Biomedical subjects
Publications and source records attributed to J L Beck.
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Explore the source record for details and available documents.
I. Introduction 61 II. Binding of Small Molecules to DNA 62 A. Covalent Binding 62 B. Reversible (Noncovalent) DNA-Binding Agents 65 III. DNA-Metal Ion Complexes 67 A. Platinum Complexes 70 B. Other Metal Ions 73 IV. DNA-Protein Complexes 74 A. Introduction 74 B. ESI-MS of DNA-Protein Complexes 76 C. ESI-MS Analysis of Proteolytic Products of DNA-Protein Complexes 79 D. ESI-MS of Ternary DNA-Protein-Ligand Complexes 80 V. Conclusions 80 Abbreviations 81 References 81 --Interactions of DNA with drugs, metal ions, and proteins are important in a wide variety of biological processes. With the advent of electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI), mass spectrometry (MS) is now a well-established tool for the characterization of the primary structures of biopolymers. The gentle nature of the ESI process, however, means that ESI-MS is also finding application for the study of noncovalent and other fragile biomolecular complexes. We outline here the progress, to date, in the use of ESI-MS for the study of noncovalent drug-DNA and protein-DNA complexes together with strategies that can be employed to examine the binding of small molecules and metal complexes to DNA. In the case of covalent complexes with DNA, sequence information can be derived from ESI-MS used in conjunction with tandem mass spectrometry (MS/MS) and/or enzymatic digestion. MS/MS can also be used to probe the relative binding affinities of drugs that bind to DNA via noncovalent interactions. Overall, the work in this area, to date has demonstrated that ESI-MS and MS/MS will prove to be valuable complements to other structural methods, offering advantages in terms of speed, specificity, and sensitivity. (c) 2001 John Wiley & Sons, Inc.
It has been well-proven that prolonged immobilization is detrimental to synovial joints. For the past 5 years, in an effort to minimize these undesirable sequelae, we have treated 94 patients with major knee trauma by early protected motion. Acute ligament injuries not requiring surgery were placed in the cast brace immediately, while operated cases were started about the 10th postoperative day. Our method of cast bracing stresses proper alignment of the joints, security of limb position, prevention of swelling complications, and economy of physician time. A special feature is a modified single axis joint that restricts the arc of motion to safe limits, generally 30 to 90 degrees. Functionally, our results compare quite favorably with our previous traditionally treated experience. Rehabilitation times were markedly shortened, patient acceptance was high, and complications were rare. Early motion was extremely well-tolerated with only one cast removed because of discomfort. Postoperative effusion rapidly disappeared with commencement of motion. Rapid return of motion did not correlate with a poor result, and the stability of operated knees did not loosen with time. Although lack of controls precludes definitive comparisons, we conclude that early protected motion is safe and provides significant benefits.
Adult male Wistar rats were exposed to 3.0 Gy local testicular irradiation. Testes of irradiated and non-irradiated rats were examined histologically and flow cytometrically, at several intervals up to 78 days after irradiation. Concentrations of follicle-stimulating hormone, luteinizing hormone and testosterone determined at these intervals were not different from those of controls. The survival of stem cells were measured 11 weeks after irradiation (with doses varying from 1.0 Gy to 6.0 Gy at 0.6 Gy/min) by means of the repopulation index and by the number of haploid cells (spermatids). Correlation between both methods and relation to stem cell survival were discussed. The dose response curves yielded D0 values of stem cell survival of 2.33 +/- 0.06 Gy (repopulation index) and 2.08 +/- 0.08 Gy (number of haploid cells). The D0 value of the rat was not much different from that found in mice. It was concluded that the used parameters can offer insight when studying hormonal substances during irradiation.
Four human renal cell carcinoma xenografts (RC2, RC14, RC43, NC65), maintained in nude mice for several years, were investigated in a multi - disciplinary study, using (immuno) histochemical, biochemical and ultrastructural techniques. Histological, cellular, nuclear and biological characteristics were investigated. All tumors showed histologically recognizable features of human renal cell carcinomas, although marked differences between the four tumors were seen, both at the histological and ultrastructural level. Flowcytometric analysis of tumor cell suspensions allowed DNA quantification as well as the detection of subpopulations. Immunohistochemical staining procedures using tissue specific antibodies against intermediate filament proteins revealed two populations of tumor cells. Most tumor cells in three of the xenografts coexpressed cytokeratins and vimentin, while in RC43 most of the tumor cells expressed only vimentin. Northern blot analysis showed a higher expression of vimentin mRNA in all tumors as compared to normal kidney tissue. RC43 showed a three-fold higher level of vimentin mRNA than the other xenografts. Growth potential in the human tumor cloning system was evaluated by temporal growth pattern analysis. These experiments showed that the xenografts resemble human primary renal cell tumors in different ways, and reflect different characteristics that can be present in human renal cell carcinoma.
The rat renal cell carcinoma system as described by deVere White and Olsson in 1980 is used widely as a model for its human counterpart. The tumor arose spontaneously in a male Wistar Lewis rat and its behaviour has been shown to be stable during multiple passages. We have compared this tumor with the human renal cell carcinoma using a multidisciplinary approach. Light microscopy and electron microscopy showed a great resemblance of this rat tumor to a human renal cell carcinoma of the clear cell type with the ultrastructural presence of desmosomes. With the use of tissue specific antibodies against intermediate filament proteins, it could be shown that their expression is comparable to human renal cell carcinoma, i.e. coexpression of vimentin and different cytokeratins in the tumor cells. The cells could also be shown to contain cytokeratin 18. An aneuploid cell population in the tumor, expressing both vimentin and keratin, could be characterized by DNA flow cytometry in double labeling experiments. Comparison of normal and malignant rat kidney tissue by Northern blot analysis revealed increased levels of vimentin mRNA. In conclusion, this tumor model seems to have several histological and biological properties in common with the human renal tumor.