Identification of Strategic Residues at the Interface of Antigen-Antibody Interactions by In Silico Mutagenesis

Structural information pertaining to antigen-antibody interactions is fundamental in immunology, and benefits structure-based vaccine design. Modeling of antigen-antibody immune complexes from co-crystal structures or molecular docking simulations provides an extensive profile of the epitope at the interface; however, the key amino acids involved in the interaction must be further clarified, often through the use of experimental mutagenesis and subsequent binding assays. Here, we describe an in silico mutagenesis method to identify key sites at antigen-antibody interfaces, using significant increase in pH-dependency energy among saturated point mutations. Through a comprehensive analysis of the crystal structures of three antigen-antibody immune complexes, we show that a cutoff value of 1 kcal/mol of increased interaction energy provides good congruency with the experimental non-binding mutations conducted in vitro. This in silico mutagenesis strategy, in association with energy calculations, may provide an efficient tool for antibody-antigen interface analyses, epitope optimization, and/or conformation prediction in structure-based vaccine design.

[Influence of sodium nitrite exposure on sulfhemoglobin and hydroxyl radicals in mice]

Objective: To investigate the influence of sodium nitrite exposure on sulfhemoglobin and hydroxyl radicals in mice. Methods: A total of 60 mice were randomly divided into low-, middle-, and high-dose groups (the concentrations of sodium nitrite were 0.055 mg/ml, 0.110 mg/ml, and 0.220 mg/ml, respectively) and control group (treated with distilled water) , with 15 mice in each group (male/female ratio=1: 1) . A free-drink model was applied and the duration of exposure was 2 weeks. The body weight of all mice was recorded before exposure and at weeks 1 and 2 of exposure. At the end of exposure, the mice were treated with intraperitoneally injected sodium salicylate to capture the hydroxyl radicals and produce 2, 5-dihydroxybenzoic acid and 2, 3-dihydroxybenzoic acid, and high-performance liquid chromatography was used to measure their content. Spectrophotometry was used to measure the relative content of sulfhemoglobin. Results: At week 2 of exposure, the low-, middle-, and high-dose groups had significantly lower body weight than the control group (22.8±2.8 g/21.6±2.8 g/21.2±3.0 g vs 25.6±2.2 g, P<0.05) . The low-, middle-, and high-dose groups had a significantly higher total content of hydroxyl radicals than the control group[ (0.015 3±0.006 5) μg/ml, (0.016 4±0.017 2) μg/ml, and (0.062 7±0.091 0) μg/ml vs (0.009 ±0.007 3) μg/ml, P<0.05]. The relative content of sulfhemoglobin was 1.54%±0.73%, 2.22%±0.44%, and 2.80%±0.69%, respectively, in the low-, middle-, and high-dose groups, and the middle- and high-dose groups had a significant increase in the relative content of sulfhemoglobin compared with the control group (2.22%±0.44%/2.80%±0.69% vs 1.76%±0.60%, P<0.05) . The content of hydroxyl radicals was positively correlated with the relative content of sulfhemoglobin (r=0.837, P<0.05) . Conclusion: Sodium nitrite exposure can increase the content of sulfhemoglobin and hydroxyl radicals in blood, and there is a positive correlation between them.

Mesenchymal stromal cells enhance the suppressive effects ofmyeloid-derived suppressor cells of multiple myeloma

Both mesenchymal stromal cells (MSCs) and myeloid-derived suppressor cells (MDSCs) have immunosuppressive properties, and their presence may confer a worse prognosis upon cancer patients. However, whether MSCs can enhance the immunosuppressive effects of MDSCs in MM remains unknown. We evaluated the influence of MSCs on MDSCs growth, apoptosis, and functions. Our results show that MSCs promote proliferation and inhibit apoptosis in MDSCs. Additionally, MSCs enhance the ability of MDSCs by inhibiting T-cell proliferation and IFN-γ production. Furthermore, both the mRNA and protein levels of Arg1 and NOS2 were upregulated in MDSCs. These results suggest that MSCs may exert immunomodulatory effects on MDSCs by upregulating Arg1 and NOS2.

[Huge esophageal foreign bodies under rigid esophagoscope case for translation]

A 36 year old man with dysphagia and swallow painafter ingestion of a stone and unable to eat anything. The esophagus computer tomography showed that image consistent with a 24 mm×25 mm diameter circular object giant smooth stone located in the proximal esophagus. A clinical diagnosis based on these findings: foreign bodies in the esophagus.

