[Current concerns and considerations regarding mesenchymal stem cells therapy in perplexing severe liver diseases]

Stem cells are type of cells that have unlimited self-renewal and multi-differentiation potential under specific conditions. Stem cell-based therapeutic techniques can provide new methods for the treatment of perplexing severe liver diseases. Umbilical cord mesenchymal stem cells are currently considered as ideal stem cells due to their low immunogenicity, convenient materials, abundant sources and advantage of no ethical controversy in the clinical treatment of diseases. Presently, there is a large number of basic and clinical application evidence, which suggests that mesenchymal stem cells can significantly improve the condition and outcome of end-stage liver diseases such as liver cirrhosis and liver failure, and its mechanism of action may include hepatocyte-like cells differentiation, immune function regulation, exosome secretion, etc. This paper briefly summarizes the current theories and clinical research status of mesenchymal stem cells application, as well as the therapeutic clinical trial issues and concerns that needs to be resolved during the perplexing severe liver diseases process.

[Dynamic analysis of the academic influence in Chinese Journal of Hepatology from 2010 to 2016]

Objective: To dynamically analyze the discipline status, influence factors and key issues of Chinese Journal of Hepatology from 2010 to 2016 and explore the development rules of citation indexes. Methods: We collected information published by the China Institute of Scientific and Technological Information [China Science and Technology Journal Citation Report (Core Edition)] and Wanfang Database Periodicals statistical analysis platform from 2010 to 2016. A bibliometric analyses on article volume, citation frequency, citation rate, h-index, ratio of fund-aided papers, periodical influence, key number published period, number of relevant articles, and so on were analyzed for annual's impact factor. Results: According to the data released by the China Institute of Science and Technology Information, from 2010 to 2011, the impact factor of Chinese Journal of Hepatology was at leading level in the field of internal medicine and ranked sixth in the Journal of Internal Medicine. From 2012 to 2016, the overall comprehensive assessment score and citation frequency score of Chinese Journal of Hepatology were ranked first in the Journal of Gastroenterology. Core impact factors kept the discipline ahead. Indexes such as immediacy index, h- index, cited half-life and all other indicators were increased. Citation rate was >90% and cited issue number had greatly increased. Conclusion: Chinese Journal of Hepatology has a leading position in the Journal of Gastroenterology and credited by inland readers and authors of digestive and infectious fields. It has played a positive role in promoting the development of the discipline.

Expression of vitamin D receptor in renal tissue of lupus nephritis and its association with renal injury activity

Objective

Vitamin D receptor (VDR) has potent anti-inflammatory activities. VDR gene polymorphism has been linked with systemic lupus erythematosus (SLE). However, its expression in the kidney has not been evaluated. This study aimed to investigate the relationship between VDR expression and renal pathology as well as clinical manifestations in lupus nephritis (LN).

Methods

A total of 20 renal biopsy specimens from 35 patients with LN were classified according to the International Society of Nephrology/Renal Pathology Society 2003 LN-type standards pathological type, and the activity index and chronicity index were determined. Five normal renal tissue samples were obtained from surrounding areas distal to nephronophthisis or renal tumors (>2 cm). The expression of VDR was assessed by immunohistochemistry. The relationships between VDR expression and histological injury index, proteinuria and Systemic Lupus International Collaborating Clinics (SLICC) renal activity scores were analyzed.

Results

As compared to the control group, the expression of VDR in the LN group was lower ( p < 0.001) and negatively correlated with activity index (r = –0.548, p = 0.012) but not with chronicity index (r = –0.277, p = 0.236). The expression of VDR in renal tissue was also associated with SLICC renal activity scores (r = –0.470, p = 0.037).

Conclusion

The down-regulation of VDR expression in renal tissues of LN patients was negatively correlated with renal activity and injury severity.

