Isotype concentrations of human antibodies to Haemophilus influenzae type b polysaccharide (Hib) in young adults immunized with the polysaccharide as such or conjugated to a protein (diphtheria toxoid)

Antibody responses of young adults to Haemophilus influenzae type b polysaccharide (Hib) or its protein conjugate were studied with special attention to the isotype composition of the antibodies. Three conclusions of interest can be made: 1) Immunoglobulin G (IgG) antibodies in polysaccharide-immunized volunteers displayed the subclass pattern previously found in antibodies to meningococcal type A polysaccharide. IgG1 was the predominant subclass in IgG antibodies of some individuals, IgG2 in others. Still others had the two subclasses in varying but more even proportions. 2) The conjugate vaccine induced a geometric mean response 2 to 3 times higher and an IgG response 4 times higher to Hib than the polysaccharide vaccine. 3) Anti-Hib antibodies induced by the conjugate vaccine still had essentially the same IgG subclass composition as anti-Hib antibodies induced by the polysaccharide. This composition was strikingly different from the composition of the anti-diphtheria toxoid response induced by the same conjugate vaccine.     

Glutathione depletion, radiosensitization, and misonidazole potentiation in hypoxic Chinese hamster ovary cells by buthionine sulfoximine

Buthionine sulfoximine (BSO) inhibits the synthesis of glutathione (GSH), the major nonprotein sulfhydryl (NPSH) present in most mammalian cells. BSO concentrations from 1 microM to 0.1 mM reduced intracellular GSH at different rates, while BSO greater than or equal to 0.1 mM (i.e., 0.1 to 2.0 mM), resulting in inhibitor-enzyme saturation, depleted GSH to less than 10% of control within 10 hr at about equal rates. BSO exposures used in these experiments were not cytotoxic with the one exception that 2.0 mM BSO/24 hr reduced cell viability to approximately 50%. However, alterations in either the cell doubling time(s) or the cell age density distribution(s) were not observed with the BSO exposures used to determine its radiosensitizing effect. BSO significantly radiosensitized (ER = 1.41 with 0.1 mM BSO/24 hr) hypoxic, but not aerobic, CHO cells when the GSH and NPSH concentrations were reduced to less than 10 and 20% of control, respectively, and maximum radiosensitivity was even achieved with microM concentrations of BSO (ER = 1.38 with 10 microM BSO/24 hr). Furthermore, BSO exposure (0.1 mM BSO/24 hr) also enhanced the radiosensitizing effect of various concentrations of misonidazole on hypoxic CHO cells.     

Replacement of natural polyamines by cadaverine and its aminopropyl derivatives in Ehrlich ascites carcinoma cells

Ehrlich ascites carcinoma cells were cultured in the presence of difluoromethyl ornithine (DFMO) and micromolar concentrations of cadaverine for several months. This treatment resulted in a complete disappearance of putrescine and spermidine and reduced spermine content to traces of its normal content. The natural polyamines were replaced by cadaverine (about 40% of total polyamines), N-(3-aminopropyl)cadaverine (about 50%) and N,N′-bis(3-aminopropyl)cadaverine (about 5%). In comparison with untreated cells or cells grown in the presence of DFMO and putrescine, the “cadaverine cells” grew definitely slower, their protein synthesis was depressed while DNA and RNA syntheses proceeded at near normal rate. In spite of the high intracellular concentrations of cadaverine and its aminopropyl derivatives, the tumor cells grown in the presence of DFMO and cadaverine, behaved exactly like cells severly depleted of putrescine and spermidine. Though exposed to DFMO, ornithine decarboxylase activity was almost 10 times higher than that in untreated cells. S-Adenosyl-L-methionine decarboxylase activity was likewise strikingly elevated, and these cells transported methylglyoxal strikingly elevated, and these cells transported methylglyoxal bis(guanylhydrazone) (MGBG) at a rate that was more than 5 times faster than that in untreated cells. Furthermore, these cells exhibited arginase activity, which was less than one fifth of that found in untreated cells.     

Regulation of vascular cell adhesion molecule 1 on human dermal microvascular endothelial cells.

Vascular endothelial cell adhesion molecule 1 (VCAM-1) is an adherence molecule that is induced on endothelial cells by cytokine stimulation and can mediate binding of lymphocytes or tumor cells to endothelium. Because these interactions often occur at the level of the microvasculature, we have examined the regulation of expression of VCAM-1 in human dermal microvascular endothelial cells (HDMEC) and compared it to the regulation of VCAM-1 in large vessel human umbilical vein endothelial cells (HUVEC). Both cell populations were judged pure as assessed by expression of von Willebrand factor and uptake of acetylated low density lipoprotein. Expression of VCAM-1 was not detectable on either unstimulated HDMEC or HUVEC when assessed by ELISA or flow cytometry. Stimulation of either HDMEC or HUVEC with TNF-alpha resulted in a time- and dose-dependent induction of VCAM-1. However, although TNF-alpha-induced cell surface and mRNA expression of VCAM-1 in HDMEC was transient, peaking after 16 h of stimulation, TNF stimulation led to persistently elevated cell surface expression of VCAM-1 on HUVEC. IL-1 alpha also induced cell surface expression of VCAM-1 on HUVEC in a time- and dose-dependent manner, but stimulation of HDMEC with IL-1 alpha at doses up to 1000 U/ml failed to induce significant cell surface expression. However, IL-1 alpha induced time- and dose-dependent increases in ICAM-1 on HDMEC. Similarly, IL-4 induced VCAM-1 expression and augmented TNF-alpha-induced expression on HUVEC but did not affect VCAM-1 expression on HDMEC. Binding of Ramos cells to cytokine-stimulated endothelial cell monolayers correlated with VCAM-1 induction. Increased binding was seen after stimulation of HDMEC with TNF-alpha, which was blocked by anti-VCAM-1 mAb, but no increases in binding were noted after stimulation of HDMEC monolayers with IL-1 alpha. These data provide additional evidence for the existence of endothelial cell heterogeneity and differences in cell adhesion molecule regulation on endothelial cells derived from different vascular beds.     

