Caffeine-induced anxiogenesis: the role of adenosine, benzodiazepine and noradrenergic receptors

The purpose of this study was to determine the mechanism by which caffeine increases anxiety. Rats were tested in the social interaction test of anxiety after administration of caffeine (20 or 40 mg/kg) alone or in combination with various compounds. In order to investigate the role of adenosine receptors, caffeine was given in combination with 2-chloroadenosine (0.1 and 1 mg/kg). To investigate the role of benzodiazepine receptors, chlordiazepoxide (5 mg/kg), a benzodiazepine antagonist, flumazenil (RO 15-1788, 1 and 10 mg/kg) and a triazolobenzodiazepine U-43,465 (32 mg/kg) were used. Finally, an alpha 2-receptor agonist, clonidine (0.1 and 0.025 mg/kg) and a beta-adrenoceptor antagonist, DL-propranolol (5 mg/kg), were used to study the role of noradrenergic systems in the effects of caffeine. Caffeine (20 and 40 mg/kg) reduced the time spent in social interaction and this effect was antagonized by chlordiazepoxide, U-43,465 and DL-propranolol, but not by flumazenil, 2-chloroadenosine or clonidine. It was therefore concluded that the anxiogenic effect of caffeine was unlikely to be due to its effects at adenosine or benzodiazepine receptors. It is suggested that the reversal of caffeine's effects by chordiazepoxide may have been "functional," i.e., merely a cancellation of two opposite effects. It is discussed whether the reversal of caffeine's effects by propranolol and U-43,465 are functional, or reflect a noradrenergic site of action.     

川芎嗪诱导大鼠骨髓间质干细胞分化为神经元样细胞的研究

目的用川芎嗪(ligustrazin hydrochloride)在体外定向诱导SD青年鼠骨髓间质干细胞(mesenchymal stem cells，rMSCs)分化为神经元样细胞。方法用低糖DMEM冲洗骨髓腔，收集骨髓细胞悬液，接种在塑料培养瓶中。经体外扩增、纯化，选用第5代后的骨髓间质干细胞进行诱导分化。用10μg／LbFcF预诱导24h，更换成含川芎嗪的无血清培养基DMEM诱导间质干细胞分化为神经元样细胞。用免疫组织化学SABC法鉴定神经丝蛋白(NF—M)、神经元特异性烯醇化酶(NSE)、巢蛋白(nestin)、微管联合蛋白-2(MAP-2)、生长相关蛋白-43(GAP-43)、胶质纤维酸性蛋白(GFAP)的表达。结果第5代间质干细胞形态达到均一，呈梭形。用川芎嗪诱导15min到3h，间质干细胞胞体逐渐增大，并伸出细长突起形似神经元样细胞。免疫组织化学显示NF-M、NSE、nestin、MAP-2和GAP-43表达阳性，而GFAP阴性。对照组上述染色均为阴性。结论川芎嗪可诱导骨髓间质干细胞分化为神经元样细胞。     

Susceptibility of bovine macrophages to infectious bovine rhinotracheitis virus infection.

Infectious bovine rhinotracheitis virus replicated in cultured bovine alveolar macrophages (AM). However, yields of infectious virus were low, with maximum titers approximately 100 times that of the residual inoculum. Immunofluorescence and electron microscopic studies indicated that the majority of macrophages produced viral antigen, but after infection at a multiplicity of 0.1, only 4.1% of AM produced infectious centers. Virus-infected AM culture supernatants possessed interfering activity, probably due to interferon. Incubation of fresh AM with these fluids rendered them refractory to infection. Although AM from infectious bovine rhinotracheitis virus-immune and -susceptible donors were equally permissive and their susceptibility was unaltered by incubation with bacterial lipopolysaccharide, bovine mammary macrophages which were elicited with lipopolysaccharide became nonpermissive when further incubated for 48 h with 1 microgram of lipopolysaccharide per ml. Under these conditions, infected mammary macrophages failed to synthesize viral DNA, and there was reduced synthesis of "late" viral polypeptides.     

Androgen receptor YAC transgenic mice carrying CAG 45 alleles show trinucleotide repeat instability

X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG repeat expansion in the first exon of the androgen receptor (AR) gene. Disease-associated alleles (37-66 CAGs) change in length when transmitted from parents to offspring, with a significantly greater tendency to shift size when inherited paternally. As transgenic mice carrying human AR cDNAs with 45 and 66 CAG repeats do not display repeat instability, we attempted to model trinucleotide repeat instability by generating transgenic mice with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions in their genomic context. Studies of independent lines of AR YAC transgenic mice with CAG 45 alleles reveal intergenerational instability at an overall rate of approximately 10%. We also find that the 45 CAG repeat tracts are significantly more unstable with maternal transmission and as the transmitting mother ages. Of all the CAG/CTG repeat transgenic mice produced to date the AR YAC CAG 45 mice are unstable with the smallest trinucleotide repeat mutations, suggesting that the length threshold for repeat instability in the mouse may be lowered by including the appropriate flanking human DNA sequences. By sequence-tagged site content analysis and long range mapping we determined that one unstable transgenic line has integrated an approximately 70 kb segment of the AR locus due to fragmentation of the AR YAC. Identification of the cis - acting elements that permit CAG tract instability and the trans -acting factors that modulate repeat instability in the AR YAC CAG 45 mice may provide insights into the molecular basis of trinucleotide repeat instability in humans.      

