Diagnostic and prognostic value of parameters of erector spinae in patients with uremic sarcopenia

AIM

This study aimed to investigate whether computed tomography (CT)-measured erector spinae parameters (ESPs) have diagnostic, severity assessment, and prognostic predictive value in uremic sarcopenia (US).

MATERIALS AND METHODS

A total of 202 uremic patients were enrolled and divided into two groups: a control group and a sarcopenia group. Sarcopenia was classified into two types: severe and nonsevere. The area, volume, and density of the erector spinae (ES) were measured using chest CT images, and the relevant ESP, including the erector spinae index (ESI), total erector spinae volume (TESV), erector spinae density (ESD), and erector spinae gauge (ESG) were calculated. The occurrence of adverse events was followed-up for 36 months. The diagnostic value and severity of US were determined using the receiver operating characteristic (ROC) curve. Survival curves diagnosed using CT were plotted and compared with the curve drawn using the gold standard. Cox regression analysis was used to identify independent risk factors associated with survival in US.

RESULTS

With an area under the curve (AUC) of 0.840 and 0.739, the combined ESP has diagnostic value and the ability to assess the severity of US. There was no significant difference in the survival curve between the combined ESP for the diagnosis of US and the gold standard (P > 0.05). ESI is a standalone predictor of survival in patients with US.

CONCLUSION

ESP measured by CT has diagnostic values for US and its severity, as well as being a predictive value for the prognosis of US.

Blocked Autophagy is Involved in Layered Double Hydroxide-Induced Repolarization and Immune Activation in Tumor-Associated Macrophages

Tumor-associated macrophages (TAMs) are important immune cells in the tumor microenvironment (TME). The polar plasticity of TAMs makes them important targets for improving the immunosuppressive microenvironment of tumors. The previous study reveals that layered double hydroxides (LDHs) can effectively promote the polarization of TAMs from the anti-inflammatory M2 type to the pro-inflammatory M1 type. However, their mechanisms of action remain unexplored. This study reveals that LDHs composed of different cations exhibit distinct abilities to regulate the polarity of TAMs. Compared to Mg-Fe LDH, Mg-Al LDH has a stronger ability to promote the repolarization of TAMs from M2 to M1 and inhibit the formation of myeloid-derived suppressor cells (MDSCs). In addition, Mg-Al LDH restrains the growth of tumors in vivo and promotes the infiltration of activated immune cells into the TME more effectively. Interestingly, Mg-Al LDH influences the autophagy of TAMs; this negatively correlates with the pro-inflammatory ability of TAMs. Therefore, LDHs exert their polarization ability by inhibiting the autophagy of TAMs, and this mechanism might be related to the ionic composition of LDHs. This study lays the foundation for optimizing the performance of LDH-based immune adjuvants, which display excellent application prospects for tumor immunotherapy.

A mitochondria-anchored supramolecular photosensitizer as a pyroptosis inducer for potent photodynamic therapy and enhanced antitumor immunity

BACKGROUND

The discovery of a potent photosensitizer with desirable immunogenic cell death (ICD) ability can prominently enhance antitumor immunity in photodynamic therapy (PDT). However, majority of commercially-available photosensitizers suffer from serious aggregation and fail to elicit sufficient ICD. Pyroptosis as a newly identified pattern for potent ICD generation is rarely disclosed in reported photosensitizers. In addition, the photosensitizer with excellent mitochondria-anchored ability evokes prominent mitochondria oxidative stress, and consequently induces ICD.

RESULTS

Herein, a novel supramolecular photosensitizer LDH@ZnPc is reported, without complicated preparation, but reveals desirable pyroptosis-triggered ability with mitochondria anchoring feature. LDH@ZnPc is obtained through isolation of ZnPc using positive charged layered double hydroxides (LDH), and excellent mitochondria-anchored ability is achieved. More importantly, LDH@ZnPc-mediated PDT can effectively initiate gasdermin D (GSDMD)-dependent pyroptosis of tumor cells. In vitro and in vivo results verify robust ICD ability and potent tumor inhibition efficacy, and antitumor immunity towards distant tumor inhibition.

CONCLUSIONS

This study reveals that LDH@ZnPc can act as an excellent pyroptosis inducer with simultaneous mitochondria anchoring ability for enhancing photodynamic therapy and boosting antitumor immunity.

Interference of layered double hydroxide nanoparticles with pathways for biomedical applications

Recent decades have witnessed a surge of explorations into the application of multifarious materials, especially biomedical applications. Among them, layered double hydroxides (LDHs) have been widely developed as typical inorganic layer materials to achieve remarkable advancements. Multiple physicochemical properties endow LDHs with excellent merits in biomedical applications. Moreover, LDH nanoplatforms could serve as "molecular switches", which are capable of the controlled release of payloads under specific physiological pH conditions but are stable during circulation in the bloodstream. In addition, LDHs themselves are composed of several specific cations and possess favorable biological effects or regulatory roles in various cellular functions. These advantages have caused LDHs to become increasingly of interest in the area of nanomedicine. Recent efforts have been devoted to revealing the potential factors that interfere with the biological pathways of LDH-based nanoparticles, such as their applications in shaping the functions of immune cells and in determining the fate of stem cells and tumor treatments, which are comprehensively described herein. In addition, several intracellular signaling pathways interfering with by LDHs in the above applications were also systematically expatiated. Finally, the future development and challenges of LDH-based nanomedicine are discussed in the context of the ultimate goal of practical clinical application.

