GaAs diodes for TiT2-based betavoltaic cells.

The GaAs semiconductor structures for the application as betavoltaic power sources were investigated. Three types of structures underwent a comparative study: a Schottky diode, a p-n junction and Schottky structure modified by deposition of a carbon layer. The power characteristics were estimated by Monte-Carlo simulation and collected current calculation using parameters obtained from the electron beam induced current technique. It was shown that carbon deposition on the top of n-GaAs allows passivating the surface states and thus improving betavoltaic performance.

Protection of human and murine hepatocytes against Fas-induced death by transferrin and iron.

Recent studies in a murine model show that transferrin (Tf) interferes with Fas-mediated hepatocyte death and liver failure by decreasing pro-apoptotic and increasing anti-apoptotic signals. We show here in vitro in murine and human hepatocyte cell lines and in vivo in mice that Fas-induced apoptosis is modulated by exogenous Tf and iron. The results obtained with iron-free Tf (ApoTf), iron-saturated Tf (FeTf), and the iron chelator salicylaldehyde isonicotinoyl hydrazone (SIH) in its iron-free and iron-saturated (FeSIH) forms indicate that apoptosis-modulating effects of Tf are not mediated by iron alone. Both the Tf molecule and iron affect multiple aspects of cell death, and the route of iron delivery to the cell may be critical for the final outcome of cellular Fas signaling. Survival of hepatocytes 'stressed' by Fas signals can be manipulated by Tf and iron and may be a target for prophylactic and therapeutic interventions.

High IGFBP-3 levels in marrow plasma in early-stage MDS: effects on apoptosis and hemopoiesis.

The pathophysiology of the myelodysplastic syndromes (MDS) is incompletely understood. Tumor necrosis factor (TNF)alpha levels are elevated, particularly in early-stage MDS, and apoptosis in marrow cells is upregulated. Observations in other models have shown a role for insulin-like growth factor binding protein 3 (IGFBP-3) in TNFalpha-mediated apoptosis. We observed increased levels of IGFBP-3 in the marrow plasma of patients with MDS (P = 0.005) and hypothesized that altered IGFBP-3 levels contribute to the dysregulation of hemopoiesis in MDS by affecting proliferation and apoptosis. Western analysis of marrow plasma from MDS patients revealed an increase in the ratio of intact vs fragmented IGFBP-3 in early-stage MDS (relative to controls) that decreased with MDS disease progression, suggesting increased proteolysis with more advanced disease. Thus, these results provide evidence for dysregulation of IGFBP-3 in patients with MDS. While the data are complex, they are consistent with a modulatory effect of IGFBP-3 on hemopoiesis in MDS. Conceivably, understanding these mechanisms may allow for the development of novel therapeutic strategies.

Dietary caloric restriction prevents the age-related decline in plasma melatonin levels of rhesus monkeys.

Rhesus monkeys exhibit an age-associated decrease in peak plasma melatonin levels analogous to that reported for humans. This decrease is essentially abolished in monkeys subjected to a 30% reduction in caloric intake over a 12-yr period. The caloric restriction (CR) effect does not seem to be a reversal, but rather a long-term prevention, of the age-related decline in hormone concentrations. The age effect does not seem to be due to a phase shift in the peak of melatonin secretions, as has been observed in some populations of aged humans. It is also extremely unlikely that the CR effect simply reflects a phase shift, since old monkeys on the diet have nocturnal melatonin levels equal to or greater than adult fully fed controls. Thus, if peak times (approximately 0200 h) were actually shifted, maximal levels in old CR monkeys would be even higher. These findings, coupled with previous observations in humans, suggest that peak plasma melatonin levels may represent a possible candidate "biomarker of aging" in primates. Moreover, this index of age-associated physiological decrement seems to be inhibited by dietary CR.

Pro-apoptotic and anti-apoptotic effects of transferrin and transferrin-derived glycans on hematopoietic cells and lymphocytes.

