The pattern and meaning of neighbor relations in high-rise housing in Israel

This paper deals with the behavioral pattern of neighbor relations and their relationships to the subjective attitudes and expectations of the residents. The sample was 318 middle-class women living in eight-to 20-story buildings. The findings indicate that respondents so desiring were able to develop active social ties with their neighbors. Moreover, they interacted with neighbors despite the fact that the majority had opportunities for alternative social relations. The distinction between localized and nonlocalized high-rise residents does not seem meaningful in this case. Actual social ties with neighbors were related to norms and expectations regarding neighbor relations. Despite active neighboring, respondents did not have difficulties obtaining privacy.     

Myosin VI walks hand-over-hand along actin

Myosin VI is a molecular motor that can walk processively on actin filaments with a 36-nm step size. The walking mechanism of myosin VI is controversial because it takes very large steps without an apparent lever arm of required length. Therefore, myosin VI is argued to be the first exception to the widely established lever arm theory. It is therefore critical to directly demonstrate whether this motor walks hand-over-hand along actin despite its short lever arm. Here, we follow the displacement of a single myosin VI head during the stepping process. A single head is displaced 72 nm during stepping, whereas the center of mass previously has been shown to move 36 nm. The most likely explanation for this result is a hand-over-hand walking mechanism. We hypothesize the existence of a flexible element that would allow the motor to bridge the observed 72-nm distance.     

Inactivation of plasminogen activator inhibitor-1 by specific proteolysis with stromelysin-1 (MMP-3)

Matrix metalloproteinase-3 (MMP-3 or stromelysin-1) specifically hydrolyzes the Ser(337)-Ser(338) (P10-P9) and Val(341)-Ile(342) (P6-P5) peptide bonds in human plasminogen activator inhibitor-1 (PAI-1). Cleavage is completely abolished in the presence of the metal chelators EDTA or 1,10-phenanthroline. A stabilized active PAI-1 variant was also cleaved by MMP-3. At an enzyme/substrate ratio of 1/10 at 37 degrees C, PAI-1 protein cleavage occurred with half-lives of 27 or 14 min for active or stable PAI-1 and was associated with rapid loss of inhibitory activity toward tissue-type plasminogen activator with half-lives of 15 or 13 min, respectively. A substrate-like variant of PAI-1, lacking inhibitory activity but with exposed reactive site loop, was cleaved with a half-life of 23 min, whereas latent PAI-1 in which a major part of the reactive site loop is inserted into the molecule, was resistant to cleavage. Biospecific interaction analysis indicated comparable binding of active, stable, and substrate PAI-1 to both proMMP-3 and MMP-3 (K(A) of 12-22 x 10(6) m(-1)), whereas binding of latent PAI-1 occurred with lower affinity (1.7-2.3 x 10(6) m(-1)). Stable PAI-1 bound to vitronectin was cleaved and inactivated by MMP-3 in a manner comparable with that of free PAI-1; however, the cleaved protein did not bind to vitronectin. Cleavage and inactivation of PAI-1 by MMP-3 may thus constitute a mechanism decreasing the antiproteolytic activity of PAI-1 and impairing the potential inhibitory effect of vitronectin-bound PAI-1 on cell adhesion and/or migration.     

Prostromelysin-1 (proMMP-3) stimulates plasminogen activation by tissue-type plasminogen activator.

Matrix metalloproteinase-3 (MMP-3 or stromelysin-1) specifically binds to tissue-type plasminogen activator (t-PA), without however, hydrolyzing the protein. Binding affinity to proMMP-3 is similar to single chain t-PA, two chain t-PA and active site mutagenized t-PA (Ka of 6.3 x 106 to 8.0 x 106 M-1), but is reduced for t-PA lacking the finger and growth factor domains (Ka of 2.0 x 106 M-1). Activation of native Glu-plasminogen by t-PA in the presence of proMMP-3 obeys Michaelis-Menten kinetics; at saturating concentrations of proMMP-3, the catalytic efficiency of two chain t-PA is enhanced 20-fold (kcat/Km of 7.9 x 10-3 vs. 4.1 x 10-4 microM-1.s-1). This is mainly the result of an enhanced affinity of t-PA for its substrate (Km of 1.6 microM vs. 89 microM in the absence of proMMP-3), whereas the kcat is less affected (kcat of 1.3 x 10-2 vs. 3.6 x 10-2 s-1). Activation of Lys-plasminogen by two chain t-PA is stimulated about 13-fold at a saturating concentration of proMMP-3, whereas that of miniplasminogen is virtually unaffected (1.4-fold). Plasminogen activation by single chain t-PA is stimulated about ninefold by proMMP-3, whereas that by the mutant lacking finger and growth factor domains is stimulated only threefold. Biospecific interaction analysis revealed binding of Lys-plasminogen to proMMP-3 with 18-fold higher affinity (Ka of 22 x 106 M-1) and of miniplasminogen with fivefold lower affinity (Ka of 0.26 x 106 M-1) as compared to Glu-plasminogen (Ka of 1.2 x 106 M-1). Plasminogen and t-PA appear to bind to different sites on proMMP-3. These data are compatible with a model in which both plasminogen and t-PA bind to proMMP-3, resulting in a cyclic ternary complex in which t-PA has an enhanced affinity for plasminogen, which may be in a Lys-plasminogen-like conformation. Maximal binding and stimulation require the N-terminal finger and growth factor domains of t-PA and the N-terminal kringle domains of plasminogen.     