Improved Proliferation and Differentiation of Bone Marrow Mesenchymal Stem Cells Into Vascular Endothelial Cells With Sphingosine 1-Phosphate

The practical use of bone marrow mesenchymal stem cells (MSCs), considered to be the best candidate in the field of regenerative medicine, is limited by the low efficiency of MSC differentiation. Sphingosine 1-phosphate (S1P) could promote proliferation, survival, and differentiation of many types of cells, but its effects on MSCs remain elusive. In this study, S1P was added during primary MSCs (PR-MSCs) culture and the effects of S1P on proliferation, survival, and differentiation of PR-MSCs were evaluated. The results showed that S1P could improve PR-MSCs proliferation activity in a concentration-dependent manner, and the apoptosis of PR-MSCs cultured in hypoxia was significantly reduced in the S1P-treated group compared to the control group. After being cultured with vascular endothelial growth factor for 7 days, the specific genes of endothelial cells were highly expressed in S1P-treated PR-MSCs compared to control group, which coincided with the augumented production of hepatocyte growth factor, stromal cell-derived factor-1, and insulin-like growth factor-1. In summary, our results suggest that S1P can promote proliferation, survival, and differentiation into vascular endothelial cells of PR-MSCs. These results will promote the clinical application of PR-MSCs and deepen our understanding of the function mechanism of S1P.

Blockage of conformational changes of heat shock protein gp96 on cell membrane by a α-helix peptide inhibits HER2 dimerization and signaling in breast cancer

Cell membrane translocation of heat shock protein gp96 from the endoplasmic reticulum has been observed in multiple tumors and is associated with tumor malignancy. However, the cancer-intrinsic function and the related mechanism of cell membrane gp96 as a pro-oncogenic chaperone remain further elucidated. In this study, we found that inhibition of gp96 intramolecular conformational changes by a single α-helix peptide p37 dramatically increased its binding to HER2, whereas decreased HER2 dimerization, phosphorylation and downstream signaling. Targeting cell membrane gp96 promoted HER2 ubiquitination and subsequent lysosomal degradation, which led to decreased cell growth and increased apoptosis, and inhibited tumor growth in vivo. We also demonstrate that gp96 inhibitory peptide p37 synergized with trastuzumab to suppress cell growth and induce apoptosis. Our work demonstrates that blocking gp96 conformational changes directs HER2 for cellular degradation, and represents a new therapeutic strategy for inhibiting HER2 signaling in cancer.

Cell membrane gp96 facilitates HER2 dimerization and serves as a novel target in breast cancer

HER2 receptor dimerization is a critical step in the HER2 activation process. Here, we demonstrated that heat shock protein gp96 on cell membrane interacts with HER2, facilitates HER2 dimerization and promotes cell proliferation. Cell membrane gp96 levels were observed to correlate with HER2 phosphorylation in primary breast tumors. Finally, we provide evidence that targeting gp96 with a specific monoclonal antibody led to decreased cell growth and increased apoptosis in vitro, and suppression of tumor growth in vivo. Our work represents a new therapeutic strategy for inhibiting HER2 signaling in cancer.

A new unconventional HLA-A2-restricted epitope from HBV core protein elicits antiviral cytotoxic T lymphocytes

Cytotoxic T cells (CTLs) play a key role in the control of Hepatitis B virus (HBV) infection and viral clearance. However, most of identified CTL epitopes are derived from HBV of genotypes A and D, and few have been defined in virus of genotypes B and C which are more prevalent in Asia. As HBV core protein (HBc) is the most conservative and immunogenic component, in this study we used an overlapping 9-mer peptide pool covering HBc to screen and identify specific CTL epitopes. An unconventional HLA-A2-restricted epitope HBc141-149 was discovered and structurally characterized by crystallization analysis. The immunogenicity and anti-HBV activity were further determined in HBV and HLA-A2 transgenic mice. Finally, we show that mutations in HBc141-149 epitope are associated with viral parameters and disease progression in HBV infected patients. Our data therefore provide insights into the structure characteristics of this unconventional epitope binding to MHC-I molecules, as well as epitope specific CTL activity that orchestrate T cell response and immune evasion in HBV infected patients.

