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Biomedical subjects

J C Martin

Publications and source records attributed to J C Martin.

At least 271 records · Page 15Linked to original sources
PubMed1976

Pulse-height light-scatter distributions using flow-systems instrumentation.

Several laboratories have recently been making light-scatter measurements on cells and other particles using flow-systems instrumentation. We at the Los Alamos Scientific Laboratory, as well as others, have obtained multimodal pulse-height distributions in certain angular regimes from particles of supposedly uniform characteristics. Because it was assumed that multimodal distributions implied characteristics of multivalue, the accuracy of such data has been doubted. In the present work, pulse-height distributions anticipated on the basis of exact electromagnetic theory were calculated for particles of known characteristics. These calculated pulse-height distributions agree quite well with those obtained experimentally. Physical optics form the basis for the explanation of the complex pulse-height distributions obtained experimentally. However, the results of this study show that certain cautions are necessary in the interpretation of light-scatter data presented in this manner.

Autoanalysis↗
PubMed1975

Effects on offspring of chronic maternal methamphetamine exposure.

Twenty-five Sprague-Dawley derived rats were administered 1.0, 3.0 or 5.0 mg/kg of methamphetamine HC1 or saline twice daily throughout gestation beginning on Day 1 of pregnancy. Rats were allowed to deliver normally; offspring were culled to 8 and sexed on Day 7, and weaned on Day 21. All females had viable litters except at the 5.0 mg/kg dose where 4 of 7 failed to deliver. The rats given methamphetamine delivered earlier than did controls. Weight gain over gestation decreased as a function of increasing drug dose. No gross anomalies were visible in the offspring. Litter size decreased as a function of increased dose and eye opening was delayed in the drug groups; the 5.0 mg/kg offspring made more conditioned avoidance responses than did the 3.0 mg/kg and saline offspring.

Animals↗
PubMed1975

A flow-system multiangle light-scattering instrument for cell characterization.

A flow-system cell-analysis instrument is described in which cells from a heterogeneous population are characterized by their light-scatter patterns alone. As the cells pass at high speed through a focused helium/neon laser beam, the scatter pattern from each cell is sampled simultaneously at up to 32 angles between 0 degrees and 30 degrees with respect to the laser beam axis, and the scatter pattern for each cell is transferred to a computer. A mathematical clustering algorithm is used to determine the number of classes into which the cells can be divided, and a linear separation algorithm is used to find the boundaries between the classes. Preliminary results on exfoliated cells from gynecological specimens are presented. This technique may be useful for automated prescreening of gynecological specimens.

Autoanalysis↗
PubMed1975

Short-and long-term experimental study of the toxicity of coal-mine dust and of some of its constituents.

The toxicity of various minerals (kaolin, muscovite, illite) was compared by tracheal tests on rats to that of reference dusts (quartz, titanium dioxide, coal). These minerals have various degrees of toxicity. Owing to their sometimes very high concentration in the respirable dust, their toxicity should be taken into consideration. In order to define the aggravating role of quartz more accurately, dust inhalation tests were also conducted on rats with coal and a coal-quartz mixture containing about 10% quartz. The difference in the toxicity of these two types of dust which is practically not detectable up to 12 months, then increases progressively after that period. In addition, in rats having inhaled either coal or a quartz-coal mixture for 24 months, there appear tumoral lesions, principally of epidermoid type.

Adenocarcinoma↗
PubMed1975

The therapeutic action of aluminium compounds on the development of experimental lesions produced by pure quartz or mixed dust.

The prophylactic and curative effect of aluminium salts administered as aerosols on the development of lung lesions caused by the dust inhalation of quartz, two coal-quartz mixtures with 17% and 8% silica, respectively, and pure coal, was studied experimentally on rats. It appears that the preventive treatment is very efficient either in the case of pure quartz or coal-quartz mixtures. The curation treatment with regard to pure quartz leads to constant lung weight and reduced rate of collagen formation; the effect is the more evident as the silica content of the dust is higher and becomes nil with pure coal. The effectiveness is slightly increased when aerosols at higher concentrations are used, but the difference is not proportional to the dose. Under these experimental conditions, the aerosols used showed no toxicity.

Aerosols↗