Biomedical subjects

M D Kuo

Publications and source records attributed to M D Kuo.

24 records · Page 2Linked to original sources

PubMed1986

Transforming growth factor activity of bovine brain-derived growth factor.

Bovine brain-derived growth factor (BDGF), whose biochemical properties resemble those of endothelial cell growth factor (ECGF) and brain-derived acidic fibroblast growth factor (acidic FGF), is able to promote colony formation of normal rat kidney fibroblasts (NRK cells) in soft agar. As in the case of transforming growth factor beta (TGF beta), EGF potentiates the anchorage-independent growth promoting activity of BDGF. In the presence of EGF (5 ng/ml), the optimal concentration of BDGF for stimulation of anchorage-independent of NRK cells is approximately 0.5 ng/ml. At higher concentrations, BDGF becomes inhibitory. The anchorage-independent cell growth promoting activity of BDGF differs from that of TGF beta in acid and reducing agent stability.

Acetates↗

PubMed1986

Bovine brain-derived growth factor. Purification and characterization of its interaction with responsive cells.

A large-scale purification procedure for brain-derived growth factors, without chromatography in 0.1% trifluoracetic acid, has been developed. Two related brain-derived growth factors have been purified to homogeneity from bovine brain using this procedure involving ammonium sulfate fractionation, followed by chromatography on CM-Sephadex C-50, sulfated Sephadex G-50, and heparin-Sepharose 4B. Brain-derived growth factor A (BDGF-A, molecular weight approximately 16,000) and brain-derived growth factor B (BDGF-B, molecular weight approximately 17,000) were eluted from heparin-Sepharose 4B at 1.2 and 1.6 M NaCl, respectively. Both BDGF-A and BDGF-B have a pI value of 5.7, have the same specific mitogenic activity, and react with mouse anti-BDGF-A antiserum. Both growth factors have a broad spectrum of mitogenic activity (vascular and aorta endothelial cells, chondrocytes, osteoblasts, epithelial cells, glial cells, fibroblasts, and smooth muscle cells), with a half-maximum effect at 10-20 pM. The binding of BDGF to bovine aorta endothelial cells and Swiss mouse 3T3 cells has been characterized. Binding of 125I-BDGF-A to these cells reached equilibrium in less than 15 min. Scatchard plot analysis of the binding of 125I-BDGF-A to endothelial cells and 3T3 cells showed a single class of high-affinity receptor with Kd values of 20 +/- 5 and 13 +/- 3 pM and receptor numbers/cell of 7,000 +/- 1,000 and 20,000 +/- 3,000, respectively. BDGF-B competed for 125I-BDGF-A binding in the same manner as unlabeled BDGF-A, suggesting that BDGF-A and BDGF-B bind to the same receptor. Basic pituitary fibroblast growth factor appeared to be a weak inhibitor, whereas platelet-derived growth factor and epidermal growth factor had no effect on 125I-BDGF-A binding. Protamine, histone, polylysine, and polyarginine are potent inhibitors of the mitogenic activity of BDGF-A and BDGF-B and of binding of 125I-BDGF-A to responsive cells. The half-time (t1/2) of internalization and degradation of cell surface-bound 125I-BDGF is 3 h.

Animals↗

PubMed1982

Solvent systems for improved isolation and separation of territrems A and B.

Territrems A and B, tremorgenic mycotoxins in the rice culture of Aspergillus terreus, were extracted with hot chloroform. The toxins were cleaned on a silica gel column by direct adsorption-concentration of the extracts followed by desorption with chloroform-acetone (9:1, vol/vol). Crude toxin mixtures were separated by silica gel column chromatography and eluted with benzene-ethyl acetate (65:35, vol/vol). The method gave 112 mg of territrem A, 379 mg of territrem B, and 80 mg of their mixture from 4 kg of rice per batch. The criteria of extraction, cleanup, and separation are provided.

