Exchangeable leaders of collectively migrating glioma abuse N-cadherin trafficking.

Collectively migrating cells consist of leaders and followers with different features. In this issue, Kim et al. (https://doi.org/10.1083/jcb.202401057) characterize the leader and follower cells in collective glioma migration and uncover important roles of YAP1/TAZ-mediated regulation of N-cadherin in the leader cells.

Nicotine Enhances Object Recognition Memory via Stimulating α4ß2 and α7 Nicotinic Acetylcholine Receptors in the Medial Prefrontal Cortex of Mice.

Nicotine has been known to enhance recognition memory in various species. However, the brain region where nicotine acts and exerts its effect remains unclear. Since the medial prefrontal cortex (mPFC) is associated with memory, we examined the role of the mPFC in nicotine-induced enhancement of recognition memory using the novel object recognition test in male C57BL/6J mice. Systemic nicotine administration 10 min before training session significantly enhanced object recognition memory in test session that was performed 24 h after the training. Intra-mPFC infusion of mecamylamine, a non-selective nicotinic acetylcholine receptor (nAChR) antagonist, 5 min before nicotine administration blocked the effect of nicotine. Additionally, intra-mPFC infusion of dihydro-ß-erythroidine, a selective α4ß2 nAChR antagonist, or methyllycaconitine, a selective α7 nAChR antagonist, significantly suppressed the nicotine-induced object recognition memory enhancement. Finally, intra-mPFC infusion of nicotine 1 min before the training session augmented object recognition memory in a dose-dependent manner. These findings suggest that mPFC α4ß2 and α7 nAChRs mediate the nicotine-induced object recognition memory enhancement.

ABCA1, ABCG1, and ABCG4 are distributed to distinct membrane meso-domains and disturb detergent-resistant domains on the plasma membrane.

ATP-binding cassette A1 (ABCA1), ABCG1, and ABCG4 are lipid transporters that mediate the efflux of cholesterol from cells. To analyze the characteristics of these lipid transporters, we examined and compared their distributions and lipid efflux activity on the plasma membrane. The efflux of cholesterol mediated by ABCA1 and ABCG1, but not ABCG4, was affected by a reduction of cellular sphingomyelin levels. Detergent solubility and gradient density ultracentrifugation assays indicated that ABCA1, ABCG1, and ABCG4 were distributed to domains that were solubilized by Triton X-100 and Brij 96, resistant to Triton X-100 and Brij 96, and solubilized by Triton X-100 but resistant to Brij 96, respectively. Furthermore, ABCG1, but not ABCG4, was colocalized with flotillin-1 on the plasma membrane. The amounts of cholesterol extracted by methyl-ß-cyclodextrin were increased by ABCA1, ABCG1, or ABCG4, suggesting that cholesterol in non-raft domains was increased. Furthermore, ABCG1 and ABCG4 disturbed the localization of caveolin-1 to the detergent-resistant domains and the binding of cholera toxin subunit B to the plasma membrane. These results suggest that ABCA1, ABCG1, and ABCG4 are localized to distinct membrane meso-domains and disturb the meso-domain structures by reorganizing lipids on the plasma membrane; collectively, these observations may explain the different substrate profiles and lipid efflux roles of these transporters.

[Relationship between red blood cell transfusion volume and posttransfusional iron overload in hematological diseases].

We retrospectively investigated the status of transfusional iron overload at Kinki University Hospital. One hundred and sixty three patients received more than 10 red blood cell (RBC) units per year in 2009 and 2010. Myelodysplastic syndrome (37.4%) and aplastic anemia (11.0%) accounted for about 50% of the underlying diseases. At the time of receiving a total of 20 RBC units, 90.8% and 66.2% of the 65 patients evaluated had more than 500 and 1,000 ng/ml of serum ferritin, respectively. The frequency of organ dysfunction associated with iron overload was 56.9% of all the patients assessed, 37.8% of patients with serum ferritin levels of 500∼999 ng/ml, and 67.4% of patients with serum ferritin levels >1,000 ng/ml. Although the Japanese guidelines propose 40 units of RBC transfusion and/or a serum ferritin level of 1,000 ng/ml as a good point to start iron chelation therapy, our results suggest that iron overload and consequent organ dysfunction may occur earlier than this. Therefore, it may be necessary to start iron chelation therapy earlier than that suggested by the Japanese guidelines.

