The role of APOE-ɛ4 and beta amyloid in the differential rate of recovery from ECT: a review.

Individual biological differences may contribute to the variability of outcomes, including cognitive effects, observed following electroconvulsive treatment (ECT). A narrative review of the research literature on carriage of the apolipoprotein E ɛ4 allele (APOE-ɛ4) and the protein biomarker beta amyloid (Aß) with ECT cognitive outcome was undertaken. ECT induces repeated brain seizures and there is debate as to whether this causes brain injury and long-term cognitive disruption. The majority of ECT is administered to the elderly (over age 65 years) with drug-resistant depression. Depression in the elderly may be a symptom of the prodromal stage of Alzheimer's disease (AD). Carriage of the APOE-ɛ4 allele and raised cerebral Aß are consistently implicated in AD, but inconsistently implicated in brain injury (and related syndromes) recovery rates. A paucity of brain-related recovery, genetic and biomarker research in ECT responses in the elderly was found: three studies have examined the effect of APOE-ɛ4 allele carriage on cognition in the depressed elderly receiving ECT, and two have examined Aß changes after ECT, with contradictory findings. Cognitive changes in all studies of ECT effects were measured by a variety of psychological tests, making comparisons of such changes between studies problematic. Further, psychological test data-validity measures were not routinely administered, counter to current testing recommendations. The methodological issues of the currently available literature as well as the need for well-designed, hypothesis driven, longitudinal studies are discussed.

Organic cation transport in the rat kidney in vivo visualized by time-resolved two-photon microscopy.

Secretion of cationic drugs and endogenous metabolites is a major function of the kidney accomplished by tubular organic cation transport systems. A cationic styryl dye (ASP(+)) was developed as a fluorescent substrate for renal organic cation transporters. The dye was injected intravenously and continuously monitored in externalized rat kidneys by time-resolved two-photon laser scanning microscopy. To investigate changes in transport activity, cimetidine, a competitive inhibitor of organic cation transport was co-injected with ASP(+). Shortly after injection, fluorescence increased in peritubular capillaries. Simultaneously, fluorescence was transiently found at the basolateral membrane of the proximal and distal tubules at a higher intensity and shorter wavelength indicating membrane association of ASP(+). Subsequently, intracellular fluorescence increased steeply within 10 s. In the proximal tubules, intracellular fluorescence decreased by 50% within 5 min, while in the distal tubules the fluorescence decreased by only 5% within the same time frame. Intracellular uptake of ASP(+) into proximal tubules was significantly reduced by cimetidine. Our studies show that organic cation transport of the kidney can be visualized in vivo by two-photon laser scanning microscopy.

Minocycline inhibits apoptosis and inflammation in a rat model of ischemic renal injury.

Tetracyclines exhibit significant anti-inflammatory properties in a variety of rheumatologic and dermatologic conditions. They have also been shown to inhibit apoptosis in certain neurodegenerative disorders. Because ischemic renal injury is characterized by both apoptosis and inflammation, we investigated the therapeutic potential of tetracyclines in a rat model of renal ischemia-reperfusion. Male Sprague-Dawley rats underwent bilateral renal artery clamp for 30 min followed by reperfusion and received either minocycline or saline for 36 h before ischemia. Minocycline reduced tubular cell apoptosis 24 h after ischemia as determined by terminal transferase-mediated dUTP nick end-labeling staining and nuclear morphology. It also decreased cytochrome c release into the cytoplasm and reduced upregulation of p53 and Bax after ischemia. The minocycline-treated group showed a significant reduction in tubular injury and cast formation. In addition, minocycline reduced the number of infiltrating leukocytes, decreased leukocyte chemotaxis both in vitro and ex vivo, and downregulated the expression of ICAM-1. Serum creatinine 24-h postischemia was significantly reduced in the minocycline-treated group. We conclude that minocycline has potent antiapoptotic and anti-inflammatory properties and protects renal function in this model of ischemia-reperfusion. Tetracyclines are among the safest and best-studied antibiotics. They are thus attractive candidates for the therapy of human ischemic acute renal failure.

Rho-kinase regulates myosin II activation in MDCK cells during recovery after ATP depletion.

Alterations in the actin cytoskeleton of renal tubular epithelial cells during periods of ischemic injury and recovery have important consequences for normal cell and kidney function. Myosin II has been demonstrated to be an important effector in organizing basal actin structures in some cell types. ATP depletion in vitro has been demonstrated to recapitulate alterations of the actin cytoskeleton in renal tubular epithelial cells observed during renal ischemia in vivo. We utilized this reversible cell culture model of ischemia to examine the correlation of the activation state and cellular distribution of myosin II with disruption of actin stress fibers in Madin-Darby canine kidney (MDCK) cells during ATP depletion and recovery from ATP depletion. We found that myosin II inactivation occurs rapidly and precedes dissociation of myosin II from actin stress fibers during ATP depletion. Myosin II activation temporally correlates with colocalization of myosin II to reorganizing stress fibers during recovery from ATP depletion. Furthermore, myosin activation and actin stress fiber formation were found to be Rho-associated Ser/Thr protein kinase dependent during recovery from ATP depletion.

