Genetic control of instrumental conditioning by striatopallidal neuron-specific S1P receptor Gpr6

Instrumental conditioning allows animals to learn about the consequences of their own actions, but the underpinning molecular mechanisms remain elusive. Here we show that the sphingosine-1-phosphate (S1P) receptor Gpr6 is selectively expressed in the striatopallidal neurons in the striatum. Gpr6-deficient mice showed reduced striatal cyclic AMP production in vitro and selective alterations in instrumental conditioning in vivo. Thus, Gpr6 is the first striatopallidal neuron-specific genetic regulator of instrumental conditioning in a mammal.     

Role of Microtubules in Low Density Lipoprotein Processing by Cultured Cells

The effect of the microtubule inhibitor colchicine on the metabolism of (125)I-low density lipoprotein (LDL) by cultured human skin fibroblasts and aortic medial cells was studied in vitro. Colchicine did not alter the binding of LDL to cell surface receptors. However, the rate of LDL endocytosis was reduced to 58% of that expected. Despite diminished endocytosis, LDL was found to accumulate within the cells to 165% of that expected, whereas the release of LDL protein degradation products into the medium was reduced to 34% of control, findings consistent with a reduced rate of intracellular LDL breakdown. Colchicine did not alter cell content of the acid protease which degrades LDL, nor did [(3)H]colchicine accumulate in lysosomal fractions. However, colchicine did alter the intracellular distribution of both fibroblast lysosomes and endosomes. After colchicine, lysosomes tended to accumulate in the perinuclear region, whereas endosomes were found at the cell periphery. These findings are consistent with the hypothesis that ingested LDL is less available to lysosomal enzymes in the presence of colchicine. The actions of colchicine appear to be a result of destruction of cell microtubules. Lumicolchicine, a mixture of colchicine isomers which (unlike the parent compound) does not bind to the subunit of microtubules, was without effect.The uptake and degradation of LDL by cultured cells consists of both a receptor-specific component and nonspecific pinocytosis. Important differences must exist between these processes because even large amounts of LDL taken up and degraded by the nonspecific route fail to regulate key aspects of intracellular cholesterol metabolism. Colchicine selectively inhibited receptor-mediated LDL degradation. No effect was demonstrable on the nonspecific degradation of LDL by familial hypercholesterolemia fibroblasts grown in medium containing serum and added sterols. The degradation of bovine albumin by normal cells was also unaffected. Colchicine sensitivity appears to be a biochemical marker for the LDL receptor-specific metabolic pathway.Cytochalasins inhibit crosslinking and polymerization of cell microfilaments (although other important cell effects also occur). Cytochalasin D reduced LDL degradation to 44% of that expected. This result and the actions of colchicine suggest that cytoskeletal components such as microtubules and possibly microfilaments facilitate normal LDL metabolism.     

Rapid emergence of quinolone resistance in Campylobacter jejuni in patients treated with norfloxacin.

15/60 subjects from one center, who all took part in a multicenter double-blind, placebo-controlled study to evaluate the effect of norfloxacin on acute enteritis, had norfloxacin sensitive strains of Campylobacter jejuni in pre-study stool specimens. Eight of the 15 subjects received active drug. In 3 of these 8, high-level quinolone resistant Campylobacter strains of the same serotype as in pre-treatment samples were isolated 4-90 days after the initiation of treatment.     

Modulation of cue‐triggered reward seeking by cholinergic signaling in the dorsomedial striatum

The dorsomedial striatum (DMS) has been strongly implicated in flexible, outcome‐based decision making, including the outcome‐specific Pavlovian‐to‐instrumental transfer effect (PIT), which measures the tendency for a reward‐predictive cue to preferentially motivate actions that have been associated with the predicted reward over actions associated with different rewards. Although the neurochemical underpinnings of this effect are not well understood, there is growing evidence that striatal acetylcholine signaling may play an important role. This study investigated this hypothesis by assessing the effects of intra‐DMS infusions of the nicotinic antagonist mecamylamine or the muscarinic antagonist scopolamine on expression of specific PIT in rats. These treatments produced dissociable behavioral effects. Mecamylamine infusions enhanced rats’ tendency to use specific cue‐elicited outcome expectations to select whichever action was trained with the predicted outcome, relative to their performance when tested after vehicle infusions. In contrast, scopolamine infusions appeared to render instrumental performance insensitive to this motivational influence of reward‐paired cues. These drug treatments had no detectable effect on conditioned food cup approach behavior, indicating that they selectively perturbed cue‐guided action selection without producing more wide‐ranging alterations in behavioral control. Our findings reveal an important role for DMS acetylcholine signaling in modulating the impact of cue‐evoked reward expectations on instrumental action selection.     