[Expression of anti-gp96 scFv fragment in Pichia pastoris and identification of its biological activity]

Secretory anti-gp96 scFv fragment was expressed in Pichia pastoris to obtain a small molecule antibody that specifically recognizes heat shock protein gp96. The gp96-scFv fragment gene was synthesized and cloned to Pichia pastoris expression plasmid pPICZa-A. Pichia pastoris X33 was electroporated with the linearized recombinant expression vector, and expression of gp96-scFv fragment was induced by methanol. The His-tagged recombinant protein was then purified by affinity chromatography and analyzed with SDS-PAGE and Western blotting assays. The biological activities of recombinant gp96-scFv fragment were determined by Western blotting, Immunofluorescence, ELISA and FACS assays. The gp96-scFv fragment was expressed successfully in Pichia pastoris. About 50 mg of recombinant protein could be purified from 1 liter of the Pichia pastoris culture supernatant. Its molecular weight was about 15 kDa. The gp96-scFv fragment could specifically bind to gp96 protein by Western blotting, immunofluorescence, ELISA and FACS analyses. Pichia pastoris-expressed gp96-scFv fragment specifically recognizes gp96 protein, which could be used for Western blotting, Immunofluorescence, ELISA and FACS analyses.

Echinoside A, a new marine-derived anticancer saponin, targets topoisomerase2alpha by unique interference with its DNA binding and catalytic cycle

BACKGROUND

Echinoside A was isolated from sea cucumber. This study demonstrates its anticancer effects and its mechanisms of action.

MATERIALS AND METHODS

Anticancer effects of echinoside A were evaluated in vitro and in vivo. TUNEL and DNA fragmentation assays were applied to examine its ability to induce apoptosis. A series of biochemical assays were applied to investigate the inhibition of echinoside A on topoisomerase2alpha (Top2alpha). Molecular docking analyses were used to demonstrate the direct interaction between echinoside A and Top2alpha.

RESULTS

Echinoside A inhibited the growth of tumors in mouse models and human prostate carcinoma xenografts in nude mouse models. Echinoside A shows the unique characteristics of inhibiting the noncovalent binding of Top2alpha to DNA by competing with DNA for the DNA-binding domain of the enzyme and of interfering predominantly with the Top2alpha-mediated prestrand passage cleavage/religation equilibrium over with the poststrand passage one. These features distinguish echinoside A from other known Top2alpha inhibitors. As a result, echinoside A induced DNA double-strand breaks in a Top2-dependent manner.

CONCLUSION

Echinoside A targets Top2alpha by unique interference with the binding of Top2 to DNA and by imparing the Top2-mediated DNA cleavage and religation, exerting potent in vitro and in vivo antitumor activities.

p38 mitogen-activated protein kinase targets the production of proinflammatory endothelial microparticles

BACKGROUND

Endothelial microparticles (EMPs) are irregularly shaped membrane fragments shed into the circulation in patients with vascular diseases, and may themselves act to enhance the endothelial response to inflammation. On the basis of the importance of p38 mitogen-activated protein kinase (MAPK) in endothelial responses to inflammatory stimuli, we sought to define the role of p38 in EMP generation and function.

METHODS

Microparticle generation from cultures of human aortic endothelial cells (hAECs) treated with tumor necrosis factor-alpha (TNF-alpha) and p38 inhibition was quantified via multiple modalities. The response of target endothelial cells was assessed by treatment of cells with EMPs generated under various conditions.

RESULTS

Inhibition of p38 in hAECs, using pharmacologic agents, resulted in a 50% reduction of TNF-alpha-induced EMPs. Importantly, suppression of microparticles was specific to p38 MAPK pathways. EMPs triggered by TNF-alpha activation induced an approximately four-fold increase in soluble intercellular adhesion molecule-1 (sICAM-1) release from targeted cells. However, inhibition of p38 MAPK in the targeted cell prior to EMP treatment did not alter the sICAM1 response.

CONCLUSIONS

Our findings implicate p38 MAPK signaling as significant and selective in the formation and maturation of EMPs. EMPs elicited a proinflammatory response from targeted hAECs that was dependent on the conditions under which EMPs were generated. However, our results imply a unidirectional model in which p38 MAPK is critical at the source of microparticle formation, but not the target cell response to EMPs. These findings indicate a novel mechanism by which p38 inhibition may offer therapeutic benefit in vivo via direct inhibition of EMP formation.

