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Biomedical subjects

G Wang

Publications and source records attributed to G Wang.

At least 901 records · Page 50Linked to original sources
PubMed1979

Selectivity of action of 5-FU: biochemical basis.

Studies have been initiated to investigate the biochemical basis for selectivity of action of 5-fluorouracil against tumor cells. These studies included the measurement of 5-fluorodeoxyuridine monophosphate pools and the amount of 5-fluorouracil incorporated into RNA at various times following the administration of labeled 5-fluorouracil-6-3H, 5-fluorouridine-6-3H and 5-fluorodeoxyuridine-6-3H to animals bearing sensitive L1210 cells and L1210 resistant to 5-fluorouracil. The data indicate that: 1) in both cell lines the order of drug uptake into cells in vivo was in the order of fluorouride greater than fluorouracil greater then fluorodeoxyuridine; 2) there was no qualitative difference between the two cell lines in term of the extent of drug activation; 3) the data suggest a strong correlation between the amount of 5-fluorodeoxyuridine-monophosphates formed and retained at the target site and responsiveness to these agents. The effects of thymidine administered by continuous infusion and i.v. bolus injection on the antitumor activity of 5-fluorouracil was also investigated in animals bearing the induced colon carcinoma. The data suggest that thymidine, in combination with 5-fluorouracil, improves the therapeutic index of 5-fluorouracil. Initial studies on the metabolism of 5-fluorouracil in patients bearing the colon carcinoma are also reported herein.

Animals↗
PubMed1978

Traumatic arteriovenous fistula of the popliteal artery associated with a closed subtrochanteric fracture: report of a case.

Major vascular injuries associated with closed fractures of the femur are rare. A 35-year-old man incurred a subtrochanteric fracture associated with an arterial injury distally. The femoral fracture type most likely to be associated with a major vascular injury is one near the junction of the middle and distal thirds of the bone. The mechanism involves tethering of the artery in the adductor hiatus. The location of the arterial injury is usually at the fracture site.

Adult↗
PubMedDate not supplied

Keratinocyte growth factor induced epithelial proliferation facilitates retroviral-mediated gene transfer to distal lung epithelia in vivo.

BACKGROUND: Cell proliferation, vector titer and accessibility of target cells represent hurdles for efficient gene transfer to lung epithelia in vivo using recombinant murine leukemia (MuLV)-based retroviruses. We tested the hypothesis that the pulmonary epithelium is susceptible to retroviral-mediated gene transfer when stimulated to proliferate by a mitogen, keratinocyte growth factor (KGF). METHODS: Rats received keratinocyte growth factor (KGF, 2.5 micrograms/g x 4 doses, two consecutive days) intratracheally followed by high titer amphotropic retrovirus expressing beta-galactosidase. Gene transfer was assessed five days later. RESULTS: KGF stimulated transient proliferation in the bronchiolar and alveolar epithelia (30-40% PCNA positive cells at peak) which decreased to background levels seven days after administration. Gene transfer to epithelia (X-Gal positive cells) occurred more frequently in KGF treated rats, but proliferation exceeded the level of gene transfer. X-gal positive cells were noted in the alveolar epithelium and occasionally in the bronchiolar epithelium. In order to understand the discrepancy between the number of proliferating and transduced cells, primary rat tracheal epithelium cultured at the air-liquid interface was infected from either the apical or basolateral side. Gene transfer was achieved only through basolateral application of vector, suggesting that epithelial polarity represents a barrier to MuLV-based lung gene transfer in vivo. CONCLUSIONS: KGF transiently stimulates epithelial proliferation in vivo, facilitating MuLV-based gene transfer. Retroviral vectors may encounter multiple barriers which have evolved to defend the lung from infections.

Animals↗
PubMedDate not supplied

Low-light image analysis of transgenic organisms using bacterial luciferase as a marker.

Methods for measurement of a novel light-emitting reporter gene system in bacteria, yeast, plant cells, plant tissues and intact plant organs are described. The principle underlying the assay procedures is the bacterial luciferase catalysed oxidation of reduced flavin mononucleotide (FMNH2) in the presence of the ten carbon aldehyde decanal, to yield FMN, decanoic acid, water and a photon of light at 490 nm which can be captured by X-ray film, a photomultiplier tube or, for in vivo measurements, an image-intensifier coupled to a video camera. This light measuring assay system is sensitive, easy to use, inexpensive, does not require radioactivity, and has been used successfully for rapid detection of bacterial transformants, the quantitative measurement of transient and stable gene expression in bacteria and yeast, and in vivo measurement of temporal and spatial gene expression throughout plant and animal development.

