In silico quantitative prediction of peptides binding affinity to human MHC molecule: an intuitive quantitative structure-activity relationship approach

In this paper, we have handpicked 23 kinds of electronic properties, 37 kinds of steric properties, 54 kinds of hydrophobic properties and 5 kinds of hydrogen bond properties from thousands of amino acid structural and property parameters. Principal component analysis (PCA) was applied on these parameters and thus ten score vectors involving significant nonbonding properties of 20 coded amino acids were yielded, called the divided physicochemical property scores (DPPS) of amino acids. The DPPS descriptor was then used to characterize the structures of 152 HLA-A*0201-restricted CTL epitopes, and significant variables being responsible for the binding affinities were selected by genetic algorithm, and a quantitative structure-activity relationship (QSAR) model by partial least square was established to predict the peptide-HLA-A*0201 molecule interactions. Statistical analysis on the resulted DPPS-based QSAR models were consistent well with experimental exhibits and molecular graphics display. Diversified properties of the different residues in binding peptides may contribute remarkable effect to the interactions between the HLA-A*0201 molecule and its peptide ligands. Particularly, hydrophobicity and hydrogen bond of anchor residues of peptides may have a significant contribution to the interactions. The results showed that DPPS can well represent the structural characteristics of the antigenic peptides and is a promising approach to predict the affinities of peptide binding to HLA-A*0201 in a efficient and intuitive way. We expect that this physical-principle based method can be applied to other protein-peptide interactions as well.

Human umbilical cord blood serum in culture medium on oocyte maturation In vitro

In vitro maturation (IVM) of immature oocytes for infertile patients is an attractive treatment. It can avoid side effects of ovarian stimulation with gonadotropins. However, at the present the successful results of IVM treatment are lower than conventional in vitro fertilization (IVF) treatment. The key issue may be the IVM medium for immature oocyte maturation. In the present study, we compared 20% (v/v) human follicular fluid (hFF) and 20% (v/v) human umbilical cord serum (hUS) as a supplement to IVM medium. A total of 47 patients with polycystic ovary syndrome (PCOS) underwent 47 IVM treatment cycles. Immature oocytes (349) collected from 32 patients were cultured in IVM medium supplemented with hFF, and immature oocytes (160) collected from 15 patients were culture in IVM medium supplemented with hUS. The results indicate that the final maturation rate of oocytes cultured in IVM medium supplemented with hUS (93.8%) is significantly higher than those cultured in IVM medium supplemented with hFF (77.1%). The percentage of high-quality embryos produced from IVM medium supplemented with hUS (50.0%) is significantly higher than IVM medium supplemented with hFF (23.8%). In addition, the results also indicate that the final maturation rate of oocytes is higher in IVM medium supplemented with hUS and the time course of oocyte maturation is hastened. Following transfer 6 out of 15 patients (40.0%) become pregnant when IVM medium was supplemented with hUS, and 7 out of 31 patients (22.6%) were pregnant when IVM medium was supplemented with hFF. These results suggest that IVM medium containing hUS appears to be a more effective means to stimulate in vitro oocyte maturation and is capable of achieving a promising clinical outcome.

TGFα and EGFR in ovine preimplantation embryos and effects on development

The present study aimed to assess location and relative amounts of transforming growth factor alpha (TGFalpha) and its receptor (EGFR) in ovine oocytes and preimplantation embryos by using immunohistochemical technique that was graded on a relative scale of 0-3, with 0 representing absence of staining, and 3 exhibiting prominent staining, and to evaluate the effects of TGFalpha/EGF on in vitro development of preimplantation embryos by adding different concentrations of EGF and TGFalpha to culture medium. The results showed that EGFR was abundant in cell plasma membranes in immature and mature oocytes, cumulus cells of immature cumulus-oocyte complexes (COC), fertilized oocytes and at different stages of embryo development. However, the relative amounts in inner cell mass (ICM) (1+) was less than that in trophectoderm (TE) cells (2+) at the blastocysts stage. The staining pattern for TGFalpha was a similar to EGFR. However, the staining for TGFalpha slightly increased in the fertilized oocytes (1-2+) as compared to immature and mature oocytes (1+). TGFalpha was mainly detected in the cytoplasm close to the membrane in both ICM and trophectoderm (TE) cells. The developmental rate of 8-cell stage embryos cultured with 5 ng/ml TGFalpha was increased as compared to other treatments (P<0.05). There was no significant difference in the rate of development of blastocysts cultured with 5 ng/ml TGFalpha, 20 ng/ml EGF, 20 ng/ml EGF+5 ng/ml TGFalpha or the control treatment (P>0.05). In addition, there was no significant difference in the number of cells in blastocyst stage as compared with different treatments (P>0.05). However, TGFalpha alone enhanced cell survival rated (P<0.01) and reduced apoptosis. We concluded that TGFalpha can improve development of ovine preimplantation embryos at the 8-cell and blastocyst stages in vitro.