Role of collagen and fibronectin in neural crest cell adhesion and migration

Cultured neural crest cells which are freshly trypsinized require serum or purified fibronectin to attach to collagen substrates of types I–V. Furthermore, neural crest cells migrate in a Boyden chamber in response to fibronectin, and a “checkerboard” analysis demonstrates that fibronectin is both chemotactic and chemokinetic for these cells. It is proposed that collagen serves as a substrate for neural crest cells as they migrate in the early embryo. By mediating the cells' attachment to collagen, fibronectin may influence the movement of the cells. Local differences in fibronectin concentration or availability in the matrix could affect the degree of attachment of the cells to the collagen substrate and could also direct their migration by serving as a chemoattractant.     

Immunocytochemical double staining of cytokeratin and prostate specific antigen in individual prostatic tumour cells

Early dissemination of malignant cells is the main cause for metastatic relapse in patients with solid tumours. By use of monoclonal antibodies (mAbs) specific for cytokeratins, disseminated individual epithelial tumour cells can now be identified in mesenchymal organs such as bone marrow. Further to characterize such cells in patients with prostate cancer, an immunocytochemical procedure was developed for simultaneous labelling of cytokeratin component no. 18 (CK18) and prostate specific antigen (PSA). In a first step, cells were incubated with mAb ER-PR8 against PSA and secondary gold-conjugated goat anti-mouse antibodies. In a second step, biotinylated mAb CK2 to CK18 was applied as primary antibody and subsequently incubated with complexes of streptavidin-conjugated alkaline phosphatase, which were developed with the Newfuchsin substrate. The binding of gold-labelled antibodies was visualized by silver enhancement. The sensitivity and specificity of the technique was demonstrated on cryostat sections of hyperplastic prostatic tissue, and cytological preparations of LNCaP prostatic tumour cells. Double staining was restricted to cells derived from the secretory epithelium of the prostate. Cross-reactivity between both detection systems was excluded by several controls, including the use of unrelated antibodies of the same isotype and the staining of CK18⁺/PSA^– HT29 colon carcinoma cells. CK18⁺ cells co-expressing PSA were found in bone marrow aspirates from 5 out of 13 patients with carcinomas of the prostate, a finding that is consistent with the relative fraction of double-positive LNCaP cells. The specificity of CK18 for epithelial tumour cells in bone marrow was supported by negative staining of 12 control aspirates from patients with benign prostatic hypertrophy. In conclusion, the approach presented appears to be a reliable method to phenotype individual prostatic carcinoma cells.     

Monoacylglycerol Lipases Act as Evolutionarily Conserved Regulators of Non-oxidative Ethanol Metabolism

Fatty acid ethyl esters (FAEEs) are non-oxidative metabolites of ethanol that accumulate in human tissues upon ethanol intake. Although FAEEs are considered as toxic metabolites causing cellular dysfunction and tissue damage, the enzymology of FAEE metabolism remains poorly understood. In this study, we used a biochemical screen in Saccharomyces cerevisiae to identify and characterize putative hydrolases involved in FAEE catabolism. We found that Yju3p, the functional orthologue of mammalian monoacylglycerol lipase (MGL), contributes >90% of cellular FAEE hydrolase activity, and its loss leads to the accumulation of FAEE. Heterologous expression of mammalian MGL in yju3Δ mutants restored cellular FAEE hydrolase activity and FAEE catabolism. Moreover, overexpression or pharmacological inhibition of MGL in mouse AML-12 hepatocytes decreased or increased FAEE levels, respectively. FAEEs were transiently incorporated into lipid droplets (LDs) and both Yju3p and MGL co-localized with these organelles. We conclude that the storage of FAEE in inert LDs and their mobilization by LD-resident FAEE hydrolases facilitate a controlled metabolism of these potentially toxic lipid metabolites.     

Toxoplasma infection in male mice alters dopamine-sensitive behaviors and host gene expression patterns associated with neuropsychiatric disease

During chronic infection, the single celled parasite, Toxoplasma gondii, can migrate to the brain where it has been associated with altered dopamine function and the capacity to modulate host behavior, increasing risk of neurocognitive disorders. Here we explore alterations in dopamine-related behavior in a new mouse model based on stimulant (cocaine)-induced hyperactivity. In combination with cocaine, infection resulted in heightened sensorimotor deficits and impairment in prepulse inhibition response, which are commonly disrupted in neuropsychiatric conditions. To identify molecular pathways in the brain affected by chronic T. gondii infection, we investigated patterns of gene expression. As expected, infection was associated with an enrichment of genes associated with general immune response pathways, that otherwise limits statistical power to identify more informative pathways. To overcome this limitation and focus on pathways of neurological relevance, we developed a novel context enrichment approach that relies on a customized ontology. Applying this approach, we identified genes that exhibited unexpected patterns of expression arising from the combination of cocaine exposure and infection. These include sets of genes which exhibited dampened response to cocaine in infected mice, suggesting a possible mechanism for some observed behaviors and a neuroprotective effect that may be advantageous to parasite persistence. This model offers a powerful new approach to dissect the molecular pathways by which T. gondii infection contributes to neurocognitive disorders.