High level of divergence of male-reproductive-tract proteins, between Drosophila melanogaster and its sibling species, D. simulans

We compared male-reproductive-tract polypeptides of Drosophila melanogaster and D. simulans by using two-dimensional gel electrophoresis. Approximately 64% of male-reproductive-tract polypeptides were identical between two randomly chosen isofemale lines from these two species, compared with 83% identity for third-instar imaginal wing-disc polypeptides. Qualitatively similar differences were found between reproductive tracts and imaginal discs when D. sechellia was compared with D. melanogaster and with D. simulans. When genic polymorphism was taken into account, approximately 10% of male- reproductive-tract polypeptides were apparently fixed for different alleles between D. melanogaster and D. simulans; this proportion is the same as that found for soluble enzymes by one-dimensional gel electrophoresis. Strikingly, approximately 20% of male-reproductive- tract polypeptides of either D. melanogaster or D. simulans had no detectable homologue in the other species. We propose that proteins of the Drosophila male reproductive tract may have diverged more extensively between species than have other types of proteins and that much of this divergence may involve large changes in levels of polypeptide expression.      

Mechanism of pock formation by Shope fibroma virus on monolayers of rabbit cells

Israeli, Ella (Rambam Hospital, Haifa, Israel). Mechanism of pock formation by Shope fibroma virus on monolayers of rabbit cells. J. Bacteriol. 92:727-732. 1966.-The mechanism of pock formation by the Shope fibroma virus (SFV) on rabbit cultures in vitro was studied with the use of p-fluorophenylalanine, 5-bromodeoxyuridine, and 5-iododeoxyuridine. The inhibitors were used to inhibit, and to initiate, virus replication at different times after infection. It was shown that pock formation required virus replication to a threshold value of 25 plaque-forming units per pock area, and that this amount of virus can be accumulated during a period about 3 days less than that required for pock formation. Inhibition of virus growth, and of cell multiplication, after this threshold has been reached, did not prevent pock development. A delay in the onset of virus growth required to reach the threshold virus content, caused an about equivalent delay in the time of pock formation. In the absence of inhibitors, pocks were not formed after infection of 84 rabbit embryo clones, or five mixtures of clones containing five to seven clones each. The results indicate that pock formation by SFV in vitro was the result of cell aggregation, and not of cell multiplication, in special types of cells.     

Microelectrode studies of the active Na transport pathway of frog skin

When the outer surface of short-circuited frog skin was penetrated with microelectrodes, stable negative potentials that averaged near -100 mV were recorded consistently, confirming the results of Nagel (W. Nagel. 1975. Abstracts of the 5th International Biophysics Congress, Copenhagen. P-147.). The appearance of these stable potentials, V(O), concurrent with the observations that (a) a high resistance outer barrier R(O) accounting for approximately 75 percent or more of the transcellular resistance of control skins had been penetrated and that (b) 10(-5) M amiloride and reduced [Na] outside caused the values of V(O) to increase towards means value near -130 mV while the values of percent R(O) increased to more than 90 percent. It was of relationships were the same as the values of E(1) observed in studies of the current-voltage relationships were the same as the values of E’(1) defined as the values of voltage at the inner barrier when the V(O) of the outer barrier was reduced to zero by voltage clamping of the skins. Accordingly, these data are interpreted to mean that the values of E(1), approximately 130 mV, represent the E(Na) of the sodium pump at the inner barrier. 2,4-DNP was observed to decrease the values of transepithelial voltage less than E(1) the V(O) was negative. These data can be interpreted with a simple electrical equivalent circuit of the active sodium transport pathway of the frog skin that includes the idea that the outer membrane behaves as an electrical rectifier for ion transport.     

