Characterisation of stroma-dependent blast colony-forming cells in human marrow

Human bone marrow contains a population of haemopoietic progenitor cells that can be distinguished by their ability to adhere to preformed stromal layers (cultured in the presence of methylprednisolone [MP+] and form blast cell colonies. The stromal layers function in the colony assay after they have been heavily irradiated but not after they have been passaged. The binding of the progenitor cells to the stromal cells is complete after 2 hours of coincubation, and stromal layers of 9.6 cm2 can provide adhesion sites for at least 2,000 blast colony-forming cells. The blast colony-forming cells were shown by micromanipulation to self-renew as well as to give rise to multipotential and lineage-committed colony-forming progenitor cells.     

A review of the taxonomy and systematics of the pentastomid genus Raillietiella Sambon, 1910 with a description of a new species

Systematic Parasitology - Four previously established Raillietiella spp. are redescribed. Two of these, R. kochi and R. shipleyi from African monitor lizards, cannot be reliably separated, R....     

Extracellular Ca2+ mobilization in potential-dependent contraction of trachealis of maturing swine.

We studied the effect of maturation on potassium-induced parasympathetic activation and Ca2+ entry in tracheal smooth muscle (TSM) from fifteen 2-wk-old (2ws) and sixteen 10-wk-old (10ws) male domestic farm swine. Atropine (10(-7) M) caused inhibition of the maximal contraction elicited by potassium to 50.3 +/- 2.6% maximum of control response (P less than 0.001) in TSM from 2ws but had no significant effect in TSM from 10ws (94.6 +/- 4.2% maximum; P = NS vs. control). Verapamil (10(-7) M) plus 10(-7) M atropine reduced contraction elicited by potassium in both 2ws (23.7 +/- 5.8% maximum; P less than 0.001 vs. control) and 10ws (50.6 +/- 6.3% maximum; P less than 0.001 vs. control, P less than 0.05 vs. 2ws); 10(-6)M verapamil caused greater than 95% blockade of contraction caused by potassium in both 2ws and 10ws. In separate studies, atropine-treated strips were equilibrated with extracellular Ca2+ concentrations ([Ca2+]o) ranging from normal (1X [Ca2+]o) to four times normal (4x [Ca2+]o). Increasing [Ca2+]o increased maximal contractile response in atropine-treated TSM strips from 68.7 +/- 3.8% maximum for 1x [Ca2+]o to 100.8 +/- 4.8% maximum for 4x [Ca2+]o (P less than 0.001) in 2ws. Neither atropine nor [Ca2+]o affected maximal responses of TSM in 10ws (103.5 +/- 3.0% maximum for 1x [Ca2+]o; P = NS vs. control). However, in the presence of atropine and verapamil, 4x [Ca2+]o augmented KCl-elicited contraction of TSM from both 2ws (46.9 +/- 6.3% maximum; P less than 0.01 vs. control) and 10ws (78.6 +/- 2.3% maximum; P less than 0.005 vs. control).(ABSTRACT TRUNCATED AT 250 WORDS)     

Human serum catalase decreases endothelial cell injury from hydrogen peroxide.

Serum from normal human subjects contained variable amounts of catalase activity, which was inhibitable by heat, azide, trichloroacetic acid (TCA), or aminotriazole treatment. Serum also decreased hydrogen peroxide (H2O2) concentrations in vitro and H2O2-mediated injury to cultured endothelial cells. By comparison, heat-, azide-, TCA-, or aminotriazole-treated serum neither decreased H2O2 concentrations in vitro nor reduced H2O2-mediated damage to endothelial cells. We conclude that serum catalase activity can alter H2O2-dependent reactions. We speculate that variations in serum catalase activity may alter individual susceptibility to oxidant-mediated vascular disease or be a factor when added to test systems in vitro.     

Notes on the use of wood refugia by Physella heterostropha (say) in a thermally disturbed swamp

Physella heterostropha size distributions and densities were measured in Pen Branch delta, a thermally altered swamp of the Savannah River, South Carolina. During cessation of thermal input, measurements were taken in a highly impacted area and more natural area. Of the three substrates sampled, logs, small woody material and benthos, snail density was highest on small pieces of submerged wood and < 20% of the snails on logs were out of the water. Following resumption of thermal input, snail density was four times higher on logs than previously measured. Snails responded to elevated water temperatures by congregating in a narrow band slightly above the water. Snail size did not appear to affect their response. However, the thermal history of the snails influenced their behaviour and survival rates. Logs may be a potential refuge for snails when water temperature are greater greater than 38°C. However, our results indicate that long-term survival in this manner may be impossible.