The aim of this study was to test the hypothesis that transferrin (Tf) has anti-apoptotic properties and thereby exerts a cytoprotective effect against tissue damage induced by irradiation and other cytotoxic modalities. This hypothesis was tested in several models, including in vitro human short-term marrow cultures, subpopulations of marrow cells, particularly, CD56(+) natural killer cells (and natural killer cell lines), and in vivo radioprotection of murine marrow cells. Reverse transcriptase polymerase chain reaction analysis was used for determination of cytokine mRNA. Preincubation of human marrow with Tf protected cells (except for a CD56(+) subpopulation) against cell death induced by gamma-irradiation, tumor necrosis factor-alpha (TNF-alpha), and agonistic anti-Fas monoclonal antibody. Deglycosylation of Tf abrogated this action of Tf; conversely, Tf-derived glycans (Tf-Gly) (but not glycans isolated from other proteins) mimicked the effects of the intact Tf molecule on apoptosis. Antibodies specific for the Tf receptor (CD71) did not block the effects of Tf or Tf-Gly on apoptosis. Determination of cytokine mRNA in the course of Fas-mediated apoptosis in the presence of Tf or Tf-Gly showed upregulation of mRNA for Fas ligand and TNF-alpha in CD56(+) and downregulation of these transcripts along with upregulation of mRNA for interleukin-10 in CD3(+) marrow cells. Under these conditions, a distinct increase in Fas-associated phosphatase-1 message was observed in CD3(+) cells that were protected by Tf or Tf-Gly against apoptosis. The in vitro data were confirmed in a murine in vivo model in which pretreatment of mice with Tf protected marrow cells against gamma-irradiation-induced cell death. These data suggest a role for Tf and particularly Tf-Gly in the regulation of programmed cell death, apparently via alterations in cytokine expression, and provide a basis for additional studies on the use of Tf in cytoprotective protocols.

Upregulation of interleukin-10 and inhibition of alloantigen responses by transferrin and transferrin-derived glycans.

Previous studies have shown that critically timed administration of transferrin (Tf) facilitates induction of immunologic unresponsiveness. Here, we determined in mixed leukocyte culture (MLC) and in concanavalin A (ConA)-driven cultures the effect of exogenous Tf and Tf-derived glycans (Tf-Gly) on lymphocyte proliferation. In cultures of human blood lymphocytes, Tf inhibited selectively alloantigen-driven proliferation in MLC, but not ConA-stimulated lymphocyte proliferation. Deglycosylation of Tf abrogated the inhibitory effect of Tf on alloantigen-induced lymphocyte proliferation, and, consistent with a role for glycans, an effect qualitatively and quantitatively similar to Tf was exerted by purified Tf-Gly. Glycans isolated from other proteins, for example, immunoglobulin G (IgG) or fibrinogen, failed to inhibit alloantigen-induced proliferation selectively. Rather, they suppressed lymphocyte proliferation in a non-specific manner. Determination of cytokines in MLC supernatant showed a downregulation of interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), IL-2, and IL-12 (p40), along with an upregulation of IL-10, a pattern entirely consistent with the observed effects of Tf and Tf-Gly on alloantigen-induced lymphocyte proliferation. The effect of Tf on MLC was directly IL-10-dependent. IL-10 levels were inversely correlated with lymphocyte proliferation and CD86 expression. Neutralization of IL-10 by anti-IL-10 monoclonal antibody (mAb) blocked the effect of Tf. The MLC-modulating effect of Tf (or Tf-Gly) was not dependent upon the Tf receptor CD71 but appeared to be mediated by a Gly-responsive receptor. These data suggest a role of Tf, and, in particular, Tf-Gly, in allo-interactions that is independent from the role of Tf in iron metabolism, and appears to involve co-stimulatory signals.

MHC class II and negative regulators of hematopoiesis.

HLA-DR antigens a side from their antigen-presenting function have recently been shown to allow for transmembrane signaling. Findings in several models suggest that such a signaling function may occur in hematopoietic tissues. Signals generated via HLA-DR result in upregulation of tumor necrosis factor alpha (TNF-alpha) and nitric oxide as well as an enhanced expression of Fas and its natural ligand (Fas-L), all molecules associated with programmed cell death (apoptosis). While a role of HLA-DR in hematopoietic failure remains hypothetical, the data presented here can be accommodated into a model of hematopoietic failure initiated by HLA-DR mediated signals.

Theoretical considerations on the nature of the pineal 'ageing clock'.

The models developed in our laboratory demonstrate that ageing initiates and progresses in the pineal gland. However, the ageing postponing effects of pineal grafting into older recipients cannot be explained by a simple maintenance and/or normalization of the night melatonin synthesis and release. We propose here that the pineal gland monitors and regulates, via its control of neuroendocrine function, the maintenance of 'self-identity' and the capacity of the immune system to recognize and react against any noxious, endogenous or exogenous agent. Senescence is characterized by the extinction of this central pineal function. The progressive decline of the self-recognition capacity distinguishes the typical diseases of ageing expressed as emergence of peripheral desynchronization and autoimmune, anaplastic, neoplastic and degenerative processes. Our approaches aim at a prevention and/or restoration of central pineal functions.

