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PubMed2002

The cytoplasmic tail of invariant chain regulates endosome fusion and morphology.

The major histocompatibility complex class II associated invariant chain (Ii) has been shown to inhibit endocytic transport and to increase the size of endosomes. We have recently found that this property has a significant impact on antigen processing and presentation. Here, we show in a cell-free endosome fusion assay that expression of Ii can increase fusion after phosphatidylinositol 3-kinase activity is blocked by wortmannin. In live cells wortmannin was also not able to block formation of the Ii-induced enlarged endosomes. The effects of Ii on endosomal transport and morphology depend on elements within the cytoplasmic tail. Data from mutagenesis analysis and nuclear magnetic resonance-based structure calculations of the Ii cytoplasmic tail demonstrate that free negative charges that are not involved in internal salt bridges are essential for both interactions between the tails and for the formation of enlarged endosomes. This correlation indicates that it is interactions between the Ii cytoplasmic tails that are involved in endosome fusion. The combined data from live cells, cell-free assays, and molecular dynamic simulations suggest that Ii molecules on different vesicles can promote endosome docking and fusion and thereby control endosomal traffic of membrane proteins and endosomal content.

Amino Acid Sequence↗
PubMed2004

Geminating pollen has tubular vacuoles, displays highly dynamic vacuole biogenesis, and requires VACUOLESS1 for proper function.

Vacuoles perform multiple functions in plants, and VCL1 (VACUOLESS1) is essential for biogenesis with loss of expression in the vcl1 mutant leading to lethality. Vacuole biogenesis plays a prominent role in gametophytes, yet is poorly understood. Given the importance of VCL1, we asked if it contributes to vacuole biogenesis during pollen germination. To address this question, it was essential to first understand the dynamics of vacuoles. A tonoplast marker, delta-TIP::GFP, under a pollen-specific promoter permitted the examination of vacuole morphology in germinating pollen of Arabidopsis. Our results demonstrate that germination involves a complex, yet definable, progression of vacuole biogenesis. Pollen vacuoles are extremely dynamic with remarkable features such as elongated (tubular) vacuoles and highly mobile cytoplasmic invaginations. Surprisingly, vcl1 did not adversely impact vacuole morphology in pollen germinated in vitro. To focus further on VCL1 in pollen, reciprocal backcrosses demonstrated reduced transmission of vcl1 through male gametophytes, indicating that vcl1 was expressive after germination. Interestingly, vcl1 affected the fertility of female gametophytes that undergo similarly complex vacuole biogenesis. Our results indicate that vcl1 is lethal in the sporophyte but is not fully expressive in the gametophytes. They also point to the complexity of pollen vacuoles and suggest that the mechanism of vacuole biogenesis in pollen may differ from that in other plant tissues.

Arabidopsis↗
PubMed2006

A Bayesian belief network for quality assessment: application to employment officer support.

BACKGROUND: 'Supported' employment stipulates that disabled people should have real jobs for real pay. This paper models kinds of supported employment, assesses how the support and placement features affect its outcomes and its quality from the perspective of the employees, and provides a dynamic model to help explore what types of interventions might promote greater social inclusion for people with learning and other disabilities. METHOD: Bayesian belief networks (BBNs) provide the general framework for modelling the relationships between the variables and features of interest. The structure, probabilistic specification and quality indicators were elicited from project advisory groups, including people with learning disability, and took into account a pilot survey of 30 individuals. A subsequent survey of 1,461 supported employees was used to update the model and to provide actual assessments of quality of placement. RESULTS: We present the BBN methodology in some detail, as novel to this discipline. We show how the model was constructed, and its implications for supported employment. We derive indices for quality of placement, taking into account the views of clients. We show how survey and individual results can be used to update the model. Use of the model suggests that quality of placement is, on average, relatively high, with small differences between groups with differing primary disability. CONCLUSIONS: The BBN is the appropriate methodology to model complex relationships and interventions for problems such as these. The model developed in this study can be used to assess and improve the fit between people and jobs, both at the individual level and for groups of employees, and can take into account different kinds of quality for different stakeholders.

Adult↗
PubMed2004

Chronic pain, stress, and the dynamics of affective differentiation.

We describe a program of research examining how the relationship between positive and negative affect varies both between individuals and within individuals over time. This Dynamic Model of Affect (DMA) proposes that under conditions that promote maximal information processing, positive and negative affective systems function relatively independently. In contrast, under conditions characterized by uncertainty, including pain and stress, the affects become strongly inversely related. Included in our consideration are potential individual differences in the ability to sustain affective differentiation during pain and other stressors and the implications of this model for perceptions of social relations and for interventions to improve well-being among the chronically ill.

