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Biomedical subjects

D W Misch

Publications and source records attributed to D W Misch.

14 recordsLinked to original sources
PubMed1992

A novel bioassay system for evaluating the toxicity of Bacillus thuringiensis israelensis against mosquito larvae.

A bioassay system employing acutely toxic concentrations of a spore-crystal mixture of Bacillus thuringiensis subspecies israelensis against fourth instar larvae of Aedes aegypti (L.) is described. Individual larvae are separately exposed to toxin in glass-lined miniature wells or scintillation vials. This method is free from the deaths due to predation among larvae. Such larval deaths are commonly encountered in bioassay groups of 25 larvae as currently specified in the World Health Organization guidelines. Our method offers shortened testing time, increased accuracy, and improved statistical precision.

Aedes↗
PubMed1984

Regulation of mucociliary transport. Response of mucous cells to stimulation by amiloride applied to the frog palate in vitro.

Mucociliary transport (MCT) over the surface of isolated frog palatal epithelium was significantly inhibited by the diuretic drug amiloride (50% at 10(-5)M); this occurred when the drug was applied to the mucosal but not to the submucosal surface. The rate of ciliary beating was unchanged by treatment with amiloride (13.5 +/- 1.3 Hz, amiloride; 13.4 +/- 1.4 Hz, control). Spontaneous reversal of inhibition of MCT occurred after extended rinsing (1.5 to 3 h) with Ringer's solution; however, addition of mucus immediately restored MCT to control level. Amiloride applied to the mucosal surface stimulated 2.5 to 3 times as many cells to discharge mucus; this was correlated with an increase of 28% in apparent viscoelasticity of the mucus transport layer measured in situ (approximated by determining breaking strength of mucus using a surface tension balance). Other effects of mucosal application of amiloride included reduction of the transepithelial electrical potential by 62% and increased sodium (17%) in secreted mucus. This is the first report of a stimulatory effect by amiloride on mucous secretory cells.

Amiloride↗
PubMed1980

Intestinal microvilli: responses to feeding and fasting.

Membrane-bound bodies are formed individually and in groups from the plasma membrane surrounding the microvilli in cells of hamster small intestine. These bodies are vesiculate structures, are slightly smaller in diameter than the microvilli from which they are released, and retain at least a portion of glycocalyx. The production of the membrane-bodies occurs regularly, perhaps continuously in vivo, and appears to be related to the feeding cycle. The brush border of jejunal cells from animals which had been feeding ad lib contained more membrane-bodies andhad taller microvilli than comparable cells from those which had been fasted for 48 hours. Since membrane-bodies are also found among the microvilli of cells which have no digestive function, we propose that their formation and release may be of general significance in the normal functioning of active epithelial cells.

Animals↗
PubMed1971

The cytological effect of ecdysterone on the midgut cells of the flesh-fly Sarcophaga bullata.

Larvae of the flesh-fly, Sarcophaga bullata, were injected with the synthetic moulting hormone ecdysterone or saline at the beginning of the third and final larval instar. One group was left untreated. The ecdysterone-injected larvae showed an increase in number of secondary lysosomes in the midgut epithelial cells similar to that observed at the onset of metamorphosis, an event which would normally occur about 48 hr later in these larvae.

Acid Phosphatase↗