Direct intracardiac injection of umbilical cord-derived stromal cells and umbilical cord blood-derived endothelial cells for the treatment of ischemic cardiomyopathy

The development of new therapeutic strategies is necessary to reduce the worldwide social and economic impact of cardiovascular disease, which produces high rates of morbidity and mortality. A therapeutic option that has emerged in the last decade is cell therapy. The aim of this study was to compare the effect of transplanting human umbilical cord-derived stromal cells (UCSCs), human umbilical cord blood-derived endothelial cells (UCBECs) or a combination of these two cell types for the treatment of ischemic cardiomyopathy (IC) in a Wistar rat model. IC was induced by left coronary artery ligation, and baseline echocardiography was performed seven days later. Animals with a left ventricular ejection fraction (LVEF) of ≤40% were selected for the study. On the ninth day after IC was induced, the animals were randomized into the following experimental groups: UCSCs, UCBECs, UCSCs plus UCBECs, or vehicle (control). Thirty days after treatment, an echocardiographic analysis was performed, followed by euthanasia. The animals in all of the cell therapy groups, regardless of the cell type transplanted, had less collagen deposition in their heart tissue and demonstrated a significant improvement in myocardial function after IC. Furthermore, there was a trend of increasing numbers of blood vessels in the infarcted area. The median value of LVEF increased by 7.19% to 11.77%, whereas the control group decreased by 0.24%. These results suggest that UCSCs and UCBECs are promising cells for cellular cardiomyoplasty and can be an effective therapy for improving cardiac function following IC.     

A Moment Dead, a Moment Alive: How a Situational Personhood Emerges in the Vegetative State in an Israeli Hospital Unit

ABSTRACT  Here we address the personhood of patients in a permanent vegetative state (PVS), who fall outside categories of "alive" or "dead" and "subject" or "object." Drawing on fieldwork in an Israeli hospital, we examine multiple and shifting approaches to PVS patients, which are articulated in the course of caring for and living with them. We argue that, alongside the institutional definition of these patients as being in a PVS, which, as Kaufman showed, evokes irresolvable confusion as to their ontological nature, there appear and disappear other senses of their personhood. Allying with other studies of cognitively impaired patients (e.g., those with dementia and Alzheimer's), we explore this relational person-concept while demonstrating its situational nature. We analyze patients' admission to the hospital, showing how their essentialistic personhood is "emptied" and how and when their fluid, relational personhood appears and disappears, further showing how this personhood is reified by imagined life stories.     

α-Synuclein expression selectively affects tumorigenesis in mice modeling Parkinson's disease

Alpha Synuclein (α-Syn) is a protein implicated in mechanisms of neuronal degeneration in Parkinson's disease (PD). α-Syn is primarily a neuronal protein, however, its expression is found in various tumors including ovarian, colorectal and melanoma tumors. It has been hypothesized that neurodegeneration may share common mechanisms with oncogenesis. We tested whether α-Syn expression affects tumorigenesis of three types of tumors. Specifically, B16 melanoma, E0771 mammary gland adenocarcinoma and D122 Lewis lung carcinoma. For this aim, we utilized transgenic mice expression the human A53T α-Syn form. We found that the in vivo growth of B16 and E0771 but not D122 was enhanced in the A53T α-Syn mice. The effect on tumorigenesis was not detected in age-matched APP/PS1 mice, modeling Alzheimer's disease (AD), suggesting a specific effect for α-Syn-dependent neurodegeneration. Importantly, transgenic α-Syn expression was detected within the three tumor types. We further show uptake of exogenously added, purified α-Syn, by the cultured tumor cells. In accord, with the affected tumorigenesis in the young A53T α-Syn mice, over-expression of α-Syn in cultured B16 and E0771 cells enhanced proliferation, however, had no effect on the proliferation of D122 cells. Based on these results, we suggest that certain forms of α-Syn may selectively accelerate cellular mechanisms leading to cancer.     

Kinetics and mechanism of the comproportionation reaction between oxoammonium cation and hydroxylamine derived from cyclic nitroxides

Cyclic nitroxides demonstrate antioxidative activity in numerous in vitro and in vivo models, which frequently involves the participation of the reduced and oxidized forms of the nitroxide, namely, the hydroxylamine and oxoammonium cation. Generally, cellular reducing equivalents facilitate rapid enzymatic as well as nonenzymatic reduction of nitroxides in the tissue. On the other hand, the reaction of nitroxides with various radicals yields the highly oxidizing oxoammonium cation, which mediates the catalytic effect of nitroxides in selective oxidation of alcohols. Hence, nitroxides might act as both anti- and pro-oxidants. Therefore, the comproportionation reaction between the oxoammonium cation and the hydroxylamine might play a role in lowering the pro-oxidative activity of nitroxides. Although the comproportionation reaction has previously been studied, there is no agreement regarding its kinetic features. We investigated the reaction of the reduced forms of 2,2,6,6-tetramethylpiperidinoxyl (TPO) and 4-OH-2,2,6,6-tetramethylpiperidinoxyl (4-OH-TPO) with the oxoammonium cation derived from TPO at various pHs using rapid-mixing stopped-flow and EPR spectrometry. From the pH dependence of the reaction rate constants we determined the pK(1) of the respective hydroxylamines to be 7.5 and 6.9, respectively. The reduction potentials of the hydroxylamines were determined by cyclic voltammetry, and from their dependence on pH, we obtained the same pK(1) values. The rate constant of the comproportionation reaction does not exceed 20 M(-1) s(-1) in the physiological pH range and, therefore, cannot greatly contribute toward recycling of the nitroxides in the tissue.     

