed products and mixed feed: collaborative study.

A joint AOAC/IUPAC (International Union of Pure and Applied Chemistry) interlaboratory study of an enzyme-linked immunosorbent screening assay (ELISA) for aflatoxins was conducted in laboratories in Canada, France, Japan, South Africa, Switzerland, The Netherlands, Tunisia, and the United States. Twenty-eight samples of raw and roasted peanuts, corn, whole cottonseed, cottonseed meal, ammoniated cottonseed meal, and poultry feed containing various quantities of natural aflatoxins and supplemented when appropriate with aflatoxin B1 were distributed to participating laboratories for testing. The assay is based on conjugation of pure aflatoxin B1 to an enzyme and the competition between this conjugate and (free) aflatoxins in the product for aflatoxin-specific antibodies coated onto microtiter well walls. After a wash step to remove all unbound aflatoxins, a substrate, added to each well, is catalyzed from a colorless to a green solution by any bound enzyme-conjugated aflatoxin B1 present. The intensity of the color decreases as the amount of free aflatoxin B1 in the product increases. Overall correlation was good between ELISA and thin-layer chromatographic (TLC) results for cottonseed products and mixed feed. Variable results were reported for corn and peanut product samples. Although some positive samples (greater than 15 ng/g) of cottonseed products and mixed feed were reported to contain less than 15 ng/g by visual determination, a review of data for absorbance measurements showed that the contamination level was close to the greater than or equal to 15 ng/g standard and would not have been reported as negative under routine screening.(ABSTRACT TRUNCATED AT 250 WORDS)

Aflatoxin B1↗