Effects of hypothalamic and amygdaloid stimulation on reaching behaviour in the rat

Thirty adult rats were trained in a reaching behaviour schedule, after which bipolar steel electrodes were bilaterally implanted into the ventromedial hypothalamus (VMH), lateral hypothalamic area (LHA) or basolateral amygdala (BLA). On subsequent training sessions, these structures were electrically stimulated employing a movement-synchronized stimulation design. The results show that VMH stimulation produces aversive effects: the animals go away from the feeder after the first stimulus. Reaching impairment resulting from LHA or BLA stimulation mainly affected the grasping phase; additionally, repetition of movement sequence was observed. The results are discussed in the framework of Kornhuber's concept of preprogrammed ballistic movements.     

Liver gene expression and increase in albumin synthesis by fetal hepatocytes transplanted into analbuminemic rats

This report describes the evolution of hepatocytes isolated from 21-day fetuses and transplanted into spleens of Nagase analbuminemic rats which have negligible serum albumin levels due to a mutation affecting albumin mRNA processing. Albumin and alpha-fetoprotein expression, in addition to other parameters related to cellular proliferation status (thymidine kinase and proliferating cell nuclear antigen expression) were studied as indicative of the behavior and evolution of the cells. In recipient rats, only a few clusters of hepatocytes could be observed in the red pulp of the spleen 24 h after transplantation. The fetal hepatocytes migrated to the liver and could be seen in portal branches immediately after transplantation. Fifteen days later, albumin mRNA was detected in recipient livers and was expressed throughout the entire 3-month study. Alpha-fetoprotein was not detected. Cell proliferation was not relevant, although 3 months after transplantation, the proliferation rates appeared to show a tendency to increase. These data demonstrate that fetal hepatocytes transplanted into spleen migrate to liver, settle there and acquire an adult phenotype free of malignant transformation. Our study is a first step towards the thorough understanding of fetal hepatocyte transplantation. The next steps will involve in-depth studies of the possibilities of genetic manipulation to achieve a high degree of repopulation/expression, employing the least possible number of donor cells, and of how the cells reach the liver parenchyma, overcoming the endothelial barrier.     

Modulation of peripheral T-cell function by interleukin-7 in rheumatoid arthritis

Introduction

Interleukin-7 (IL-7) is a cytokine essential for T-cell lymphopoiesis, survival and polarization with an emerging role in autoimmunity. We previously demonstrated reduced levels of circulating IL-7 in rheumatoid arthritis (RA), although high amounts are expressed in joints, suggesting differences between systemic and synovial effects. We observed healthy levels of IL-7 in 48% of RA patients in clinical remission (CR) and aimed to investigate the consequences of IL-7 deficiency on T-cell responses.

Methods

We used RA patients with active disease and in CR presenting various levels of IL-7, to investigate its modulatory effects on T cells by analysing responses to phyto-haemagglutinin (PHA), expression of polarization or survival factors, or suppression by regulatory T cells (Tregs).

Results

IL-7 levels were normal (>10 pg/ml) in 48% of RA patients in CR. Amongst 63 CR patients followed up for 18 months, lack of IL-7 recovery was observed in 13 out of 15 (86%) patients experiencing relapse but only 11 out of 48 (23%) of those who did not (P = 0.0002). Binary regressions showed high significance for below normal IL-7 levels for self-reported maternal family history of arthritis (odds ratio (OR): 7.66, P = 0.006) and a trend for smoking (OR: 3.33, P = 0.068) with no further demographic or clinical associations. Serum IL-7 correlated with restored CD4⁺T-cell response to PHA (rho = 0.879); this was not related to an increase in T-cell proliferation capacity or expression of survival factors B-cell lymphoma 2 (BCL2) and BCL2-associated protein X (BAX). Expression of Th1 polarization factor (TBET) was also dependent on exposure to IL-7 in vivo (rho = 0.600). In contrast CD25^highTregs’ response to PHA was not affected by in vivo IL-7, but their suppression capabilities were related to circulating IL-7 (rho = 0.589). Co-stimulation with IL-7 (mimicking the joint environment) increased responsiveness of CD4⁺T-cells to PHA, lowering the ability of CD25^highTregs to suppress them.

Conclusions

Our data demonstrate that IL-7 has a critical role in modulating T-cell function in vivo, possibly explaining opposing effects observed systemically and in the joint. Lack of IL-7 recovery in CR by maintaining a suppressed immune system may be a determinant factor in the occurrence of relapse.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-014-0511-3) contains supplementary material, which is available to authorized users.     

A COMPARED STUDY ON THE PURIFICATION OF FETAL AND ADULT RAT HEPATOCYTE SUSPENSIONS BY BIOMAGNETIC ISOLATION TECHNIQUES AND FLOW CYTOMETRY ANALYSIS

An analysis of liver cell populations from both adult and 21 day pregnancy rat fetuses (E21) was carried out. The results show that E21 hepatocytes express OX-43, as do endothelial cells but not adult hepatocytes. OX-43 could be used in future as a cell marker for the hepatocyte maturation.