[Cloning and characterization of a novel mouse short-chain dehydrogenase/reductases cDNA mHsdl2#, encoding a protein with a SDR domaid and a SCP2 domain]

The short-chain dehydrogenases/reductases (SDRs) play important roles in body's metabolism. We cloned a novel mouse SDR cDNA which encodes a deduced HSD-like protein with a conserved SDR domain and a SCP2 domain. The 1.8 kb cDNA consists of 11 exons and is mapped to mouse chromosome 4B3. The corresponding gene is widely expressed in normal mouse tissues and its expression level in liver increases after inducement with cholesterol food. The predicted mouse HSDL2 protein, which has a peroxisomal target signal, is localized in the cytoplasm of NIH 3T3 cells.

TCR beta chain influences but does not solely control autoreactivity of V alpha 14J281T cells

CD1d-dependent accumulation of alphabeta T cells bearing a canonical Valpha14Jalpha281 alpha-chain (Valpha14+ T cells) is thought to model positive selection of lipid-specific T cells, based on their ability to recognize CD1d-presented self glycolipid(s). However, it has been difficult to demonstrate self ligand specificity in this system, as most Valpha14+ T cells do not exhibit significant autoreactivity despite high reactivity to alpha-galactosylceramide presented by CD1d (alpha-GalCer/CD1d). To assess the role of TCRbeta chain in determining the alpha-GalCer/CD1d vs autoreactive specificity of Valpha14+ T cells, we conducted TCRalpha or TCRbeta chain transduction experiments. In this study we demonstrate, by combining different TCRbeta chains with the Valpha14 alpha-chain in retrovirally transduced T cell lines, that the Valpha14 alpha-chain plays a primary role, necessary but not sufficient for imparting alpha-GalCer/CD1d recognition. beta-Chain usage alone is not the sole factor that controls the extent of autoreactivity in Valpha14+ T cells, since transduction of TCRalphabeta chains from a high CD1d autoreactive Valpha14+ T cell line conferred the alpha-GalCer/CD1d specificity without induction of autoreactivity. Thus, heterogeneity of Valpha14+ T cell reactivity is due to both beta-chain diversity and control mechanism(s) beyond primary TCR structure.

Structural requirements for antigen presentation by mouse CD1

The structural basis for the T cell response to glycolipid antigens (Ags) remains poorly understood. T lymphocytes autoreactive for mouse CD1 (mCD1.1) or reactive for the glycosphingolipid alphagalactosylceramide (alpha-GalCer) presented by mCD1.1 have been described previously. In this paper it is shown that mutations at the top of the alpha helices and in the bottom of the Ag-binding groove can disrupt both mCD1.1 autoreactivity and alpha-GalCer recognition. The locations of the positions that affect T cell responses indicate that recognition of mCD1.1 is not likely to be unconventional or superantigen-like. Furthermore, the effects of the bottom of the pocket mutation suggest that the autoreactive response could require an autologous ligand, and they indicate that alpha-GalCer binds to the groove of mCD1.1, most likely with the shorter 18-carbon hydrophobic chain in the A' pocket. Natural killer T cell hybridomas with identical T cell antigen receptor (TCR) alpha chains and different beta chains respond differently to alpha-GalCer presented by mCD1.1 mutants. This finding indicates a role for TCR beta in defining natural killer T cell specificity, despite the more restricted diversity of the alpha chains in these cells. Overall, the data are consistent with a mode of lipoglycan recognition similar to that proposed for glycopeptides, in which the TCR alpha and beta chains survey a surface composed of both mCD1.1 and the carbohydrate portion of alpha-GalCer.

B-cell commitment, development and selection

Here we review three areas in B-cell development in the mouse, with a focus on relevance to B-1/CD5+ B cells. Multiparameter flow cytometry has allowed the dissection of intermediate stages of developing B cells, both in fetal liver and bone marrow. In the first area, we present recent work that has delineated a fraction of pre-pro-B cells, committed to the B lineage, but lacking any immunoglobulin rearrangements. Next, the role of the pre-B-cell receptor in B-cell repertoire selection has become clear in the past few years, but we present work suggesting that the action of this process during fetal life is different, resulting in selection of a very distinct repertoire compared with adult. Finally, we describe a new VH3609 antithymocyte Ig transgenic mouse model system that has provided the first definitive evidence for the role of self-antigen in development and maintenance of natural autoreactive B cells.

