Functional activation of plasma membrane anion exchangers occurs in a pre-Golgi compartment.

Folding and oligomerization of most plasma membrane glycoproteins, including those involved in ion transport, occur in the ER and are frequently required for their exit from this organelle. It is currently unknown, however, where or when in the biosynthetic pathway these proteins become functionally active. AE1 and AE2 are tissue-specific, plasma membrane anion transport proteins. Transient expression of AE2 in a eukaryotic cell line leads to an increase in stilbene inhibitable whole cell 35SO4(2-)-efflux consistent with its function as a plasma membrane anion exchanger. No such increased transport activity was observed in AE1 transfectants, despite the fact that the two proteins were synthesized in roughly equal portions. In contrast, both AE1 and AE2 expression resulted in significant increase in Cl-/SO4(2-)-exchange in crude microsomes demonstrating that both AE1 and AE2 cDNAs encode functional proteins. Immunofluorescence staining and pulse-chase labeling experiments revealed that while 60% of AE2 is processed to the cell surface of transfectants, AE1 is restricted to an intracellular compartment and never acquires mature oligosaccharides. Crude microsomes from transfected cells were fractionated into plasma membrane and ER-derived vesicles by con A affinity chromatography. All of the AE1 and approximately half of the cellular AE2 was eluted with the ER vesicles, confirming their intracellular localization. Anion transport measurements on these fractions confirmed that the ER-restricted anion exchangers were functional. We conclude that AE1 and AE2 acquire the ability to mediate anion exchange at an early stage of their biosynthesis, before their exit from the ER.

An analysis of changes in sensory thresholds to mild tactile and cold stimuli after experimental spinal cord injury in the rat.

Changes in sensory function including chronic pain and allodynia are common sequelae of spinal cord injury (SCI) in humans. The present study documents the extent and time course of mechanical allodynia and cold hyperalgesia after contusion SCI in the rat using stimulation with graded von Frey filaments (4.97-50.45 g force) and ice probes. Fore- and hind-paw withdrawal thresholds to plantar skin stimulation were determined in rats with a range of SCI severities (10-g weight dropped from 6.25, 12.5, or 25 mm using the MASCIS injury device); animals with 25-mm injuries most consistently showed decreased hind-paw withdrawal thresholds to touch and cold, which developed over several weeks after surgery. Stimulation of the torso with graded von Frey hairs was performed at specified locations on the back and sides from the neck to the haunch. Suprasegmental responses (orientation, vocalization, or escape) to mechanical stimulation of these sites were elicited infrequently in the laminectomy control rats and only during the first 3 weeks after surgery, whereas in 25-mm SCI rats, such responses were obtained for the entire 10 weeks of the study. These data suggest that rats with contusion SCI may exhibit sensory alterations relevant to human spinal cord injuries.

GM1 ganglioside restores abnormal responses to acute thermal and mechanical stimuli in aged rats.

We investigated the effect of aging on the responses to thermal and mechanical stimuli in rats. Young (3-5 months old) and aged (22-24 months old) male Sprague-Dawley rats were tested in the hot plate, high- and low-intensity radiant heat tail flick, and von Frey hair assays. Compared to young rats, aged rats displayed longer latencies in the hot plate and the high-intensity tail flick assays (hypoalgesia), but there was no difference in the low-intensity tail flick assay. In addition, aged rats had decreased thresholds to mechanical stimuli produced by von Frey hairs compared with young rats (mechanical allodynia). Administration of GM1 ganglioside, 30 mg/kg, i.p., once daily for 30 days, to aged rats partially restored the responses in the hot plate and von Frey hair assays. GM1 had no effect on the altered responses in the tail flick test in aged rats, and in general, had no effect on any sensory modality tested in young rats.

Community health promotion nursing practice.

Evolving definitions of community and health promotion require the examination of community nursing practice. This article critically explores how the meanings of community may influence community nursing practice. In nursing, the most common definitions of community are of community as context/resource and community as client. The authors postulate that these definitions of community influence the nature of community practice. Moreover, if nurses are to practice within the context of health promotion, focusing on community as a relational experience, new patterns of community health promotion practice will need to emerge. This pattern of practice must honor people's experiences of community including power relations present in community. A new pattern of community health promotion nursing practice encompasses the four components of listening and critical reflection; participatory dialogue and critical questioning; pattern emergence and recognition; and movement to action.

Education and practice collaboration: a strategy for curriculum development.

