290 research outputs found
The Estonian organizations - the subjects of transformation
Estonia stayed fifty years under the communist regime. This paper explores the transformation of Estonian organizations within the framework of the Leavitt's model of change where the process is analyzed from the perspective of four organizational elements: people, organizational goals, structure, and technology. In respect with the people the role of individuals is emphasized as well as the polarization of mindsets is discussed. The new era forced to clarify the organizational task because of market economy. The organizational structure does not change as fast as the other elements do and hierarchy considered being important. The formalization tactics (personnel selection and training) have gained new meaning in the process of transformation of organizations. The technology has varied due to the twofold possibilities- advantage to introduce the new informational technology and the usage of the old fashion machinery. Change of the society led to the change of organizations, which had the transformational nature. There was shown that all the elements of the organizations had the pressure to find new forms of existence
Force generation examined by laser temperature-jumps in shortening and lengthening mammalian (rabbit psoas) muscle fibres
We examined the tension change induced by a rapid temperature jump (T-jump) in shortening and lengthening active muscle fibres. Experiments were done on segments of permeabilized single fibres (length (L0) ā¼2 mm, sarcomere length 2.5 Ī¼m) from rabbit psoas muscle; [MgATP] was 4.6 mm, pH 7.1, ionic strength 200 mm and temperature ā¼9Ā°C. A fibre was maximally Ca2+-activated in the isometric state and a ā¼3Ā°C, rapid (< 0.2 ms), laser T-jump applied when the tension was approximately steady in the isometric state, or during ramp shortening or ramp lengthening at a limited range of velocities (0ā0.2 L0 sā1). The tension increased to 2- to 3 Ć P0 (isometric force) during ramp lengthening at velocities > 0.05 L0 sā1, whereas the tension decreased to about < 0.5 Ć P0 during shortening at 0.1ā0.2 L0 sā1; the unloaded shortening velocity was ā¼1 L0 sā1 and the curvature of the forceāshortening velocity relation was high (a/P0 ratio from Hill's equation of ā¼0.05). In isometric state, a T-jump induced a tension rise of 15ā20% to a new steady state; by curve fitting, the tension rise could be resolved into a fast (phase 2b, 40ā50 sā1) and a slow (phase 3, 5ā10 sā1) exponential component (as previously reported). During steady lengthening, a T-jump induced a small instantaneous drop in tension, followed by recovery, so that the final tension recorded with and without a T-jump was not significantly different; thus, a T-jump did not lead to a net increase of tension. During steady shortening, the T-jump induced a pronounced tension rise and both its amplitude and the rate (from a single exponential fit) increased with shortening velocity; at 0.1ā0.2 L0 sā1, the extent of fibre shortening during the T-jump tension rise was estimated to be ā¼1.2% L0 and it was shorter at lower velocities. At a given shortening velocity and over the temperature range of 8ā30Ā°C, the rate of T-jump tension rise increased with warming (Q10 ā 2.7), similar to phase 2b (endothermic force generation) in isometric muscle. Results are discussed in relation to the previous findings in isometric muscle fibres which showed that a T-jump promotes an early step in the crossbridgeāATPase cycle that generates force. In general, the finding that the T-jump effect on active muscle tension is pronounced during shortening, but is depressed/inhibited during lengthening, is consistent with the expectations from the Fenn effect that energy liberation (and acto-myosin ATPase rate) in muscle are increased during shortening and depressed/inhibited during lengthening
IgD attenuates the IgM-induced anergy response in transitional and mature B cells
Self-tolerance by clonal anergy of B cells is marked by an increase in IgD and decrease in IgM antigen receptor surface expression, yet the function of IgD on anergic cells is obscure. Here we define the RNA landscape of the in vivo anergy response, comprising 220 induced sequences including a core set of 97. Failure to co-express IgD with IgM decreases overall
expression of receptors for self-antigen, but paradoxically increases the core anergy response,
exemplified by increased Sdc1 encoding the cell surface marker syndecan-1. IgD expressed on
its own is nevertheless competent to induce calcium signalling and the core anergy mRNA response. Syndecan-1 induction correlates with reduction of surface IgM and is exaggerated
without surface IgD in many transitional and mature B cells. These results show that IgD attenuates the response to self-antigen in anergic cells and promotes their accumulation. In this way, IgD minimizes tolerance-induced holes in the pre-immune antibody repertoire.This work was supported by NIH grant U19 AI100627 and NHMRC grants 585490,
1016953 and 1081858 to C.C.G., NHMRC CJ Martin Fellowship 595989 to J.H.R., an
Endeavour Award from the Australian Government to Z.S. and the National Collaborative
Research Infrastructure Scheme Australian Phenomics Facilit
IgD attenuates the IgM-induced anergy response in transitional and mature B cells
Self-tolerance by clonal anergy of B cells is marked by an increase in IgD and decrease in IgM antigen receptor surface expression, yet the function of IgD on anergic cells is obscure. Here we define the RNA landscape of the in vivo anergy response, comprising 220 induced sequences including a core set of 97. Failure to co-express IgD with IgM decreases overall expression of receptors for self-antigen, but paradoxically increases the core anergy response, exemplified by increased Sdc1 encoding the cell surface marker syndecan-1. IgD expressed on its own is nevertheless competent to induce calcium signalling and the core anergy mRNA response. Syndecan-1 induction correlates with reduction of surface IgM and is exaggerated without surface IgD in many transitional and mature B cells. These results show that IgD attenuates the response to self-antigen in anergic cells and promotes their accumulation. In this way, IgD minimizes tolerance-induced holes in the pre-immune antibody repertoire
An analysis of the temperature dependence of force, during steady shortening at different velocities, in (mammalian) fast muscle fibres