Biotransformation of Panax notoginseng saponins into ginsenoside compound K production by Paecilomyces bainier sp. 229

AIMS

Development and optimization of an efficient and inexpensive biotransformation process for ginsenoside compound K production by Paecilomyces bainier sp. 229.

METHODS AND RESULTS

We have determined the optimum culture conditions required for the efficient production of ginsenoside compound K by P. bainier sp. 229 via biotransformation of ginseng saponin substrate. The optimal medium constituents were determined to be: 30 g sucrose, 30 g soybean steep powder, 1 g wheat bran powder, 1 g (NH(4))(2)SO(4), 2 g MgSO(4) x 7H(2)O and 1 g CaCl(2) in 1 l of distilled water. An inoculum size of 5-7.5% with an optimal pH range of 4.5-5.5 was essential for high yield.

CONCLUSIONS

The Mol conversion quotient of ginseng saponins increased from 21.2% to 72.7% by optimization of the cultural conditions. Scale-up in a 10 l fermentor, under conditions of controlled pH and continuous air supply in the optimal medium, resulted in an 82.6% yield of ginsenoside compound K.

SIGNIFICANT AND IMPACT OF THE STUDY

This is the first report on the optimization of culture conditions for the production of ginsenoside compound K by fungal biotransformation. The degree of conversion is significantly higher than previous reports. Our method describes an inexpensive, rapid and efficient biotransformation system for the production of ginsenoside compound K.

304 HUMAN AUGMENTER OF LIVER REGENERATION TRANSGENIC OVINE EMBRYO DERIVED FROM SOMATIC CELL NUCLEAR TRANSFER

The aim of this research was to develop an efficient screening technique to detect transgenic ovine embryos using neomycin resistance (NeoR) and enhanced green fluorescence protein (EGFP) genes as genetic markers. A 0.8-kb fragment of the ovine β-lactoglobulin promoter sequence (BLG) and 1.8 kb of the human augmenter of liver regeneration (ALR) genomic sequence were derived by PCR amplification. These 2 fragments were inserted into the MCS of pGEM-7zf(+) plasmid; this vector was named p7Z-BA. The coding sequence of NeoR was derived by PCR amplification from the plasmid pIRES2-EGFP and was assembled into the MCS of the pIRES2-EGFP plasmid. The resultant vector (pNIE) contained a NeoR gene coding sequence and an EGFP coding sequence linked by an internal ribosome entry site (IRES) sequence downstream of the CMV promoter. The vector pNIE was excised as an NsiI-SspI fragment and inserted into the vector p7Z-BA. In the end, we had a vector named pNEA, which contained the NeoR gene and the EGFP gene regulated by a CMV promoter for expression in a non-tissue specific mode, and the human ALR gene regulated by the BLG promoter for expression specifically in mammary gland. Sheep fetal fibroblast (SFFB) cells were isolated by attachment of tissue pieces from the ear skin of a 1- to 2-month ovine fetus. Karyotypes of the cells at the third passage and after 15 passages were analyzed. The cells proliferated well and more than 72% of the cells maintained a diploid karyotype after 15 passages. Therefore, the SFFB cells are amenable for transgenic cloning manipulations. For transfection, third-passage SFFB cells at 70% confluency were transfected in a 100-mm dish with pNEA (0.5, 1.0, 2.0, 3.0, 5.0, and 7.0 µg) using Lipofectamine 2000 (2, 4, 6, 8, 10, and 12 µL; Invitrogen, Carlsbad, CA). Cells were checked 24 to 48 h after transfection under fluorescence microscopy for GFP expression, and G418 selection (800 µg mL–1) was applied at that time. After 2 weeks, selected colonies were counted and propagated in culture medium containing 300 µg mL–1 G418 for 2 to 3 passages and cryopreserved. A small portion of the cells was analyzed by PCR for gene integration. Bright green fluorescence could be detected 24 to 48 h after transfection. More colonies were selected when transfection parameters were 2 µg of DNA and 10 µL of Lipofectamine. The results of PCR detection showed that the foreign gene was integrated into the genome. A total of 612 oocytes were aspirated from 2- to 5-mm follicles of ovine ovaries collected from an abattoir; 78% of them were matured after 18 h in culture. Four hundred forty-three oocytes were enucleated, and 332 enucleated oocytes were treated for electrofusion with green fluorescence cells. Of these, 180 (54.2%) couplets were fused. A total of 172 reconstructed embryos were stimulated and cultured in vitro, 31 (18%) of which developed to the blastocyst stage, and 19 blastocysts expressed GFP. In conclusion, we established an effective method to select transgenic embryos formed by nuclear transfer using transfected donor cells.

