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.

Regulation of Mitochondrial Respiration by Hydrogen Sulfide

Hydrogen sulfide (H2S), the third gasotransmitter, has positive roles in animals and plants. Mitochondria are the source and the target of H2S and the regulatory hub in metabolism, stress, and disease. Mitochondrial bioenergetics is a vital process that produces ATP and provides energy to support the physiological and biochemical processes. H2S regulates mitochondrial bioenergetic functions and mitochondrial oxidative phosphorylation. The article summarizes the recent knowledge of the chemical and biological characteristics, the mitochondrial biosynthesis of H2S, and the regulatory effects of H2S on the tricarboxylic acid cycle and the mitochondrial respiratory chain complexes. The roles of H2S on the tricarboxylic acid cycle and mitochondrial respiratory complexes in mammals have been widely studied. The biological function of H2S is now a hot topic in plants. Mitochondria are also vital organelles regulating plant processes. The regulation of H2S in plant mitochondrial functions is gaining more and more attention. This paper mainly summarizes the current knowledge on the regulatory effects of H2S on the tricarboxylic acid cycle (TCA) and the mitochondrial respiratory chain. A study of the roles of H2S in mitochondrial respiration in plants to elucidate the botanical function of H2S in plants would be highly desirable.

The transcription factor OsMYBc and an E3 ligase regulate expression of a K+ transporter during salt stress

Sodium (Na+) and potassium (K+) homeostasis is essential for plant survival in saline soils. A member of the High-Affinity K+ Transporter (HKT) family in rice (Oryza sativa), OsHKT1;1, is a vital regulator of Na+ exclusion from shoots and is bound by a MYB transcription factor (OsMYBc). Here, we generated transgenic rice lines in the oshkt1;1 mutant background for genetic complementation using genomic OsHKT1;1 containing a native (Com) or mutated (mCom) promoter that cannot be bound by OsMYBc. In contrast to wild-type (WT) or Com lines, the mCom lines were not able to recover the salt-sensitive phenotype of oshkt1;1. The OsMYBc-overexpressing plants were more tolerant to salt stress than WT plants. A yeast two-hybrid screen using the OsMYBc N-terminus as bait identified a rice MYBc stress-related RING finger protein (OsMSRFP). OsMSRFP is an active E3 ligase that ubiquitinated OsMYBc in vitro and mediated 26S proteasome-mediated degradation of OsMYBc under semi-in vitro and in vivo conditions. OsMSRFP attenuated OsMYBc-mediated OsHKT1;1 expression, and knockout of OsMSRFP led to rice salt tolerance. These findings uncover a regulatory mechanism of salt response that fine-tunes OsHKT1;1 transcription by ubiquitination of OsMYBc.

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

Seed specifically over-expressing DGAT2A enhances oil and linoleic acid contents in soybean seeds

Triacylglycerol (TAG), a main component of oil, is mainly biosynthesized by diacylglycerol acyltransferase (DGAT), which is critical for oil accumulation in plants. Intensive focus has been on DGAT2 functioning in unsaturated fatty acids biosynthesis. In this study, we analyzed the coding sequence (CDS) and amino acid sequence of GmDGAT2A and determined its key active sites through site-directed mutagenesis. As a consequence, H132, G201, and P152-X-I154-K155 were found to be essential active sites for GmDGAT2A. The spatial structure of the protein may bring the three active sites into close proximity, constituting an active domain. Additionally, N-terminus of GmDGAT2A was found to be an important regulator for the activity. Further, in vitro activity results uncovered GmDGAT2A was prone to utilize C18:2-CoA as the substrate. Consequently, overexpression of GmDGAT2A driven by a seed-specific promoter of Gmole1 in soybean significantly increased linoleic acid content specifically and total oil content, concomitant with accelerated elongation.

Interplay Among Hydrogen Sulfide, Nitric Oxide, Reactive Oxygen Species, and Mitochondrial DNA Oxidative Damage

Hydrogen sulfide (H2S), nitric oxide (NO), and reactive oxygen species (ROS) play essential signaling roles in cells by oxidative post-translational modification within suitable ranges of concentration. All of them contribute to the balance of redox and are involved in the DNA damage and repair pathways. However, the damage and repair pathways of mitochondrial DNA (mtDNA) are complicated, and the interactions among NO, H2S, ROS, and mtDNA damage are also intricate. This article summarized the current knowledge about the metabolism of H2S, NO, and ROS and their roles in maintaining redox balance and regulating the repair pathway of mtDNA damage in plants. The three reactive species may likely influence each other in their generation, elimination, and signaling actions, indicating a crosstalk relationship between them. In addition, NO and H2S are reported to be involved in epigenetic variations by participating in various cell metabolisms, including (nuclear and mitochondrial) DNA damage and repair. Nevertheless, the research on the details of NO and H2S in regulating DNA damage repair of plants is in its infancy, especially in mtDNA.