O-057 The pregnant outcome after laparoscopy treatment for subtle distal fallopian tube abnormalities in infertile population: a prospective cohort study

Study question

What is the the pregnancy outcome after laparoscopy treatment for subtle distal fallopian tube abnormalities and the factors related with natural pregnancy.

Summary answer

The natural pregnancy rate is 46.58% after laparoscopy and patients' age, duration time of infertility and concurrent number of abnormalities are related with natural pregnancy.

What is known already

Subtle distal fallopian tube abnormalities are a group of diseases that are characterized by subtle variations in tubal anatomy including fimbrial agglutination, tubal diverticula, accessory ostium, fimbrial phimosis, and accessory fallopian tube. The prevalence of subtle distal fallopian tube abnormalities is high in infertile women.This group of diseases is highly related to endometriosis, especially its early stage, and may indicate fimbrial abnormalities in endometriosis.

Study design, size, duration

This was a prospective cohort study conducted in the Reproductive Medicine Center of an university-affiliated teaching hospital from January 2017 to December 2018.

Participants/materials, setting, methods

234 patients with subtle distal fallopian tube abnormalities were included. Laparoscopies were performed by four senior reproductive surgeons who were familiar with the diagnostic criteria and surgery treatment for subtle abnormalities. The fallopian tube abnormalities were corrected and endometriosis was treated by either electrical ablation for peritoneal lesions or endometrioma excision.The participants were followed up by phone every 12 months for pregnancy outcome until 36 months after surgery.

Main results and the role of chance

167 patients conceived after surgery(clinical pregnancy rate 71.37%). 109 patients conceived naturally (natural pregnancy rate 46.58%) and 59 patients conceived after in IVF（One case conceived naturally after live birth after IVF, four cases conceived naturally twice) . The average time for natural conception after surgery is 8.36±7.47 months. 51.4% of natural pregnancy occurred within 6 months and 79.8% occurred within 12 months.Among the 109 naturally conceived patients, there were 94 cases of live birth, 13 cases of natural abortion (natural abortion rate 11.92%) and 2 cases of ectopic pregnancy (ectopic pregnancy rate 1.83%). No preterm birth, multiple pregnancy or birth defects were reported in this group.The patient age(HR = 0.917,95%CI 0.870-0.917,P=0.001), duration of infertility(HR = 0.846,95%CI 0.740-0.966,P=0.014) and concurrent number of subtle abnormalities (HR = 0.636,95%CI 0.416-0.970,P=0.036) are the factors associated with natural pregnancy. The type of subtle abnormalities, type of infertility, body mess index, concurrent endometriosis, uterine cavity abnormalities and myoma are not related with natural pregnancy.

Limitations, reasons for caution

Not all kinds of subtle distal abnormalities are included such as paratubal cyst is excluded from the study. Not all the patients had the test of ovarian reserve such as AMH, antral follicle count and FSH level, so we couldn’t evaluate the relationship between ovarian reserve and natural pregnancy.

Wider implications of the findings

This is the largest clinical study that investigated the pregnancy outcome of subtle fallopian tube abnormalities in the infertile population.Laparoscopy surgery is an effective treatment for infertility patients with subtle distal fallopian tube abnormalities, especially for the young, short duration time of infertility and ≤2 types of subtle abnormalities.

Trial registration number

ChiCTR2000029095

Layered Double Hydroxide Nanoparticles with Osteogenic Effects as miRNA Carriers to Synergistically Promote Osteogenesis of MSCs

Inefficient differentiation and poor engraftment hinder the clinical applications of mesenchymal stem cell (MSC)-based cell therapies in regenerative medicine. Layered double hydroxide (LDH) nanoparticles are sheet-like materials with desirable biocompatibility and anion-exchange properties and have been widely applied as drug and nucleotide carriers in the field of tissue repair. However, few studies have focused on the biological effects of LDH itself. In this study, we demonstrated the novel function of LDH in stimulating osteogenic differentiation of bone marrow-derived MSCs (BMSCs). The expression of osteogenic-related genes, alkaline phosphatase (ALP) activity, and calcium deposits were significantly increased after LDH treatment. Mechanistic analysis performed with RNA sequencing revealed that LDH promoted osteogenesis by targeting the LGR5/β-catenin axis. LDH also inactivated IKK/NF-κB signaling under LPS-triggered inflamed conditions, suggesting the dual benefits of LDH in enhancing bone regeneration and alleviating the inflammatory response. Furthermore, we utilized LDH as the transport vehicle of the osteoinductive miRNA let-7d to synergistically regulate BMSCs toward the osteoblastic lineage. The LDH/let-7d complex resulted in a better induction of osteogenesis than LDH alone. For cell transplantation, BMSCs were seeded in LDH/let-7d-incorporated fibrin scaffolds, which proved enhanced osteoinduction capability in the subcutaneous ectopic osteogenesis model in nude mice. Taken together, this study provides a novel strategy for effective and synergistic improvement of osteogenesis via LDH-mediated delivery of miRNA let-7d, thus shedding light on the future application of LDH in regenerative medicine.

