Trifluoperazine stimulates the coordinate degradation of sphingomyelin and phosphatidylcholine in GH3 pituitary cells

Prior studies demonstrated that 1,2-diacylglycerols stimulated degradation of the choline-containing phospholipids, phosphatidylcholine and sphingomyelin, in GH3 pituitary cells by a phospholipase A2 and a sphingomyelinase, respectively (Kolesnick, R. N. (1987) J. Biol. Chem. 262, 16759-16762). The present studies demonstrate that the phenothiazine trifluoperazine also stimulates degradation of these phospholipids. Trifluoperazine (25 microM) reduced phosphatidylcholine and sphingomyelin levels to 81 and 58% of control, respectively, after 30 min in cells labeled for 48 h with [3H] choline. Choline-containing metabolites were released specifically into the cytosolic fraction. The level of cytosolic phosphocholine, but not choline or CDP-choline, increased to 150% of control. These events were not mediated by inhibition of phosphatidylcholine synthesis. The level of 1,2-diacylglycerols, but not lysophosphatidylcholine or glycerol-3-phosphocholine, also increased. These data are most consistent with phosphatidylcholine degradation via a phospholipase C. Trifluoperazine-stimulated sphingomyelin degradation was accompanied by quantitative generation of ceramides consistent with activation of a sphingomyelinase. In contrast to trifluoperazine, choline-containing metabolites were released into the medium during stimulation by the 1,2-diacylglycerol 1,2-dioctanoyl-glycerol. Although both trifluoperazine and 1,2-dioctanoylglycerol increased ceramide levels, only 1,2-dioctanoylglycerol increased the sphingoid base level from 24 to 43 pmol/10(6) cells. Hence, trifluoperazine appears to deplete an intracellular pool of phosphatidylcholine and sphingomyelin by a different mechanism than 1,2-diacylglycerols. This is the first report of phenothiazine-induced degradation of choline-containing phospholipids.     

Emplacement and resistance: Social and political complexities in development‐induced displacement in Papua New Guinea

This paper argues that attending to social and political factors in development‐induced displacement is critical even for projects that involve resettlement of small populations. Taking the resettlement of two villages by the Lihir Gold Mine in Papua New Guinea as a unique case study, I analyse why one village was relatively successfully resettled, while the other has been very complicated, leading to hostility and conflict. In these cases the initial focus of all concerned in reaching a resettlement agreement was on the adequacy of compensation and housing, which mimicked the focus in the literature during the 1990s on impoverishment and compensation. From the late 1990s there have been calls for greater attention to social and political aspects of displacement and resettlement. Early attention to these factors in the Lihir case, particularly the key concepts of emplacement and disemplacement, would have highlighted flaws in the resettlement agreement and would have made it easier to avert the conflict and resistance that arose.     

Grief as social experience: Death and bereavement in Lihir,Papua New Guinea1

This paper explores the nature of grief in Lihir, Papua New Guinea, in light of psychological theories of bereavement and grief. Anthropologists have demonstrated that culture has an impact on both the expression and experience of grief and can offer both a challenge to established theories and new perspectives on the conceptualisations and experiences of the bereaved. Until recently, ‘grief work’ was the foremost model for understanding bereavement as a psychological process and was also used by anthropologists in cross‐cultural work. However, since the 1990s, a number of alternative models of normal grief have emerged, including the dual process coping model and the model that proposes resilience as a central concept. These newer models, particularly the one which incorporates resilience, offer more for understanding grief in Lihir. The article argues that grief in Lihir has a phase of sorrow and worry that is dealt with through the sociality and activity of the mourning period, and then a longer phase of active remembering and forgetting of the deceased. The social and cultural context of bereavement is not adequately captured in current psychological conceptualisations of social support, which need to be broadened to encompass cross‐cultural material.     

Physiologic 1,2-diacylglycerol levels induce protein kinase C-independent translocation of a regulatory enzyme

Phorbol esters and 1,2-diacylglycerols have been used interchangeably to study protein kinase C action. This laboratory first suggested that 1,2-diacylglycerols may also act independent of protein kinase C using protein kinase C-"down-modulated" cells (Kolesnick, R. N., and Paley, A. E. (1987) J. Biol. Chem. 262, 9204-9210). Unfortunately, down-modulation was never complete. The present studies establish an in vitro system of enzyme translocation to resolve this issue. Choline phosphate cytidylyltransferase (EC 2.7.7.15), the regulatory enzyme for phosphatidylcholine biosynthesis, was utilized. Cytidylyltransferase translocation from cytosol to membranes mediates phorbol ester-induced phosphatidylcholine synthesis in GH3 pituitary cells. In the present studies, 1,2-diacylglycerols similarly induced phosphatidylcholine synthesis and cytidylyltransferase translocation. 1,2-Diacylglycerol-induced phosphatidylcholine synthesis, however, was not concentration-dependent but proportional to the moles of 1,2-diacylglycerol added per cell, i.e. subject to surface dilution. For instance, at constant cell number (1.67 x 10(6)/sample) and 1,2-dioctanoylglycerol concentration (diC8; 20 micrograms/ml), 32Pi incorporation into phosphatidylcholine varied from 150 to 350% above control as the incubation volume increased from 0.3 to 1.2 ml. Hence, the effective diC8 concentrations 0.5-30 micrograms/ml are preferably referred to as doses and reported as 0.25-15 nmol/10(6) cells. These doses increased cellular 1,2-diacylglycerol levels within a few fold of basal (374 pmol/10(6) cells). In vitro, diC8 also induced translocation of purified cytidylyltransferase devoid of protein kinase C to microsomes. Translocation was again subject to surface dilution. Translocation occurred with the same ratio of diC8 to microsomal membrane as phosphatidylcholine synthesis in intact cells (1-10 nmol of diC8/10(6) cell membranes). Despite stimulating cytidylyltransferase translocation in intact cells, phorbol esters failed to stimulate translocation in vitro. Hence, 1,2-diacylglycerols are not always interchangeable with phorbol esters and at physiologic levels may stimulate enzyme translocation by an alternative mechanism to protein kinase C.     

