The relationship of cell division to the acquisition of adrenergic characteristics by developing sympathetic ganglion cell precursors

The relationship of the acquisition of defining characteristics by precursor cells of sympathetic ganglia to the withdrawal of these cells from the cell cycle was investigated in the developing chick. The characteristics studied included the ability to synthesize catecholamines (CA), the development of characteristic subcellular storage granules, and the specific uptake of norepinephrine (NE). All were present in presumptive sympathicoblasts and adrenal medullary precursors, which also became labeled after the injection of tritiated thymidine and so retained the ability to divide. These dividing CA-containing cells were found in both primary ganglia and secondary preand paravertebral ganglia. The developing sympathetic neuronal population was found to be a heterogeneous one. Some sympathetic precursor cells appeared to become postmitotic (or to enter a pause in division) early in ontogeny, while others continued to divide throughout the time of hatching. As embryogenesis proceeded, the proportion of CA-containing cells or their precursors which were dividing decreased. However, those cells which did divide probably divided repeatedly. It is concluded that some of the definitive characteristics of mature neurons are expressed by dividing precursor cells. The specific characteristic that marks the transition from immature dividing cells to mature postmitotic neurons has not yet been determined.     

Antigen-specific T contrasuppressor factor in cell-mediated immunity: interactions leading to eradication of the tolerant state

Interactions between a T cell-derived, antigen-specific, contrasuppressor factor (TcsF) and immune T cells that block the action of T suppressor factors and allow the transfer of cellular immunity into tolerant recipients are described. Immune T cells from contact-sensitized donors are capable of transferring specific immunity into normal recipients but not into animals rendered tolerant to the specific antigen. Brief exposure of the immune cells to the TcsF enables the effective transfer of immunity into such tolerant recipients. In addition, treated immune cells become resistant to subsequent exposure to T suppressor factor (capable of inhibiting transfer of immunity to normal recipients). A cyclophosphamide-sensitive, I-J+, Ly-2 T transducer cell is required in the immune donor cell population for contrasuppression to be induced by the TcsF plus specific antigen. These cells release an antigen-non-specific contrasuppressive factor capable of rendering immune targets, depleted of transducer cells, resistant to suppression (either by suppressor factor or in the tolerant recipient). The results indicate that contrasuppression in contact sensitivity is antigen specific and that the balance of suppression and contrasuppression determines tolerance vs responsiveness in this system. The symmetrical resemblance of the contrasuppressive interactions to those of suppression in contact sensitivity are discussed.     

Ethanol and prostaglandin E1: Biochemical and behavioral interactions

Low concentrations of ethanol enhanced prostaglandin (PG) E₁-stimulated adenosine-3′, 5′-cyclic monophosphate (cAMP) accumulation in human platelets and in rat brain slices. Ethanol also potentiated platelet synthesis of PGE₁ from dihomo-gamma-linolenic acid. These interactions may derive from the fluidizing effects of ethanol on lipid-containing cell membranes, and suggest a possible role for PGE₁ as a mediator of certain acute effects of ethanol. The derivative possibility that “down regulation” of PGE₁ systems is involved in the development of ethanol dependence is supported by data showing that PGE₁ administered to mice following chronic exposure to ethanol reduced withdrawal syndrome intensity.     

Antifungal Activity of Ring Poly-Chlorinated Pyrimidines: Structure Activity Relationships

A total of 48 ring chlorinated pyrimidines was screened against strains of five fungi by the disc-plate method, in liquid culture, and for activity of the vapors of the compounds. Correlations of the results obtained by the three methods were made, and structure to activity relationships were discussed. The outstanding members of this series were found to be 2,4,5-trichloropyrimidine, 4,5,6-trichloropyrimidine, and 2-chloromethyl-4,5,6-trichloropyrimidine, in this screening system.     