Multifunctional silica nanocomposites prime tumoricidal immunity for efficient cancer immunotherapy

The tumor immune microenvironment (TIME) has been demonstrated to be the main cause of cancer immunotherapy failure in various malignant tumors, due to poor immunogenicity and existence of immunosuppressive factors. Thus, establishing effective treatments for hostile TIME remodeling has considerable potential to enhance immune response rates for durable tumor growth retardation. This study aims to develop a novel nanocomposite, polyethyleneimine-modified dendritic mesoporous silica nanoparticles loaded with microRNA-125a (DMSN-PEI@125a) to synergistically enhance immune response and immunosuppression reversion, ultimately generating a tumoricidal environment. Our results showed that DMSN-PEI@125a exhibited excellent ability in cellular uptake by murine macrophages and the cervical cancer cell line TC-1, repolarization of tumor associated macrophages (TAMs) to M1 type in a synergistic manner, and promotion of TC-1 immunogenic death. Intratumor injection of DMSN-PEI@125a facilitated the release of more damage-related molecular patterns and enhanced the infiltration of natural killer and CD8⁺ T cells. Meanwhile, repolarized TAMs could function as a helper to promote antitumor immunity, thus inhibiting tumor growth in TC-1 mouse models in a collaborative manner. Collectively, this work highlights the multifunctional roles of DMSN-PEI@125a in generating an inflammatory TIME and provoking antitumor immunity, which may serve as a potential agent for cancer immunotherapy.

Layer-Number-Dependent Effects of Graphene Oxide on the Pluripotency of Mouse Embryonic Stem Cells Through the Regulation of the Interaction Between the Extracellular Matrix and Integrins

Introduction

Embryonic stem cells (ESCs) possess great application prospects in biological research and regenerative medicine, so it is important to obtain ESCs with excellent and stable cellular states during in vitro expansion. The feeder layer culture system with the addition of leukemia inhibitory factor (LIF) is currently applied in ESC cultures, but it has a series of disadvantages that could influence the culture efficiency and quality of the ESCs. With the development of nanotechnology, many studies have applied nanomaterials to optimize the stem cell culture system and regulate the fate of stem cells. In this study, we investigated the layer-number-dependent biofunction of graphene oxide (GO) on the pluripotency of ESCs from mice (mESCs).

Methods

Single-layer GO (SGO) and multi-layer GO (MGO) were characterized and their effects on the cytotoxicity and self-renewal of mESCs were detected in vitro. The differentiation potentials of mESCs were identified through the formation of embryoid bodies and teratomas. The regulatory mechanism of GO was verified by blocking the target receptors on the surface of mESCs using antibodies.

Results

Both SGO and MGO were biocompatible with mESCs, but only MGO effectively sustained their self-renewal and differentiation potential. In addition, GO influenced the cellular activities of mESCs by regulating the interactions between extracellular matrix proteins and integrins.

Conclusion

This work demonstrates the layer-number-dependent effects of GO on regulating the cell behavior of mESCs and reveals the extracellular regulatory mechanism of this process.

Layered double hydroxide eliminate embryotoxicity of chemotherapeutic drug through BMP-SMAD signaling pathway

Recent studies indicate that exogenous chemotherapy agents can cross the placenta barrier and cause fetal toxicity, while there exists barely alternative therapy for pregnant cancer patients. Here, we show a robust protective effect of layered double hydroxide (LDH) against etoposide (VP16) induced in vitro mouse embryonic stem cells (mESCs) toxicity and in vivo embryo developmental disorders. The nano-composite system (L-V) abrogated the original VP16 generated mitochondrial mediated mESCs toxicity totally, surprisingly maintained the pluripotency without leukemia inhibitory factor (LIF) and prevented the down-regulation of ectoderm marker expression during spontaneous embryoid bodies differentiation. Fetal growth retardation, the related placenta and skeletal structural abnormalities and long-term toxicity in the offspring were generated when pregnant mice exposed to VP16, while these detrimental effects were abolished when substituted with L-V. The different uterine drug accumulation of VP16 and L-V contributed to partly cause for the functional variation. And further transcriptome analysis confirmed developmental related BMP4-SMAD6 signaling pathway is of crucial importance. Our study revealed the devastating effects of VP16 on embryonic development and the toxicity-relieve method using nano-carrier system, which will provide important guidance for clinical application of LDH as alternative therapeutic system with minimal side effects for pregnant women diagnosed with cancer.