Attachment,Mothering and Mental Illness: Mother–Infant Therapy in an Institutional Context

This paper is an ethnographic exploration of how attachment theory underpins therapeutic practices in an Australian institutional context where mothers of infants have been diagnosed and are undergoing treatment for mental illness. We argue that attachment theory in this particular context rests on a series of principles or assumptions: that attachment theory is universally applicable; that attachment is dyadic and gendered; that there is an attachment template formed which can be transferred across generations and shapes future social interactions; that there is understood to be a mental health risk to the infant when attachment is characterised as problematic; and that this risk can be mitigated through the therapeutic practices advocated by the institution. Through an in-depth case study, this paper demonstrates how these assumptions cohere in practice and are used to assess mothering as deficient, to choose therapeutic options, to shape women’s behaviour, and to formulate decisions about child placement.     

Deep aspirations: towards a sustainable offshore Blue Economy

Reviews in Fish Biology and Fisheries - The ocean economy is experiencing rapid growth that will provide benefits but will also pose environmental and social risks. With limited space and degraded...     

The ethics and obligations of long-term ethnographic relationships: revelatory moments and the concept of solidarity

This article reflects on an ethical and revelatory moment in the development of my long-term fieldwork relationships with people of the Lihir Islands in Papua New Guinea. Ethnographic research globally is now shaped through formal processes of ethical review, with the requirements for informed consent, privacy, and consideration of harm and beneficence. Researchers then have to put these procedures into practice, often encountering the need to weigh competing ethical principles, particularly when unforeseen events occur. Reflexivity has been argued to be crucial on these occasions. Yet both ethical codes and reflexivity fall short of managing ethical and relational implications of long-term field relationships. This article suggests that the concept of solidarity as theorized recently in bioethics may be helpful, particularly the discernment of three layers of relationship. What responsibilities might we as anthropologists have to the people we work with that go beyond procedural ethics? And how do moments such as the one described in this article shape ongoing field research?     

Broadcasting Your Death Through Livestreaming: Understanding Cybersuicide Through Concepts of Performance

Cybersuicide, or suicide mediated by the internet in various ways, is a growing phenomenon worldwide and one which makes an often private act highly public. This paper provides an exploration of one version of cybersuicide: suicide that is livestreamed on the internet. Through an analysis of three case studies, this paper asks what light anthropological concepts of performance can shed on cybersuicide? It argues that as a public and social act, cybersuicide needs to be analyzed in terms of how an audience is attracted and retained, as well as the key roles the audience plays in the social practice. This means that cybersuicide has a different structure from suicide offline, impacting how it should be analyzed and understood.

     

Characterization of a ceramide kinase activity from human leukemia (HL-60) cells. Separation from diacylglycerol kinase activity

This laboratory first provided evidence for a potential signal transduction pathway involving sphingomyelin and its derivatives (Kolesnick, R.N., and Clegg, S. (1988) J. Biol. Chem. 263, 6534-6537). Recently, this laboratory demonstrated the existence of the novel sphingolipid ceramide 1-phosphate in human leukemia (HL-60) cells. Ceramide 1-phosphate was synthesized from ceramide derived from sphingomyelin but not glycosphingolipids. This suggested that a specific pathway extended from sphingomyelin to ceramide 1-phosphate. The present studies provide additional support for this notion by demonstrating the existence of a ceramide kinase activity distinct from diacylglycerol (DG) kinase in HL-60 cells. Microsomal membranes contained a kinase activity that phosphorylated ceramide but not 1,2-DG in the presence of physiologic and higher Ca2+ concentrations (60 nM-3 mM). Kinetic analyses demonstrated an apparent Vmax for ceramide and ATP of 70 pmol.min-1.mg protein-1; apparent Km values were 45 and 25 microM, respectively. The pH optimum was within the physiologic range (pH 6-8). Magnesium but not other divalent cations (Mn2+, Ba2+, Cd2+, Zn2+) also stimulated ceramide phosphorylation. Magnesium also induced 1,2-DG phosphorylation. Since DG kinase is a Mg2(+)-stimulable enzyme that may utilize ceramide as substrate, additional studies separated calcium-dependent ceramide kinase from DG kinase activity. 1,2-DGs competitively inhibited magnesium- but not calcium-dependent ceramide phosphorylation. Hence, calcium-dependent ceramide kinase activity neither utilized DG as substrate nor was inhibited by DG. These activities were physically separable. Both activities were solubilized by n-octyl-beta-D-glucopyranoside and stabilized by glycerol. Ceramide kinase activity bound weakly to a DEAE-cellulose anion exchange column and eluted with 4-fold purification as a single peak of activity in the flow-through and 0.05 M NaCl elutions. In contrast, the majority of DG kinase activity bound more tightly and was recovered as a broad peak in the 0.2-0.35 M NaCl elutions. These studies demonstrate the existence of a ceramide kinase activity in HL-60 cells which is functionally and physically separable from DG kinase. These studies provide further support for the notion of a specific pathway from sphingomyelin to ceramide 1-phosphate.