[Influence of n-hexane on vascular endothelial active substances in brain tissue in mice]

Objective: To investigate the influence of n-hexane on vascular endothelial active substances in brain tissue in mice and its significance. Methods: A total of 48 healthy Kunming mice were randomly divided into high-dose exposure group, middle-dose exposure group, low-dose exposure group, and control group, with 12 mice in each group. All groups except the control group were exposed to n-hexane via static inhalation (0.035 g/L, 0.018 g/L, and 0.009 g/L for the high-, middle-, and low-dose exposure groups, respectively) 4 hours a day for 21 days. the mice in the control groups were not exposed to n-hexane. After the exposure, the lev-els of endothelin-1 (ET-1) , nitric oxide (NO) , and angiotensin II (Ang II) in brain tissue were measured in all groups. Results: There were significant differences in the levels of ET-1, NO, and Ang II between the three ex-posure groups and the control group (P<0.05). Compared with the control group, the high-and middle-dose expo-sure group had significant increases in the levels of ET-1 and Ang II and the high-dose exposure group had a sig-nificant reduction in the level of NO (P<0.05 or P<0.01). Conclusion: n-Hexane can affect the vascular endothe-lial active substances in brain tissue in mice, and the changes and imbalance in vascular endothelial active sub-stances may be one of the reasons for central nervous system impairment caused by n-hexane.

Antiviral Therapy by HIV-1 Broadly Neutralizing and Inhibitory Antibodies

Human immunodeficiency virus type 1 (HIV-1) infection causes acquired immune deficiency syndrome (AIDS), a global epidemic for more than three decades. HIV-1 replication is primarily controlled through antiretroviral therapy (ART) but this treatment does not cure HIV-1 infection. Furthermore, there is increasing viral resistance to ART, and side effects associated with long-term therapy. Consequently, there is a need of alternative candidates for HIV-1 prevention and therapy. Recent advances have discovered multiple broadly neutralizing antibodies against HIV-1. In this review, we describe the key epitopes on the HIV-1 Env protein and the reciprocal broadly neutralizing antibodies, and discuss the ongoing clinical trials of broadly neutralizing and inhibitory antibody therapy as well as antibody combinations, bispecific antibodies, and methods that improve therapeutic efficacy by combining broadly neutralizing antibodies (bNAbs) with latency reversing agents. Compared with ART, HIV-1 therapeutics that incorporate these broadly neutralizing and inhibitory antibodies offer the advantage of decreasing virus load and clearing infected cells, which is a promising prospect in HIV-1 prevention and treatment.

MicroRNA-19a functions as an oncogene by regulating PTEN/AKT/pAKT pathway in myeloma

MicroRNAs (miRNAs) are involved in human cancers including myeloma. MiR-19a is one of the oncogenic miR-17-92 clusters, which is identified as a key oncogenic component in many cancers. Nevertheless, the function of miR-19a in myeloma has not been totally elucidated. The purpose of this study is to investigate the biological functions of miR-19a in MM. In vitro, we detected that the miR-19a-3p is overexpressed in myeloma cells. The proliferation and invision of myeloma cells are analyzed by MTT and BD matrigel assays, respectively. Western blot was performed to evaluate the expression of apoptotic/drug resistance-related main control proteins BCL-2 and MDR1 in myeloma cells after transfected with miR-19a-3p. Finally, we found miR-19a acts as an oncogene in MM by promoting cell proliferation/invision and inhibiting apoptosis. Additionally, We further showed that the mRNA and protein of BCL-2 and MDR were upregulated significantly after elevated expression of miR-19a, the process of which was regulated by PTEN/AKT/pAKT-signaling pathway. Our results suggest that miR-19a acted as an oncogenic miRNA by targeting PTEN in myeloma. This novel miR-19a/PTEN/AKT axis sheds new light on the mechanisms underlying apoptosis and invision and may provide potentially therapeutic targets for the treatment of myeloma.

[Effects of expression of calpain mRNA in rabbits exposed to vibration by hind legs]

OBJECTIVE

To study the effects of expression of calpain mRNA in rabbits exposed to vibration by hind legs.

METHODS

32 New Zealand rabbits were randomly divided into a control group and 3 experimental groups according to 4-hour energy-equivalent frequency-weighted acceleration[ahw (4)]: low (4.33 m/s(2)) , moderate (8.67 m/s(2)) and high (17.34 m/s(2)) intensity group to accepted the vibration by hind legs. 45 ds later, brain and skeletal muscle tissue of rabbits were taken to detect the expression of calpain-1 and calpain-2 mRNA by RT-qPCR technique.