Epidermal Langerhans cells promote skin allograft rejection in mice with NF-kappa B-impaired T cells

T cells play a major role in the acute rejection of transplanted organs. Using mice transgenic for a T-cell-restricted NF-kappaB super-repressor (IkappaBalphaDeltaN-Tg mice), we have previously shown that T-cell-NF-kappaB is essential for the acute rejection of cardiac but not skin allografts. In this study, we investigated the mechanism by which skin grafts activate IkappaBalphaDeltaN-Tg T cells. Rejection was not due to residual T-cell-NF-kappaB activity as mice with p50/p52(-/-) T cells successfully rejected skin grafts. Rather, skin but not cardiac allografts effectively induced proliferation of graft-specific IkappaBalphaDeltaN-Tg T cells. Rejection of skin grafts by IkappaBalphaDeltaN-Tg mice was in part dependent on the presence of donor Langerhans cells (LC), a type of epidermal dendritic cells (DC), as lack of LC in donor skin grafts resulted in prolongation of skin allograft survival and injection of LC at the time of cardiac transplantation was sufficient to promote cardiac allograft rejection by IkappaBalphaDeltaN-Tg mice. Our results suggest that LC allow NF-kappaB-impaired T cells to reach an activation threshold sufficient for transplant rejection. The combined blockade of T-cell-NF-kappaB with that of alternative pathways allowing activation of NF-kappaB-impaired T cells may be an effective strategy for tolerance induction to highly immunogenic organs.

Immune response after high-intensity focused ultrasound ablation for H22 tumor

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Background: Previous results have shown that high intensity focused ultrasound (HIFU) ablation can potentially activate a host anti-tumor immunity. This study was to investigate whether acoustic cavitaion may enhance host immune responses after HIFU treatment for solid malignancy, and to explore the potential mechanisms regarding the enhanced anti-tumor immunity. Methods: (1) Tumor cell vaccine preparation: H22 cells were irradiated with HIFU (0.8MHz, 1050W/cm2, 90s); H22 cells were heated for one hour in 65°C water bath. (2) Animal study: 150 KM mice were randomly divided into three groups: control group, thermal group, and HIFU group. Each group had 50 mice for immune experiments. By using hypodermic injection, the mice in thermal group and HIFU group received either 0.2ml heat-treated H22 vaccine or 0.2ml HIFU-treated H22 vaccine in the left flank of each mouse. Those in control group received only injection with same amount of saline solution. The vaccination times were 4 sessions, once a week for 4 consecutive weeks. One week after last vaccination, each mouse was challenged with H22 tumor cells. All mice were followed up to observe the long-term survival in each group, and peripheral blood was collected to detect changes in T lymphocytes and their subsets by flow cytometry technique. Results: The tumor incidences and 6-week survival rates were observed 100% and 88% of mice in control group, 72.5% and 40% in thermal group, and 42.5% and 14% in HIFU group respectively. Compared to the values in either control group or thermal group, there was a significant decrease of tumor incidences and 6-week survival rates in HIFU group. The volume of tumor was obviously lower in HIFU group, and a significant difference was observed between HIFU group and thermal group or control group. Compared to the values in control group, there were a significant increase of CD4+ levels and CD4+/CD8+ ratio, and a significant decrease of CD8+ level in both HIFU group and thermal group. Conclusions: Antitumor immune response could be enhanced after HIFU ablation for H22 implanted tumor in mice, and acoustic cavitation could play an important role to stimulate host antitumor immune system.

No significant financial relationships to disclose.