We examined, over a wide range of temperatures (10ā35Ā°C), the isometric tension and tension during ramp shortening at different velocities (0.2ā4 L0/s) in tetanized intact fibre bundles from a rat fast (flexor hallucis brevis) muscle; fibre length (L0) was 2.2Ā mm and sarcomere length ~2.5Ā Ī¼m. During a ramp shortening, the tension change showed an initial inflection of small amplitude (P1), followed by a larger exponential decline towards an approximate steady level; the tension continued to decline slowly afterwards and the approximate steady tension at a given velocity was estimated as the tension (P2) at the point of intersection between two linear slopes, as previously described (Roots etĀ al. 2007). At a given temperature, the tension P2 declined to a lower level and at a faster rate (from an exponential curve fit) as the shortening velocity was increased; the temperature sensitivity of the rate of tension decline during ramp shortening at different velocities was low (Q10 0.9ā1.5). The isometric tension and the P2 tension at a given shortening velocity increased with warming so that the relation between tension and (reciprocal) temperature was sigmoidal in both. In isometric muscle, the temperature T0.5 for half-maximal tension was ~10Ā°C, activation enthalpy change (āH) was ~100Ā kJĀ molā1 and entropy change (āS) ~350Ā JĀ molā1Ā Kā1. In shortening, these were increased with increase of velocity so that at a shortening velocity (~4 L0/s) producing maximal power at 35Ā°C, T0.5 was ~28Ā°C, āH was ~200Ā kJĀ molā1 and āSĀ ~Ā 700 JĀ molā1Ā Kā1; the same trends were seen in the tension data from isotonic release experiments on intact muscle and in ramp shortening experiments on maximally Ca-activated skinned fibres. In general, our findings show that the sigmoidal relation between force and temperature can be extended from isometric to shortening muscle; the implications of the findings are discussed in relation to the crossbridge cycle. The data indicate that the endothermic, entropy driven process that underlies crossbridge force generation in isometric muscle (Zhao and Kawai 1994; Davis, 1998) is even more pronounced in shortening muscle, i.e. when doing external work
Cross sections for single and double strand breaks in SV-40 virus in EO buffer after heavy ion irradiation: Experiment and theory
Earthworm activity and availability for meadow birds is restricted in intensively managed grasslands
Earthworms are an important prey for the endangered meadow birds of northwest Europe. Although intensive grassland management with high manure inputs generally promotes earthworm abundance, it may reduce the effective food availability for meadow birds through desiccation of the topsoil, which causes earthworms to remain deeper in the soil. We studied the response of Red Worm Lumbricus rubellus, a detritivore, and Grey Worm Aporrectodea caliginosa, a geophage, to soil moisture profiles in the field and under experimental conditions. Surfacing earthworms were counted weekly in eight intensively managed grasslands (treated with high inputs of slurry by slit injection) with variable groundwater tables in the Netherlands. At each count, soil penetration resistance, soil moisture tension and groundwater level were measured, while air temperature and humidity were obtained from a nearby weather station. The response to variation in the vertical distribution of soil moisture was also experimentally studied in the two earthworm species. In the field, earthwormsā surfacing activity at night was negatively associated with soil moisture tension and positively by relative air humidity. Surprisingly, there was no effect of groundwater level; an important management variable in meadow bird conservation. Under experimental conditions, both L. rubellus and A. caliginosa moved to deeper soil layers (>20Ā cm) in drier soil moisture treatments, avoiding the upper layer when moisture levels dropped below 30%. Synthesis and applications. We propose that in intensively managed grasslands with slurry application, topsoil desiccation reduces earthworm availability for meadow birds. This can be counteracted by keeping soil moisture tensions of the top soil above ā15Ā kPa. We suggest that the late raising of groundwater tables in spring and the disturbance of the soil by slit injection of slurry increase topsoil desiccation. This decreases earthworm availability when it matters most for breeding meadow birds. Meadow bird conservation will benefit from revised manure application strategies that promote earthworm activity near or at the soil surface.</p
Attenuated Fatigue in Slow Twitch Skeletal Muscle during Isotonic Exercise in Rats with Chronic Heart Failure
During isometric contractions, slow twitch soleus muscles (SOL) from rats with chronic heart failure (chf) are more fatigable than those of sham animals. However, a muscle normally shortens during activity and fatigue development is highly task dependent. Therefore, we examined the development of skeletal muscle fatigue during shortening (isotonic) contractions in chf and sham-operated rats. Six weeks following coronary artery ligation, infarcted animals were classified as failing (chf) if left ventricle end diastolic pressure was >15mmHg. During isoflurane anaesthesia, SOL with intact blood supply was stimulated (1s on 1s off) at 30Hz for 15 min and allowed to shorten isotonically against a constant afterload. Muscle temperature was maintained at 37Ā°C. In resting muscle, maximum isometric force (Fmax) and the concentrations of ATP and CrP were not different in the two groups. During stimulation, Fmax and the concentrations declined in parallel sham and chf. Fatigue, which was evident as reduced shortening during stimulation, was also not different in the two groups. The isometric force decline was fitted to a bi-exponential decay equation. Both time constants increased transiently and returned to initial values after approximately 200 s of the fatigue protocol. This resulted in a transient rise in baseline tension between stimulations, although this effect which was less prominent in chf than sham. Myosin light chain 2s phosphorylation declined in both groups after 100 s of isotonic contractions, and remained at this level throughout 15 min of stimulation. In spite of higher energy demand during isotonic than isometric contractions, both shortening capacity and rate of isometric force decline were as well or better preserved in fatigued SOL from chf rats than in sham. This observation is in striking contrast to previous reports which have employed isometric contractions to induce fatigue
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