Advances and trends in encapsulation of essential oils.

There is a huge concern regarding the potential carcinogenic and mutagenic risks associated with the usage of synthetic chemicals as preservatives in various consumer products such as food and pharmaceutical formulations. In this aspect, there is a need for the development of alternative natural preservatives to replace these synthetic chemicals. More recently, naturally occurring essential oils have emerged as popular ingredients owing to their unique characteristics like antioxidant and antimicrobial activity, to enrich and enhance the functional properties of consumer products. However, due to their high volatility and hydrophobicity, their functionality is lost and their incorporation in aqueous products is challenging. One of the promising strategies to overcome this challenge is encapsulation which involves the entrapment of the essential oil inside a biocompatible material for its controlled release and increased bioavailability. Also, the choice of encapsulation method depends on the component to be encapsulated and the shell material. In this review, encapsulation in various colloidal systems that facilitate the potential delivery of essential oils is discussed. The focus is on encapsulation techniques along with their advantages and disadvantages, encapsulation efficiency, and in vitro release studies.

Epstein-Barr virus-related lymphocyte stimulation inhibitor: a possible prognostic tool for undifferentiated nasopharyngeal carcinoma.

It is demonstrated in this study that a serum factor, a lymphocyte stimulation inhibitor (LSI), which inhibits Epstein-Barr virus (EBV)-induced lymphocyte stimulation, is a potentially useful tool in the diagnosis and monitoring of nasopharyngeal carcinoma (NPC). In a study of 25 patients with undifferentiated NPC, 20 healthy controls, and 20 patients with other head and neck tumors, LSI was found only in the NPC patients with active disease. In a more complete study of 8 patients longitudinally followed up for at least 20 months, a comparison of LSI with antibodies to a variety of EBV antigens including viral capsid antigen, early antigen, and nuclear antigen indicated that LSI levels provided a reliable and sensitive indicator of disease activity that should be added to clinical markers currently in use as monitors of disease activity in NPC.

Induction of interleukin-1 in various brain regions after peripheral and central injections of lipopolysaccharide.

The presence of bioactive interleukin-1 (IL-1) in various brain regions (cerebellum, cortex, brainstem, diencephalon or hippocampus) after either intraperitoneal (i.p.) or intraventricular (i.c.v.) injection of lipopolysaccharide (LPS) was studied in the rat. To detect IL-1, extracellular fluid and cell lysate were fractionated by gel exclusion chromatography and fractions tested for thymocyte stimulation; presence of IL-1 was confirmed by blockade of stimulation by addition to the assay of a monoclonal antibody (mAb) to IL-1 receptor. When LPS was infused i.c.v., IL-1 was detected in the brainstem and diencephalon 2 h after injection, and in all the brain regions except cerebellum 6 h after injection; IL-1 was not detected in the plasma of these animals. When LPS was injected i.p., IL-1 was detected in the plasma but not in the brain 2 h after the injection, and in all brain regions but not in the plasma 6 h after the injection. In all of these cases, IL-1 was found in extracellular fluid; in some cases (cortex, cerebellum) cell lysate of the region did not produce detectable bioactivity, thereby indicating that IL-1 in these brain regions is processed to active peptide during release, as has been reported in the periphery. In those cases where bioactivity was detected in cell lysate (brainstem, diencephalon), bioactivity was not blocked by IL-1 receptor mAb, indicating presence of a non-IL-1 stimulating factor. These results further support the idea that IL-1 is secreted by cells in the brain, and indicate that it is found in the extracellular fluid of many brain regions following an appropriate stimulus in the periphery as well as in the brain.

Alterations in renal interleukin-1 production during kidney transplant rejection in the rat. The effects of high-dose methylprednisolone.