[A cohort study on the association between dietary patterns which benefit for normal kidney function and the cognitive performance in the Chinese elderly]

Objective: To explore the association between dietary pattern which benefit for normal kidney function and the risk of cognitive decline or impairment in the elderly. Methods: In 2015, subjects aged 60 and over from four counties in the Nutrition and Chronic Disease Family Cohort project, were followed up in 2017. Cognitive function was repeatedly assessed, using the Mini Mental State Evaluation (MMSE) scale. Dietary pattern that benefit for normal kidney function was extracted, using the reduced rank regression method and followed by logistic regression models to explore the associations between scores that showing the kidney function on dietary patterns and the risk of cognitive deterioration and impairment in two years among those who were with normal cognition in 2015. Results: Dietary pattern that benefit for normal kidney function, was characterized by high consumption of cereal, vegetables, legume and fruits but with less meat and soy products. Comparing with the group with lowest score quartile on this dietary pattern, the risk of cognitive deterioration in the highest quartile group was significantly low (P<0.01) in two years, with an odds ratio as 0.57 (95%CI: 0.37-0.85). Linear trend was also obviously visible (P=0.007) in this group. The ones at the highest quartile group among the normal cognition ones in 2015, the risk of cognitive impairment also significantly reduced (P<0.05) in two years time, with an odds ratio as 0.52 (95%CI: 0.29-0.93). Also, linear trend could obviously be seen (P=0.01). Conclusion: Dietary pattern that benefit for normal kidney function was both inversely associated with cognitive deterioration and impairment, in two years.

Mouse Avatar Models of Colorectal Cancer Liver Metastasis: The Molecularly Annotated Platforms for Preclinical Evaluation of Novel Therapeutics

Background: Liver is the most common metastatic site in advanced colorectal cancer. Most patients with colorectal cancer liver metastasis (CRLM) could not benefit from the current treatment. Patient-derived xenograft (PDX) models with definite molecular signature are attractive preclinical models and essential for development of novel drugs. Aim: This study was designed to focus on the establishment, characterization of pathologic and molecular features of PDX models. Furthermore, we also validate potential therapeutic targets and explore novel drug therapies guided by genotyping or expression profiling, leading to potential implications for precision medicine. Methods: CRLM PDX models were established and elucidated their possible implications for preclinical research and personalized treatment from their fidelity of clinicopathologic characteristics, genomic landscape, and antitumor activities of novel targeted drugs. Response biomarkers were also explored. Results: A total of 56 PDX models from CRLM were successfully established (transplantation success 76.7%, 56/73). The transplantation rate was higher than that of primary specimens (61.5%, 16/26). No differences were observed between latency period and characteristics except the level of CEA. Along with the passaging, latency period became shorter and shorter. PDXs from CRLM recapitulated the pathologic, genetic, and protein properties of corresponding parental tumors. Frequent altered genes showed high consistency compared with patients' genomic alterations, and were enriched in MAPK, ErbB, cell cycle, focal adhesion, adherence junction pathways. Several potential drug targets, such as KRAS, HER2 and FGFR2, were selected and validated by corresponding inhibitors. In addition, PDX models could also used for patients with no druggable alterations identified to screen the efficient regimen. Conclusion: In this study, we have successfully established and validated a large panel of molecularly annotated CRLM platforms for preclinical evaluation of novel therapeutics and biomarker discovery.

Suspended graphene oxide nanosheets maintain the self-renewal of mouse embryonic stem cells via down-regulating the expression of Vinculin

Graphene oxide (GO), with good hydrophilicity and biocompatibility, is widely explored as a carrier for various factors in the field of stem cell differentiation. However, its function of sustaining the stemness of mouse embryonic stem cells (mESCs) and the underlying mechanisms of this process remains undiscovered. Herein, we explored the biofunction of GO on mESCs and revealed the involved signaling pathways and key gene. The alkaline phosphatase activity detection, pluripotency genes quantification and the teratomas formation in vivo confirmed that GO nanosheets could sustain the self-renewal ability of mESCs instead of influencing its pluripotency. The underlying signaling pathways were uncovered by RNA-seq that integrin signaling pathway was involved in the biofunction of GO on mESCs and Vinculin turned to be a key gene for the effect of GO. Further experiments confirmed that the downregulation of Vinculin influenced the fate of mESCs through decreasing the expression of MEK1. Altogether, the study demonstrated for the first time that GOs hold the potential in sustaining the self-renewal of mESCs and clarified the mechanism of this function, which make it play a new role in stem cell research and regenerative medicine.

Antidepressant effects of curcumin and HU-211 coencapsulated solid lipid nanoparticles against corticosterone-induced cellular and animal models of major depression

Major depression is a complex neuropsychiatric disorder with few treatment approaches. The use of nontargeted antidepressants induced many side effects with their low efficacy. A more precise targeting strategy is to develop nanotechnology-based drug delivery systems; hence, we employed solid lipid nanoparticles (SLNs) to encapsulate HU-211 and curcumin (Cur). The antidepressant effects of the dual-drug nanoparticles (Cur/SLNs-HU-211) for major depression treatment were investigated in corticosterone-induced cellular and animal models of major depression. Cur/SLNs-HU-211 can effectively protect PC12 cells from corticosterone-induced apoptosis and can release more dopamine, which may be associated with the higher uptake of Cur/SLNs-HU-211 shown by cellular uptake behavior analysis. Additionally, Cur/SLNs-HU-211 significantly reduced the immobility time in forced swim test, enhanced fall latency in rotarod test, and improved the level of dopamine in mice blood. Cur/SLNs-HU-211 can deliver more Cur to the brain and thus produce a significant increase in neurotransmitters level in brain tissue, especially in the hippocampus and striatum. The results of Western blot and immunofluorescence revealed that Cur/SLNs-HU-211 can significantly enhance the expression of CB1, p-MEK1, and p-ERK1/2. Our study suggests that Cur/SLNs-HU-211 may have great potential for major depression treatment.

