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M K Wolf

Publications and source records attributed to M K Wolf.

66 records · Page 4Linked to original sources
PubMed1977

A simple method for examining organotypic CNS cultures with Nomarski optics.

This paper describes a method for examination of living organotypic cultures of CNS with Nomarski differential interference-contrast optics. Cultures grown in Maximow assemblies, which promote the best differentiation of the tissue but are optically faulty, are transferred for Nomarski observation to a simple sandwich chamber which combines the optical perfection of the usual sandwich chamber with the flexibility and safeguarding of sterility characteristic of the Maximow assembly. Thus cultures can be transferred repeatedly between their maintenance and observation chambers. In the resulting microscopic images, it is possible to visualize delicate unmyelinated fibers, myelinated cell bodies and other features which are normally impossible to demonstrate in living cultures as well as to improve the images of other structures such as large neuronal perikarya and myelinated axons.

Axons↗
PubMed1965

Studies on nucleic acid metachromasy. I. The effect of certain fixatives on the dye stacking properties of nucleic acids in solution.

The stacking coefficients (K's) of nucleic acids have been thought to influence the color contrast between DNA and RNA in tissue sections stained with metachromatic dyes. This idea was tested by titrating toluidine blue (TB) and acridine orange (AO) in solution against DNA and RNA, native or treated with formaldehyde, acrolein, or Carnoy's fluid. Absorption spectra at varying polymer-dye ratios were used to compute K values by the methods of Bradley and colleagues. Results with both dyes fit Bradley's stacking equations. Fixatives did not block dye-binding sites but markedly altered K values. K of DNA was low, unaffected by aldehyde fixative, increased by Carnoy's fluid or heat denaturation. K of RNA was higher than that of DNA and was increased greatly by formaldehyde, almost as much by acrolein, considerably less by Carnoy's fluid. Aldehyde effects were partially reversed upon removal of aldehyde by dialysis. These observations accord with known effects of aldehydes and denaturation upon nucleic acid conformation. Differences between K's of DNA and RNA were greater after aldehyde treatment than after Carnoy's, and were greater with AO than with TB. This is generally consistent with the magnitude of the color contrasts observed in tissues. Additional factors must contribute to the intense color contrast observed in acrolein-fixed tissues stained with TB.

Acetates↗
PubMed1965

Studies on nucleic acid metachromasy. II. Metachromatic and orthochromatic staining by toluidine blue of nucleic acids in tissue sections.

Acrolein-fixed, polyester wax-embedded tissue sections showed excellent preservation of light microscopic architecture and, when stained with toluidine blue, intense color contrast between DNA, which stained orthochromatically, and RNA, which stained metachromatically. This method has practical value for differentiating DNA from RNA in the same section. The color contrast was impaired by substituting formaldehyde for acrolein or paraffin for polyester wax, and was negligible in tissues fixed in formaldehyde or Carnoy's fluid and embedded in paraffin. Quality of structural preservation paralleled degree of color contrast. Metachromatic staining can be analysed, by the quantitative parameters of Bradley and colleagues, to provide inferences regarding the conformation of biopolymers in tissue sections. Comparison of the nucleic acid color contrasts in toluidine blue-stained sections with titrations of fixative-treated nucleic acids against toluidine blue in solution indicated a greater difference in conformation between DNA- and RNA-protein in acrolein-polyester sections than between acrolein-treated free DNA and RNA in solution. This is supported by recent evidence that the conformation of ribosomal RNA is quite different in whole ribosomes from that assumed by the same RNA free in solution. The acrolein-polyester method may enhance color contrast by providing superior preservation of ordered nucleoprotein conformations.

Acetates↗
PubMedDate not supplied

Phase II trial of echinomycin for the treatment of advanced renal cell carcinoma. A Southwest Oncology Group study.

Forty-nine patients with metastatic or recurrent renal cell carcinoma were treated on a phase II trial of Echinomycin. Treatment consisted of Echinomycin 1.25 mg/m2 intravenously every 28 days. Among the 47 evaluable patients there were no complete responses and only one partial response for an overall response rate of 2% (95% confidence interval, 0-11%). Eighteen patients (38%) experienced toxicity of grade 3 or worse. The most common toxicities were nausea and vomiting. The results of this study indicate that Echinomycin is not sufficiently active to warrant further trials for the treatment of renal cell carcinoma.

Adult↗