To characterize the role of interleukin-1 in renal allograft rejection, we examined the temporal relationship of IL-1 production to changes in renal function and histology in a rat kidney transplantation model. In rat renal allografts, both glomerular filtration rate and renal plasma flow (RPF) fell progressively from days 4 through 6 following transplantation. The reduction in allograft function was accompanied by histologic changes consistent with rejection and enhanced steady-state levels of IL-1 beta mRNA measured by Northern blot. This increase in IL-1 beta mRNA levels was associated with a forty-fold increase in IL-1 bioactivity in eluates of kidney allografts compared with isografts. In rejecting allografts, these changes also coincided with increased production of thromboxane B2 (TxB2) by the graft. To attempt to modify IL-1 production in the transplanted kidney, a separate group of animals with renal allografts were treated with 80 mg/kg/day of methylprednisolone for 6 days. GFR in MP-treated animals was significantly preserved compared with vehicle-treated animals. However, similar histologic manifestations of rejection were found in both groups. Although IL-1 beta mRNA levels in the kidney were not changed with MP treatment, renal IL-1 bioactivity was reduced four-fold in animals that received MP compared with controls. Thus, IL-1 beta gene expression and IL-1 protein production are stimulated in rejecting kidney transplants. MP administration improves allograft function and inhibits IL-1 production, apparently at a post-transcriptional level. We hypothesize that overproduction of IL-1 during kidney transplant rejection may promote allograft dysfunction and injury. Some of the beneficial effects of corticosteroids in acute rejection may be mediated through inhibition of IL-1 release within the allograft.

Behavioral and neural influences on cellular immune responses: effects of stress and interleukin-1.

A series of experiments examined effects of stressful conditions on several cellular immune responses and attempted to elucidate the physiological mechanisms underlying these effects. Initial studies showed that stressful conditions can profoundly suppress immune responses of blood and splenic lymphocytes, including T-cell mitogenesis, natural killer cell activity, production of interleukin-2 (IL-2) and interferon and IL-2 receptor expression. Subsequent studies found that (1) multiple physiological pathways mediate stress-induced suppression of these responses; (2) stress-induced suppression of these responses is produced, at least in part, by a peptide with molecular weight greater than 10 kilodaltons, which stressed animals release into circulation; (3) whereas most stressful conditions suppress immune responses, stressful conditions of moderate intensity can enhance cellular immune responses; and (4) extremely small quantities of interleukin-1 (IL-1) acting in the brain (e.g., 3.1-12.4 X 10(-15) moles) bring about suppression of cellular immune responses very rapidly and for a prolonged period of time. The relationship between the newly-discovered immunosuppressive influence of IL-1 in the brain and immunosuppression produced by stressful conditions remains to be determined.

Widespread activation and consequences of interleukin-1 in the brain.

The results described herein indicate that elevation of IL-1 in rat brain, either by infusion of IL-1 into the brain or by stimulation of release of endogenous IL-1 in the brain by LPS, rapidly suppresses a variety of immune responses measured in peripheral lymphocytes. This effect can be blocked by infusion of alpha-MSH into brain, an attribute that was used to indicate that the effects of LPS infusion occurred by stimulation of endogenous IL-1 and not some other influence of LPS. That suppression of cellular immune responses indeed describes the consequences of elevating IL-1 in brain was shown by determining the time course of effects and thereby demonstrating that rebound enhancement of cellular immune responses did not occur after either IL-1 or LPS. Studies that examined the mechanisms by which brain IL-1 affects immune responses indicated that IL-1 influences peripheral lymphocytes by stimulation of CRF in the central nervous system and that CRF in turn causes suppression of cellular immune responses through activation of both the pituitary-adrenal axis and the autonomic nervous system. These findings have also been observed in another laboratory. Moreover, Brown et al. have shown that IL-1 in brain suppresses macrophage function in addition to the suppression of lymphocyte functions described herein. The physiologic significance of IL-1 actions in the brain on immune responses remains to be determined, but the demonstration that this cytokine influences immune processes by acting in brain opens for study another means by which brain and immune system interact.

Effects of interleukin-1 infused into brain are antagonized by alpha-MSH in a dose-dependent manner.