Interferon-α-2b as an adjuvant therapy prolongs survival of patients with previously resected oral muscosal melanoma

Two major subtypes of melanoma include cutaneous melanoma and mucosal melanoma. The latter type is rare and usually occurs in the head and neck region. High-dose interferon-α-2b (IFN-α-2b) has proven effective in the treatment of cutaneous melanoma. Recently, a regimen of temozolomide plus cisplatin was reported more likely to improve relapse-free survival and overall survival than high-dose IFN-α-2b for mucosal melanoma. We conducted this study to analyze the therapeutic effect of high-dose IFN-α-2b for patients with oral mucosal melanoma who had received prior chemotherapy. One hundred and seventeen patients with stage III-IVa oral mucosal melanoma who had received chemotherapy were analyzed. The overall survival and relapse-free survival were compared between the patients with/without high-dose IFN-α-2b. The results indicate that the IFN-α-2b treatment group had a longer relapse-free survival rate (P = 0.0169) as compared to the control group. However, the overall survival was not significant between the two groups (P = 0.096), except in patients in stage IVa, whose overall survival increased by 20 months (P = 0.0146). The adverse reactions included a drug-induced influenza-like syndrome, gastrointestinal responses, myelosuppression, and hepatoxicity, which were predominantly of grade 1-2 and reversible. Thus, patients with resected oral mucosal melanoma, even those who have received chemotherapy, could benefit from the treatment of high-dose IFN-α-2b.

Drying of colloidal suspensions and polymer solutions near the contact line: deposit thickness at low capillary number

Drying experiments with a receding contact line have been performed with silica colloidal suspensions and polyacrylamide (PAAm) polymer solutions. The experimental setup allows to control the receding movement of the contact line and the evaporation flux separately. Deposit thickness as a function of these two control parameters has been investigated. The different systems exhibit a similar behavior: in the regime of very low capillary numbers the deposit thickness scaled by the solute volume concentration and the evaporation rate is proportional to the inverse of the contact line velocity. Both the scaling exponent and the constant (which has the dimension of a length) do not depend on the system under study. The observation of this evaporative regime confirms some recent results obtained by Le Berre et al. on a very different system (phospholipidic molecules) and fully supports their interpretation. Following their approach, a simple model based on mass balance accounts for these results. This implies that this regime is dominated by the evaporation and that the deformation of the meniscus induced by viscous forces does not play any significant role. When increasing the velocity, another regime is observed where the thickness does not depend significantly on the velocity.

Left atrial myxoma presenting with erythematous macules and loss of memory

Left atrial myxoma was diagnosed in a 42-year-old woman who had cutaneous and neurological manifestations without cardiac symptoms or signs. A two-dimensional echocardiogram revealed an orange-sized mobile mass in the left atrium. Magnetic resonance imaging showed multiple cerebral infarctions. Cardiac surgery for removal of the left atrial myxoma was successful and histopathology confirmed myxoma. Cutaneous and neurological manifestations were improved after the operation. Early surgical intervention may prevent the onset of severe neurological deficits in such patients.

Conformational and functional significance of residue proline 17 in chicken muscle adenylate kinase

The effect of mutation proline 17 on the multiple conformations and catalytic function in chicken muscle adenylate kinase (AK) has been studied. The substitution of proline 17 with glycine or valine altered the distribution of multiple conformations. Compared with the wild-type enzyme, the P17G and P17V mutants contained decreased fraction of minor conformer from 18% to 9% and 11%, respectively. Due to the mutation, the enzyme showed lower secondary structural content, poorer affinity to substrates or substrate analogues, and reduced catalytic efficiency. The results revealed the significance of proline 17 in the conformation and function of AK.

Probing the conformational state of a truncated staphylococcal nuclease R using time of flight mass spectrometry with limited proteolysis

The conformational state of C-terminally truncated staphylococcal nuclease R (SNR135), with and without bound ligands, has been studied by performing limited proteolysis with a specific endoproteinase Glu-C followed by electrophoresis and mass spectrometry. Comparison of the accessibility of the cleavage sites shows that the C-terminal truncation of 14 amino-acid residues causes significant unfolding of the C-terminal part of alpha helix 1 and the center of alpha helix 2, but there is little effect on other regions of the nuclease, in particular the N-terminal subdomain, which includes the active site of the nuclease. The truncation also makes the overall conformation of the nuclease more loose and flexible. Binding of ligands makes helices 1 and 2 more resistant to protease Glu-C attack and converts the partially unfolded state to a native-like state, although the conformational stability of the SNR135 complex is still much lower than that of the full-length enzyme. The results suggest that the amino-acid residues around the active site in the truncated nuclease are arranged in a similar topology to those in the full-length nuclease. The study shows that there is a clear-cut correlation between protease susceptibility and conformational stability of the protein, and the initial proteolytic events are the most critical for evaluating the conformational features of the protein. This study demonstrates how mass spectrometry can be combined with limited proteolysis to observe conformational changes induced by ligand binding.