RESULTS

The relative content of calpain-1 mRNA in the brain tissues in rabbits of low, medium and high intensity group were 8.35±3.75,9.64±4.54,5.10±5.26. While the relative content of calpain-2 mRNA in the brain tissues in rabbits of low, medium and high intensity group were 7.34±4.97,8.50±5.66, 8.16±5.59. Compared with the control group (1.10±0.29, 0.56±0.43) , the expression of calpain-1 and calpain-2 mRNA of the intensity groups showed an significantly increasing trend (P<0.01). In skeletal muscle tissue, the relative content of calpain-1 mRNA were 4.36±2.05, 7.37±4.06, 12.46±6.21.Compared with the control group (0.98±0.59) , the expression of calpain-1 mRNA of experiment groups were significantly higher (P<0.05) .The expression of calpain-2 mRNA of the intensity groups had no significantly difference with the control group (P>0.05).

CONCLUSION

The expression of calpain-1 and calpain-2 mRNA can be promoted by the vibration by the hind legs.

Purification and Characterization of Angiotensin-I Converting Enzyme Inhibitory Peptides from Prickly Ash (Zanthoxylum bungeanum Maxim) Seed Protein Hydrolysates

Prickly ash (Zanthoxylum bungeanum Maxim) seed protein was hydrolyzed with papain to obtain hydrolysates with inhibitory activity against angiotensin-I converting enzyme (ACE). ACE inhibitory peptides (ACEIPs) were successfully purified from seed protein hydrolysates through ultrafiltration and gel chromatography. In vitro ACE inhibitory assay revealed an IC50 value of 0.032± 0.008 mg·mL−1 for a component with <5 kDa molecular weight. Four fractions were isolated by Sephadex G-25 gel chromatography under the following elution conditions: flow rate, 0.6 mL·min−1; initial volume, 2.0 mL; and sample concentration, 30 mg·mL−1. The second fraction showed the highest inhibitory activity with an IC50 value of 0.021±0.007 mg·mL−1. The stability of the ACE inhibitory activity of the obtained ACEIPs was identified under storage conditions with varied temperature, pH, and gastrointestinal protease digestion. Peptides derived from prickly ash seed protein hydrolysates may be a potential resource for exploring functional food or pharmaceuticals against hypertension.

Computed tomography findings of hepatic veno-occlusive disease caused by Sedum aizoon with histopathological correlation

This study investigated the value of computed tomography (CT) in the diagnosis and treatment of hepatic veno-occlusive disease (HVOD) caused by Sedum aizoon (SA). The clinical manifestations, treatment results, imaging findings, and histological findings of the liver were analyzed in 39 patients with HVOD caused by SA. Hepatomegaly, liver dysfunction, abdominal effusion, and geographic density changes on liver CT scans were found in all 39 patients. The pathological findings of histological liver examination included swelling and point-like necrosis of liver cells, significant expansion and congestion of the sinuses, endothelial swelling, and wall thickening with incomplete lumen occlusion of small liver vessels. CT geographic density changes were confirmed by histological examination of the liver in 18 patients. Sixteen patients with small amounts of ascites that started within 4 weeks of treatment recovered completely or significantly improved after symptomatic and supportive treatment. However, only 43.75% of the patients with larger amounts of ascites improved following symptomatic and supportive treatment. In conclusion, liver CT examination is a valuable, safe, and noninvasive tool for the diagnosis of HVOD caused by SA. In selected cases, liver CT examination may replace liver biopsy and histological analysis.

Histone Acetylation Regulation in Sleep Deprivation-Induced Spatial Memory Impairment

Sleep disorders negatively affect cognition and health. Recent evidence has indicated that chromatin remodeling via histone acetylation regulates cognitive function. This study aimed to investigate the possible roles of histone acetylation in sleep deprivation (SD)-induced cognitive impairment. Results of the Morris water maze test showed that 3 days of SD can cause spatial memory impairment in Wistar rats. SD can also decrease histone acetylation levels, increase histone deacetylase 2 (HDAC2) expression, and decrease histone acetyltransferase (CBP) expression. Furthermore, SD can reduce H3 and H4 acetylation levels in the promoters of the brain-derived neurotrophic factor (Bdnf) gene and thus significantly downregulate BDNF expression and impair the activity of key BDNF signaling pathways (pCaMKII, pErk2, and pCREB). However, treatment with the HDAC inhibitor trichostatin A attenuated all the negative effects induced by SD. Therefore, BDNF and its histone acetylation regulation may play important roles in SD-induced spatial memory impairment, whereas HDAC inhibition possibly confers protection against SD-induced impairment in spatial memory and hippocampal functions.

