The opposing actions in vivo on murine myelopoiesis of purified preparations of lactoferrin and the colony stimulating factors

The actions of purified iron-saturated human lactoferrin (LF), purified preparations of human MiaPaCa colony stimulating factor-1 (CSF-1), and recombinant murine interleukin-3 (IL-3) were evaluated in vivo in mice. Studies in vitro were compared at lowered (5%), as well as at normal incubator (20%), oxygen (O2) tension because of the potentially greater physiologic relevance of in vitro studies performed at lowered O2 tension. The results demonstrate that 1) increased release of granulocyte-macrophage colony stimulating factor (GM-CSF) in vitro from pokeweed mitogen stimulated mouse spleen cells and from human mononuclear blood cells occurred at lowered O2 tension, and that human mononuclear blood leukocytes were more sensitive to the LF-induced suppression of GM-CSF release when cells were cultured at 5%, compared to 20%, O2 tension; 2) LF administered intravenously (IV) to mice pretreated with sublethal intraperitoneal dosages of Cytoxan decreased the cycling status of marrow and spleen granulocyte-macrophage (CFU-GM), erythroid (BFU-E-2 and BFU-E-1) and multipotential (CFU-GEMM) progenitor cells and the absolute numbers of these progenitors; these effects were most noticeable if care was taken to deplete endotoxin from the LF samples prior to testing LF in vivo and if the control medium was endotoxin free; 3) endotoxin-depleted LF decreased the cycling status of marrow and spleen CFU-GM, BFU-E, and CFU-GEMM and the numbers of these progenitors in the marrows of mice previously untreated with Cytoxan; these effects were most apparent when assessment of progenitor cells and their cycling rates were evaluated in vitro at lowered (5%) O2 tension; 4) purified natural human CSF-1 increased the absolute numbers of marrow CFU-GM and the cycling status of marrow CFU-GM and CFU-GEMM in mice pretreated with LF; and 5) purified recombinant murine IL-3 stimulated proliferation of day 8 and day 12 CFU-S (colony forming unit-spleen) in mice not previously treated with Cytoxan. These results substantiate the in vivo myelosuppressive effects of LF on CFU-GM and extend these effects to erythroid and multipotential progenitor cells, provide evidence that human CSF-1 has an in vivo action in mice, and confirm the studies of others showing that IL-3 stimulates the proliferation of CFU-S in vivo.     

Spermine binding to subsynaptosomal fractions of rat brain cortex

Binding sites for [¹⁴C]spermine have been identified in rat brain cortex subcellular fractions. The binding, characterized by using synaptosomal membranes, is specific for spermine. It was not detected below 20°C and increased about three/four-fold with a temperature rise of 10°C. Binding occurred only in the presence of-SH reducing agents. It was completely suppressed by metal chelating agents, and was stimulated about four-fold by 1–5×10^–5 M Fe²⁺. Smaller increases were observed in the presence of Mn²⁺, Ni²⁺, Ca²⁺, Mg²⁺, and Zn²⁺; in ocntrast, millimolar concentrations of most divalent cations inhibited the binding differently (Mn²⁺=Ni²⁺=Zn²⁺=Co²⁺Mg²⁺>Ca²⁺).Bound radioactive spermine was not displaced by the addition of high concentrations of unlabelled polyamine or chelating agents, nor by precipitation and washing of the membranes with 10 percent trichloroacetic acid, or by boiling of the precipitate in the presence of 1.0 percent SDS and 10 percent -mercaptoethanol. The trichloroacetic acid precipitate showed two radioactive bands, corresponding to low Mr (<8,000) components, after SDS-polyacrylamide gel electrophoresis and fluorography. The Fe²⁺-stimulated [¹⁴C]spermine binding was neither influenced by a previous heating of the membranes at 100°C for 30 minor by trypsin or pronase digestion, whereas the heat-treatment increased the binding occurring in the absence of Fe²⁺ by about two fold. A non-enzymatic formation of a spermine-metal complex tightly bound to some membrane peptide(s) is suggested.     

Polynesian origins and affinities: globin gene variants in eastern Polynesia.

Analysis of copy number variants of the duplicated alpha-, zeta-, and gamma-globin genes in eastern Polynesians revealed a high frequency of both triplicated-zeta-gene chromosomes and a specific alpha thalassemia deletion. This deletion and a novel restriction-enzyme-site polymorphism associated with a zeta zeta zeta chromosome are found only in Melanesians and Polynesians. Analysis of alpha-globin restriction-enzyme haplotypes indicated further similarities to Melanesians but suggested an additional non-Melanesian genetic component in eastern Polynesia. Several globin gene alleles showed evidence of marked frequency fluctuations due to genetic drift.     