N-methyl-D-aspartate receptor activation results in regulation of extracellular signal-regulated kinases by protein kinases and phosphatases in glutamate-induced neuronal apototic-like death

Extracellular signal-regulated kinases (ERK1/ERK2) have been shown transiently activated and involved in excitotoxicity. We searched for upstream molecules responsible for the regulation of glutamate-induced ERK1/ERK2 activation and ERK1/ERK2-mediated apototic-like death in cultured rat cortical neurons. ERK1/ERK2 activation (monitored by anti-active ERK1/ERK2 antibody) was almost completely prevented by blockage of NMDA receptor (NMDA-R) or elimination of extracellular Ca(2+), but not any other glutamate receptor or L-type voltage-gated Ca(2+) channel. It was prevented largely by inhibition of protein kinase C (PKC), protein-tyrosine kinases (PTK), respectively, but mildly by that of CaM kinase II. Combined inhibition of CaM kinase II (but not PTK) and PKC had an additive effect. Reversion of ERK1/ERK2 activation was largely prevented by inhibition of protein phosphatase (PP) 1 or protein tyrosine phosphatase (PTP). Combined inhibition of PP 1 and PTP had no additive effect. Glutamate-induced apoptotic-like death (determined by DAPI staining) was largely prevented by inhibition of NMDA-R, PKC, CaM kinase II, PTK and MEK1/MEK2 (ERK1/ERK2 kinase), respectively. Combined inhibition of CaM kinase II (but not PKC or PTK) and MEK1/MEK2 had an additive effect. Glutamate-induced apoptotic-like death was promoted by inhibition of PP1 and PTP, respectively. The above results suggested that in glutamate-induced cortical neurotoxicity ERK1/ERK2 activation be mainly mediated by NMDA-R. Subsequently, a pathway dependent on both PKC and PTK was mainly involved, which was also mainly responsible for ERK1/ERK2-mediated apoptotic-like death, and a CaM kinase II-dependent pathway was relatively mildly involved. Reversion of ERK1/ERK2 activation was mainly mediated by a pathway dependent on both PP1 and PTP, which might be involved in the restrain of glutamate-induced neurotoxicity.

Double point mutant F34W/W140F of staphylococcal nuclease is in a molten globule state but highly competent to fold into a functional conformation

The double point mutant F34W/W140F of staphylococcal nuclease was created and then characterized by far and near-UV CD, size-exclusion chromatography, ANS-binding fluorescence. The results show that this mutant has properties consistent with the classical definition of a molten globule, i.e., substantial secondary structure but no unique tight packing of tertiary structure, a relatively compact size and a larger exposed hydrophobic surface area as compared with the wild type enzyme, indicating that a molten globule can occur under physiological conditions. However, the activity assay showed that the mutant still maintains wild-type levels of activity. To further clarify the mechanism of the substrate-induced reactivation, enzymatic parameters such as K(M)(DNA), K(S)(DNA), K(M)(Ca), K(A)(Ca), K(d)(pdTp), and V(max) were determined, showing that all the parameters of this mutant are similar to those of the wild type enzyme. The results indicate that the F34W/W140F mutant has a similar substrate affinity to the wild type enzyme, and the functional conformation can be restored by substrate binding, which corresponds to the conformational adjustment capability of the mutant upon binding to ligands pdTp and Ca(2+). The severely disrupted tertiary structure and high activity of the mutant indicate that it is highly competent to fold to its functional conformation. The results suggest that the primary structure can only guide the mutant to a molten globule state and that ligand-binding causes the mutant to fold further into its functionally active conformation, indicating that ligand-binding plays an important role in protein folding and catalysis.

Tryptophan 140 is important, but serine 141 Is essential for the formation of the integrated conformation of staphylococcal nuclease

A series of N-terminal fragments of staphylococcal nuclease with different chain lengths has been taken as an in vitro nascent peptide folding model. Previous studies have shown that nascent peptide folding of the nuclease may begin early in the synthetic process with the content of ordered secondary structure increases with increasing peptide chain length, and that conformational adjustments are observed at certain stages during nascent peptide folding. Here, we focus attention on the conformational changes in the later stage of nascent peptide folding of the nuclease when the N-terminal fragment elongates nearly to the C-terminus of the nuclease in order to determine the role of the C-terminal region of the nuclease in the formation of the integrated conformation of the nuclease. We compared the conformational features of SNase R and its larger N-terminal fragments SNR135, SNR139, SNR140, and SNR141 using circular dichroism spectra, ANS-binding fluorescence and intrinsic fluorescence spectra. The results show that Trp140 is important for the enrichment of ordered secondary structure and for producing a greater ability to fold into a native-like conformation, but Ser141 is essential for the formation of the integrated conformation of the nuclease with a tightly packed tertiary structure. Note that the addition of only one residue to the C-terminus of elongating peptide chain can cause a dramatic change in conformation. The data also show the occurrence of continuous adjustments in conformation during peptide elongation, even after a rigid tertiary structure has formed, suggesting that the last eight residues (residues 142-149), which are disordered at the C-terminus of the nuclease, also possess a structural role, forming the native tertiary structure to provide a framework for the active site, even though they are remote from the active site in both sequence and spatial structure.