Animals↗
PubMedDate not supplied

Half-scan cone-beam x-ray microtomography formula.

An x-ray shadow projection microtomographic system using a scannable point source is under development at AMIL-ARTS, SUNY at Buffalo. To overcome the limitations of the commonly used Feldkamp's cone-beam reconstruction formula, we have developed a generalized Feldkamp-type cone-beam reconstruction formula. In the generalized Feldkamp-type cone-beam reconstruction, a scanning locus can be either planar or helix-like, and a transaxial slice is reconstructed using projection data collected from a 360 degrees angular range (full scan). In this paper, the full-scan cone-beam formula is modified to require only projection data of approximate 180 degrees plus two fan-angles (half scan). First, a half-scan derivative-free noncircular fan-beam reconstruction formula is formulated. Then, a half-scan cone-beam reconstruction formula is derived as an extension of the half-scan fan-beam reconstruction formula using Feldkamp's procedure. Typical numerical simulation results are given for both half-scan formulae. Compared with the full-scan cone-beam formula, the half-scan cone-beam formula reduces the involved angular range of projection data and allows better longitudinal/temporal resolution.

Image Processing, Computer-Assisted↗
PubMedDate not supplied

Nonfluoroscopic reduction of intussusception by air enema.

Intussusception is a common pediatric condition in China. Hydrostatic reduction with barium sulfate or pneumatic reduction using air and fluoroscopy has become the standard method in most centers throughout the world. To avoid radiation exposure, reduction without fluoroscopic confirmation was studied. Between 1981 and 1985 a total of 224 children were diagnosed and treated for intussusception. The diagnosis was made correctly on clinical grounds in 184 cases; in 40 cases ultrasonography confirmed the clinical diagnosis. Pressurized air reduction was successful in 217 patients (96.9%); seven patients required operative reduction. Ultrasonograms of the abdomen supported the diagnosis in 40 patients and confirmed subsequent reduction. This experience demonstrates that childhood intussusception can be reduced using pneumatic pressure without exposing the patient to ionizing radiation.

Air↗
PubMedDate not supplied

Investigation of the metabolism of 7-(4-chlorbenzyl)-7,8,13,13a-tetrahydroberberine chloride in the rat.

The metabolism of 7-(4-chlorbenzyl)-7,8,13,13a-tetrahydroberberine chloride (CTHB), a compound with promising pharmacological effects against arrhythmia, was investigated in rat bile. A metabolite and unchanged CTHB were found in the bile. Characterization and structural elucidation of the metabolite was achieved by LC/MS and LC/NMR. The following metabolic pathway is proposed: CTHB is metabolized by demethylation at position 10 to produce a new entity.

Animals↗
PubMedDate not supplied

EEG analysis of epilepsy by directed coherence method. A data processing approach.

Directed coherence (DCOH) was proposed in our previous work as a measure of the correlation between the EEGs of different sites of human brain. In the present research, we applied this method to the interpretation of intrahemispheric information flow in the EEGs of thirteen epileptic patients. This paper discusses the bidirectional communication pattern with DCOH between the frontal and the occipital cortex in the EEGs of epileptics. Comparing with the high values in the alpha-band for the controls, significantly (P < 0.001) small DCOH values were found in the thirteen epileptic patients. The DCOH values of epileptic patients were scattered over the beta-, theta- and delta-bands. This may suggest that the dysfunction of the epileptic brain may be due to an abnormality of the neural networks in the brain.

Adult↗
PubMedDate not supplied

Synthesis of novel phosphoramidite reagents for the attachment of antisense oligonucleotides to various regions of the benzophenanthridine ring system.

Four benzophenanthridine phosphoramidite reagents have been prepared in which the linker chain between the benzophenanthridine and the phosphoramidite moiety is attached to C-2, C-6, C-9, and C-12 of the benzophenanthridine ring system. These benzophenanthridine phosphoramidites should prove to be useful in the syntheses of antisense oligonucleotide-intercalator conjugates in which the linker chain is attached to various regions of the benzophenanthridine intercalator. One of the new benzophenanthridine phosphoramidite reagents was used to prepare an antisense oligonucleotide-intercalator conjugate in which the oligonucleotide TCAGTGGTp was connected at its 5'-hydroxyl group through a linker chain to the C-2 hydroxyl group of a benzophenanthridine.

