In vivo IL-10 production reactivates chronic pulmonary tuberculosis in C57BL/6 mice

The production of immunosuppressive cytokines, such as IL-10 and TGF-beta, has been documented in individuals diagnosed with active tuberculosis. In addition, IL-10 production is increased within the lungs of mice that have chronic mycobacterial infection. Therefore, we hypothesized that the down-regulatory properties of IL-10 might contribute to the reactivation of chronic Mycobacterium tuberculosis infection in mice. To determine the influence of IL-10 on the course of infection, transgenic mice producing increased amounts of IL-10 under the control of the IL-2 promotor were infected with M. tuberculosis via the respiratory route. Mice that overexpressed IL-10 showed no increase in susceptibility during the early stages of infection, but during the chronic phase of the infection showed evidence of reactivation tuberculosis with a highly significant increase in bacterial numbers within the lungs. Reactivation was associated with the formation of macrophage-dominated lesions, decreased mRNA production for TNF and IL-12p40, and a decrease in Ag-specific IFN-gamma secretion. These data support the hypothesis that IL-10 plays a pivotal role during the chronic/latent stage of pulmonary tuberculosis, with increased production playing a potentially central role in promoting reactivation tuberculosis.     

The balance between donor T cell anergy and suppression versus lethal graft-versus-host disease is determined by host conditioning

Graft-vs-host disease (GVHD) remains the most life-threatening complication following the transfer of allogeneic bone marrow into immunocompromised hosts. Transferred alloreactive T cells respond in a complex manner. While massive T cell expansion is observed upon entry into an allogeneic environment, anergy, apoptosis, and repertoire selection are also observed. The study presented here shows that alloreactive T cell expansion and differentiation vs anergy and suppression are dramatically influenced by host conditioning. Using alloreactive CD4(+) and CD8(+) TCR transgenic (Tg) T cells, a novel GVHD model is presented that allows for the visualization of how alloreactive T cells behave when host conditioning is manipulated. Following the transfer of alloreactive CD4(+) and CD8(+) TCR Tg T cells into sublethally irradiated hosts, both Tg T cells populations expand, develop effector function, and cause GVHD. In contrast, when Tg T cells are transferred in non-irradiated hosts, expansion is observed, but there is no development of effector function or disease. Assessment of CD4(+) Tg T cell function following transfer into non-irradiated hosts reveals that these CD4(+) Tg cells are profoundly anergic and have acquired a regulatory function, as manifested in their ability to suppress the expansion of naive TCR Tg T cells in vitro and in vivo as well as the development of GVHD. These findings underscore the decisive effect of the inflammatory environment created by irradiation in determining the ultimate fate and function of alloreactive T cells in vivo     

Hypertension alters the participation of contractile prostanoids and superoxide anions in lipopolysaccharide effects on small mesenteric arteries

The involvement of cyclooxygenase-2 (COX-2)-derived products and superoxide anion in the effect of lipopolysaccharide in noradrenaline (NA)-induced contraction was investigated in small mesenteric arteries (SMA) from normotensive, Wistar Kyoto (WKY), and spontaneously hypertensive (SHR) rats. In WKY, lipopolysaccharide (10 microg/ml, 1 and 5 h) only inhibited the NA response (0.1-30 microM) in the presence of dexamethasone (1 microM), indomethacin (10 microM), the selective COX-2 inhibitor, NS 398 (10 microM), and the TXA(2)/PGH(2) receptor antagonist, SQ 29,548 (10 microM) but not of superoxide dismutase (SOD, 100 U/ml). In SHR, lipopolysaccharide inhibited the NA response by itself; this inhibition was potentiated by dexamethasone, indomethacin, NS 398, SQ 29,548 and SOD. The effect of lipopolysaccharide plus indomethacin, NS 398 or SQ 29,548 was higher in SMA from WKY than SHR only after 1 h lipopolysaccharide incubation. N(G)-nitro-L-arginine methyl ester (100 microM) and endothelium removal abolished the indomethacin-induced potentiatory effect of lipopolysaccharide in both strains. Endothelium removal also abolished the SOD potentiatory effect in SMA from SHR. Lipopolysaccharide increases COX-2 expression to a similar level in both strains and iNOS expression in a greater extent in SHR; these increases were reduced by dexamethasone. These results indicate: 1) lipopolysaccharide induces the endothelial production of contractile prostanoids from COX-2 in SMA, probably to compensate the increase in NO from iNOS; 2) the production of prostanoids in the presence of lipopolysaccharide seems to be greater in normotensive than hypertensive rats only after lipopolysaccharide short incubation times; 3) endothelial production of O(2)(.-) contributes to counteract depression of NA contraction caused by lipopolysaccharide only in SHR.     