Extracellular cAMP formation from host cell ATP by Bordetella pertussis adenylate cyclase

The effect of exogenously added adenylate cyclase from Bordetella pertussis (strain 114) has been investigated in Y-1 mouse adrenal tumor, chinese hamster ovary (CHO) and several other cells. A partially purified adenylate cyclase was found not to enter cells but, nevertheless, produced large amounts of cAMP in the medium. We could show that this resulted from release of ATP (and not larger molecules). The ATP released by the cells could be (1) directly measured and was replenished after each change of medium; (2) was reciprocally related to the cAMP produced; and (3) was competed for by ATPases present in added serum or by hexokinase and, less effectively, by exoenzymes on the cell surface. The extent of ATP leakage varied widely between different cell lines, being marked in CHO and Y-1 adrenal cells but negligible in transformed lymphocyte lines. The uncertainty of the origin of cAMP found in media of cultured cells requires separate analysis of cell and medium cAMP and an assessment of ATP leakage.     

Ecdysteroid titers in pupae of highly social bees relate to distinct modes of caste development

Modifications in endocrine programs are common mechanisms that generate alternative phenotypes. In order to understand how such changes may have evolved, we analyzed the pupal ecdysteroid titers in two closely related, highly social bees: the honey bee, Apis mellifera, and a stingless bee, Melipona quadrifasciata. In both species, the ecdysteroid titers in queens reached their peak levels earlier than in workers. Titer levels at peak maxima did not differ for the honey bee castes, but in Melipona they were twofold higher in queens than in workers. During the second half of pupal development, when the ecdysteroid titers decrease and the cuticle progressively melanizes, the titer in honey bee queens remained higher than in workers, while the reverse situation was observed in Melipona. Application of the juvenile hormone analog Pyriproxyfen^® to spinning-stage larvae of Melipona induced queen development. Endocrinologically this was manifest in a queen-like profile of the pupal ecdysteroid titer. Comparing these data with previous results on preimaginal hormone titers in another stingless bee, we conclude that the timing and height of the pupal ecdysteroid peak may depend on the nature of the specific stimuli that initially trigger diverging queen/worker development. In contrast, the interspecific differences in the late pupal ecdysteroid titer profiles mainly seem to be related to caste-specific programs in tissue differentiation, including cuticle pigmentation.     

Characterization of Salmonella occurring at high prevalence in a population of the land iguana Conolophus subcristatus in Galápagos Islands, Ecuador

The aim of the study was to elucidate the association between the zoonotic pathogen Salmonella and a population of land iguana, Colonophus subcristatus, endemic to Galápagos Islands in Ecuador. We assessed the presence of Salmonella subspecies and serovars and estimated the prevalence of the pathogen in that population. Additionally, we investigated the genetic relatedness among isolates and serovars utilising pulsed field gel electrophoresis (PFGE) on XbaI-digested DNA and determined the antimicrobial susceptibility to a panel of antimicrobials. The study was carried out by sampling cloacal swabs from animals (n = 63) in their natural environment on in the island of Santa Cruz. A high prevalence (62/63, 98.4%) was observed with heterogeneity of Salmonella subspecies and serovars, all known to be associated with reptiles and with reptile-associated salomonellosis in humans. Serotyping revealed 14 different serovars among four Salmonella enterica subspecies: S. enterica subsp. enterica (n = 48), S. enterica subsp. salamae (n = 2), S. enterica subsp. diarizonae (n = 1), and S. enterica subsp. houtenae (n = 7). Four serovars were predominant: S. Poona (n = 18), S. Pomona (n = 10), S. Abaetetuba (n = 8), and S.Newport (n = 5). The S. Poona isolates revealed nine unique XbaI PFGE patterns, with 15 isolates showing a similarity of 70%. Nine S. Pomona isolates had a similarity of 84%. One main cluster with seven (88%) indistinguishable isolates of S. Abaetetuba was observed. All the Salmonella isolates were pan-susceptible to antimicrobials representative of the most relevant therapeutic classes. The high prevalence and absence of clinical signs suggest a natural interaction of the different Salmonella serovars with the host species. The interaction may have been established before any possible exposure of the iguanas and the biocenosis to direct or indirect environmental factors influenced by the use of antimicrobials in agriculture, in human medicine or in veterinary medicine.     

Effect of Chemical Thymectomy on Skin Homografts: A Preliminary Report

In an attempt to combine the results obtained by Miller (mice thymectomized at birth accepted homograft at six weeks of age) and those obtained by Selye (selective calcification of the cortex of the thymus with calciphylaxis), calcification of the thymus was produced by the combined injection of dihydrotachysterol and triamcinolone, in non-inbred Sprague-Dawley and hooded, eight-week-old rats. Six days after the beginning of treatment, full-thickness skin homografts were performed on the rats.Homografts exchanged between two rats with complete calcification of the thymus cortex were accepted for an extended period of time, which in the oldest rats at the time of writing was seven months. Homografts exchanged between rats with incomplete calcification of the thymus resulted in a prolonged homograft survival with final rejection within a period of three weeks. Homografts exchanged between rats that were not treated, surgically thymectomized at the same age as the treated animals, or treated with only one of the two substances used for thymus calcification, resulted in rejection in the average time of eight days.