Peripheral CD4+ T cell maturation recognized by increased expression of Thy-1/CD90 bearing the 6C10 carbohydrate epitope

The SM6C10 IgM autoantibody recognizes a surface determinant, 6C10, that is highly expressed on all immature thymocytes. In contrast, its expression on peripheral T cells appears developmentally regulated, i.e., absent from most naive T cells in spleen of neonatal mice, but expressed on 40-80% of naive CD4+ T cells in adult. In this paper, we demonstrate that SM6C10 recognizes a carbohydrate epitope on the Thy-1 glycoprotein using immunoprecipitation analysis, by binding to affinity-purified Thy-1 in an ELISA, and by sensitivity to N-glycosidase-F treatment. Retroviral Thy-1 gene transduction experiments into Thy-1- variant T cell lines and a pro-B cell line provide evidence that 6C10 glycosylated Thy-1 expression is not restricted to T cells but depends on the recipient cell. Therefore, differences in 6C10 levels among Thy-1+ T cells in mice likely reflect developmental regulation of posttranslational modification of the Thy-1 glycoprotein. The ability of naive CD4+ T cells to respond to anti-Thy-1 stimulation increases from neonate to adult, and 6C10- naive cells from adult mice respond poorly compared with 6C10+ cells, similar to the cells in neonatal mice. These results suggest that there is functional maturation by peripheral CD4+ T cells that coincides with 6C10 glycosylated Thy-1 up-regulation, and natural autoantibody recognizes this 6C10 carbohydrate epitope.

Positive selection of natural autoreactive B cells

Lymphocyte development is critically influenced by self-antigens. T cells are subject to both positive and negative selection, depending on their degree of self-reactivity. Although B cells are subject to negative selection, it has been difficult to test whether self-antigen plays any positive role in B cell development. A murine model system of naturally generated autoreactive B cells with a germ line gene-encoded specificity for the Thy-1 (CD90) glycoprotein was developed, in which the presence of self-antigen promotes B cell accumulation and serum autoantibody secretion. Thus, B cells can be subject to positive selection, generated, and maintained on the basis of their autoreactivity.

Selective ability of mouse CD1 to present glycolipids: alpha-galactosylceramide specifically stimulates V alpha 14+ NK T lymphocytes

Mouse CD1 (mCD1) glycoproteins are known to present peptides, while human CD1 molecules present glycolipids. In mice, mCD1-autoreactive NK T cells play critical roles in various immune responses, through the secretion of high amounts of cytokines. This study was initiated to determine whether glycolipids are involved in the autorecognition of mCD1 by NK T cells. Alpha-galactosylceramide (alpha-GalCer) was the only glycolipid tested capable of eliciting an mCD1-restricted response by splenic T cells. Moreover, splenic T cells derived from mCD1-deficient mice were not stimulated by alpha-GalCer, suggesting that the responsive T cells are selected by mCD1. Using cytoflow techniques, we confirmed that, in response to alpha-GalCer, IFN-gamma-secreting cells displayed an NK T cell phenotype. The predominance of IFN-gamma vs IL-4, however, is determined by the type of mCD1+ APC, suggesting the potential for APC regulation of cytokine production by NK T cells. Among a panel of 10 mCD1-autoreactive T cell hybridomas, only the ones that express the typical V alpha 14 J alpha 281 TCR rearrangement of NK T cells responded to alpha-GalCer. Fixation or treatment of mCD1+ APCs with an inhibitor of endosomal acidification and the use of mCD1 mutants unable to traffic through endosome still allowed alpha-GalCer to stimulate NK T cells. Thus, endosomal trafficking and Ag processing are not required for glycolipid recognition. In summary, alpha-GalCer might be the autologous ligand, or a mimic of a glycolipid ligand, involved in the mCD1-mediated stimulation of NK T cells.

