Starvation selection restores elastase and rhamnolipid production in a Pseudomonas aeruginosa quorum-sensing mutant

The las quorum-sensing system of Pseudomonas aeruginosa controls the expression of elastase and rhamnolipid. We report that starvation can select a mutant producing these virulence factors in spite of a lasR deletion. Expression of the autoinducer synthase gene rhlI was increased in this suppressor mutant, suggesting compensation by the rhl system. These data show that P. aeruginosa can restore elastase and rhamnolipid production in the absence of a functional las quorum-sensing system.     

Dual control by divalent cations and mitogenic cytokines of alpha 4 beta 1 and alpha 5 beta 1 integrin avidity expressed by human hemopoietic cells

Beta-1 integrins have essential functions in hemopoietic and immune systems by controlling phenomenons such as cell homing and cell activation. The function alpha 4 beta 1 and alpha 5 beta 1 integrins is regulated by divalent cations and, as demonstrated more recently, by mitogenic cytokines which activate them by "inside-out" mechanisms. Using the adhesive interaction of a cytokine-dependent human hemopoietic cell line to immobilized fibronectin, we have analyzed the requirements in divalent cations Mn2+, Mg2+ and Ca2+ for alpha 4 beta 1 and alpha 5 beta 1 activation by "inside-out" mechanisms triggered by cytokines such as granulocyte-macrophage colony stimulating factor or KIT ligand, or by external conformational constraints with the function-activating anti-beta 1 integrin monoclonal antibody 8A2. The intrinsic difference between these two modes of beta 1 integrin activation was revealed by their different requirements in divalent cations. We found that in the absence of any divalent cations, alpha 4 beta 1 and alpha 5 beta 1 were non-functional even after further stimulation by cytokines or 8A2. However, whilst either Ca2+, Mg2+ or Mn2+ were able to restore adhesive functions of alpha 4 beta 1 and alpha 5 beta 1 when activated by 8A2, only Mg2+ and Mn2+ were able to support activation of alpha 4 beta 1 and alpha 5 beta 1 by cytokines. Furthermore, high concentrations of Ca2+ exceeding 20 mM dramatically inhibited cell adhesion to fibronectin induced by Mn2+ and cytokines but not by 8A2. On the contrary, in the presence of both Ca2+ and Mg2+, Mn2+ had an additive effect on the activation of alpha 4 beta 1 and alpha 5 beta 1 by mitogenic cytokines. The presence of the absence of these divalent cations did not inhibit early tyrosine phosphorylation induced by the binding of KIT ligand to its tyrosine-kinase receptor KIT. Therefore, we propose that in hemopoietic cells, Ca2+, Mg2+ and Mn2+ may modulate in vivo alpha 4 beta 1 and alpha 5 beta 1 regulation by mitogenic cytokines, a phenomenon involved in the regulation of hemopoietic progenitor cell homing within the bone marrow.     

Risk assessment for patients with chronic myeloid leukaemia before allogeneic blood or marrow transplantation. Chronic Leukemia Working Party of the European Group for Blood and Marrow Transplantation

BACKGROUND: Transplantation of blood or bone-marrow stem cells is the treatment of choice for selected patients with chronic myeloid leukaemia (CML). Transplantation is used with increasing frequency and success, but remains associated with substantial risks of morbidity and mortality. Other treatments with satisfactory short-term outcome are available. For appropriate counselling of patients, a rapid and simple way to assess risk is needed. METHODS: Data from 3142 patients (1873 [60%] male, 1269 [40%] female; mean age 34 years, range <1-60 years) treated with allogeneic blood or marrow transplants for CML between 1989 and 1997, reported to the European Group for Blood and Marrow Transplantation (EBMT), were used to develop and test a simple risk score based on previously reported major pretransplant risk factors: histocompatibility, stage of disease at time of transplantation, age and sex of donor and recipient, and time from diagnosis to transplantation. We analysed probabilities of survival, leukaemia-free survival, transplant-related mortality, and relapse incidence with respect to these risk factors. FINDINGS: At the time of analysis, 1922 (61%) of the 3142 patients were alive-1567 (65%) of those with HLA-identical sibling donors and 417 (57%) of those with unrelated donors. 1682 (54%) were alive without relapse. 1220 (39%) patients had died, 1013 (83%) of transplant-related causes, 207 (17%) of relapse. 447 (14%) patients had relapsed. The final scoring system was highly predictive for leukaemia-free survival, survival and transplant-related mortality. Survival at 5 years was 72%, 70%, 62%, 48%, 40%, 18%, and 22% for patients with scores 0, 1, 2, 3, 4, 5, and 6, respectively. Risk of transplant-related mortality was 20%, 23%, 31%, 46%, 51%, 71%, and 73%. Data showed the same trends for HLA-identical sibling transplants and unrelated transplants for transplants done in 1989-93 and 1994-96. INTERPRETATION: Pretransplant risk factors are cumulative for individual patients with CML having blood or marrow transplantation. A simple system based on five main factors gives adequate risk assessment for counselling of patients and taking decisions.     