Interleukin-1 (IL-1) in the brain stimulates the pituitary-adrenal axis and markedly suppresses cellular immune responses. alpha-Melanocyte-stimulating hormone (alpha-MSH) introduced into the ventricular system simultaneously with IL-1 blocked these effects of IL-1 in a dose-dependent manner, with 10 ng of alpha-MSH totally blocking the elevation of plasma ACTH and corticosterone and suppression of Natural Killer (NK) cell activity produced by a dose of IL-1 (100 pg) that otherwise causes maximal effects. In that IL-1 has been shown to promote production of alpha-MSH, these results suggest that actions of IL-1 in brain are under negative feedback control and, consequently, that the effects of this cytokine in brain are of biological significance.

Retinoic acid and steroids inhibit Epstein-Barr virus-induced nuclear antigen, DNA synthesis and lymphocyte transformation.

Retinoic acid, dexamethasone and prednisolone were evaluated for their effects on Epstein-Barr virus (EBV)-induced nuclear antigen (EBNA), DNA synthesis and transformation of human thymus-independent, B lymphocytes. It was found that continuous treatment of target cells with these agents completely inhibited EBV-induced transformation events. However, discontinuous treatment of the virus-infected cultures with these agents resulted in the recovery of DNA synthesis, and the appearance of EBNA and transformation. When the cells were treated with these agents 8 days after the virus infection, the inhibitors had no effect. These results show that only continuous treatment with these agents inhibited EBV-mediated transformation; these inhibitors had no effect once the EBNA and EBV-induced DNA synthesis were initiated in target lymphocytes.

AM Fungal Diversity in Selected Medicinal Plants of Kanyakumari District, Tamil Nadu, India.

The association of Arbuscular Mycorrhizal Fungi (AMF) with three medicinally important plants viz., Eclipta prostrata, Indigofera aspalathoides, I. tinctoria collected from three different localities of Kanyakumari District, South India was examined. The study reports the colonization percentage, diversity and species richness of different AM fungi in the rhizosphere of the three medicinal plants and discusses the impact of soil physicochemical characteristics such as soil texture, pH and available macro- and micro nutrient content on AM fungal communities. A total 21 AM fungal species were identified in field conditions of the three plants from three sites. AM fungal species richness, colorization percentage and Shannon index were found to be high in the two Indigofera sp. growing in the hilly areas of Kanyakumari District and were low in E. prostrata collected from the damp regions in the foothills of the three study sites. Five species registered 100% frequency in all the study sites of the three medicinally important plants with Glomus as the dominant genera. The study states that the mean colonization and diversity patterns were dependant on edaphic factors and type of vegetation.

Isoprinosine abolishes the blocking factor-mediated inhibition of lymphocyte responses to Epstein-Barr virus antigens and phytohemagglutinin.

Acute infectious mononucleosis (IM) is accompanied by measurable abnormalities of immune function, including a transient immunosuppression. The sera of patients with acute IM contain an IgG blocking factor which binds to T-lymphocytes and decreases their responses to antigens and mitogens. The experiments reported herein indicate that isoprinosine, an immunopotentiating agent, can reverse this inhibition of T cells by IM-associated IgG blocking factor. Isoprinosine may be a useful tool in understanding the interactions between blocking factors and lymphocytes; moreover, isoprinosine may be of value in patients with abnormal clinical responses to Epstein-Barr virus (EBV) such as chronic IM or persistent active EBV infections.

Epstein-Barr virus immunosuppression: II. Generation of nonspecific suppressor T lymphocytes in vitro.

We have previously shown that antigen-specific T-suppressor (Ts) cells can be generated in vitro by antigens of Epstein-Barr virus (EBV). However, patients with EBV-associated disorders and particularly those with EBV-induced infectious mononucleosis characteristically have nonspecific Ts cells in their peripheral circulation. To explore this apparent paradox, we have now examined the interaction of EBV antigens with either an unrelated antigen (tuberculo-protein-PPD) or a T-cell mitogen (phytohemagglutinin-PHA) in the in vitro generation of Ts cells. Our findings are: (1) the presence of unrelated antigens results in the generation of nonspecific Ts cells in a system wherein an EBV antigen (in excess) alone otherwise induces only antigen-specific Ts cells; (2) the unrelated antigen may be present in a wide range of concentrations and (3) can contribute to nonspecific Ts cell generation when added as long as 2 days after initiation of induction by EBV antigen; (4) the unrelated antigen must be recognized by the sensitized lymphocytes in order for nonspecific Ts cells to be induced; and most interestingly (5) when a second, immunologically different, EBV antigen is substituted for the unrelated antigen (PPD), again nonspecific Ts cells are induced in this system. We propose that the presence of unrelated (or multiple) antigens, in addition to the antigen-specific Ts cell-inducing antigen, contributes to the generation of nonspecific Ts cells in vivo, and that this phenomenon may be important in infections, malignancies, and immunodeficiency states.