Blastogenic response of bovine lymphocytes to Brucella abortus lipopolysaccharide.

Brucella abortus lipopolysaccharide was tested in a blastogenesis assay with unfractionated and nylon wool-separated peripheral blood lymphocytes of Brucella-naive cattle and cattle immunized with B. abortus. Our results indicated that in cattle the lipopolysaccharide of B. abortus is not a B-cell mitogen. In immunized animals it stimulated predominantly nylon wool-adherent cells. The lipopolysaccharide of Escherichia coli O128:B12, in contrast, induced a substantially greater proliferative response in circulating lymphocytes, predominantly those adherent to nylon wool, of the Brucella-naive cattle.     

Dendritic cell populations in Leishmania major-infected skin and draining lymph nodes

Using a metacyclic promastigote ear infection model of cutaneous leishmaniasis, we examined the phenotype, parasite load, and cytokine production of dendritic cells in the skin and draining lymph nodes of resistant C57BL/6J and susceptible BALB/c mice. Five dendritic cell populations were isolated from the skin and lymph nodes, and the main difference between the groups of mice was an increased number of plasmacytoid dendritic cells in the lymph nodes of the susceptible mice. Although similar cell types were present in the skin emigrants of both strains, there was a 10-fold larger number of cells in BALB/c mouse skin early in infection than in C57BL/6J mouse skin. None of the dendritic cells in the lymph nodes harbored parasites until 3 weeks after infection, with the Langerhans cells having the largest load and the plasmacytoid dendritic cells having the smallest load but the longest lasting infection. Although parasites could be detected in the lymph nodes a few hours after infection, none of the skin emigrants harbored parasites, indicating that they are not the vehicle that ferries the parasites from the skin to the lymph nodes. The presence of larger numbers of plasmacytoid cells in infected BALB/c mice, the more protracted infection of these cells, and their production of alpha interferon point to a complex and important role for the plasmacytoid cells in leishmaniasis.     

In vitro activation of natural killer-like cytotoxicity by specifically in vivo primed T-helper lymphocytes in the rat.

The interaction between the rat non-cytotoxic T lymphocyte subset, which is marked by the W3/25 monoclonal antibody, and natural killer cells was investigated. Specifically in vivo primed lymph node cells were restimulated in vitro with the priming antigen and co-cultured with a source of natural killer cells and their precursors. Cytotoxic activity, generated during a 4 day incubation period, was assessed by lysis of a rat natural killer cell-sensitive tumour target cell line, y3Ag123. This cytotoxic activity was more fully described as natural killer cell cytotoxicity on the basis of target cell specificity, using a range of natural killer cell-susceptible and -resistant targets. The W3/25-positive T cell, separated from the in vivo primed lymph node cells by nylon wool column elution, antibody labelling and sorting on the fluorescence-activated cell sorter, was shown to be necessary to stimulate the generation of this activity. W3/25-negative cells were not active in this respect. The activation was shown to be mediated via lymphokine(s), probably interleukin-2, present in concanavalin A-induced lymphocyte culture supernatants. These supernatants could be used to substitute for in vivo primed, restimulated W3/25-positive lymph node cells in activating natural killer cell cytotoxicity from normal spleen cells. Nylon wool column-eluted spleen cells, activated in vitro with conditioned medium were separated into OX8-positive and OX8-negative subsets using the fluorescence-activated cell sorter. The distribution of cytotoxic activity related to that of freshly derived rat natural killer cells.     

Outer membrane proteins of Brucella abortus: isolation and characterization.

Outer membrane proteins were derived from one rough and four smooth strains of Brucella abortus by sequential extraction of physically disrupted cells with N-lauroylsarcosinate and dipolar ionic detergent. Extraction of outer membrane proteins was ineffective, however, without predigestion with lysozyme. Three groups of proteins were present and could be separated in their native state by sequential anion-exchange chromatography and gel filtration. Membrane proteins contained substantial quantities of tightly adherent lipopolysaccharide which could be reduced but not eliminated by extraction of cells with trichloroacetic acid before disruption. Group 2 proteins, apparently trimers in their native state, gave rise to 43,000- and 41,000-molecular-weight bands after complete denaturation in sodium dodecyl sulfate. They were antigenically identical among all the strains, showed close resemblance in amino acid composition to each other and a general similarity to OmpF of Escherichia coli, and are proposed to be the porins of B. abortus. Group 3 proteins occurred as 30,000-molecular-weight bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, although additional bands were frequently observed in this region. In none of the strains did group 3 proteins manifest heat-modifiable characteristics. Proteins of different strains bore a high degree of similarity to each other in amino acid composition, except in methionine, isoleucine, tyrosine, and histidine. Differences occurred consistently in amino acid composition between group 2 and 3 proteins, and some of these correspond to differences between OmpF and OmpA. Group 2 and 3 proteins were antigenically distinct from each other, but the principal group 3 antigens were shared among all the strains. Despite the lack of heat modifiability, perhaps influenced by adherent lipopolysaccharide, group 3 proteins are proposed as counterparts to OmpA. Most of the group 1 proteins, minor components, were physically associated with those of group 3 unless in sodium dodecyl sulfate. Group 1 proteins produced a major band at 94,000 and exhibited heat modifiability. No evidence was found of a low-molecular-weight lipoprotein in the outer membrane of B. abortus, but this is not taken to exclude its occurrence.