Continuity and change: past experience as adaptive repertoire in occupational adaptation

Narratives are gaining recognition as important ways occupational therapists and other clinicians can think about the life stories of clients. The purpose of this article is to examine a conceptualization of how changes from one chapter to another occur in life stories, using the metaphor of an adaptive repertoire, and to consider how this notion can be useful in helping clients maintain continuity and a coherent life story in times of change. Three premises based on the concept of adaptation address (a) configurations of occupational forms embedded in particular local worlds, (b) cumulative development of an adaptive repertoire that allows one to perform both competently and appropriately, and (c) adaptive transitions and application of one's repertoire to new circumstances. Implications for research and clinical practice in occupational therapy also are examined.     

Occlusion of large atrial septal defects with a centering buttoned device: early clinical experience

A feasibility clinical study was conducted for the transcatheter occlusion of large ostium secundum atrial septal defects with the centering buttoned device. The centering buttoned device is a modification of the regular buttoned device in which a centering counter-occluder is sutured at the central 40% portion of the occluder. During centering it is stretched, forming a parachute-shaped structure and pulling the occluder over the center of the defect. During buttoning, the counter-occluder forms a double figure eight, opposing the right atrial side of the atrial septum. Occlusion was performed in 12 patients aged 6 to 56 years. All had been rejected for transcatheter occlusion by the regular buttoned device, because of either their defect size or the lack of adequate septal rim. The defect size varied between 23 and 31 mm, and the device size varied between 45 and 60 mm. Nine had immediate effective occlusions of their defects and three residual shunts. One patient with unbuttoning had hemolysis at 2 weeks and underwent surgery. Early results of the transcatheter occlusion of large atrial septal defects are promising, and larger clinical trials are justified.     

Computational study of packing a collagen-like molecule: quasi-hexagonal vs "Smith" collagen microfibril model

The lateral packing of a collagen-like molecule, CH3CO-(Gly-L-Pro-L-Pro)4-NHCH3, has been examined by energy minimization with the ECEPP/3 force field. Two current packing models, the Smith collagen microfibril twisted equilateral pentagonal model and the quasi-hexagonal packing model, have been extensively investigated. In treating the Smith microfibril model, energy minimization was carried out on various conformations including those with the symmetry of equivalent packing, i.e., in which the triple helices were arranged equivalently with respect to each other. Both models are based on the experimental observation of the characteristic axial periodicity, D = 67 nm, of light and dark bands, indicating that, if any superstructure exists, it should consist of five triple helices. The quasi-hexagonal packing structure is found to be energetically more favorable than the Smith microfibril model by as much as 31.2 kcal/mol of five triple helices. This is because the quasi-hexagonal packing geometry provides more nonbonded interaction possibilities between triple helices than does the Smith microfibril geometry. Our results are consistent with recent x-ray studies with synthetic collagen-like molecules and rat tail tendon, in which the data were interpreted as being consistent with either a quasi-hexagonal or a square-triangular structure.     

Reaching the global minimum in docking simulations: a Monte Carlo energy minimization approach using Bezier splines

The docking problem faces two major challenges: the global optimization of a multivariable function, such as the energy, and the ability to discriminate between true and false positive results, i.e., native from nonnative structures based on the input energy function. Among all energy evaluation tools, only a local energy-minimization method using an accurate enough potential function is able to discriminate between native and nonnative structures. To meet these requirements, a Monte Carlo with energy-minimization method has been incorporated into a new ECEPP/3 docking program. The efficiency of the simulation results from the use of an energy-grid technique based on Bezier splines and from a simplification of the receptor by switching on the energy of only important residues of the active site. Simulations of a thrombin-inhibitor complex show that the global minimum of the energy function was reached in every independent run within less than 3 min of time on an IBM RX 6000 computer. For comparison, 10 standard independent Monte Carlo simulations with 10(6) steps in each were carried out. Only three of them led to a conformation close to the x-ray structure. The latter simulations required an average of 24 min and about 10 hr with and without the grid, respectively. Another important result is that the Bezier spline technique not only speeds up the calculation by reducing the number of operations during the energy evaluation but also helps in reaching the global minimum by smoothing out the potential energy surface.     

Exceptional convergent evolution in a virus

Replicate lineages of the bacteriophage phiX 174 adapted to growth at high temperature on either of two hosts exhibited high rates of identical, independent substitutions. Typically, a dozen or more substitutions accumulated in the 5.4-kilobase genome during propagation. Across the entire data set of nine lineages, 119 independent substitutions occurred at 68 nucleotide sites. Over half of these substitutions, accounting for one third of the sites, were identical with substitutions in other lineages. Some convergent substitutions were specific to the host used for phage propagation, but others occurred across both hosts. Continued adaptation of an evolved phage at high temperature, but on the other host, led to additional changes that included reversions of previous substitutions. Phylogenetic reconstruction using the complete genome sequence not only failed to recover the correct evolutionary history because of these convergent changes, but the true history was rejected as being a significantly inferior fit to the data. Replicate lineages subjected to similar environmental challenges showed similar rates of substitution and similar rates of fitness improvement across corresponding times of adaptation. Substitution rates and fitness improvements were higher during the initial period of adaptation than during a later period, except when the host was changed.     