Lack of Effect of Cholesterol Esterase Inhibitor CVT-1 on Cholesterol Absorption and LDL cholesterol in Humans

Two clinical trials were performed to test the hypothesis that CVT-1, a potent inhibitor of pancreatic cholesterol esterase, reduces percent cholesterol absorption and LDL cholesterol in humans. Measurements of cholesterol absorption were made with deuterated cholesterol tracers given orally and intravenously and detected in plasma by a new technique using negative ion mass spectrometry. Study 1 was a randomized, double-blind parallel study of CVT-1 treatment of doses of 0, 300, 1500, and 3000 mg/day in 19 subjects. Percent cholesterol absorption measured at baseline and again after 2 and 6 weeks showed no treatment effect and LDL cholesterol was unchanged. Study II was a randomized open-label crossover comparison between CVT-1 given as 1000 mg three times daily for 2 weeks and 187.5 mg hourly 16 hours/day for 2 weeks. Percent cholesterol absorption and plasma LDL cholesterol were not different between periods. We conclude that cholesterol esterase is not required for unesterified cholesterol absorption in human subjects.     

The influence of Pavlovian cues on instrumental performance is mediated by CaMKII activity in the striatum

Pavlovian cues associated with reward exert a powerful motivational influence on the performance of goal-directed actions. This motivational process depends critically on the ventral striatum, although little is known about the cellular and molecular mechanisms that mediate it. In the current experiments we examined the role of calcium calmodulin-dependent kinase II (CaMKII) by using transgenic mice that express a constitutively active form of this kinase. We found that controlled expression of active CaMKII in the striatum did not affect learning but did impair the motivation of goal-directed actions by Pavlovian cues associated with reward. Mutant mice learned to lever press for reward, remained sensitive to outcome devaluation and contingency degradation manipulations, and were able to acquire Pavlovian responses to cues paired with reward. However, Pavlovian cues were completely unable to motivate lever pressing in mutant mice. This was true even in mice trained with the CaMKII transgene turned off and then tested with it turned on. We were also able to suppress transgene expression in impaired mutants and fully restore the motivational effects of reward cues in these animals. Therefore, the current experiments demonstrate that normal CaMKII activity in the striatum is essential for the motivational effects of reward cues on goal-directed actions.     

Identifying care actions to conserve dignity in end-of-life care

Community nurses have a central role in the provision of palliative and end-of-life care; helping people to die with dignity is an important component of this care. To conserve dignity, care should comprise a broad range of actions addressing the distress that might impact on the patient's sense of dignity. These care actions need to be defined. This study aims to suggest care actions that conserve dignity at the end of life based on evidence from local experience and community nursing practice. Data were collected by focus group interviews and analysed by framework analysis using the Chochinov model of dignity as a predefined framework. Suggestions on care actions were given in relation to all themes. As part of a multi-phase project developing and testing a dignity care pathway, this study might help community nurses to conserve dying patients' dignity.     

Endothelin-1 and macrophage colony-stimulating factor are co-localized in human amnion membrane cells and secreted into amniotic fluid

We have examined the cellular localization and human amniotic fluid content of endothelin-1 (ET-1) and macrophage colony-stimulating factor (M-CSF). The study material consisted of amniotic fluid from 20 patients referred for amniocentesis, and placental samples from normal deliveries. ET-1 and M-CSF were analysed by radioimmunoassay and enzyme-linked immunosorbent assay respectively. The cellular localization of ET-1 and M-CSF in the amnion membranes was analysed by double-labelling immunocytochemistry using fluorescein isothiocyanate- and Cy3-labelled secondary antibodies. Release of ET-1 and M-CSF was studied in cultured amniocytes. We found that the mean +/- SD concentrations of ET-1 and M-CSF in fetal amniotic fluid were 45.6 +/- 17.3 pmol/l (range 16.8-85.5) and 7323 +/- 3415 ng/l (range 2640-12 110) respectively. Double-labelling immunocytochemistry showed that both M-CSF and ET-1 were co-localized in the same cells to a high extent. Further analysis revealed that levels of M-CSF, but not ET-1, were significantly correlated with pregnancy length. Both M-CSF and ET-1 were released from cultured amniocytes in response to interleukin-1. These findings show that ET-1 and M-CSF are partly co-localized to specific cells in the human amniotic membrane. As both M-CSF and ET-1 were released from cultured amniocytes in vitro, this suggests that they both may be secreted into fetal amniotic fluid in vivo as well.