Effects of follicular atresia and size on the developmental competence of bovine oocytes: A study using the well-in-drop culture system

The effect of granulosa cell (GC) apoptosis and follicle size on the competence of bovine oocytes were studied using a well-in-drop (WID) oocyte/embryo culture system, which allows identification of follicular origin. Hatching rates of blastocysts did not differ (P>0.05) between oocytes cultured in the WID system (13%) and those cultured in the conventional group system (16%). Hatching rates of blastocysts were higher (P<0.05) in early atretic (17%) than in non-atretic (8%) and late atretic follicles (10%) of the same size (4-8mm), and in 6-8mm (22%) than in 4-5mm follicles (15%) at the early atretic stage. More oocytes (P<0.05) from late atretic (17%) than from non-atreteic (7%) or early atretic follicles (9%) of the same size (4-8mm) were arrested at Grade 1 cumulus expansion (only cells in the peripheral two layers began to expand). Similarly, more oocytes from 2 to 3mm follicles (30%) than from 6 to 8mm follicles (21%) at the same (late) atretic stage had Grade 1 cumulus expansion (P<0.05). Hatching blastocyst percentages of oocytes with Grade 3 (all layers of the cumulus except corona radiate cells expanded) or Grade 4 (full) cumulus expansion were higher in early atretic (20%) than in non-atretic (13%) or late atretic follicles (12%). Hatching blastocyst percentages of oocytes from follicles at the early atretic stage increased as cumulus expanded from Grade 2 (9%) to Grade 4 (27%). Regardless of the degree of follicle atresia, 72-76% of the floating cells in the follicular fluid (FF) were undergoing apoptosis. The floating cell density in FF was highly (r=0.6-0.7) correlated with oocyte developmental potency. In conclusion, the WID culture system was as efficient as group culture and allowed identification of follicular origin. Furthermore, the developmental potential of oocytes was affected by GC apoptosis, follicle size and cumulus expansion, and the floating cell density in FF could be used as a simple and non-invasive marker of oocyte quality.

NUP98 Dysregulation in Myeloid Leukemogenesis

Nucleoporin 98 (NUP98) is a component of the nuclear pore complex that facilitates mRNA export from the nucleus. It is mapped to 11p15.5 and is fused to a number of distinct partners, including nine members of the homeobox family as a consequence of leukemia-associated chromosomal translocations. NUP98-HOXA9 is associated with the t(7;11)(p15;p15) translocation in acute myeloid leukemia (AML), myelodysplastic syndrome, and blastic crisis of chronic myeloid leukemia. Expression of NUP98-HOXA9 in murine bone marrow resulted in a myeloproliferative disease progressing to AML by 7-8 months. Transduction of NUP98 fusion genes into human CD34(+) cells confers a proliferative advantage in long-term cytokine-stimulated and stromal cocultures and in NOD-SCID engrafted mice, associated with a five- to eight-fold increase in hematopoietic stem cells. NUP98-HOXA9 expression inhibited erythroid and myeloid differentiation but enhanced serial progenitor replating. NUP98-HOXA9 upregulated a number of homeobox genes of the A and B cluster as well as MEIS1 and Pim-1, and downmodulated globin genes and C/EBPalpha. The HOXA9 component of the NUP98-HOXA9 fusion protein was protected from cullin-4A-mediated ubiquitination and subsequent proteasome-dependent degradation. In NUP98-HOX-transduced CD34(+) cells and cells from AML patients with t(7;11)(p15;p15) NUP98 was no longer associated with the nuclear pore complex but formed intranuclear aggregation bodies. Analysis of NUP98 allelic expression in AML and myelodysplastic syndrome showed loss of heterozygosity observed in 29% of the former and 8% of the latter. This was associated with poor prognosis.

A pulsed electron gun for ultrafast electron diffraction at surfaces

The construction of a pulsed electron gun for ultrafast reflection high-energy electron diffraction experiments at surfaces is reported. Special emphasis is placed on the characterization of the electron source: a photocathode, consisting of a 10 nm thin Au film deposited onto a sapphire substrate. Electron pulses are generated by the illumination of the film with ultraviolet laser pulses of femtosecond duration. The photoelectrons are emitted homogeneously across the photocathode with an energy distribution of 0.1 eV width. After leaving the Au film, the electrons are accelerated to kinetic energies of up to 15 keV. Focusing is accomplished by an electrostatic lens. The temporal resolution of the experiment is determined by the probing time of the electrons traveling across the surface which is about 30 ps. However, the duration of the electron pulses can be reduced to less than 6 ps.