Interactions between subdomains in the partially folded state of staphylococcal nuclease

Staphylococcal nuclease can be roughly divided into a beta-subdomain in N-terminal and an alpha-subdomain in C-terminal. They fold sequentially under certain conditions, causing a partially folded intermediate state in which the native-like beta-barrel persists while alpha-helix regions largely disorder. To investigate the possible long-range interactions between the two subdomains in the intermediate, N-terminal fragments have been used as intermediate analogues, with polypeptide ending at positions 102, 110, 121 and 135 and with a tryptophan substitution at position 66 or 88 to facilitate the observation of the beta-barrel. Segment-resolved interactions between beta-barrel and residues 103-135 were identified by comparing their spectroscopic properties of fluorescence, circular dichroism and NMR and by their stability. Except for unstable V66W102, the guanidine and thermal denaturation of fragments are cooperative and well approximated by the two-state transition. Minimal stable structure units of both tryptophan-containing fragments comprise residues 1-110. With the main interaction in segment 103-135, residues 103-110 contribute approximate 2 kcal/mol to the stability. Elongation of C-terminal from 110 residue neither increases the stability nor alters the structure core of the G88W fragments. However, residues 111-121 influence the tertiary structure of the V66W fragments suggesting its minor interactions with beta-barrel.

Diphosphorylation and involvement of extracellular signal-regulated kinases (ERK1/2) in glutamate-induced apoptotic-like death in cultured rat cortical neurons

Glutamate-induced excitotoxicity, with certain characteristics of apoptosis, has been implicated in a variety of neuronal degenerative disorders. In some physiological cases, extracellular signal-regulated kinases (ERK1/2) are activated by stimulation of glutamate receptors. In the present study, the activation (diphosphorylation) and role of ERK1/2 in glutamate-induced apoptotic-like death in cultured cortical neurons were investigated. Protein levels and activation (diphosphorylation) levels of ERK1/2 were examined by Western immunoblot, probed with anti-ERK1/2 and anti-active (diphosphorylated) ERK1/2 antibodies, respectively. Apoptotic-like death was determined by DAPI staining. Before a remarkable increase of apoptotic-like cell death was observed at 9-18 h after 15 min exposure to 50 microM glutamate, diphosphorylation levels of ERK1/2 were rapidly increased, peaked at 5-15 min of the exposure, and reverted to sham control level 3 h after the exposure, while the protein levels of ERK1/2 were unaffected. The glutamate concentration effective for inducing apoptotic-like cell death was correlated with that for inducing ERK1/2 diphosphorylation. Both ERK1/2 diphosphorylation and the apoptotic-like cell death were largely prevented by MK-801, a specific NMDA receptor (a subtype receptor of glutamate) antagonist, or the elimination of extracellular Ca(2+) with EGTA. PD98059, a specific inhibitor of ERK1/2 kinase, completely inhibited ERK1/2 diphosphorylation and partially inhibited the apoptotic-like cell death. These results suggest that largely via NMDA receptor-mediated influx of extracellular Ca(2+), ERK1/2 were rapidly and transiently activated and were involved in glutamate-induced apoptotic-like death in cultured rat cortical neurons.

An in vitro peptide folding model suggests the presence of the molten globule state during nascent peptide folding

Although molten globules have been widely accepted as a general intermediate in protein folding, there is no clear evidence to show their presence during nascent peptide folding. This paper concentrates on whether the molten globule state occurs, and if it does, when does it form during nascent peptide folding, by comparing the changes in conformation during peptide chain extension of staphylococcal nuclease R. The results show that a large N-terminal fragment of staphylococcal nuclease, SNR121, which already contains more than 80% amino acid sequence of the nuclease, is found to fulfill all the criteria for the molten globule state, suggesting that the molten globule should occur at a later stage of peptide elongation. At this stage the hydrophobic collapse of the polypeptide chain occurs driven by the hydrophobic force, which leads to the formation of a solvent-accessible non-polar core, characterized by the high ANS-binding fluorescence. The nascent peptide folding of the nuclease is a hierarchical process that at the very least includes the following steps: secondary structure accumulation, pre-molten globule state, molten globule state, post-molten globule state and finally the native state. Constant conformation adjustment is necessary for correct folding and active expression of the protein.