Limited influence of the mesothelium on the influx of monocytes into the peritoneal cavity

Exposure of Farage, a human B-cell line, to interleukin 4 (IL4) reduced the amount of CD38 antigen on the surface of the cells and in cell lysates. No evidence was obtained for accelerated breakdown, shedding, or internalization of CD38 molecules following IL4 treatment, nor the accumulation of CD38 molecules in the cell interior. The inhibition of protein synthesis with cycloheximide (CXM) diminished the down-regulation of CD38 induced by IL4. CXM decreased the expression of CD38 in Farage cells with arrested mitosis, and IL4 failed to further reduce CD38 expression. Staurosporine, an inhibitor of serine/threonine protein kinases, and H7 (1-(5-isoquinolinylsulfonyl)-2-methylpiperazine), a preferential inhibitor of protein kinase C (PKC), abrogated the effect of IL4 on CD38, while inhibitors of other serine protein kinases W7 (N-(aminohexyl)-5-chloro-1-naphthalenesulfoamide) and H8 (N-(2-[methylamino]ethyl)-5-isoquinolinesulfonamide) failed to interfere with the effect of IL4. Phorbol 12-myristate 13-acetate (PMA), an activator of PKC, resembled IL4 in decreasing the expression of CD38, and either staurosporine or H7 abolished this effect. Genistein, an inhibitor of tyrosine kinases, increased the expression of CD38, but failed to abrogate the inhibitory effect of IL4 on CD38. It is concluded that serine/threonine protein kinases mediated the IL4-induced down-regulation of the expression of CD38 molecules in B cells.     

On-line coupled liquid chromatography-gas chromatography (LC-GC) and LC-LC-GC for detecting irradiation of fat-containing foods

Summary On-line coupled liquid chromatography-gas chromatography-flame ionisation detection (LC-GC-FID) enables efficient and unambiguous determination of irradiation for some fat-containing foods (e.g. meat). Other products, however, contain interfering components or are contaminated, e.g., with mineral oil. Since more selective detection by mass spectrometry has limited success, the determination was improved by a more selective isolation of some key components among the fat degradation products, e.g. the dienes or trienes, by LC-LC-GC-FID. Applications are shown for soup mixes, some spices, fish, and shrimps.

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Nachweis der Bestrahlung fetthaltiger Lebensmittel durch direkt gekoppelte LC-GC und LC-LC-GC

Zusammenfassung Die Bestrahlung einiger fetthaltiger Lebensmittel, z. B. Fleisch, kann mit direkt gekoppelter LC-GC-FID rationell und eindeutig nachgewiesen werden. In anderen Proben wird die Analyse aber durch Inhaltsstoffe des Produktes oder durch Verunreinigungen (z. B. mit Mineralöl) gestört. Da selektivere Detektion durch Massenspektrqmetrie wenig verspricht, wurde der Nachweis durch selektivere Isolierung von Schlüsselkomponenten unter den Bestrahlungsprodukten, z. B. der Diene oder Triene, mittels LC-LC-GC yerbessert. Anwendungen werden gezeigt für Suppenpulver, einige Gewürze, Fisch und Garnelen.

     

Expression and circular dichroism studies of the extracellular domain of the alpha subunit of the nicotinic acetylcholine receptor

To provide material suitable for structural studies of the nicotinic acetylcholine receptor, we have expressed and purified the NH2-terminal extracellular domain of the mouse muscle alpha subunit. Several constructs were initially investigated using Xenopus oocytes as a convenient small scale expression system. A fusion protein (alpha210GPI) consisting of the 210 NH2-terminal amino acids of the alpha subunit and a glycosylphosphatidylinositol anchorage sequence conferred surface alpha-bungarotoxin binding in oocytes. Coexpression of alpha210GPI with an analogous construct made from the delta subunit showed no evidence of heterodimer formation. The alpha210GPI protein was chosen for large scale expression in transfected Chinese hamster ovary cells. The alpha210GPI protein was cleaved from these cells and purified on an immunoaffinity column. Gel and column chromatography show that the purified protein is processed as expected and exists as a monomer. The purified protein also retains the two distinct, conformation-specific binding sites expected for the correctly folded alpha subunit. Circular dichroism studies of alpha210GPI suggest that this region of the receptor includes considerable beta-sheet secondary structure, with a small proportion of alpha-helix.