Fluconazole susceptibility of 3,056 clinical isolates of Candida species from 2005 to 2009 in a tertiary-care hospital

In recent years, Candida infections have been increasing significantly. This study was to investigate the distribution and fluconazole susceptibility of such infections. Totally, 3,056 clinical isolates were analysed, C. albicans was the most prevalent species from respiratory and vaginal specimens. However, non-albicans species constituted the majority of isolates from blood, urine, intensive care unit (ICU), organ transplant and burned patients. Similarly, Candida spp. from different specimens and clinical services had different degrees of susceptibility to fluconazole. Isolates from vagina and burned patients had the highest resistance rate, while all of the isolates from ascites and dermatological services were susceptible to fluconazole.

Cross-talk between Arg methylation and Ser phosphorylation modulates apoptosis signal-regulating kinase 1 activation in endothelial cells

Protein arginine methyltransferase 5 interacts with and methylates apoptosis signal–regulating kinase 1 at arginine residue 89, thereby negatively regulating its activity by promoting the interaction between ASK1 and Akt and thus phosphorylating ASK1 at serine residue 83.

We describe a novel functional interaction between ASK1 and PRMT5. We show that PRMT5 interacts with and methylates ASK1 at arginine residue 89 and thereby negatively regulates its activity by promoting the interaction between ASK1 and Akt and thus phosphorylating ASK1 at serine residue 83. Furthermore, the association between ASK1 and Akt is enhanced by VEGF stimulation, and PRMT5 is required for this association. Moreover, PRMT5-mediated ASK1 methylation impaired the H₂O₂-induced activity of ASK1, and this inhibitory effect of PRMT5 was abolished by replacement of arginine 89 with Trp or depletion of PRMT5 expression by RNA interference. Together the results demonstrate cross-talk between arginine methylation and serine phosphorylation in ASK1.

Chondrogenesis of mesenchymal stem cells in a novel hyaluronate-collagen-tricalcium phosphate scaffolds for knee repair

Scaffolds are expected to play a key role in the induction of chondrogenesis of mesenchymal stem cells (MSCs) for cartilage tissue regeneration. Here, we report the development of a novel tricalcium phosphate-collagen-hyaluronate (TCP-COL-HA) scaffold that can function as a stem cell carrier to induce chondrogenesis and promote cartilage repair, and the investigation of chondroinductive properties of scaffolds containing varying amounts of TCP, COL and HA. TCP-COL-HA scaffolds, as well as TCP-COL scaffolds at two different TCP/COL ratios (50:50 and 25:75), were evaluated for their ability to induce cartilage regeneration from rabbit mesenchymal stem cells (rMSCs) in vitro and in vivo. Chondrogenic differentiation was evaluated by sulphated glycosaminoglycan quantification, collagen type II immunohistochemistry, and qRT-PCR. Mechanical strength was evaluated by the compression test. The results showed that the TCP-COL-HA scaffolds enhanced rMSC chondrogenesis to a greater degree than did the TCP-COL scaffolds; for the latter, the scaffold with the lower TCP/COL ratio (25:75) was superior in terms of promoting rMSC chondrogenesis. Similar results were obtained in an ectopic implantation model in nude mice. In a critical-size rabbit osteochondral defect-repair model, rMSCs seeded on TCP-COL-HA scaffolds showed greater cartilage regeneration and integration into surrounding tissue than the TCP-COL groups, in which cartilage repair was more efficient at the 25:75 than at the 50:50 ratio. These results indicate that the addition of HA and different TCP/COL ratios can affect the chondroinductive capacity of scaffolds, and suggest that the TCP-COL-HA scaffold can serve as an effective cell carrier for cartilage regeneration.

Water filling and electric field-induced enhancement in the mechanical property of carbon nanotubes

The effects of water filling and electric field on the mechanical property of carbon nanotubes (CNTs) are investigated with molecular dynamics simulations. The simulation results indicate that the water filling and electric field could enhance the elastic modulus but reduce the Poisson's ratio of the CNTs. As for the buckling behaviors, a significant enhancement could be observed in the yield stress and average post-buckling stress of the CNTs. In particular, the enhancement in the yield stress induced by the water filling and electric field could be even higher than that resulted from the solid filling. Moreover, a transition mechanism from the rod instability to shell buckling is shown to explain the nonmonotonic variation of yield stress, and the critical diameter can be tuned through filling the water molecules and applying the electric field. The present findings provide a valuable route for the optimized design and application of the nanoscale functional devices based on the water-filled CNTs.

