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Biomedical subjects

A Ross

Publications and source records attributed to A Ross.

At least 235 records · Page 13Linked to original sources
PubMed1981

Protein-depleted chromosomes. II. Experiments concerning the reality of chromosome scaffolds.

Chromosome scaffolds are chromosome-shaped bodies, composed of non-histone proteins, which remain when the histones are extracted from chromosomes. Because of the well-known tendency of chromosomal proteins to aggregate, we have tested the possibility that chromosome scaffolds might be produced by aggregation of proteins during the preparation of scaffolds. Extraction of histones in the presence of sucrose, which inhibits aggregation, results in a much looser structure lacking the characteristic appearance of a scaffold, although sucrose does not extract any extra proteins. Extraction of histones from chromosomes in situ on EM grids produced only a network of fine fibres without a scaffold-like structure, while digestion of DNA from typical chromosome scaffolds in situ fell only discrete particles of protein and not a continuous structure. We conclude, therefore, that the typical appearance of chromosome scaffolds produced by histone extraction may well represent an artefact resulting from protein aggregation. Our experiments suggest further that DNA, as well as protein, is a structural component of whatever type of core structure is responsible for maintaining the form of chromosome.

Animals↗
PubMed1981

A histochemical and electron microscopic study of a fast- and a slow-twitch muscle in genetically spastic mice.

Fast and slow muscle fibers were studied in the flexor digitorum longus (FDL) and soleus (SOL) muscles, respectively, in control and spastic mice. HIstochemical and electron microscopic studies indicated an increased number of mitochondria, a decreased deposition of glycogen and a vesiculation and distension of the sarcoplasmic reticulum in many fast-twitch fibers of the spastic FDL. Similar findings were not evident in the slow-twitch fibers of the spastic SOL. Since the spastic condition causes increased muscular activity as a result of more rapid and prolonged nerve impulse firing, these findings reinforce the idea that a muscle fiber's oxidative capabilities are a function of its activity.

Adenosine Triphosphatases↗
PubMed1981

Methylation of hamster DNA by the carcinogen N-nitroso-bis (2-oxopropyl)amine.

The alkylation of hamster liver, lung and pancreas DNA by [1-14C]- and [2,3-14C]N-nitrosobis (2-oxopropyl) amine (BOP) has been examined. The specific activity of pancreas DNA after [2,3-14C]BOP administration was only 2% of that when [1-14C]BOP was given. 7-Methylguanine, but not O-6-methylguanine, was found in hydrolysates of liver and pancreas DNA. Nearly equal amount of alkylation were produced in the liver when [1-14C]- and [2,3-14C]BOP were given. At least one-half of the radioactivity in the liver was associated with N-alkylated purines, whereas only 20% was in this form in the pancreas.

Animals↗
PubMed1981

Experimentally induced ankylosis and facial asymmetry in the macaque monkey.

Six Macaca nemestrina were used for induction of ankylosis by different methods. One TMJ capsule was either (a) mechanically damaged, (b) injected with sodium morrhuate, or (c) injected with a strain of Staphylococcus aureus. The other capsule served as a control. Facial asymmetry of varying degrees was evident from dry-skull preparations and histologically. Sodium morrhuate caused the least degree of alteration; mechanical damage, the most. The effects of Staph. aureus injection into the TMJ seemed to depend upon the length of time elapsed since injection. In one animal there was no change at autopsy after two injections several weeks apart, once on each side; in the other, the capsule injected initially showed no change at autopsy, whereas that injected several weeks prior to autopsy was considerably altered. Induction of ankylosis was achieved with varying degrees of success, causing differing degrees of facial asymmetry.

Animals↗
PubMed1981

Preparation and assessment of frozen-hydrated sections of mammalian tissue for electron microscopy and X-ray microprobe analysis.

A system is described for preparing and examining frozen-hydrated sections of mammalian tissue, using commercially available equipment. An essential part of the system is a liquid nitrogen cooled vacuum transfer system. Minor modifications were required to interface the various manufacturers' equipment, and also to facilitate handling of specimens in the cryoultramicrotome. A variety of criteria indicates that our sections are truly frozen-hydrated, but negligible image contrast in the sections is a serious problem both for morphological work and X-ray microanalysis.

Animals↗
PubMed1981

Extracellular glycoprotein from virulent and avirulent Cryptococcus species.

Two virulent strains of Cryptococcus neoformans and two nonvirulent forms (C. albidus and C. laurentii) were grown in liquid culture to produce maximal capsule formation. A glycoprotein was isolated from the culture medium and was homogeneous as determined by cellulose acetate electrophoresis and anion-exchange chromatography. The amino acid, neutral sugar, amino sugar, uronic acid, and O-acetyl compositions and the infrared spectra of the glycoprotein were determined. The product of the C. neoformans strains contained more mannose and uronic acid than did that from the nonpathogenic strains. O-acetyl groups were absent from glycoprotein of the two nonpathogens.

Amino Acids↗
PubMed1980

[Carpal tunnel syndrome. Examples of false-positive diagnoses].

The most frequent peripheral entrapment neuropathy is the carpal tunnel syndrome. Clinical signs may be misleading. Therefore electrodiagnosis is of essential importance: EMG and ENG make is possible to confirm the diagnosis with high reliability. 4 cases with false positive diagnosis of carpal tunnel syndrome are discussed.

Adult↗
PubMed1980

Application of an electrochemical detector to the determination of procarbazine hydrochloride by high-performance liquid chromatography.

An amperometric flow-through detector with a carbon paste working electrode was utilized as a high-performance liquid chromatographic (HPLC) detector to determine procarbazine hydrochloride, an antineoplastic agent, in both buffer solution and biological fluids. The HPLC system included an amino-cyano stationary phase and an aqueous (pH 7)-methanolic mobile phase which enabled the separation of procarbazine from its only electroactive degradation product, N-isopropyl-alpha-(2-methylhydrazono)-p-toluamide. The electrochemical detector, with an approximate limit of detection of 2 ng procarbazine injected, was 20 times more sensitive to procarbazine than a typical UV detector. The low dead volume (1 microliter) and superior selectivity of the electrochemical detector enabled the HPLC determination of procarbazine in untreated human urine and plasma.

Chromatography, High Pressure Liquid↗