The α1 subunit of laminin-1 promotes the development of neurons by interacting with LBP110 expressed by neural crest-derived cells immunoselected from the fetal mouse gut

A plasmalemmal protein, LBP110, which binds to the α1 chain of laminin-1, is acquired by the neural crest-derived precursors of enteric neurons after they colonize the gut. We tested the hypothesis that laminin-1 interacts with LBP110 to promote enteric neuronal development. The effects of laminin-1 on neuronal development were studied in cultures of cells immunoselected from fetal mouse gut (E14–15) with antibodies to LBP110 or p75^NTR, a marker for enteric crest—derived cells. No matter which antibody was used, the development of cells expressing neuronal markers was increased three- to fourfold by culturing the cells on a laminin-1—containing substrate. To determine whether this effect of laminin-1 is due to the selective adherence of a neurocompetent subset of precursors, immunoselected cells were permitted to preadhere to poly-D-lysine. Addition of soluble laminin-1 24 h later promoted neuronal but not glial development. The laminin-1 induced increment in neuronal development was abolished both by a peptide containing the sequence of the LBP110-binding domain, IKVAV, and by antibodies to laminin α1 that recognize the IKVAV domain. Neither reagent affected the total number of cells. In contrast, the response to laminin-1 was not affected by control peptides, preimmune sera, or antibodies to laminin β1. Laminin-1 transiently induced the expression of nuclear Fos immunoreactivity; this action was blocked specifically by the IKVAV peptide. These data are consistent with the hypothesis that LBP110 interacts with the IKVAV domain of laminin α1 to promote the differentiation of neurons from enteric crest—derived precursors. © 1997 John Wiley & Sons, Inc. J Neurobiol 33: 118–138, 1997     

Countering Countermeasures in the Concealed Information Test Using Covert Respiration Measures

The effects of physical and mental countermeasures on the accuracy of the concealed information test (CIT) were examined in a mock crime experiment with 64 participants. To combat countermeasures, two covert respiration measures, hidden in the seat and back of the examination chair, were used in addition to the standard physiological measures (SCR, FPWL, RLL). Some guilty participants were trained to use either physical or mental countermeasures and apply them to distort the outcomes of the CIT. In the second phase of the experiment participants were detached from the standard polygraph devices and examined solely with the two covert measures. Results indicated that physical countermeasures lowered SCR accuracy but had a relatively small effect on the other standard measures. On the other hand, SCR was relatively resistant to mental countermeasures. Both covert measures were resistant to physical countermeasures in the polygraph phase. When the standard devices were removed, the covert seat measure was effective in the no countermeasure and in the mental countermeasure conditions but not when physical countermeasures were applied. The back measure was entirely ineffective.

The meeting of Eastern Europe and Yemen: ‘Idealistic workers’ and ‘natural workers’ in early Zionist settlement in Palestine

This study questions the customary thesis according to which the dominant status of the ashkenazim (European Jews) over the mizrachim (Middle Eastern and North African Jews) in Israeli society is to be explained by the earlier arrival of the former in Palestine. It does so by demonstrating that an early wave of Yemenite Jews, who arrived in Palestine simultaneously with the founding fathers, remained in a subservient social position. Archival sources, memoirs, and contemporary newspapers are used to explain the low status of Yemenite Jews by reference to the broader context of the Jewish‐Arab conflict as it took shape in Palestine's labour and land markets.     

The expression of interleukin-15 and interleukin-18 by human term placenta is not affected by lipopolysaccharide

The aim of the study was to examine the stimulatory effect of the inflammatory agent lipopolysaccharide (LPS) on the capacity of human term placenta to secrete interleukin (IL)-15 and IL-18. Isolated placental cotyledons from normal human term deliveries were dually perfused for ten hours with perfusion medium alone (n=5) or with perfusion medium containing LPS (1 microg/kg perfused placental tissue) (n=5). Placental tissue was collected from three different placental compartments (amnion, chorion, and placenta) before and after perfusion. The placental tissues collected were homogenized and examined for IL-15 and IL-18 by ELISA. In addition, formalin-fixed and paraffin-embedded sections from term placentas before perfusion were stained by immunohistochemistry to characterize the cellular origin of placental IL-15 and IL-18. Statistical significance was determined using paired/unpaired t-test. p<0.05 was considered significant. Our results show that IL-15 and IL-18 are produced more by chorionic tissue, as compared to the amnion and placental tissues. Moreover, we show that IL-15 and IL-18 are expressed by epithelial cells of the amnion, chorionic cells of the chorion and decidual cells of the decidua. However, IL-15, but not IL-18, was expressed also by syncytiotrophoblasts of the villi. Perfusion of LPS did not affect the capacity of amnion, chorion and placental tissues to secrete IL-15 and IL-18, as compared to control. The expression of IL-15 and IL-18 in the different compartments of the human placenta suggests a possible role for these two cytokines in normal placental development, pregnancy and labor. Moreover, our results indicate that IL-15 and IL-18 are not part of the mechanism of the response of human placenta to LPS.