Chromatography, Thin Layer↗

PubMedDate not supplied

Artifacts and pitfalls in MR imaging of the orbit: a clinical review.

High-resolution magnetic resonance (MR) imaging of the orbit has become widely accepted as a valuable diagnostic technique. However, there are a number of artifacts and pitfalls associated with orbital MR imaging. Chemical shift artifacts may be induced by orbital fat or silicone oil used to treat retinal detachment. Motion artifacts are caused primarily by unavoidable globe motion during imaging. Artifacts due to a nonuniform magnetic field are particularly noticeable at air-tissue interfaces but may also be caused by incomplete fat saturation or highly magnetic materials near the orbit. Protocol errors may cause artifacts such as saturation, phase wraparound, truncation, shading, and partial-volume artifacts. This information can be used to improve orbital image quality and avoid misinterpretation of image artifacts. Use of fat saturation, silicone saturation, and careful patient screening for metal near the eyes and instruction to reduce motion can help reduce the occurrence of artifacts. In addition, optimal imaging technique is essential and should include use of proper surface coils, plane of section, and pulse sequences.

Artifacts↗

PubMedDate not supplied

Vascular gene therapy.

Gene therapy is an exciting frontier in medicine today. Radiologists will be involved in tracking the effects of these new therapies through imaging. Vascular and interventional radiology techniques also are ideally suited for minimally invasive, readily monitored gene delivery. Gene therapy is accomplished through gene augmentation or gene blocking. The latter is accomplished through antisense oligonucleotides or transcription factor decoys. Vectors are agents that facilitate gene delivery and expression and can be viral or nonviral. The vascular wall is an ideal target for gene therapy because of its central role in many biologic processes and its ready accessibility. Recombinant genes can be delivered ex vivo and in vivo, with the latter approaches involving open surgical, percutaneous injection, and endovascular catheter-based methods. Perforated, hydrogel-coated, and double balloon catheters have been used with varying success. Optimal catheter systems for gene transfer will enable delivery of the vector to the precise anatomic location with transfection limited to the cells of interest and will minimize shedding of the vector to distal sites, systemic effects of the therapeutic agent, and morbidity from the delivery method. Radiologists must become familiar with the basic rationale, strategies, and mechanisms of gene therapy and involved in its clinical trials to ensure an active role in this field.

Coronary Disease↗

PubMedDate not supplied

Local overexpression of thrombomodulin for in vivo prevention of arterial thrombosis in a rabbit model.

-Endothelial thrombomodulin plays a critical role in hemostasis by binding thrombin and subsequently converting protein C to its active form, a powerful anticoagulant. Thrombomodulin thus represents a central mechanism by which patency is maintained in normal vessels. However, thrombomodulin expression decreases in perturbed endothelial cells, predisposing to thrombotic occlusion. An adenoviral construct expressing thrombomodulin (Adv/RSV-THM) was created and functionally characterized in vitro and in vivo. The impact of local overexpression of thrombomodulin on in vivo thrombus formation was subsequently examined in a stasis/injury model of arterial thrombosis. The construct prevented arterial thrombosis formation in all animals, while viral and nonviral controls typically developed occluding thrombi. By histological analysis, nonviral controls exhibited intravascular thrombus occluding a mean of 70.52+/-3.72% of available lumen, while viral controls reached 86. 85+/-2.82% thrombotic occlusion; in contrast, Adv/RSV-THM reduced thrombosis to 28.61+/-3.31% of lumen in cross section. No significant intima-to-media ratio was observed in the thrombomodulin group relative to controls. Local infiltration of granulocytes and macrophages significantly decreased in the Adv/RSV-THM group relative to controls, while neutrophilic infiltration increased in viral controls relative to nonviral controls. This construct thus offers a viable technique for promoting a locally thromboresistant small-caliber artery, without the inflammatory damage that has limited many other adenoviral applications.

Adenoviridae↗