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Biomedical subjects

D M Smith

Publications and source records attributed to D M Smith.

At least 397 records · Page 22Linked to original sources
PubMed1980

Effects of steroids on mouse oocyte maturation in vitro.

Oestrone and dihydrotestosterone had no significant action. Other steroids inhibited maturation. The stage of maturation most affected and the median effective concentration (MEC) at this stage varied with different steroids. The predominant effect of pregnenolone (MEC = 6.4 microM), progesterone (MEC = 5.3 microM), androstenedione (MEC = 28.0 microM) and oestradiol-17 beta (MEC = 23.0 microM) was to block maturation after the resumption of meiosis but before completion of the first meiotic division. Testosterone was also effective at this stage (MEC = 23.5 microM) but at higher concentrations it prevented germinal vesicle breakdown (MEC = 40 microM) without causing oocyte degeneration. The inhibitory actions of all steroids were reversible in oocytes exposed for 4 or 18 h.

Androstenedione↗
PubMed1979

Lung tumors from PuO2-ZrO2 aerosol particles in Syrian hamsters.

Syrian golden hamsters were given PuO2/ZrO2 particles via inhalation and/or Pu-laden ZrO2 ceramic 10-micron diameter microspheres lodged in the capillary bed of the lung. The mean initial lung burdens ranged from 8 nCi to 143 nCi for the six experimental groups of animals. Significant numbers of primary lung tumors (5-50% per group) were induced in those animals that received inhalation exposures. Additional alpha radiation administered via Pu-laden intravenous microspheres had little or no effect on tumorigenesis or the production of non-neoplastic, degenerative changes in the respiratory tract.

Aerosols↗
PubMed1979

Reduced cell proliferation in fetal lung after maternal administration of pilocarpine: a scintillation autoradiographic study.

Fetuses were obtained on the 28th gestational day from pregnant New Zealand white rabbits treated daily, on the 24th through the 27th gestational day, with pilocarpine HCl, 5 mg/kg in saline, or saline alone. Lung fragments from these fetuses were incubated for two hours in medium containing 3H-thymidine. Scintillation autoradiography of 1-micrometer-thick sections of these fetal lungs revealed that the lung tissue from pilocarpine-treated fetuses had significantly lower labelled cell indices for both alveolar epithelial cells and interstitial cells. These results indicate that pilocarpine treatment promotes differentiation of immature cells in the fetal lung at the expense of cell proliferation.

Animals↗
PubMed1979

Prostaglandins in experimental otitis media.

Levels of prostaglandins in serum, plasma and middle ear effusions (MEE) in chinchilla were measured by radioimmunoassay. Higher levels of PGE2 and PGF2alpha were observed in the POM group than in the SOM group. Prostaglandins appear to play important roles as a mediator of the inflammatory response in experimentally induced purulent otitis media.

Animals↗
PubMed1979

Visual and computer-assisted assessment of the EEG in epilepsy of late onset.

A study was made of 275 patients presenting with suspected epilepsy after the age of 20 years. In 122 it was concluded that the attacks were non-epileptic. In 60 others cerebral pathology was found. If the EEG was visibly abnormal the risk of cerebral pathology was 8 times greater than when the record was normal. The EEGs were also assessed by an automatic pattern recognition technique, which classified them as abnormal by reference to a control population of 300 volunteers. 90% of EEGs from patients with pathology were classified as abnormal and, conversely, 86% of patients with abnormal records (as assessed by the automatic analysis) had pathology.

Adult↗
PubMed1979

Biological effects of raw and processed oil shale particles in the lungs of laboratory animals.

Environmental and occupational health concerns will have an effect on the developing oil shale technologies. The mining and crushing of large volumes of rock will be a characteristic of at least some of these technologies, and above ground disposal of proceessed shale will require adequate control measures. Exposure by inhalation to the dusts that may arise from shale oil technologies may present a hazard both in the work force and in the local population. Animal studies dealing with the effects of oil shale-related materials in the lung are in progress. Experiments involving Syrian hamsters exposed by inhalation and by intratracheal instillation are described.

Animals↗
PubMed1979

Effect of hypophysectomy on mouse oocyte maturation in vitro.

There was no difference in frequency of maturation of oocytes obtained from mice hypophysectomized for 2 weeks compared to those from sham-operated or untreated (control) animals of the same age. By 7 weeks, and also at 12 and 17 weeks, the incidence of polar body formation in vitro was significantly reduced. The number of oocytes which remained meiotically inactive in culture was increased at 7, 12 and 17 weeks after hypophysectomy. This decrease in spontaneous oocyte maturation in vitro could be partly overcome by administering exogenous PMSG, oestradiol-17beta or PMSG + oestradiol-17beta, but not progesteron or hCG, to hypophysectomized mice.

Animals↗
PubMed1978

Miniature stimulator for chronic animals.

A small lightweight pulse train generator is described. Train frequency and duration and pulse frequency and duration are continuously variable over a range that is suitable for many types of nerve stimulation experiments. Complete electrical specifications and schematics are shown. Also presented are the changes in contraction time of the cat hind leg muscles after 6-week chronic stimulation of the sciatic nerve. The stimulator, with batteries which are sufficient for more than six weeks operation, is small enough to be mounted on cats.

Animals↗
PubMed1978

Computer-assisted interpretation of clinical EEGs.

A multivariate pattern recognition technique has been developed, to distinguish the EEGs of patients with cerebral pathology from those of normal controls and to localize any abnormalities detected. Two methods of feature extraction have been used, power spectral density and slope descriptor analysis, together with various types of feature compression. These techniques have been evaluated on EEGs from 63 patients with proven pathology. Spectral analysis proved more reliable than slope descriptor analysis and predicted the site of cerebral pathology more accurately than did visual assessment of the EEGs. This apparent improvement over the diagnostic reliability of visual analysis in considered to justify further development and evaluation of this technique.

Adult↗