[X-ray photoelectron spectroscopy and mass spectrum study of tin and germanium compounds]

The relationship between the chemical displacement of binding energy and the different chemical environment for tin and germanium compounds was studied by means of X-ray photoelectron spectroscopy and mass spectrum.

Inhibition of human glutathione reductase by S-nitrosoglutathione

S-Nitrosoglutathione (GSNO) represents a major transport form in nitric oxide (NO) in biological systems. Since NO and GSNO have been shown to modulate the function of various proteins, we studied the influence of GSNO and other NO donors on human glutathione reductase (GR). Catalyzing the reaction NADPH+GSSG+H(+)-->NADP(+) + 2 GSH, the dimeric flavoprotein GR is the central enzyme of the glutathione redox metabolism. GSNO was found to inhibit crystalline erythrocyte GR in two ways: (a) as a reversible inhibitor GSNO is competitive with glutathione disulfide (GSSG), the Ki being appr. 0.5 mM; (b) as an irreversible inhibitor; after 1 h (3 h) incubation with 1 mM GSNO, GR (2.5 U/ml, representing intraerythrocytic concentrations) was inhibited by 70% (90%). This inhibition depended on the presence of NADPH and could not be reversed by dilution nor by reducing agents. Absorption spectra indicate that the charge-transfer interaction between Cys63 and the flavin is abolished by this modification. In a GR sample inhibited by 90% with GSNO, the Km values for the substrates GSSG and NADPH were not significantly changed nor did the modification induce oxidase activity of the enzyme. GSNO was found not to be a substrate in the forward reaction of GR. This implies that GSNO is not accounted for by methods which employ GR for determining total glutathione. Incubating isolated GR for 60 min with other NO donors, namely 1 mM sodium nitroprusside or 1 mM S-nitroso-N-acetyl-DL-penicillamine (SNAP), resulted in only 25% and 10% inhibition, respectively. This attests to a specific affinity of GSNO to the enzyme. GSNO inhibition patterns comparable to purified authentic GR were obtained for purified recombinant GR, a GR mutant lacking the 15 N-terminal amino acids including Cys2, and for the enzyme present in diluted fresh haemolysates (0.02 U/ml); in concentrated haemolysates the inhibition was less pronounced. GR of intact erythrocytes was not affected when exposed to GSNO in the medium. Our results suggest that the irreversible inhibition of GR by GSNO involves nitrosylation of Cys63 and/or Cys58 at the catalytic site of the enzyme. To further investigate the mechanism of inactivation we have crystallized GSNO-modified GR for X-ray diffraction analysis.

Comparative phenotypic analysis of lymph node cells in mice after infection or vaccination with normal or ultraviolet-attenuated cercariae of Schistosoma japonicum or S. mansoni

Mice were infected with 200 untreated or vaccinated with 500 ultraviolet-attenuated cercariae of either Schistosoma japonicum or S. mansoni. For three weeks, cell numbers in axillary and mediastinal lymphnodes were counted and cell populations typed by cytofluorometry. In the axillary lymphnodes, numbers of B-cells and CD3+CD4+ T-cells but not CD3+CD8+ T-cells increased. Following vaccination with either species, parasite migration was apparently delayed in the skin and interrupted at the lungs, the lymphnodes gained weight, and cell numbers of axillary lymph nodes increased more than after infection. In mediastinal lymphnodes, only immunization with S. japonicum but not S. mansoni cercariae led to an increase of CD3+CD4+ T-cells. Following infection, both schistosome species induced higher CD3+CD4+, but not CD3+CD8+ T-cells in mediastinal nodes, and the peak was earlier with S. japonicum (about seven days after infection) than with S. mansoni (about 10 days). In analogy to T-cell observations by others using a gamma-attenuated cercarial vaccine in S. mansoni, the present results suggest that CD3+CD4+ cells also play a role in the ultraviolet-attenuated vaccine against S. japonicum.