Amides↗
PubMedDate not supplied

Near-field mapping of the emission distribution in semiconductor microdiscs.

We have used a scanning near-field optical microscope to study the fluorescent light distribution in the near- and far-fields with two types of microdiscs, InGaP and GaN, fabricated in our laboratory. The InGaP microdisc has a radius of 2.5-5.0 microm, a thickness of 0.15-0.2 microm and a circular shape and the GaN disc has a radius of 5-8 microm with a thickness of 0.5-2 microm. Spontaneous emission enhancement in these microdiscs has been observed with emitting wavelengths of 650 and 550 nm respectively In both types of microdisc, the whispering-gallery mode (WCM) has been observed on the top surface using near-field optical and far-field microscopic methods. However, due to the different disc structures and optical confinements, the light distributions of the type types of disc are quite different. In the case of the InGaP disc, WGM is the dominant mode with a mixture of other modes. Interference-like ring intensities have been observed both inside the disc surface and outside, with a period ratio of 1:2. In addition, the propagating waves emitted from the side of the disc have been collected for the first time by using near-field optical microscopy. A theoretical calculation based on the theory of optical modes in microdisc lasers confirmed this observation. It also predicted the behaviour of the electric field distribution (transverse electric) inside and outside the disc, as well as the period of the wave propagation. In contrast, the near-field mapping of the GaN fluorescence showed not only a ring-like emission intensity along the circumference of the disc, an indication of WGM, but also an even intensity distribution inside the disc. This can be explained as the combination of the WGM with the Fabry-Perot mode of multi-reflection between the GaN layer and the substrate. The results also demonstrate the potential application of near-field optics to explore the light emission mode of a microdisc on a nanometre scale.

Journal Article↗
PubMedDate not supplied

Analysis of polycyclic aromatic hydrocarbons in cooking oil fumes.

Various samples of cooking oil fumes were analyzed to an effort to study the relationship between the high incidence of pulmonary adenocarcinoma in Chinese women and cooking oil fumes in the kitchen. Polycyclic aromatic hydrocarbons (PAHs) in samples of cooking oil fumes were extracted, chromatographed, and measured by fluorescence spectrophotometer. The samples included oil fumes from three commercial cooking oils and fumes from three catering shops. All samples contained benzo(a)pyrene (BaP) and dibenzo (a,h)anthracene (DBahA). In addition, the concentration of DBahA was 5.7 to 22.8 times higher than that of BaP in the fume samples. Concentrations of BaP and DBahA were, respectively, 0.463 and 5.736 micrograms/g in refined vegetable oil, 0.341 and 3.725 micrograms/g in soybean oil, and 0.305 and 4.565 micrograms/g in vegetable oil. Investigation of PAH concentrations at three catering shops showed that the level of BaP at a Youtiao (deep-fried twisted dough sticks) shop was 4.18 micrograms/100 m3, 2.28 micrograms/100 m3 at a Seqenma (candied fritters) workshop, and 0.49 micrograms/100 m3 at a kitchen of a restaurant; concentrations of DBahA were 33.80, 14.41, and 3.03 micrograms/100 m3, respectively. The high concentration of carcinogens, such as BaP and DBahA, in cooking oil fumes might help explain why Chinese women, who spend more time exposed to cooking oil fumes than men, have a high incidence of pulmonary adenocarcinoma.

Adenocarcinoma↗
PubMedDate not supplied

Synthesis of unsaturated carboacyclic nucleoside analogues via Mitsunobu reactions.

2-Substituted allyl alcohols 9 and 14 were prepared starting from butane-1,2,4-triol and glycerol, respectively. Mitsunobu condensations of 9 and 14 with purine and pyrimidine bases, followed by deprotection, afforded a number of acyclonucleosides having 4-hydroxy-2-methylenebutyl or 3,3-bis(hydroxymethyl)-2-methylenepropyl chain.

