More on the need for circadian,circaseptan and circannual optimization of cyclosporine therapy

Summary Cyclosporine chronotherapy of pancreas-allotransplanted rats revealed, beyond a circadian stage-dependence of equal daily doses, further gain in graft function from doses varying from day to day with an about 7-day periodicity, the first highest dose being given on the 3rd or 5th day after surgery.     

The in vitro characterization of the inhibition of mouse brain protein kinase-C by retinoids and their receptors

Summary The mechanism of the in vitro inhibition of Ca²⁺-, phosphatidylserine-dependent protein kinase C (PK-C)² by the purifiedholo (ligand-saturated) forms of cellular retinol-binding protein (cRBP) and cellular retinoic acid-binding protein (cRABP) was studied. We report here that i) the PK-C-inhibitory action ofholo-cRBP andholo-cRABP is due to their respective ligands, all-trans-retinol and all-trans-retinoic acid; ii) the reduced phosphorylation of theholo-retinoid-binding proteins and brain cytosolic proteins is not the result of a retinoid-induced soluble phosphatase or protease activity; iii) retinoids reduce PK-C affinity for calcium and phosphatidylserine in vitro; and iv) the structure-function activity of the retinoids and the specific interaction of these effect of retinoids on plasma membrane-associated PK-C activity pays a significant role in defining the early epigenetic aspects of PK-C-dependent tumor promotion and may be a physiological mechanism by which retinoids induce terminal differentiation in cell types that do not express soluble retinoid-binding proteins.We would like to thank Dr L.M. De Luca (NIH, USA) for his contribution of retinylphosphate, Dr H.N. Bhagavan (Hoffmann-La Roche) for his contribution of the arotinoids, and Merrill-Dow Corp. for their contribution of difluoromethylornithine. This work was supported by NIH Grants CA-34968, CA-07175, CA-22484, and CA-09020.     

Patch clamp technique and biophysical study of membrane channels

The present work describes the patch clamp technique, which first allowed the recording of single channel currents in biological membranes. In particular, it describes procedures for preparation and applications of the four different patch clamp configurations. Briefly, the cell-attached configuration is widely used for investigating channel modulation by transmitters acting via second messengers. The cell-free configurations (inside-out and outside-out), complementary to one another with respect to the orientation of the membrane surface, are particularly indicated for the study of the biophysics (kinetics, conductivity, selectivity, mechanism of permeation and block) of ionic channels. Finally, the whole-cell configuration which, because of the remarkable feature that it allows voltage clamp of very small cells, has given access to a number of physiologically important preparations never studied before.     

Dopamine in the visual cortex of the cat

The endogenous content of noradrenaline (NA) and dopamine (DA) was determined by radioenzymatic assays in three different areas of the occipital (visual) cortex, in normal cats as well as in DA-deafferented animals. The use of HPLC methodology enabled us to detect and measure in addition two metabolites of DA: 3, 4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), thus confirming the existence of a DA innervation in this cortical region.     

Mitochondrial activity: a possible determinant of anoxic injury in renal medulla

In brain, heart and kidney, cell work in the absence of oxygen has been thought to precipitate anoxic damage by increasing the rate of depletion of cellular energy stores. In the medullary thick ascending limb of isolated perfused rat kidneys, however, reduction of ATP synthesis by a variety of mitochondrial or metabolic inhibitors caused ATP depletion comparable to that produced by oxygen deprivation but did not reproduce the lesions of anoxia. In these cells, unrestrained mitochondrial activity may be an important source of anoxic injury.