Multiphoton ionization in dielectrics: comparison of circular and linear polarization

Ionization mechanisms in bulk dielectrics irradiated by single intense 50-fs-laser pulses are investigated by ultrafast time-resolved imaging interferometry. Polarization-sensitive 6-photon ionization is shown to be the dominant ionization mechanism in fused silica and sapphire at intensities around 10 TW/cm2. For both materials the cross sections of 6-photon ionization are found to be significantly higher for linear polarization than for circular. Our experimental results corroborate an earlier theoretical prediction on the dominance of linear polarization in high-order multiphoton ionization.

TLR engagement prevents transplantation tolerance

In many experimental models, heart, pancreas and kidney allografts are accepted long-term following costimulation-targeting therapies, whereas skin, lung and intestine resist the induction of tolerance under the same regimens. We noted that a common feature of the resistant organs is their constant exposure to commensal microbes and hypothesized that these microorganisms may stimulate Toll-like receptors (TLRs), promote alloresponses and prevent tolerance induction. This hypothesis prompts the predictions that TLR engagement at the time of transplantation should avert tolerance to heart allografts in animals treated with costimulation-targeting therapies, whereas inhibition of TLR signaling should promote tolerance to skin allografts under the same conditions. Indeed, engagement of a single TLR was sufficient to prevent anti-CD154-mediated long-term cardiac allograft acceptance and correlated with abolished intragraft recruitment of CD4+/FoxP3+ regulatory T cells and the development of linked-suppression. Conversely, a lack of donor and recipient MyD88-dependent signaling led to successful skin allograft acceptance in anti-CD154-treated animals. Thus, the status of TLR signaling contributes to the resistance versus susceptibility of organs to transplantation tolerance.

Studies on the preparation, crystal structure and bioactivity of ginsenoside compound K

Microbial transformation of Panaxnotoginseng saponins (PNS) using Aspergillus niger afforded, as the main metabolite, ginsenoside compound K (20-O-beta-glucopyranosyl-20(S)-protopanaxadiol). Its structure was determined spectroscopically and by X-ray analysis, and this is the first time the crystal structure of ginsenoside has been reported. In comparison with ginsenoside Rb1, the pro-drug for this metabolite, compound K exhibits potent cytotoxic activity against tumor cell lines. The mean concentrations of compound K needed to inhibit the proliferation of cells by 50% (IC50) were 12.7, 11.4, 8.5 and 9.7 microM for mouse high-metastatic melanoma (B16-BL6), human hepatoma (HepG2), human myeloid leukemia (K562) and human high-metastatic lung carcinoma (95-D) cell lines, respectively. The data show that ginsenoside compound K is a good antitumor drug candidate.

Role of natural killer cell subsets in cardiac allograft rejection

To achieve donor-specific immune tolerance to allogeneic organ transplants, it is imperative to understand the cell types involved in acute allograft rejection. In wild-type mice, CD4(+) T cells are necessary and sufficient for acute rejection of cardiac allografts. However, when T-cell responses are suboptimal, such as in mice treated with costimulation-targeting agents or in CD28-deficient mice, and perhaps in transplanted patients taking immunosuppressive drugs, the participation of other lymphocytes such as CD8(+) T cells and NK1.1(+) cells becomes apparent. We found that host NK but not NKT cells were required for cardiac rejection. Ly49G2(+) NK cells suppressed rejection, whereas a subset of NK cells lacking inhibitory Ly49 receptors for donor MHC class I molecules was sufficient to promote rejection. Notably, rejection was independent of the activating receptors Ly49D and NKG2D. Finally, our experiments supported a mechanism by which NK cells promote expansion and effector function of alloreactive T cells. Thus, therapies aimed at specific subsets of NK cells may facilitate transplantation tolerance in settings of impaired T-cell function.

Transplanted islets from lpr mice are resistant to autoimmune destruction in a model of streptozotocin-induced type I diabetes

The mechanism by which beta-cells die during autoimmune diabetes has remained a subject of intense investigation. The loss of beta-cells in the disease is T cell mediated and thought to result from a number of different insults including apoptosis induction through the death receptor CD95. However, the role of CD95 in autoimmune diabetes, studied primarily in the non-obese diabetic (NOD) mouse model, has been controversial. We have used an alternative model of autoimmune diabetes triggered by repeated low doses of streptozotocin. In this model, islet grafts from C3H mice that carry the lpr mutation, and therefore lack the ability to undergo apoptosis through CD95-CD95L interaction, were completely protected when grafted in autoimmune diabetic mice despite periinsulitis (infiltration of T cells) which however did not progress to islet destruction. In contrast wild-type grafts were rapidly eliminated in autoimmune recipients. Our data provide strong support for a major role of CD95 in the destruction of islets in autoimmune mice.