Supplementation of DHA-rich microalgal oil or fish oil during the suckling period in mildly n-3 fatty acid-deficient rat pups.

Long-chain polyunsaturated fatty acids (LC-PUFA), particularly arachidonic acid (ARA) and docosahexaenoic acid (DHA), are considered critical for the development of infants and are commonly supplemented in infant formulae. In this study, two common sources of n-3 LC-PUFA, fish oil (FO) and DHA-rich microalgal oil (DMO), were fed to rat pups of mildly n-3 PUFA-deficient dams to compare changes in LC-PUFA of tissue phospholipids. The milk from dams fed a n-3 PUFA-deficient diet contained less n-3 LC-PUFA than that of dams fed a control diet (AIN-93G). The pups' were given orally 1 mg/g weight of either FO or DMO for 17 days between the ages of 5 and 21 days, the pups were weaned, and sacrificed 1 week later for analysis of fatty acid compositions of brain, heart, kidney, spleen, and thymus phospholipids. Although both FO and DMO brought about a recovery in the tissue DHA levels compared to those of the control group (pups from AIN-93G-fed dams), DMO was more effective at restoring tissue LC-PUFA status because it was richer in DHA than FO. FO had a slightly lower PUFA level than that required to bring the LC-PUFA status completely to normal levels in this experiment, and EPA did not accumulate in tissues under the conditions tested here. These results demonstrate the effectiveness of ingesting either FO or DMO in the pre-weaning period for improving mild n-3 PUFA deficiency.

Brain death: ethical challenges to palliative care concepts of family care.

Brain death is a controversial issue that is often difficult for families to understand or accept. Palliative care interventions can help families to accept the death. However, delaying pronouncement of brain death may be detrimental to the family and lead to financial, ethical, and legal complications, including the potential for insurance fraud. We describe a case of brain death in which the passage of time along with continuation of life support without concomitant testing for brain death led to decreased acceptance of the patient's death by the family. Clinicians should weigh the risks and benefits of harm to the family when deciding how long to keep a brain dead patient on a ventilator. Pronouncement of death, which is good basic medical care regardless of the cause or mechanism of death, should not be delayed for family considerations. Risk management should be involved early in the decision process, if life support is withdrawn without the family's assent.

Myoclonus associated with high-dose parenteral methadone.

Methadone is generally believed to be devoid of neuroexcitatory properties, and its use is increasing. This paper reports two cases of myoclonus with high-dose parenteral methadone in patients with cancer under hospice care. This side effect may be dose related and/or due to the parenteral route of administration. Reduction of the dose and change of route was sufficient to eliminate the myoclonus while maintaining an adequate pain control. Possible mechanisms for methadone causing myoclonus include a redistribution of receptor saturation in the N-methyl-D-aspartate (NMDA) and delta receptors. Ketamine may be an option for patients with intractable pain who develop methadone-induced myoclonus.

Long-term supplementation of docosahexaenoic acid-rich, eicosapentaenoic acid-free microalgal oil in n-3 fatty acid-deficient rat pups.

Rat pups deficient in n-3 fatty acids received an oral administration of docosahexaenoic acid (DHA)-rich, eicosapentaenoic acid (EPA)-free microalgal oil (DMO) or fish oil (FO). DMO administration almost restored liver EPA to the level of the control diet-fed dam's pups, but FO administration did not. This suggests that EPA could be recovered in the liver, even though EPA-free DMO was supplemented.