Function of galanin in the anterior pituitary of estrogen-treated Fischer 344 rats: autocrine and paracrine regulation of prolactin secretion

Estrogen is a robust stimulator of galanin synthesis and secretion in the anterior pituitary. Galanin is colocalized in lactotrophs in the estrogen-treated anterior pituitary, and its roles in lactotroph function are still being elucidated. In the present studies, we quantified the phenotypes of estrogen-treated Fischer 344 rat anterior pituitary cells expressing the galanin gene by dual in situ hybridization. The total population of galanin-positive pituitary cells increased from undetectable levels to 16% of all cells after 2 weeks of estrogen treatment. More than 90% of the galanin-positive cells coexpressed PRL messenger RNA, and one-third of the lactotrophs expressed galanin messenger RNA. We hypothesized that galanin in the anterior pituitary may contribute to the heterogeneous secretion of PRL, and that one of the functions of galanin is to regulate PRL secretion in an autocrine/paracrine manner. To test this hypothesis, we performed the reverse hemolytic plaque assay combined with in situ hybridization to measure PRL secretion and galanin gene expression within the same individual cells. PRL secretion from galanin-positive lactotrophs was significantly greater than that from galanin-negative lactotrophs. Moreover, treatment with galanin antiserum significantly attenuated PRL secretion from galanin-positive cells, and treatment with galanin significantly enhanced PRL secretion from galanin-negative lactotrophs. In conclusion, these data provide direct evidence that galanin derived from the estrogen-treated anterior pituitary stimulates PRL secretion in both autocrine and paracrine manners.     

Activation of the Na+-K+(NH4+)-2Cl(-)- cotransporter from rat submandibular glands in response to VIP

A cellular suspension from rat submandibular glands was prepared with collagenase. The intracellular pH (pHi) was estimated with 2',7'-bis-(2-carboxy-ethyl)-5(6)-carboxyfluorescein (BCECF). After exposure to NH4Cl, the pHi transiently increased (diffusion of NH3) and then dropped (influx of NH4+). Isoproterenol increased 2.5-fold the rate of NH4+ influx; bumetanide, an inhibitor of the Na+-K+-2Cl(-)-cotransporter blocked the response to isoproterenol, confirming that the beta-adrenergic agonist stimulated the cotransporter. Forskolin (1 micromol/L) mimicked the response to isoproterenol. VIP (1 nmol/L(-1) micromol/L) also increased the activity of the cotransporter. Cyclic AMP rather than calcium was the mediator of this activation since 1) carbachol which increased the [Ca2+]i fivefold increased the uptake of NH4+ by only 50%; 2) only high concentrations of VIP significantly increased the [Ca2+]i; 3) incubation in the presence of EGTA had no effect on the response to VIP; 4) low concentrations (nmol/L) of the neuropeptide increased the intracellular level of cAMP; and 5) the stimulation of the cotransporter by VIP, forskolin, and isoproterenol was inhibited by H8, an inhibitor of cAMP-dependent protein kinase. It is concluded that the Na+-K+-2Cl(-)-cotransporter of rat submandibular glands is activated by isoproterenol, forskolin, and neuropeptides of the VIP family by a mechanism involving cAMP-dependent processes. The activation of the cotransporter by VIP could partly explain the potentiating effect of VIP on the response to sialagogues like substance P or muscarinic agonists.     

Coparental and family group-level dynamics during infancy: early family precursors of child and family functioning during preschool

This study examines longitudinal correlates of coparental and family group-level dynamics during infancy. Thirty-seven couples observed at play with their 8-11-month-old infants (15 boys, 22 girls) rated their child's internalizing and externalizing symptoms, and their own coparenting behavior 3 years later. Teachers also rated child behavior at the 3-year follow-up. Several significant relationships emerged between observed family process (high hostility-competitiveness, low family harmony, and high parenting discrepancies in the triad) at Time 1, and subsequent reports of child and coparenting behavior at Time 2. Larger parenting discrepancies at Time 1 predicted greater child anxiety as rated by teachers; greater hostility-competitiveness and lower harmony forecast higher child aggression. Time 1 family process continued to predict Time 2 aggression even after controlling for individual and marital functioning. Several links were also found between distressed family process and later parental reports of negative coparenting behavior. These parental reports of coparenting also explained unique variance in concurrent child behavior ratings. The significance of coparenting as a distinct family construct is discussed.     

Heterologous expression of the Desulfovibrio gigas [NiFe] hydrogenase in Desulfovibrio fructosovorans MR400

The ability of Desulfovibrio fructosovorans MR400 DeltahynABC to express the heterologous cloned [NiFe] hydrogenase of Desulfovibrio gigas was investigated. The [NiFe] hydrogenase operon from D. gigas, hynABCD, was cloned, sequenced, and introduced into D. fructosovorans MR400. A portion of the recombinant heterologous [NiFe] hydrogenase was totally matured, exhibiting catalytic and spectroscopic properties identical to those of the native D. gigas protein. A chimeric operon containing hynAB from D. gigas and hynC from D. fructosovorans placed under the control of the D. fructosovorans hynAp promoter was constructed and expressed in D. fructosovorans MR400. Under these conditions, the same level of activity was obtained as with the D. gigas hydrogenase operon.