Generation of Epstein-Barr virus antigen-specific suppressor T cells in vitro.

Immunosuppression is a commonly observed phenomenon in Epstein-Barr virus (EBV)-associated disorders and malignancies. The purpose of this study was to determine whether EBV antigens could generate suppressor cell activity in vitro. Peripheral blood lymphocytes (PBL) were first treated with various concentrations of EBV antigens or culture medium for 5 days and then with mitomycin C. The cells were then washed and tested for their ability to abrogate the blastogenic response of fresh, autologous PBL to previously determined optimal concentrations of EBV antigens. It was found that excess of both EBV antigens tested (soluble antigen and virus particles) induced suppressor cells, while optimal antigen concentrations failed to do so. In addition, PBL incubated with excess of EBV antigens for 10 days, without mitomycin treatment, inhibited the response of fresh autologous lymphocytes to EBV antigens. The generated suppressor cells were found to be antigen-specific since they inhibited the response of sensitized lymphocytes to the inducing antigen only. Moreover, experiments performed using purified lymphocyte subpopulations indicated that the suppressor activity was associated with T-cell populations. Using T-cells specific monoclonal antibodies, we further determined that the inhibitory activity was due to suppressor (OKT 8+) T-lymphocytes; treatment of T-lymphocyte populations (exhibiting suppressor activity) with OKT 8 antibody and complement abrogated the inhibitory effect of these populations on the response of sensitized lymphocytes to EBV antigens. Taken together, these observations suggest that similar suppressor cells may be at least partly responsible for the immunosuppression observed in patients with an antigenic overload, particularly during persistently active virus infection or malignancy.

Synthesis and release of plasminogen activator by lymphoid cell lines of malignant origin and its effect on lymphocyte cytotoxicity.

Lymphoid B, T. Null and plasma cell lines of malignant origin were evaluated for their ability to produce plasminogen activator (PA) in the 125I-fibrinolysis assay. These cell lines produced PA at varying extent. PA was detected in cell-free conditioned medium as well as in cell lysates. The fibrinolysis due to PA was dependent on the presence of plasminogen in the medium. PA purified by affinity chromatography not only abrogated cytotoxicity of peripheral blood lymphocytes significantly, but also the lysis of autologous EBV-transformed cells by in vitro generated cytotoxic lymphocytes. These results indicate that PA produced by malignant cells could inhibit host cellular immunity, thus providing the tumor cells with an escape mechanism from host defences.

IgG from Epstein-Barr virus infectious mononucleosis patients inhibits interleukin-2 production.

Patients with Epstein-Barr virus (EBV)-associated dissorders usually demonstrate evidence of immunosupression during active disease. Sera of some patients with EBV-induced infectious mononucleosis (IM), contain an IgG-blocking factor (IM-IgG) which inhibits in vitro cell-mediated immune responses and which we postulate plays an important role in viral immunosuppression. We had shown earlier that Isoprinosine (an immunostimulator) has a counterinhibitory effect on this IM-IgG activity. Here we describe evidence showing for the first time that the immunosuppressive activity of IM-IgG is aimed at inhibition of interleukin-2 (IL-2) synthesis and does not affect IL-2 receptors.

Isoprinosine enhances the activation of sensitized lymphocytes by Epstein-Barr virus antigens.

