Cytokine production pathway in the elderly

It is well known that aging is associated with various alterations in lymphoid cell functions, particularly with a progressive decline in immune responsiveness to exogenous antigens and increasing incidence of autoimmune phenomena. Many studies have been focused on the mechanisms of the immunologic features of aging. This review describes our results of studies performed to determine the influence of age on the capacity to produce interleukin-2 (IL-2), interferon-γ (IFN-γ), interleukin-4 (IL-4), interleukin-5 (IL-5), interleukin-6 (IL-6) and tumor necrosis factor (TNF). Mitogen-stimulated cultures of mononuclear cells (MNC) from human beings were assessed for cytokine-producing capacity. A significant decrease in IFN-γ and IL-2 production by MNC cultures from elderly individuals was observed. No significant difference was instead observed between cultures from elderly individuals and those from young ones as regards TNF-α, IL-4 and IL-6 production. Mitogen or antigen-stimulated cultures of MNC from aged mice also displayed a significant decrease in IFN-γ and IL-2 production as well as TNF-β. Instead IL-4 and IL-5 production significantly increased in these cultures. We suggest that this imbalanced cytokine production may well account for the pattern of immune response which may be observed in the elderly, i.e. a normal or increased humoral response (including autoimmune responses) in face of a low T cell immune responsiveness.     

CTLA-4 expression on antigen-specific cells but not IL-10 secretion is required for oral tolerance

CD4(+) T cells play a vital role in mediating the tolerance induced at mucosal sites following exposure to non-pathogenic stimuli, and further understanding of the precise mechanisms by which these cells prevent aberrant responses is required. We have developed a model using transfer of DO11.10 TCR-transgenic bone marrow into irradiated recipients in which it has been possible to track antigen-specific CD4(+) cells in mesenteric lymph nodes (mLN), Peyer's patches (PP) and lamina propria following primary exposure to antigen. Using this model we have demonstrated initial activation in all three gut-associated lymphoid tissue compartments characterized by increases in the frequency of transgenic cells expressing CD69 and CD25. These cells subsequently enter a state of hyporesponsiveness both locally in the mLN and PP and in the periphery following feeding and challenge. Investigating the role of CTLA-4 either using anti-CTLA-4 mAb or by generating chimeras using DO11.10xCTLA-4(-/-) mice as donors we have clearly shown that antigen-specific cells require the expression of this regulatory molecule for oral tolerance. In contrast, oral tolerance was intact in chimeras generated using DO11.10xIL-10(-/-) cells, indicating that secretion of this cytokine by antigen-specific cells is not required.     

Heteroplasmic Segregation Associated with Trisomy-9 in Cultured Human Cells

In cybrid cells carrying the mitochondrial A3243G MELAS mutation, which were also heteroplasmic for the G12300A suppressor mutation, we observed a transient episode of heteroplasmic instability, resulting in a wide diversification in G12300A heteroplasmy levels and a shift in the average heteroplasmy level from 11 to 29%. These cells were found to be trisomic for chromosome 9, whereas a minority of cells that retained disomy-9 showed no instability. Coculture experiments implied that trisomy-9 cells exhibited a significant growth advantage, but neither heteroplasmy levels, respiratory phenotype nor trisomy-9 itself had direct selective value under standard culture conditions. Mitochondrial nucleoid number was the same (50–100) in cells that had or had not experienced transient heteroplasmic instability, but 1–2 orders of magnitude less than the segregation number in such cells. These findings support the idea that mtDNA partition is under nuclear genetic control, and implicate a locus on chromosome 9 in this regulation.     

Albumin adsorption onto pyrolytic carbon: a molecular mechanics approach.

A number of implants of cardiac valve prosthesis, vascular prosthesis, and coronary stents present a pyrolytic carbon interface to blood. Plasma protein adsorption is essential for the hemocompatibility of the implanted devices. This work quantitatively evaluates the molecular interaction force between a biomaterial surface (pyrolytic carbon) and plasma protein (albumin) binding sites through a simplified molecular model of the interface consisting of (i) multioriented graphite microcrystallites; (ii) selected fragments of albumin; and (iii) a water environment. A number of simplifying assumptions were made in the calculation: the albumin molecule was divided into hydrophobic and hydrophilic subunits (helices); an idealized clean, nonoxidized polycrystalline graphite surface was assumed to approximate the surface of pyrolytic carbon. The interaction forces between albumin helices and pyrolytic carbon surfaces are evaluated from potential energy data. These forces are decomposed into a normal and a tangential component. The first one is calculated using a docking procedure (F( perpendicular tot MAX) = 4.16 x 10(-20) N). The second one (F( parallel)), calculated by mean of geometric models estimating the energy variation associated with the protein sliding on the material surface, varies within the range +/-9.62 x 10(-21) N. The molecular simulations were performed using the commercial software package Hyperchem 5.0 (Hyperchem, Hypercube, Canada).     