Modified technique for transscleral fixation of posterior chamber intraocular lenses

Background

Suture exposure remains to be a potential problem of transscleral fixated posterior chamber intraocular lens (PCIOL). We report a modified technique to minimize the risk of suture exposure for the transscleral fixation of PCIOL.

Methods

The modified surgical technique is as following: at first, two 3 mm × 4 mm square scleral pockets were created from groove incisions at opposite positions. A straight needle attached to a 10–0 polypropylene suture was passed through one incision groove. Then, a 27-Gauge hollow needle passed through the opposite sclera incision bed was used to retrieve the straight fine needle via its barrel. The sutures were tied to themselves after one more bite on the scleral bed. At last, the suture ends were left long (about 4 mm) and laid flat into corresponding laminar scleral pockets. This modified technique of PCIOL was performed in 48 post-traumatic aphakic vitrectomized eyes from 48 patients (47 male, one female) with mean age of 34.8 ± 14.8 years. Main outcome measures included best corrective visual acuity (BCVA), IOL decentration, IOL tilt, and postoperative complications.

Results

The mean follow-up was 32.3 ± 10.8 months (3–67 months). The LogMAR BCVA remained stable, from a preoperative value of 0.46 ± 0.34 to postoperative 0.44 ± 0.34 (p = 0.69). Mild IOL tilt (5–10°) was observed in five eyes, and slight IOL decentration (0.5–1.0 mm) was seen in three cases. No case of suture exposure, suture breakage, IOL dislocation, or endophthalmitis was observed during the follow up period.

Conclusion

The modified technique allowed stable placement of PCIOLs in post-traumatic aphakic eyes with a wide range of follow-up. Our procedure might have the potential benefit to avoid suture exposure in scleral-fixated IOL implantation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-015-0118-8) contains supplementary material, which is available to authorized users.

A cross sectional study between the prevalence of chronic pain and academic pressure in adolescents in China (Shanghai)

Background

The purpose of this study was to investigate the prevalence of four types of chronic pain (headache, abdominal pain, neck and shoulder pain (NSP), and low back pain (LBP)) and to explore the relationship between the prevalence of chronic pain and self-reported academic pressure in high school students in Shanghai, China.

Method

Three thousand students were randomly surveyed on related issues using a questionnaire, and the results were analyzed using a multivariate logistic regression model.

Results

Among the 2849 high school students who completed the questionnaire, the overall prevalence rates of headache, abdominal pain, NSP, and LBP were 30.3, 20.9, 32.8, and 41.1 %, respectively. The students in general experienced a heavy burden of learning, a high level of stress, and sleep deprivation, which were closely related to the four types of chronic pain.

Conclusion

Chronic pain is a common condition in Chinese adolescents and is closely related to self-reported academic pressure.

Molecular insights into the inhibition of HIV-1 infection using a CD4 domain-1-specific monoclonal antibody

An HIV-1 infection in a host cell occurs through an ordered process that involves HIV-1 attachment to the host's cellular CD4 receptor, co-receptor binding to CCR5 or CXCR4, and the subsequent fusion with the cellular membrane. The natural viral entry pathway into a host cell provides an opportunity to develop agents for the treatment of HIV-1 infections. Several engineered monoclonal antibodies specifically targeting CD4 have shown antiviral activities in clinical trials. Here, we report on an anti-CD4 mAb (15A7) that displays a unique binding specificity for domain 1 of CD4, whose epitope partially overlaps with the gp120 binding region. Moreover, 15A7 displays a much stronger binding affinity to CD4(+) cell lines after HIV infection. 15A7 is able to block and neutralize a broad range of primary HIV-1 isolates and T cell-line passage strains. Notably, the bivalent F(ab')2 form of 15A7 is more effective than the Fab form in blocking HIV-1 infection, which is further supported by molecular docking analyses. Together, these results suggest that this novel antibody may exert its antiviral activity by blocking gp120 targeting to the CD4 receptor or competing with gp120 for CD4 receptor binding and might present post-attachment neutralization activity. This antibody could provide a new candidate to efficiently block HIV-1 infection or provide new starting materials for HIV treatment, especially when HIV-1-resistant strains against the current CD4 mAb treatments have already been identified.