Overexpression of soybean GmPLDγ enhances seed oil content and modulates fatty acid composition in transgenic Arabidopsis

Phospholipase D (PLD) hydrolyzes the phosphodiester bond of glycerophospholipids to yield phosphatidic acid (PA) and a free headgroup. PLDs are important for plant growth, development, and responses to external stresses. However, their roles in triacylglycerol (TAG) synthesis are still unclear. Here, we report that a soybean (Glycine max) PLDγ (GmPLDγ) is involved in glycerolipid turnover and seed oil production. GmPLDγ was targeted to mitochondria and exhibited PLD activity that was activated by oleate and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]. Overexpression of GmPLDγ (abbreviated GmPLDγ-OE) in Arabidopsis thaliana resulted in enhanced seed weight, elevated levels of TAGs with 18-, 20-, and 22-carbon fatty acids (FAs), and altered oil-body morphology. Furthermore, the levels of membrane lipids in vegetative tissues decreased significantly, whereas no overt changes were found in mature seeds except for a decrease in the digalactosyldiacylglycerol (DGDG) level in the GmPLDγ-OE lines. Additionally, the expression of genes involved in glycerolipid metabolism was significantly upregulated in developing siliques in GmPLDγ-OE lines. Together, our data indicate a regulatory role for GmPLDγ in TAG synthesis and fatty-acid remodeling, highlighting the importance of mitochondria-directed glycerophospholipid homeostasis in seed oil accumulation.

Genome-wide analysis and functional characterization of Acyl-CoA:diacylglycerol acyltransferase from soybean identify GmDGAT1A and 1B roles in oil synthesis in Arabidopsis seeds

Acyl-CoA:diacylglycerol acyltransferase (DGAT) is a key enzyme in the Kennedy pathway of triacylglycerol (TAG) synthesis. It catalyzes the acyl-CoA-dependent acylation of sn-1, 2-diacylglycerol to form TAG. DGATs in soybean (Glycine max) have been reported, but their functions are largely unclear. Here we cloned three members of DGAT1 and four members of DGAT2 family from soybean, named GmDGAT1A to GmDGAT1C, and GmDGAT2A to GmDGAT2D, respectively. GmDGAT1A and GmDGAT1C were expressed at a high level in immature seeds, GmDGAT2B in mature seeds, and GmDGAT2C in older leaves. The seven genes were transformed into the H1246 quadruple mutant yeast strain, in which GmDGAT1A, GmDGAT1B, GmDGAT1C, GmDGAT2A, and GmDGAT2B had the ability to produce TAG. Six genes were transformed into Arabidopsis respectively, and constitutive expression of GmDGAT1A and GmDGAT1B resulted in an increase in oil content at the cost of reduced protein content in seeds. Overexpression of GmDGAT1A produced heavier weight of individual seed, but did not affect the weight of total seeds from a plant. Our results reveal the functions of soybean DGATs in seed oil synthesis using transgenic Arabidopsis. The implications for the biotechnological modification of the oil contents in soybeans by altering DGAT expression are discussed.

[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.

Effects of nitric oxide on mitochondrial oxidative defence in postharvest peach fruits

BACKGROUND

It has been confirmed that the accumulation of reactive oxygen species (ROS) in fruit can cause oxidative damage and nitric oxide (NO) can regulate the accumulation of ROS and the antioxidative defence of fruit. However, little is known about the roles of NO on the antioxidant system in mitochondria of fruit. In this study, Feicheng peach fruits were dipped with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) and NO solutions to explore the effects of NO on the membrane permeability transition and antioxidant system in mitochondria of peach fruit.

RESULTS

Treatment with 15 µmol L(-1) NO solution could delay the decrease of mitochondrial permeability transition and decrease the content of ROS in mitochondria. Besides, when the endogenous NO was scavenged by c-PTIO, the ROS in mitochondria increased greatly and superoxide dismutase activity decreased, while the content and activities of peroxidase and catalase changed slightly.

CONCLUSION

By delaying the decrease of mitochondrial permeability transition, 15 µmol L(-1) NO treatment could promote a more stable internal medium in mitochondria of Feicheng peach fruit. The increases in the activities of antioxidant enzymes in mitochondria caused by the remove of endogenous NO suggested that NO also plays an important role in the mitochondrial antioxidant system of Feicheng peach fruit.

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.