The unc-11 gene of Caenorhabditis elegans encodes multiple isoforms of a protein homologous to the mammalian brain-specific clathrin-adaptor protein AP180. The UNC-11 protein is expressed at high ...levels in the nervous system and at lower levels in other tissues. In neurons, UNC-11 is enriched at presynaptic terminals but is also present in cell bodies. unc-11 mutants are defective in two aspects of synaptic vesicle biogenesis. First, the SNARE protein synaptobrevin is mislocalized, no longer being exclusively localized to synaptic vesicles. The reduction of synaptobrevin at synaptic vesicles is the probable cause of the reduced neurotransmitter release observed in these mutants. Second, unc-11 mutants accumulate large vesicles at synapses. We propose that the UNC-11 protein mediates two functions during synaptic vesicle biogenesis: it recruits synaptobrevin to synaptic vesicle membranes and it regulates the size of the budded vesicle during clathrin coat assembly.
Glia are thought to regulate ion homeostasis, including extracellular pH; however, their role in modulating central CO2 chemosensitivity is unclear. Using a push-pull cannula in chronically ...instrumented and conscious rats, we administered a glial toxin, fluorocitrate (FC; 1 mM) into the retrotrapezoid nucleus (RTN), a putative chemosensitive site, during normocapnia and hypercapnia. FC exposure significantly increased expired minute ventilation (VE) to a value 38% above the control level during normocapnia. During hypercapnia, FC also significantly increased both breathing frequency and expired VE. During FC administration, maximal ventilation was achieved at approximately 4% CO2, compared with 8-10% CO2 during control hypercapnic trials. RTN perfusion of control solutions had little effect on any ventilatory measures (VE, tidal volume, or breathing frequency) during normocapnic or hypercapnic conditions. We conclude that unilateral impairment of glial function in the RTN of the conscious rat results in stimulation of respiratory output.
Over the years, a large number of drugs have been used in isolated perfusion of extremities or organs. To interpret the pharmacokinetics of these drugs correctly, the contributions of tissue or organ ...clearance and chemical degradation, respectively, to overall drug elimination from the circuit need to be identified. In support of a phase I clinical trial of isolated hepatic perfusion (IHP), delivering 5-fluorouracil (5-FU) and oxaliplatin to patients with colorectal cancer hepatic metastases, we aimed to characterize the stability of 5-FU and oxaliplatin in the IHP circuit. Stability of 5-FU and oxaliplatin was assessed in human blood, lactated Ringer infusion (LRI), and in an in vitro IHP circuit consisting of both blood and LRI. Samples were analyzed with liquid chromatography tandem mass spectrometry (5-FU) and atomic absorption spectrophotometry (oxaliplatin). 5-FU was stable under all tested in vitro conditions, but ultrafilterable platinum concentrations decreased slowly with a half-life of 85 minutes in both IHP perfusate and whole blood. The stability of 5-FU in the media containing blood is likely attributable to saturation of dihydropyrimidine dehydrogenase. The decrease of ultrafilterable platinum in blood-containing media with an 85 minutes half-life is in agreement with previous reports on oxaliplatin biotransformation. Oxaliplatin and 5-FU are sufficiently stable in the circuit for the 1-hour perfusion in ongoing and planned clinical trials.
Mouse fibrosarcoma (3T3 cells transfected with different oncogenes), human neuroblastoma, or human prostate carcinoma cells have been genetically-tagged with different histochemical marker genes (E. ...coli lacZ, placental alkaline phosphatase, or Drosophila alcohol dehydrogenase). Injection into athymic nude mice permits their tracking at all stages of primary tumor formation and micrometastasis to various organs at the singlecell level. Two different tumor classes, tagged with different marker genes, can be tracked together. Primary tumors display regional dominance of one tumor class with exclusion of other classes. During micrometastasis, tumor cells are detected binding to the endothelium of lung blood vessels, followed by establishment of multiple-cell micrometastases. Micrometastases in some organs are transient while in other organs there is differential expansion into overt metastases. Tagged tumors also reveal the timing of angiogenesis of developing primary tumors and overt metastases. In all three tumor systems, there are three classes of genetic stability of marker gene expression in clonal populations-high stability, intermediate stability, and high instability. Instability in marker gene expression in one tagged prostate carcinoma system does not depend on a hypermethylation mechanism, suggesting a genetic basis for loss of activity. Use of histochemical marker genes, combined with laser-capture microdissection and various PCR methods, can now be used to evaluate gene activities in single or multiple tumor cells in virtually any organ and primary tumor of the animal model system.
This phase I trial evaluated two schedules of escalating vorinostat in combination with decitabine every 28 days: (i) sequential or (ii) concurrent. There were three dose-limiting toxicities: grade 3 ...fatigue and generalized muscle weakness on the sequential schedule (n = 1) and grade 3 fatigue on the concurrent schedule (n = 2). The maximum tolerated dose was not reached on both planned schedules. The overall response rate (ORR) was 23% (three complete response CR, two CR with incomplete incomplete blood count recovery CRi, one partial response PR and two morphological leukemic free state MLFS). The ORR for all and previously untreated patients in the sequential arm was 13% (one CRi; one MLFS) and 0% compared to 30% (three CR; one CRi; one PR; one MLFS) and 36% in the concurrent arm (p = 0.26 for both), respectively. Decitabine plus vorinostat was safe and has clinical activity in patients with previously untreated acute myeloid leukemia. Responses appear higher with the concurrent dose schedule. Cumulative toxicities may limit long-term usage on the current dose/schedules.
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