Unresponsiveness to human leukocytes in immunosuppressed mice by combined donor-derived human transferrin and antigens.

Previous work on the facilitation of xenogeneic and allogeneic bone marrow engraftment in irradiated mice and dogs with transferrins allowed the development of a model for induction of an apparently durable state of immunological unresponsiveness or 'tolerance' in chemically immunosuppressed mice. The system is based on the simultaneous and combined administration of donor-derived cell antigens, namely human leukocytes, and specific donor-derived or plasma pool human transferrin into BALB/c or C57BL/6 mice previously treated with prednisolone and cyclophosphamide on day 0 and day 1 of the experiment. A properly timed presentation of both donor-specific or plasma pool transferrin and leukocyte antigens into the mice on day 3 and day 16 of the experiment, in the course of initial restoration of their lymphohaemopoietic tissues and cells after severe immunosuppression, results 1-3 months later, in their inability to 'recognize' human donor lymphocytes and to mount an immediate or a delayed-type immune response against human antigens. This durable state of unresponsiveness was evaluated by a complement-mediated cytotoxicity assay, with a mixed lymphocyte culture method and confirmed by the abrogation of the humoral (antibody response to human erythrocytes) and of the cell-mediated (popliteal lymph node test) immune responses in vivo. Our findings demonstrate the capacity of human plasma-derived transferrins to induce a state of durable unresponsiveness (xenogeneic tolerance?) in mice when administered with human antigens in the course of regeneration of stem cells in the bone marrow and lymphatic organs.

Donor-derived plasma transferrin facilitates the engraftment of xenogeneic (rat) bone marrow in irradiated mice.

Endogenous factors originally found in the bone marrow (BM) and facilitating the engraftment of xenogeneic (rat) BM in lethally irradiated mice have been recently identified as transferrins (Tf). Tf have been separated and purified from plasma pools of inbred Rii/2 rats and injected in lethally irradiated BALB/c and C57BL/6 mice 1 h before the infusion of BM and for several days after BM transplantation. Other groups of irradiated mice have been similarly treated with human Tf, Tf from other strains of rats different from the BM donors and with human or rat serum albumin. A remarkable facilitation of BM engraftment and a durable graft-versus-host disease (GVHD)-free hemopoietic chimerism have been achieved in the irradiated mice when a combination of BM and Tf from the same donor rat (Rii/2) strain was used for transplantation. Durable survival and persistent chimerism were not observed in the control groups. It seems that donor Tf profoundly affects the outcome of BM transplantation when combined with donor BM. These results indicate that the mechanism by which Tf promotes engraftment of xenogeneic BM deserves investigation in order to improve this novel procedure and to extend it to other species and possibly to man.

The zinc pool is involved in the immune-reconstituting effect of melatonin in pinealectomized mice.

Melatonin (MEL) affects the immune system by direct or indirect mechanisms. An involvement of the zinc pool in the immune-reconstituting effect of MEL in old mice has recently been documented. An altered zinc turnover and impaired immune functions are also evident in pinealectomized (px) mice. The present work investigates further the effect of "physiological" doses of MEL on the zinc pool and on thymic and peripheral immune functions in px mice. Daily injections of MEL (100 micrograms/mouse) for 1 month in px mice restored the crude zinc balance from negative to positive values. Thymic and peripheral immune functions, including plasma levels of interleukin-2, also recovered. The nontoxic effect of MEL on immune functions was observed in sham-operated mice. Because the half-life of MEL is very short (12 min), interruption of MEL treatment in px mice resulted, after 1 month, in a renewed negative crude zinc balance and a regression of immune functions. Both the zinc pool and immunological parameters were restored by 30 further days of MEL treatment. The existence of a significant correlation between zinc and thymic hormone after both cycles of MEL treatment clearly shows an involvement of the zinc pool in the immunoenhancing effects of MEL and thus suggests an inter-relationship between zinc and MEL in px mice. Moreover, the existence of significant positive correlations between zinc or thymulin and interleukin-2 suggests that interleukin-2 may participate in the action of MEL, via zinc, on thymic functions in px MEL-treated mice.