Affect↗
PubMed2004

Specific localization of the annexin II heterotetramer in brain lipid raft fractions and its changes in spatial learning.

Annexin-II (AII) is a Ca(2+)-dependent phospholipid-binding protein that is present in both intracellular and extracellular compartments. In the present study AII immunoreactivity was found in a subpopulation of neurons in specific brain regions, including the cerebral cortex and the surface of hippocampal pyramidal neurons from adult rats. AII from synaptic membranes was detected by immunoblotting as multiple species containing the monomer (AII36) and heterotetramer (AIIt). AIIt was resistant to beta-mercaptoethanol and dithiothreitol in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but was completely reduced to monomers (36 kDa) by two-dimensional electrophoresis. AIIt resided exclusively in the detergent-resistant lipid rafts concentrated in neuronal dendrites, and its recruitment to those structures was enhanced by antibody cross-link. AII abundantly distributed on the outer leaflet of neuronal membranes and between spaces of neurons appeared to be neuronal adhesive. The formation of AIIt required synthesis of sphingolipids and cholesterol, and its stability depended on Ca2+. Increases in neuronal activities such as depolarization and learning were shown to promote formation of AIIt. Our results suggest that, via a dynamic association with dendritic lipid rafts, AII may play a role in synaptic signal transduction and remodeling. This probably involves focal adhesion and interactions with actin that are associated with brain development and memory consolidation.

Animals↗
PubMed2001

Survival of Campylobacter jejuni during stationary phase: evidence for the absence of a phenotypic stationary-phase response.

When Campylobacter jejuni NCTC 11351 was grown microaerobically in rich medium at 39 degrees C, entry into stationary phase was followed by a rapid decline in viable numbers to leave a residual population of 1% of the maximum number or less. Loss of viability was preceded by sublethal injury, which was seen as a loss of the ability to grow on media containing 0.1% sodium deoxycholate or 1% sodium chloride. Resistance of cells to mild heat stress (50 degrees C) or aeration was greatest in exponential phase and declined during early stationary phase. These results show that C. jejuni does not mount the normal phenotypic stationary-phase response which results in enhanced stress resistance. This conclusion is consistent with the absence of rpoS homologues in the recently reported genome sequence of this species and their probable absence from strain NCTC 11351. During prolonged incubation of C. jejuni NCTC 11351 in stationary phase, an unusual pattern of decreasing and increasing heat resistance was observed that coincided with fluctuations in the viable count. During stationary phase of Campylobacter coli UA585, nonmotile variants and those with impaired ability to form coccoid cells were isolated at high frequency. Taken together, these observations suggest that stationary-phase cultures of campylobacters are dynamic populations and that this may be a strategy to promote survival in at least some strains. Investigation of two spontaneously arising variants (NM3 and SC4) of C. coli UA585 showed that a reduced ability to form coccoid cells did not affect survival under nongrowth conditions.

Adaptation, Physiological↗
PubMed1984

Treatment of immigrant Indian patients.

When immigrant Indian patients develop psychiatric illness, they face many disadvantages such as the lack of family support and shame for becoming sick. In treating them, a knowledge of their cultural values and communication, is necessary. While taking history, reluctance of these patients to discuss sexual and aggressive feelings should be respected. Patients' harmony with the family and significant others is the goal of treatment rather than the patients' growth; interdependence and not independence is favored. Free expression of emotions create a dysphoric milieu. A careful assessment of psychopathology and dynamics and psychotherapy integrating these cultural factors is important to promote changes that are therapeutic.

Cultural Characteristics↗
PubMed2006

Pathways to health: a framework for health-focused research and practice.

Public health research and practice is faced with three problems: 1) a focus on disease instead of health, 2) consideration of risk factor/disease relationships one at a time, and 3) attention to individuals with limited regard for the communities in which they live. We propose a framework for health-focused research and practice. This framework encompasses individual and community pathways to health while incorporating the dynamics of context and overall population vulnerability and resilience. Individual pathways to health may differ, but commonalities will exist. By understanding these commonalities, communities can work to support health-promoting pathways in addition to removing barriers. The perspective afforded by viewing health as a dynamic process instead of as a collection of risk factors and diseases expands the number of approaches to improving health globally. Using this approach, multidisciplinary research teams working with active community participants have the potential to reshape health and intervention sciences.

Journal Article↗
PubMed1995

The role of PRP8 protein in nuclear pre-mRNA splicing in yeast.