Most nuclear systemic autoantigens are extremely disordered proteins: implications for the etiology of systemic autoimmunity

Patients with systemic autoimmune diseases usually produce high levels of antibodies to self-antigens (autoantigens). The repertoire of common autoantigens is remarkably limited, yet no readily understandable shared thread links these apparently diverse proteins. Using computer prediction algorithms, we have found that most nuclear systemic autoantigens are predicted to contain long regions of extreme structural disorder. Such disordered regions would generally make poor B cell epitopes and are predicted to be under-represented as potential T cell epitopes. Consideration of the potential role of protein disorder may give novel insights into the possible role of molecular mimicry in the pathogenesis of autoimmunity. The recognition of extreme autoantigen protein disorder has led us to an explicit model of epitope spreading that explains many of the paradoxical aspects of autoimmunity – in particular, the difficulty in identifying autoantigen-specific helper T cells that might collaborate with the B cells activated in systemic autoimmunity. The model also explains the experimentally observed breakdown of major histocompatibility complex (MHC) class specificity in peptides associated with the MHC II proteins of activated autoimmune B cells, and sheds light on the selection of particular T cell epitopes in autoimmunity. Finally, the model helps to rationalize the relative rarity of clinically significant autoimmunity despite the prevalence of low specificity/low avidity autoantibodies in normal individuals.     

FGF6 mediated expansion of a resident subset of cells with SP phenotype in the C2C12 myogenic line

Fibroblast growth factor 6 (FGF6) is selectively expressed during muscle development and regeneration. We examined its effect on muscle precursor cells (mpc) by forcing stable FGF6 expression in C2C12 cells in vitro. FGF6 produced in genetically engineered mpc was active, inducing strong morphological changes, altering cell adhesion and compromising their ability to differentiate into myotubes. Expression of MyoD and myogenin, but not of Myf5, was abrogated in FGF6 engineered mpc. These effects were reversed by FGF inhibitors. Ectopic expression of MyoD also restored fiber formation indicating that FGF6 interferes with the myogenic differentiation pathway upstream of MyoD. We also report that in the presence of FGF6, the minor (0.5-2%) subpopulation of cells actively excluding Hoechst 33342 in a verapamil-dependent manner (SP phenotype) was increased to 15-20% and the expression of the mdr1a gene (but not mdr1b) was upregulated by 400-fold. Our data establish a previously undescribed link between FGF6--a muscle specific growth factor--and a multidrug resistance gene expressed in stem cells, and suggest a role for FGF6 in the maintenance of a reserve pool of progenitor cells in the skeletal muscle.     

Direct measurements of the kinematics and dynamics of bat flight

Experimental measurements and analysis of the flight of bats are presented, including kinematic analysis of high-speed stereo videography of straight and turning flight, and measurements of the wake velocity field behind the bat. The kinematic data reveal that, at relatively slow flight speeds, wing motion is quite complex, including a sharp retraction of the wing during the upstroke and a broad sweep of the partially extended wing during the downstroke. The data also indicate that the flight speed and elevation are not constant, but oscillate in synchrony with both the horizontal and vertical movements of the wing. PIV measurements in the transverse (Trefftz) plane of the wake indicate a complex 'wake vortex' structure dominated by a strong wing tip vortex shed from the wing tip during the downstroke and either the wing tip or a more proximal joint during the upstroke. Data synthesis of several discrete realizations suggests a 'cartoon' of the wake structure during the entire wing beat cycle. Considerable work remains to be done to confirm and amplify these results.