Schistosoma japonicum and S. mansoni: comparison of larval migration patterns in mice

Mice were infected percutaneously with cercariae of Schistosoma japonicum or S. mansoni and parasites recovered by tissue-mincing from the skin or lungs or by perfusion of the mesenteric veins. S. japonicum had a narrow peak of recovery (up to 30%) from the lungs 3 days after infection, whereas lung recovery of S. mansoni peaked only on day 6 and levelled off during the following week. Infection with S. japonicum induced lung petechiae, but only after most of the parasites had left the lungs. The axillary lymph nodes draining the infection site increased in weight after infection and this effect was much greater and longer with S. mansoni than with S. japonicum. S. japonicum was perfusable from the mesenteric veins earlier (from day 3 onwards) and in higher number (40-60% from days 6 to 10) than S. mansoni (20% on day 20). The percentage of cercariae developing to adult worms was 57% for S. japonicum and 33% for S. mansoni. The data demonstrate that S. japonicum might escape from local tissue reactions in the skin and lungs and, due to its rapid migration, might induce only poor lymphocyte proliferation. As a possible consequence, S. japonicum may establish more efficiently in mice than S. mansoni.

Redox processes in malaria and other parasitic diseases. Determination of intracellular glutathione

The role of oxidative stress resulting from production of reactive oxygen species and/or from suppression of the cellular antioxidant capacity in parasitic infections is shortly reviewed. The experimental part of the paper deals with the glutathione (GSH)--glutathione reductase (GR) system, a cornerstone of intracellular antioxidant defence mechanisms. For studying this system in parasitic diseases such as malaria new or modified methods are required. Total glutathione comprising GSH and glutathione disulphide (GSSG) in blood samples was assayed as follows. One volume of blood (> or = 10 microliters) is mixed with two volumes of 5% sulphosalicylic acid; after centrifugation (5 min, 10000 g), 10 microliters of supernatant is taken for spectrophotometric analysis using the 5,5'-dithiobis(2-nitrobenzoate) (DTNB)-glutathione recycling assay. When compared with the original method, the procedure reported here is more sensitive, less time-consuming, avoids unfavourable pH-values and leads to a sample which when frozen is stable for months. In a pilot study, the method was applied to 14 patients suffering from malaria caused by Plasmodium falciparum. The concentrations of erythrocyte glutathione were significantly decreased in the patients (1.42 +/- 0.47 mM, mean +/- SD) when compared to age- and sex-matched controls (2.11 +/- 0.45 mM, P < 0.01). The findings are contrasted with P. falciparum cultures in vitro where glutathione levels are known to be elevated. Based on the characteristics of GR a concept of determining the redox state of single cells is introduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Reactivity of Schistosoma japonicum and S. mansoni antigen preparations in indirect haemagglutination (IHA) with sera of patients with homologous and heterologous schistosomiasis

Sera of patients infected with Schistosoma japonicum, S. mansoni or S. haematobium were tested in an indirect haemagglutination assay (IHA) using soluble S. japonicum egg antigen (SjSEA) and soluble S. mansoni adult antigen prepared either from a Puerto Rican strain (SmAWA) or an Egyptian strain (SmBW; Cellognost-Schistosomiasis Kit). Reactions were best, in terms of titres and sensitivity, in homologous systems. Heterologous systems were less reliable, particularly those using sera from urinary schistosomiasis patients. It is suggested that IHA is a suitable test to detect Schistosoma infections, especially when homologous systems are used.

Miracidia of Schistosoma japonicum: approach and attachment to the snail host

Schistosoma japonicum miracidia swim directed along a chemical gradient toward the snails Oncomelania hupensis and Biomphalaria glabrata, and they turn back when the concentration of attractive chemicals decreases. The host signal for this chemotactic response has a molecular weight of more than 30,000. When swimming miracidia encounter the surface of O. hupensis or agar containing O. hupensis snail-conditioned water (SCW) they perform the host-specific responses "contact with return," "repeated investigation," and "attachment," but they do not exhibit such behavior when encountering B. glabrata surface or agar containing B. glabrata SCW. Thus S. japonicum miracidia respond to different host signals when they approach snails than when they attach to snails.