Subject cell surface

Another proposed mechanism is inhibition of cell-surface receptors for adenosine. These receptors modulate adenylyl cyclase activity, and adenosine has been shown to provoke contraction of isolated airway smooth muscle and histamine release from airway mast cells. It has been shown, however, that xanthine derivatives devoid of adenosine antagonism (eg, enprofylline) may be potent in inhibiting bronchoconstriction in asthmatic subjects. 

A biologic surface that develops an endothelial cell surface is referred to as a neointima. If it is covered with blood components such as fibrin, it is called a pseudointima. In both cases, the surfaces are passive with respect to the blood to which they come into contact. A pseudointima, however, is typically unstable and subject to further ihrombic response. If the surface is damaged, as during surgical implantation, a catastrophic failure can result. This coupled with the difficulty of developing a complete endothelial layer caused one researcher to describe a device as physiologically tolerable rather than biocompatible or hemocompatible. 

The mechanism whereby fat droplets are directed to the apical cytoplasm and become coated with membrane has been the subject of much speculation. There is some evidence that microtubules and microfilaments, elements of the cytoskeleton, may be involved. During lactation a majority of the microtubules in the apical cytoplasm are oriented parallel to the lateral cell surfaces (Nickerson and Keenan 1979 Nickerson et al. 1982). These may act as guides for the directional transfer of lipid droplets to the apical plasma membrane. How-... 

The rate of exocytosis from any type of cell is a very important factor and is therefore subject to strict regulation. This rate can be changed through the modification of different parameters of the exocytotic machinery. Analysis of pancreatic /J-cells shows that the latency time in the Ca2+ sensing system of the exocytotic machinery and the clustering of channels on the cell surface may be two convenient targets for adjusting the rate of the release of hormones or neurotransmitters from cells. 

When the major transition from an animal population to human subjects is proposed, the statistical probabilities derived by the statistician must be discussed by experts familiar with the similarities and differences between human organ systems and cell surface receptors and those of the laboratory animals. Thus, the extrapolations in the IND from the preclinical work in animals to the probable effects in humans rest on a combination of statistical inferences and comparative assessments by experts in pharmacology, toxicology, pathology, and biochemistry. Their expertise, in turn, rests to some extent on the statistical... 

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