Alkenes↗
PubMedDate not supplied

Synthesis and anticancer activity of 4-amino-5-oxo-8-(beta-D-xylofuranosyl)pyrido[2,3-d]pyrimidine.

4-Amino-5-oxo-8-(beta-D-xylofuranosyl)pyrido[2,3-d]pyrimidine (4) was recently synthesized and evaluated in our laboratories for anticancer activities. This compound showed potent in vitro inhibitory effects on the growth of HTB-81 prostate cancer cells and Daudi-lymphoma. In vivo studies showed that the compound could inhibit HTB-81 tumor growth in syngeneic mice by 93% at a daily dose of 8.5 mg/kg for 10 days.

Animals↗
PubMedDate not supplied

Highly sensitive quantitation of methamphetamine by time-resolved fluoroimmunoassay using a new europium chelate as a label.

A simple and highly sensitive time-resolved fluoroimmunoassay of methamphetamine (MA) using a new fluorescent europium chelate (BHHCT-Eu3+) as a label is described. Two variations of competitive immunoassay were attempted. In the first (one-step) assay, microtiter plates coated with anti-MA were used, and the new label was bound to a conjugate of bovine serum albumin and N-(4-aminobutyl)-MA (MA-BSA). In the second (two-step) assay, instead of the labeled MA-BSA, biotinylated MA-BSA and BHHCT-Eu3+-labeled streptavidin-BSA were used. The lowest measurable concentrations of MA for the one-step and the two-step methods were 1 ng/mL (25 pg/assay) and 1 pg/mL (25 fg/assay), respectively. These were 10 to 1000 times superior to the detection limits of MA in any other immunoassay. Intra-assay coefficient of variation was approximately 2-8% at eight different concentrations (n = 4). Analysis of 34 urine samples with the new method and conventional gas chromatography showed a good correlation (r = 0.954). The high detectability of the present assay also enabled segmental hair analysis with a few centimeters of a hair.

Adult↗
PubMedDate not supplied

Total hip prosthesis metal-artifact suppression using iterative deblurring reconstruction.

PURPOSE: CT of total joint prostheses is limited by metal artifact produced mainly by missing projection data. Iterative deblurring reconstruction is less sensitive to missing projection data than filtered backprojection. A software CT simulator was used to compare total hip prosthesis images reconstructed using standard filtered backprojection, filtered backprojection after linear interpolation of missing data, and iterative deblurring. METHOD: Unilateral and bilateral total hip replacements with metal-backed or all-polyethylene acetabular prostheses were simulated using bone, metal, and polyethylene annuli and circles of metal and water (soft tissue). Material attenuation properties were taken from the literature. The simulation assumed that no X-rays penetrated the metal. Simulated projection data were reconstructed using filtered backprojection, filtered backprojection after linear interpolation of missing data, and iterative deblurring. Visual observations and objective region-of-interest analyses were made. RESULTS: Even with no X-rays penetrating the metal, iterative deblurring produced almost no visible artifact within the bone or soft tissues. Bone edge detection and sizing were more easily and accurately done from the iterative deblurring images. All reconstruction techniques underestimated bone and water CT attenuation values. Metal artifact was worse for the bilateral or metal-backed prostheses. CONCLUSION: Iterative deblurring generated nearly metal-artifact-free images in this simulation. Filtered backprojection, even after linear interpolation, produced typical clinical metal-artifact images.

Artifacts↗
PubMedDate not supplied

Helical CT image noise--analytical results.

Helical CT is an important recent development in x-ray CT. In helical CT, planar projection sets are synthesized from raw projection data via interpolation. Among various interpolation schemes, linear interpolation is usually preferred due to its efficiency and performance. In this paper, image noise variance is derived for typical helical CT linear interpolation techniques, including the full scan (FS), under-scan (US), full scan with interpolation (FI), half-scan (HS), half-scan with interpolation (HI) and half-scan with extrapolation (HE) methods. Image noise deviation ratios of helical CT to conventional 360 degrees reconstruction (CR) are tabulated. These are consistent with previously reported simulation results. The theoretical results provide further understanding of helical CT noise performance. It is shown that helical CT image noise deviation is independent of transaxial position, proportional to the raw projection noise deviation, and not affected by the fan angle (approximately for the HE method). Also, helical CT image noise variance is proportional to the area under the square of the reconstruction filter.

Computer Simulation↗