Evidence that [3H]forskolin binding in the substantia nigra is intrinsic to a striatal-nigral projection: an autoradiographic study of rat brain

The neuronal localization of binding sites for the diterpene activator of adenylate cyclase, forskolin, has been determined. Kainic or ibotenic acid lesions were administered into the caudate-putamen or substantia nigra of Sprague-Dawley rats. The binding of 20 nM [3H]forskolin was examined autoradiographically and quantitated using computerized densitometry with tritium standards. Neurochemical lesions placed in the caudate-putamen markedly reduced [3H]forskolin binding in this structure and distal to the site of injection in the substantia nigra. Ibotenic acid lesions placed in the substantia nigra did not appreciably alter binding in the substantia nigra, caudate-putamen, nucleus accumbens or olfactory tubercle. These results indicate that 'forskolin-identified' adenylate cyclase in the substantia nigra is located in nerve terminals from the caudate-putamen. In addition, these sites are presumably located on cell bodies or interneurons in the caudate-putamen.     

Semiquantitative detection by real-time PCR of Aspergillus fumigatus in bronchoalveolar lavage fluids and tissue biopsy specimens from patients with invasive aspergillosis

A real-time PCR method was developed and used to detect Aspergillus fumigatus mitochondrial DNA (mtDNA) in bronchoalveolar lavage (BAL) fluids and tissue biopsy specimens. The analytical sensitivity of the assay was one A. fumigatus conidium per reaction, and the assay was linear at least over 4 orders of magnitude above the detection limit. BAL fluids from 66 immunocompromised patients at risk of invasive pulmonary aspergillosis (IPA) and 33 immunocompetent controls and tissue biopsy specimens from 10 immunocompromised patients were analyzed. The results were related to the clinical diagnosis established according to recently published consensus criteria. A. fumigatus mtDNA positivity was encountered in 16 of 81 (20%) BAL fluid specimens from patients at risk and 1 of 33 (3%) specimens from immunocompetent controls. PCRs were positive in six of seven, two of four, and four of five of the patients with proven, probable, and possible IPA, respectively, as well as in four patients at risk but without any other evidence of IPA. With qualitative detection, the diagnostic sensitivity of PCR was 73%, specificity was 93%, and predictive values of positive (PPV) and negative (NPV) results were 73 and 95%, respectively. Using a threshold cycle of <35 as a limit for positive PCR, the specificity and PPV of PCR in the diagnosis of invasive aspergillosis were 100%, but its sensitivity was only 45% and NPV was 92%. PCR was positive in tissue biopsy specimens from all patients with invasive aspergillosis caused by A. fumigatus. Semiquantitative detection of A. fumigatus mtDNA in BAL fluid may be helpful in the diagnosis of IPA. PCR is well suited for the verification of the presence of A. fumigatus in tissue biopsy specimens.     

Investigations on the turnover of adrenocortical mitochondria. X. A correlated biochemical and stereological study of the effects of Chronic treatment with chloramphenicol on the mitochondria of the rat zona fasciculata

The effects of chloramphenicol (CAP) on rat adrenocortical cells were investigated by biochemical and stereological methods. It was found that administering 50 mg/kg of CAP every 12 hours provoked a persistent inhibition of the incorporation of ³H-leucine into mitochondrial proteins. Chronic treatment (up to 15 consecutive days) with this dose of CAP induced a significant decrease in the volume of the mitochondrial compartment, in the surface area of the outer and inner mitochondrial membranes and in the number of mitochondria per cell. These results confirm the hypothesis that the ACTH-induced maintenance of adrenocortical mitochondrial growth requires continuous mitochondrial DNA-dependent protein synthesis.     

Facilitators and Barriers to the Sustainability of a School-Based Bullying Prevention Program

Prevention Science - The long-term sustainment of bullying prevention programs has rarely been investigated. This study addresses this gap by identifying facilitators and barriers to the systematic...