Imazethapyr, an inhibitor of the branched-chain amino acid biosynthesis, induces aerobic fermentation in pea plants

Acetolactate synthase (ALS; EC 4.1.3.18) inhibition is the primary mechanism of action of imazethapyr (IM). However, the precise mechanisms that links ALS inhibition with plant death have not been elucidated. Supply of IM to pea ( Pisum sativum L) plants produced an immediate cessation of growth, caused a 50% inhibition of the in vivo ALS activity within 1 day of treatment, and a remarkable accumulation (2.7-times) of free amino acids after 3 days. Carbohydrates (soluble and starch) were accumulated in both leaves and roots. Accumulation of soluble sugars in roots preceded that of starch in leaves, suggesting that the accumulation of carbohydrates in leaves is not the reason for the arrested root growth. A transient pyruvate accumulation was observed in roots, 1 day after the onset of IM supply. This was coincident with an increase in pyruvate decarboxylase (EC 4.1.1.1), and later increases in alcohol dehydrogenase (EC 1.1.1.1), lactate dehydrogenase (EC 1.1.1.27), and alanine amino transferase (EC 2.6.1.2) activities. This enhancement of fermentative activities was coincident with a slight decrease in aerobic respiration. The overall data suggest that the impairment of ALS activity may lead to a fermentative metabolism that may be involved in growth inhibition and plant death.     

A tunable hydrogel for encapsulation and controlled release of bioactive proteins

A N,N-dimethylacrylamide-based hydrogel (2) with the new cross-linker (ethylenedioxy) bis[2,2'-(N-acryloylamino)ethane] (1) has been prepared, and its physicochemical properties in aqueous solution were studied. Three different native proteins (lysozyme, bovine serum albumin, and rabbit IgG) were encapsulated within the polymeric matrix 2, and the kinetics of their release from the swollen hydrogel were determined. The rate of protein release exhibits a clear dependence on both the molecular weight of the protein and the amount of cross-linker utilized to prepare the hydrogel. This is reflected by the fact that the low molecular weight proteins are released at an increased rate versus higher molecular weight proteins. In addition a greater amount of protein is released from the hydrogels with a lower percentage of cross-linker. The polymerization procedure used in this study is sufficiently mild to safeguard the functional integrity of attendant biomolecules as determined by the retention of catalytic activity of encapsulated alpha-chymotrypsin and aldolase catalytic antibody 38C2. The potential utility of these hydrogels for the controlled release of bioactive agents in vivo is strengthened by both their lack of toxicity against human dermal fibroblasts and their lack of immunogenicity in mice.     

Cholera and climate: revisiting the quantitative evidence

Cholera dynamics in endemic regions display regular seasonal cycles and pronounced interannual variability. We review here the current quantitative evidence for the influence of climate on cholera dynamics with reference to the early literature on the subject. We also briefly review the incipient status of mathematical models for cholera and argue that these models are important for understanding climatic influences in the context of the population dynamics of the disease. A better understanding of disease risk related to the environment should further underscore the need for changing the socioeconomic conditions conducive to cholera.     

Improved paclitaxel and baccatin III production in suspension cultures of Taxus media

A cell suspension culture of Taxus media was established from a stable callus line of this species. The growth rate and production of paclitaxel and baccatin III of this cell suspension were significantly increased during the shake flask culture in its respective optimum media for cell growth and product formation, which were selected after assaying 24 different culture media. The highest yields of paclitaxel (2.09 mg L(-1)) and baccatin III (2.56 mg L(-1)) in the production medium rose (factors of 7.0 and 3.0, respectively) in the presence of methyljasmonate (220 microg g(-1) FW). When the elicitor was added together with mevalonate (0.38 mM) and N-benzoylglycine (0.2 mM), the increase in the yields of paclitaxel and baccatin III was even higher (factors of 8.3 and 4.0, respectively). Thereafter, a two-stage culture for cell suspension was carried out using a 5-l stirred bioreactor running for 36 days, the first stage being in the cell growth medium until cells entered their stationary growth phase (12 days) and the second stage being in the production medium supplemented with the elicitor and two putative precursors in the concentrations indicated above. Under these conditions, 21.12 mg L(-1) of paclitaxel and 56.03 mg L(-1) of baccatin III were obtained after 8 days of culture in the production medium.     

A review of gene expression patterns in the malformed brain

Major advances in the identification of genes expressed in malformation-associated epileptic disorders have been made. Some of these changes reflect the complex gene interactions necessary for proper neurodevelopment, whereas others suggest specific synaptic aberrations that could result in a hyperexcitable, and ultimately, epileptic condition. Here we review reported changes in gene expression associated with a malformed brain, with particular emphasis on how these changes provide clues to seizure genesis.