Folding of SNase R begins early during synthesis: the conformational feature of two short N-terminal fragments of staphylococcal nuclease R

To further understand the folding of nascent peptide during the early course of peptide synthesis, two short N-terminal fragments of staphylococcal nuclease R (SNase R), SNR52 and SNR79, were made by deleting 97 and 70 amino acid residues from the C-terminus. The conformations of SNR52 and SNR79 were studied by FTIR and far-ultraviolet CD. The results demonstrate that even the short N-terminal fragments of SNase R still have a certain amount of residual ordered secondary structure in the physiological condition. The ordered secondary structures were mainly assigned as beta-strands and turns, which corresponds well to the structures of the N-terminal part in the native protein. The conformational changes during unfolding and refolding in different concentrations of guanidine hydrochloride (GuHCl), monitored by far-ultraviolet CD and intrinsic fluorescence, show that the interaction between amino acid residues, which governs the formation of their conformation are not random. Considered together with earlier studies (Jing et al., Biochim Biophys Acta 1995;1250:189-196; Zhou et al., J Biochem 1996:120: 881-888), the results suggest that the folding of nascent peptide chains begins early in the synthesis process and that the amount of ordered structure increases with increasing peptide chain length until the conformation of the biologically active protein is generated.

Monoclonal antibody, a novel probe for protein folding

Two monoclonal antibodies (McAb2C9, McAb1E5) against Staphylococcal nuclease R (SNase R) and its N-terminal peptide fragments were prepared, purified and characterized. Further studies show that the intact enzyme SNase R and its seven N-terminal peptide fragments differ in their interaction with McAb2C9. SNase R, SNR121, SNR102, SNR79 and SNR52 can bind to McAb2C9 readily, while fragments of SNR141, SNR135, SNR110 react with the antibody poorly. If this difference is due to diverse extent of exposure of the specific epitope in the fragments, it is suggested that the conformation of the peptide is subjected to continuous adjustments through chain elongation until the biologically active protein is formed. This result supports Tsou's hypothesis of nascent peptide folding experimentally.

Resolution of proteins on a phenyl-Superose HR5/5 column and its application to examining the conformation homogeneity of refolded recombinant staphylococcal nuclease

In order to examine the effect of amino acid substitutions on protein retention in hydrophobic interaction chromatography and the resolution of a phenyl-Superose HR5/5 column, two groups of staphylococcal nucleases, named Y113/W140 (wild-type), Y113W/W140 and Y113/W140F, Y113W/W140F, were produced by substituting tryptophan (W) for tyrosine (Y) at residue 113 and phenylalanine (F) for tryptophan (W) at residue 140. For each group, the proteins have the same amino acid at residue 140, but a different amino acid at residue 113. The solvent perturbation of nuclease fluorescence and 1,8-anilinoaphthalene-8-sulfonate binding studies showed that the substitutions do not change the side-chain positions of amino acids at residues 113 and 140. Chromatography of the proteins on the Phenyl-Superose HR5/5 column showed that the proteins with tryptophan at residue 113 have longer retention times than the proteins having tyrosine at residue 113; the proteins with the same amino acid at residue 113 have almost the same retention time regardless of substituting phenylalanine for tryptophan at residue 140. The studies clearly indicate that not all amino acid substitutions have an effect on protein retention; the contribution to retention of a given amino acid substitution depends on its position in a protein. Single amino acid substitutions at the exterior surface of a protein, which change the strength of hydrophobic interaction, can affect the protein retention in hydrophobic interaction chromatography. Staphylococcal nuclease and its mutants with only one amino acid difference on their surfaces can be discriminated by the phenyl-Superose column.(ABSTRACT TRUNCATED AT 250 WORDS)

Cetirizine does not influence the immune response

Antihistamines are frequently employed in the treatment of allergic rhinitis and urticaria-angioedema syndrome. We analyzed the in vitro effects of cetirizine on the immune response. To this end the proliferation of peripheral mononuclear cells induced by mitogen and by -CD3, -CD2, or -CD28 monoclonal antibodies has been studied. Since the plasma peak of cetirizine following ingestion of 10 mg is about 1 microgram/mL, the drug was tested in the cultures at the concentration of 0.1, 1, or 10 micrograms/mL. No influence of cetirizine on T cell proliferation was detected. We also evaluated the effect of cetirizine on the expression of the following markers expressed by T cells upon activation: lymphocyte markers ICAM-1, HLA-DR, and CD25 surface expression, alpha-1-acid glycoprotein has been also studied. There was no effect of cetirizine on the investigated immunologic parameters; these data acquire clinical relevance when related to previous reports showing a depression of the immunologic response exerted by other compounds such as ketotifen and theophylline and when related to the recent data about the modulation of ICAM-1 expression on eosinophils by cetirizine. Cetirizine does not affect ICAM-1 expression of lymphocyte membrane.

High-level expression of staphylococcal nuclease R gene in Escherichia coli

Staphylococcal nuclease R, an analogue of nuclease A, was overproduced under the transcriptional control of the bacteriophage lambda PRPL promoters regulated by temperature sensitive repressors. The expression level reached 200-300 mg l-1 and showed little host dependence in different strains. The investigations of the recombinant nuclease R have revealed that the amino terminal formyl methionine residue of the nuclease is precisely processed, the protein consists of 155 amino acid residues. The experiment shows that the pBV221-DH5 alpha is a quite suitable vector-host system for high-level expression and precise processing of heterologous genes in Escherichia coli. The comparative studies between the codons used in the staphylococcal nuclease R gene and the optimal codon usage in E. coli indicate that high level expression of heterologous genes in E. coli may not always require a high degree of codon usage bias.