The removal of introns from precursor messenger RNAs occurs in a large complex, the spliceosome, that contains many proteins and five small nuclear RNAs (snRNAs). The snRNAs interact with the intron-containing substrate RNA and with each other to form a dynamic network of RNA interactions that define the intron and promote splicing. There is evidence that protein splicing factors play important roles in regulating RNA interactions in the spliceosome. PRP8 is a highly conserved protein that is associated in particles with the U5 snRNA and directly binds the substrate RNA in spliceosomes. UV crosslinking has been used to map the binding sites, and shows extensive interaction between PRP8 protein and the 5' exon prior to the first step of splicing and with the 3' splice site region subsequently. It is proposed that PRP8 protein may stabilize fragile interactions between the U5 snRNA and exon sequences at the splice sites, to anchor and align them in the catalytic centre of the spliceosome.

Exons↗
PubMed1990

The context of health promotion in the NHS.

In connection with "Working for Patients" health authorities have been asked by the NHS Management Executive how they intend to perform their "core" functions. "Core" tasks for regions include: "monitoring and promoting the health of their populations (including the functions set out in HC(88)64), determining with districts and FPCs, the health needs of their resident populations; collecting and managing information which facilitates this. . ." ". . . District, in close collaboration with FPCs, will retain a key role in ensuring that the health needs of their populations are met; that there are effective services for the prevention and control of diseases and the promotion of health." Amanda Killoran reviews the context of health promotion in the NHS, and indicates the importance of developing nationally integrated programmes of disease prevention and health promotion.

Catchment Area, Health↗
PubMed1991

Respiratory muscle function in asthma.

Asthma increases the load on the ventilatory pump by causing simultaneous increases in airway resistance, lung volume, and minute ventilation. The inspiratory muscles bear the majority of this load, whereas expiratory muscle recruitment is relatively minor. Respiratory muscle strength and endurance appear to be normal in stable asthmatics. During acute attacks, airway closure and expiratory airflow limitation result in a dynamic increase in end-expiratory lung volume. In turn, hyperinflation compromises the function of inspiratory muscles, especially that of the diaphragm, by reducing their force-generating capacity (muscle shortening) and impairing their mechanical advantage on the chest wall. Thus, exacerbations of asthma cause an acute increase in mechanical load together with decreased ventilatory capacity, thereby predisposing to inspiratory muscle fatigue and precipitating hypercapnic respiratory failure in severe cases. Management of ventilatory failure in asthma consists of mechanical unloading of the inspiratory muscles by positive pressure ventilation together with pharmacotherapy (anti-inflammatory and bronchodilating agents) to improve airway function. The strategy of mechanical ventilation is aimed at minimizing dynamic hyperinflation, which increases inspiratory muscle load as well as promotes barotrauma.

Adrenal Cortex Hormones↗
PubMed1998

[Community nursing from the viewpoint of public health].

Findings of health science as to the incidence and dynamics of health problems and the knowledge to optimize health promotion, prevention and patient treatment as well as international comparisons indicate that the potentials of nursing--understood as a system of nurses, nursing institutions and nursing science differentiated in itself--are not exhausted to their full extent within the German system of social health assurance. Following the introductory reflections on the relation between public health and nursing, being relatively young multi-disciplines of health science in Germany, this paper tries to identify and to describe the related deficiencies and approaches for their rectification by means of the four phases of the Public Health Action Cycle--assessment: of problems and fixing of priorities; policy formulation: selection, negotiation and fixing of strategies; assurance: organisation, implementation and control as well as evaluation: evaluation of the strategy and its results. This paper is the revised version of the basic lecture that the author gave on the occasion of the Fourth International Symposium of Nursing Science in Osnabrück in November 1996.

Community Health Nursing↗
PubMed2002

Modulation of substrate adhesion dynamics via microtubule targeting requires kinesin-1.

Recent studies have shown that the targeting of substrate adhesions by microtubules promotes adhesion site disassembly (Kaverina, I., O. Krylyshkina, and J.V. Small. 1999. J. Cell Biol. 146:1033-1043). It was accordingly suggested that microtubules serve to convey a signal to adhesion sites to modulate their turnover. Because microtubule motors would be the most likely candidates for effecting signal transmission, we have investigated the consequence of blocking microtubule motor activity on adhesion site dynamics. Using a function-blocking antibody as well as dynamitin overexpression, we found that a block in dynein-cargo interaction induced no change in adhesion site dynamics in Xenopus fibroblasts. In comparison, a block of kinesin-1 activity, either via microinjection of the SUK-4 antibody or of a kinesin-1 heavy chain construct mutated in the motor domain, induced a dramatic increase in the size and reduction in number of substrate adhesions, mimicking the effect observed after microtubule disruption by nocodazole. Blockage of kinesin activity had no influence on either the ability of microtubules to target substrate adhesions or on microtubule polymerisation dynamics. We conclude that conventional kinesin is not required for the guidance of microtubules into substrate adhesions, but is required for the focal delivery of a component(s) that retards their growth or promotes their disassembly.

Animals↗