Five schools of nursing in British Columbia formed a collaborative partnership in 1989; four represented diploma programs, and one a post-RN program. Their partnership benefited each in the development of a baccalaureate nursing curriculum. Committed to the principle of a curriculum being driven by practice, rather than the reverse, the collaborative partners employed a variety of strategies to include nurses from practice in the development of the curriculum. One strategy used by the partnership was a Delphi survey of nurses in practice. This article describes the results of this survey and their implications for nursing curricula.

University-college collaboration: rethinking curriculum development in nursing education.

The behavioral approach to curriculum development is inadequate to educate nurses to practice in the future health care system. As a result of a government initiative, a Canadian university and four community colleges had an opportunity to collaborate on development of a nursing program and thereby consider alternative approaches to curriculum development. This paper describes the process used to develop this curriculum and provides an overview of the curriculum development model that emerged. A community development process characterized by a commitment to be futuristic and visionary about nursing while making curriculum decisions was established. The curriculum model that emerged used a phenomenological exploration of our common vision for nursing in the future. The resulting curriculum is based on a human science paradigm that encourages nurses to work from a health promotion perspective with an ethic of caring.

Transforming our vision: emancipatory career planning for nurses.

Canadian nurses are experiencing profound and often disturbing changes in the health care sector. Not only have the number of jobs decreased but the nature and expectations of those jobs are changing dramatically. While these changes have raised nurses' anxiety, the changes simultaneously have presented nurses with an opportunity to transform their vision of nursing and their role in health care. This article describes a career planning pilot project for nurses which employed Freire's model of emancipatory learning. Based on the theoretical foundations of narrative psychology and critical social theory a series of four workshops were offered. Comments from the evaluation results indicate that the workshop was a transformative experience for the participants. Future implications for career planning for nurses are discussed.

Family nursing assessment: meeting the challenge of health promotion.

Family nursing assessment has traditionally followed an illness-care model. This paper proposes a re-evaluation of traditional family assessment and suggests an approach which is fundamentally based in health promotion. The paper includes a discussion of varying perspectives of health and health care, the health promotion perspective adopted by the World Health Organization, and the relevance of these perspectives for family nursing practice. Central elements of health promotion are outlined and serve as the guiding principles for family nursing assessment. Two inherent aspects of health-promoting family nursing practice are proposed and described. These include an emphasis on a human caring nursing ontology, and a framework for guiding family nursing assessment. This health-promoting assessment framework contains four essential components: (a) listening to the family; (b) participatory dialogue; (c) recognizing patterns; and (d) envisaging action and positive change. These components are described, together with the strategic elements inherent in each. Based on this health-promoting family nursing assessment, implications for nursing practice are discussed, and recommendations are made for research into this assessment framework.

Regulation of intracellular pH by a neuronal homolog of the erythrocyte anion exchanger.

We have isolated AE3, a novel gene expressed primarily in brain neurons and in heart. The predicted AE3 polypeptide shares a high degree of identity with the anion exchange and cytoskeletal binding domains of the erythrocyte band 3 protein. Expression of AE3 cDNA in COS cells leads to chronic cytoplasmic acidification and to chloride- and bicarbonate-dependent changes in intracellular pH, confirming that this gene product is an anion exchanger. Characterization of an AE3 mutant lacking the NH2-terminal 645 amino acids demonstrates that the COOH-terminal half of the polypeptide is both necessary and sufficient for correct insertion into the plasma membrane and for anion exchange activity. The NH2-terminal domain may play a role in regulating the activity of the exchanger and may be involved in the structural organization of the cytoskeleton in neurons.

Functional expression and subcellular localization of an anion exchanger cloned from choroid plexus.

We have isolated rat brain cDNA clones encoding AE2, a homologue of the erythrocyte anion exchanger, band 3 (AE1). Immunocytochemistry and in situ hybridization reveal that, in brain, AE2 expression is restricted to the basolateral membrane of the choroid plexus epithelium. Expression of a full-length mouse AE2 cDNA in COS-7 cells resulted in chloride- and bicarbonate-dependent alterations in intracellular pH, demonstrating that AE2 is a Cl/HCO3 exchanger. Cation replacement studies indicate that AE2-mediated exchange is independent of extracellular sodium. COS-7 cells expressing a mutant rat AE2 cDNA clone that lacks the cytoplasmic NH2-terminal 660 amino acids exhibit identical responses to cation and anion substitution. These results indicate that this domain does not play a significant role in either correct insertion of the transporter into the plasma membrane or anion exchange.