"In vitro" and in animal model studies on a double virus-inactivated factor VIII concentrate.

To improve the safety of plasma derived factor VIII (FVIII) concentrate, we introduced a final super heat treatment (100 degrees C for 30 min) as additional virus inactivation step applied to a lyophilized, highly purified FVIII concentrate (100 IU/mg of proteins) already virus inactivated using the solvent/detergent (S/D) method during the manufacturing process. The efficiency of the super heat treatment was demonstrated in inactivating two non-lipid enveloped viruses (Hepatitis A virus and Poliovirus 1). The loss of FVIII procoagulant activity during the super heat treatment was of about 15%, estimated both by clotting and chromogenic assays. No substantial changes were observed in physical, biochemical and immunological characteristics of the heat treated FVIII concentrate in comparison with those of the FVIII before heat treatment.

Pyrogenic activity of human native and human recombinant interleukins-1 beta: stabilization with albumin enhances the pyrogenic action of recombinant IL-1 beta delivered into the rabbit brain.

The pyrogenic potential of natural and recombinant human IL-1 beta in rabbits was found to be very similar when the substances were given intravenously. Under these conditions, stabilization of rIL-1 beta with human serum albumin (HSA) failed to affect the pyrogenic activity of recombinant IL-1 beta. When the two preparations were administered directly into the PO/AH area of the brain, recombinant IL-1 beta was less pyrogenic than its natural counterpart. This lower pyrogenicity of recombinant IL-1 beta was corrected if the injected material contained HSA, which is known to stabilize in vitro the biological activities of IL-1 beta against slow degradation. The possibility is now considered that the central and peripheral systems for IL-1 inactivation are different. The existence of an intrabrain IL-1 pool is suggested and its significance for neuroimmunomodulation is stressed.

Pineal cross-transplantation (old-to-young and vice versa) as evidence for an endogenous "aging clock".

Circadian (night), chronic administration of melatonin and young-to-old pineal grafting into the thymus have provided evidence for the existence of an endogenous, primary and central "aging clock" in the pineal gland. The new model described here serves to definitely demonstrate that the replacement of the pineal gland of an old mouse with the pineal from a young, syngeneic donor mouse remarkably prolongs its life and, conversely, the "old" pineal transplanted into a younger mouse will considerably shorten its life span. Pineal cross-transplantation thus provides clear-cut evidence for the central role of the pineal gland in the initiation and progression of senescence. It offers a novel basis for interventions in the aging process.

[The pyrogenic activity of native and recombinant human interleukin-1 beta]. / Pirogennaia aktivnost' nativnogo i rekombinantnogo interleikina-1 beta cheloveka.

Comparative doses (100-180 ng/kg) of highly purified human native interleukin-1 beta (nIL-1 beta) and human recombinant IL-1 beta (rIL-1 beta) intravenously injected were found to cause similar changes in body temperature in rabbits. Under these conditions, stabilization of rIL-1 beta by human serum albumin (HSA) fails to affect rIL-1 beta pyrogenic activity. nIL-1 beta, 0.05-2.0 ng, injected into the PO/AH region of the brain causes dose-dependent fever in the animals. With intrahypothalamic nIL-1 beta (versus i.v. injection), the pyrogenic activity of rIl-1 beta is much lower than that of nIL-1 beta. Moreover, pyrogenicity appears to be dependent on the type of rIL-1 beta, namely on free or stabilized by HSA. The former has about 100-fold and the latter a 25-fold lower activity than the native cytokine (in terms of a dose-pyrogenic effect relationship). The findings are discussed in the light of the existence of various interleukin IL-1 beta pools.

The involvement of pineal gland and melatonin in immunity and aging: II. Thyrotropin-releasing hormone and melatonin forestall involution and promote reconstitution of the thymus in anterior hypothalamic area (AHA)-lesioned mice.

A stereotactic electrolytic lesion of the anterior hypothalamic area in mice produces a rapid involution of the thymus and a reduction of lymphocytes in the peripheral blood. This effect on the thymus and blood lymphoid compartment can be prevented by postoperational administration of thyrotropin-releasing hormone (TRH) or melatonin. These activities of TRH or melatonin are antagonized by the opioid receptor blocker naltrexone. They do not seem to depend on stimulation of the thyroid gland or of the endogenous opioid system but rather on a direct activity of TRH on thymic targets or binding sites on lymphocytes.