Isoprinosine, a synthetic purine derivative and a potentially useful immunostimulating agent, was tested for its ability to enhance lymphocyte responses to Epstein-Barr virus (EBV) antigens and to autologous EBV-transformed lymphocytes. Isoprinosine significantly enhanced the response of sensitized lymphocytes (i.e. from EBV-seropositive individuals) to EBV antigens, while it has no effect on the lack of response of unsensitized lymphocytes (i.e. from EBV-seronegative individuals) to these antigens. In addition, isoprinosine enhanced lymphocytes response to autologous EBV-transformed cells, and potentiated the generation of cytotoxic lymphocytes. From these observations, and since immunosuppression is commonly observed in EBV-associated malignancies and other EBV-induced disorders, it may be important to point out that the use of isoprinosine as an immunostimulating agent in patients with these diseases deserves serious consideration.

Purified plasminogen activating factor produced by malignant lymphoid cells abrogates lymphocyte cytotoxicity.

Immunosuppression is a generally observed phenomenon in patients with malignancies. Here we report that plasminogen activating factor (PAF) produced by human (P3HR-1) and simian (B95-8) lymphoid cells of malignant origin abrogates lymphocyte cytotoxicity. PAF has been purified from Epstein-Barr (EB) virus genome carrying lymphocyte cytotoxicity. PAF has been purified from Epstein-Barr (EB) virus genome carrying lymphoid lines by affinity chromatography using lysine-Sepharose columns. Purified PAF consistently inhibited Killer cell activity against the following targets: K-562, EB virus superinfected Raji cells and in vitro EB virus transformed autologous B lymphocytes. Furthermore PAF also inhibited the antibody-dependent cellular cytotoxicity. The results presented also indicate that PAF affects the effector lymphocytes and not the target cells. Taken together, these observations emphasize the importance of factors such as PAF, released by malignant cells, as inhibitors/modulators of immune mechanisms effective against tumour cells.

Mitogenic effect of 12-0 tetradecanoyl phorbol 13-acetate on non-human primate mononuclear cells and in vitro interaction with Epstein-Barr virus transformation.

12-0 tetradecanoyl phorbol 13-acetate (TPA), known to promote tumors in mice and also to enhance viral transformation as well as induction of viral antigens, was demonstrated to be mitogenic to peripheral blood mononuclear cells from rhesus monkeys and three species of marmosets. Even though mitogenic responses varied between species and within species, the mitogenic dose response due to TPA was comparable to the response of phytohemagglutinin (PHA-P). A significant synergistic effect of PHA-P and TPA on mononuclear cells from marmosets was evident when they were used together at optimal doses. TPA also increased the efficiency of in vitro transformation of marmoset lymphocytes by Epstein-Barr virus.

Brain IL-1-induced immunosuppression occurs through activation of both pituitary-adrenal axis and sympathetic nervous system by corticotropin-releasing factor.

Intracerebroventricular infusion of femtomolar quantities of interleukin-1 (IL-1) or stimulated release of endogenous IL-1 in the brain suppresses various cellular immune responses, decreasing natural killer cell (NK) activity, response to mitogen, and interleukin-2 production of splenic and blood lymphocytes (an effect hereafter called "brain IL-1-induced immunosuppression"). The present study examines mechanisms by which IL-1 produces this effect. First, because IL-1 in the brain activates the pituitary-adrenal axis by stimulating release of corticotropin-releasing factor (CRF), the role of CRF was investigated. To block CRF, affinity-purified antibody to CRF was infused into the lateral ventricle 30 min before introduction of IL-1. When this was done, suppression of cellular immune responses that normally follow IL-1 infusion was completely prevented. Infusion with an equal quantity of non-CRF IgG prior to IL-1 was without effect. Second, the role of sympathetic nervous activity was examined. To block neural transmission at sympathetic ganglia, chlorisondamine (3.0 mg/kg) was injected intraperitoneally 60 min before IL-1 infusion. When this was done, suppression of immune responses by IL-1 was partially blocked. These results indicate that IL-1 in the brain suppresses various cellular immune responses by activating both the pituitary-adrenal axis and the sympathetic nervous system, and that these systems are both activated through the influence of IL-1 on CRF.