Mechanisms of cellular injury in ischemic acute renal failure.

Significant advances have been made in understanding the pathophysiology of injury at the cellular level in ischemic acute renal failure. Alterations in the actin cytoskeleton are of central importance to the structural, physiological, and biochemical changes that occur in proximal tubule cells during acute ischemic injury. These cytoskeletal alterations occur rapidly and are dependent on the severity and duration of ischemic injury. Most importantly, alterations in the actin cytoskeleton are responsible for changes in the cell surface membrane that modify cell polarity, cell-cell interactions, and cell-matrix interactions. Ultimately, these cytoskeletal alterations play a major role in the decrement in glomerular filtration rate that is the hallmark of ischemic acute renal failure.

Phosphorylation by protein kinase C of the 20,000-dalton light chain of myosin in intact and chemically skinned vascular smooth muscle.

In the present study we tested the hypothesis that phosphorylation of the 20,000-dalton light chain subunit of smooth muscle myosin (LC20) by the calcium-activated and phospholipid-dependent protein kinase C regulates contraction of chemically-permeabilized (glycerinated) porcine carotid artery smooth muscle. Purified protein kinase C and oleic acid were used to phosphorylate LC20 in glycerinated muscles in the presence of a CaEGTA/EGTA buffer system (pCa 8) to prevent activation of myosin light chain kinase. Phosphorylation of the light chain to 1.3 mol of PO4/mol of LC20 did not stimulate contraction. Tryptic digests of glycerinated carotid artery LC20 contained two major phosphopeptides which contained phosphoserine but not phosphothreonine. Incubation of glycerinated muscles with calcium (20 microM) and calmodulin (10 microM) resulted in contraction and LC20 phosphorylation to 1.1 mol of PO4/mol of LC20; tryptic digests of LC20 from these muscles contained a single phosphopeptide which could be distinguished by phosphopeptide mapping from the two phosphopeptides derived from muscles phosphorylated with protein kinase C. Further phosphorylation of Ca2+/calmodulin-activated muscles to 2.0 mol of PO4/mol of LC20, by incubation with protein kinase C, had no effect on either the level of isometric force or the lightly-loaded shortening velocity (after-load = 0.1 peak active force); removal of Ca2+ and calmodulin, but not protein kinase C and oleic acid, resulted in normal relaxation in spite of maintained phosphorylation to 1.2 mol of PO4/mol of LC20. Comparison of LC20 phosphopeptide maps from glycerinated muscles incubated with protein kinase C plus Ca2+/calmodulin (2.0 mol of PO4/mol of LC20) to maps from intact muscles stimulated with 10(-6) M phorbol 12,13-dibutyrate (0.05 mol of PO4/mol of LC20) showed that the same three phosphopeptides were present in both the intact and glycerinated muscles. These findings show that phosphorylation of LC20 by protein kinase C in glycerinated muscles to levels at least 40 times higher than those present during contraction of intact, phorbol ester-stimulated muscles does not activate contraction nor does it significantly modify the contraction of smooth muscle which occurs in response to the Ca2+/calmodulin-dependent phosphorylation of Ser19 by myosin light chain kinase.

Phosphorylation of two sites on smooth muscle myosin. Effects on contraction of glycerinated vascular smooth muscle.

Contraction of glycerinated porcine carotid artery smooth muscle in response to calcium (20 microM), calmodulin (10 microM), and MgATP was associated with phosphorylation of the 20,000-dalton myosin light chain (LC20) to an average stoichiometry of 1.47 mol of PO4/mol of LC20. Tryptic and chymotryptic phosphopeptide maps of the mono- and diphosphorylated forms of LC20 purified from skinned muscles demonstrated the presence of a single phosphopeptide in all cases. Phosphoamino acid analysis indicated that the monophosphorylated form contained primarily phosphoserine, whereas the diphosphorylated form contained both phosphoserine and phosphothreonine. Thiophosphorylation of LC20 by adenosine 5'-O-(thiotriphosphate) resulted in the incorporation of 1 mol of thiophosphate into phosphoserine. Thiophosphorylated LC20 could be subsequently phosphorylated at a threonine residue to a stoichiometry of 1.7 mol of PO4/mol of LC20 by incubation in the presence of MgATP, calcium, and calmodulin. The extent of multiple site phosphorylation of LC20 was dependent upon both the ionic strength and the free Mg2+ concentration in the muscle bath; increasing either ionic strength (0.07-0.15 M) or [Mg2+] (1-20 mM) resulted in lower stoichiometries of LC20 phosphorylation. The effect of multiple site phosphorylation on contraction was examined in muscles which were seqentially phosphorylated at serine followed by threonine. Full activation (21 degrees C) of both isometric force (1.4 newtons/cm2) and unloaded shortening velocity (0.016 L0/s) was achieved following thiophosphorylation to 1.1 mol of PO4/mol of LC20. No further activation of either isometric force (1.5 newtons/cm2) or unloaded shortening velocity (0.015 L0/s) occurred following phosphorylation to 1.7 mol of PO4/mol of LC20.