Activation of protein kinase C inhibits retrograde transport of neurotrophins in mice

Retrograde axonal transport of neurotrophins from nerve terminal to cell body requires a number of key processes, including internalization of the receptor-neurotrophin complex into vesicles and formation of multivesicular bodies and their transport along the axon. Previous studies have shown that each of these processes can be regulated by kinases. In this study, we looked at the role of protein kinase C (PKC) in retrograde transport by injecting labeled neurotrophins together with relevant pharmacological agents into the eye and measuring the accumulation of radioactivity in the trigeminal and superior cervical ganglia. Inhibitors of PKC, Ro-31-8220 and rottlerin, did not affect the retrograde transport of nerve growth factor (NGF); however, phorbol ester activation of classical and novel PKCs blocked retrograde transport. The effect of phorbol esters was partially reversed by rottlerin and Ro-31-8220. Activation of PKC has been shown to be involved in the disorganization of actin filaments. In this study, we show that Ro-31-8220 reverses growth cone collapse by phorbol 12-myristate 13-acetate and suggest that one of the effects of activating PKC on retrograde transport is to disrupt the actin filaments.     

Evaluation of six new 99mTc-IDA agents for hepatobiliary imaging

IDA derivatives of three substituted benzothiazol, and two substituted chlorophenyl and one substituted pyrazoline compounds have been labeled with 99mTc and screened with four rat models with hepatocellular dysfunction manifesting varying degrees of change of liver architecture and hepatocellular damage associated with an active parenchymal destruction, fatty metamorphosis and cirrhosis. Organ distribution studies at 1 h postinjection have been compared in normal and diseased animal models for each agent labeled with 99mTc and with 99mTc-Disofenin (Disida) and Lidofenin (Hida) and 131I-Rose Bengal. From the data obtained with the six new IDA derivatives, the distribution kinetics of 99mTc-Arclophenin, (N-N'-2-benzoyl-4-chlorophenyl)carbamoylmethyl) imino diacetic acid (Phenida), are closely comparable to 99mTc-Disofenin in all animal models. Crossover patient studies (n = 14) for clinical evaluation of 99mTc-Arclophenin vs 99mTc-Disofenin indicate the close similarity of the 2 agents with regard to blood pool retention, gross liver/heart ratios and liver washout, suggesting Arclofenin as a suitable agent for hepatobiliary function studies. The impaired hepatocellular animal models presented should serve for fast screening of hepatobiliary agents and enable comparison of a series of closely related compounds.     

Comparison of nerve terminal events in vivo effecting retrograde transport of vesicles containing neurotrophins or synaptic vesicle components

Although vesicular retrograde transport of neurotrophins in vivo is well established, relatively little is known about the mechanisms that underlie vesicle endocytosis and formation before transport. We demonstrate that in vivo not all retrograde transport vesicles are alike, nor are they all formed using identical mechanisms. As characterized by density, there are at least two populations of vesicles present in the synaptic terminal that are retrogradely transported along the axon: those containing neurotrophins (NTs) and those resulting from synaptic vesicle recycling. Vesicles containing nerve growth factor (NGF), NT-3, or NT-4 had similar densities with peak values at about 1.05 g/ml. Synaptic-derived vesicles, labeled with anti-dopamine beta-hydroxylase (DBH), had densities with peak values at about 1.16 g/ml. We assayed the effects of pharmacologic agents in vivo on retrograde transport from the anterior eye chamber to the superior cervical ganglion. Inhibitors of phosphatidylinositol-3-OH (PI-3) kinase and actin function blocked transport of both anti-DBH and NGF, demonstrating an essential role for these molecules in retrograde transport of both vesicle types. Dynamin, a key element in synaptic vesicle recycling, was axonally transported in retrograde and anterograde directions, and compounds able to interfere with dynamin function had a differential effect on retrograde transport of NTs and anti-DBH. Okadaic acid significantly decreased retrograde axonal transport of anti-DBH and increased NGF retrograde transport. We conclude that there are both different and common proteins involved in endocytosis and targeting of retrograde transport of these two populations of vesicles.     

Transport of endosomal early antigen 1 in the rat sciatic nerve and location in cultured neurons

Early endosomal antigen 1 (EEA1) is known to be a marker of early endosomes and in cultured hippocampal neurons it preferentially localizes to the dendritic but not the axonal compartment. We show in cultured dorsal root ganglia and superior cervical ganglia neurons that EEA1 localizes to the cell bodies and the neurites of both sensory and sympathetic neurons. We then show in vivo using a ligated rat sciatic nerve that EEA1 significantly accumulates on the proximal side and not on the distal side of the ligation. This suggests that EEA1 is transported in the anterograde direction in axons either as part of the homeostatic process or to the nerve ligation site in response to nerve injury.     

Randomized Controlled Trial: Subcutaneous vs Intravenous Infliximab CT-P13 Maintenance in Inflammatory Bowel Disease

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Patterns of Drop-Outs from a Methadone Program for Narcotic Addicts

The relationships of conduct problems, attention deficit hyperactivity disorder (ADHD) signs, and depression to substance use were examined between 1994 and 1999 among 900 incarcerated young offenders in South Australia, 206 of whom were reassessed when later readmitted to secure care. At the first and second assessments, conduct problems, ADHD signs, and depression scores all had significant concurrent associations with a measure of recent substance use. Prospectively, there were no significant associations between depression and substance use. At the zero-order level, both ADHD signs and conduct problems predicted future substance use. ADHD signs remained significantly predictive after controlling for concurrent associations. The results lend support to the view that substance use is related to general deviance and that the arousal needs associated with increased ADHD signs increase the risk of substance use. There was no support for the view that substance use in this population is self-medication in response to internalizing problems.