Azapeptides with unique covalent warheads as SARS-CoV-2 main protease inhibitors

The main protease (MPro) of SARS-CoV-2, the causative agent of COVID-19, is a pivotal nonstructural protein critical for viral replication and pathogenesis. Its protease function relies on three active site pockets for substrate recognition and a catalytic cysteine for enzymatic activity. To develop potential SARS-CoV-2 antivirals, we successfully synthesized a diverse range of azapeptide inhibitors with various covalent warheads to target MPro's catalytic cysteine. Our characterization identified potent MPro inhibitors, including MPI89 that features an aza-2,2-dichloroacetyl warhead with a remarkable EC50 value of 10 nM against SARS-CoV-2 infection in ACE2+ A549 cells and a selective index of 875. MPI89 is also remarkably selective and shows no potency against SARS-CoV-2 papain-like protease and several human proteases. Crystallography analyses demonstrated that these inhibitors covalently engaged the catalytic cysteine and used the aza-amide carbonyl oxygen to bind to the oxyanion hole. MPI89 stands as one of the most potent MPro inhibitors, suggesting the potential for further exploration of azapeptides and the aza-2,2-dichloroacetyl warhead for developing effective therapeutics against COVID-19.

Discovery of First-in-Class PROTAC Degraders of SARS-CoV-2 Main Protease

We have witnessed three coronavirus (CoV) outbreaks in the past two decades, including the COVID-19 pandemic caused by SARS-CoV-2. Main protease (MPro), a highly conserved protease among various CoVs, is essential for viral replication and pathogenesis, making it a prime target for antiviral drug development. Here, we leverage proteolysis targeting chimera (PROTAC) technology to develop a new class of small-molecule antivirals that induce the degradation of SARS-CoV-2 MPro. Among them, MPD2 was demonstrated to effectively reduce MPro protein levels in 293T cells, relying on a time-dependent, CRBN-mediated, and proteasome-driven mechanism. Furthermore, MPD2 exhibited remarkable efficacy in diminishing MPro protein levels in SARS-CoV-2-infected A549-ACE2 cells. MPD2 also displayed potent antiviral activity against various SARS-CoV-2 strains and exhibited enhanced potency against nirmatrelvir-resistant viruses. Overall, this proof-of-concept study highlights the potential of targeted protein degradation of MPro as an innovative approach for developing antivirals that could fight against drug-resistant viral variants.

Discovery of First-in-Class PROTAC Degraders of SARS-CoV-2 Main Protease

We have witnessed three coronavirus (CoV) outbreaks in the past two decades, including the COVID-19 pandemic caused by SARS-CoV-2. Main protease (M Pro ) is a highly conserved and essential protease that plays key roles in viral replication and pathogenesis among various CoVs, representing one of the most attractive drug targets for antiviral drug development. Traditional antiviral drug development strategies focus on the pursuit of high-affinity binding inhibitors against M Pro . However, this approach often suffers from issues such as toxicity, drug resistance, and a lack of broad-spectrum efficacy. Targeted protein degradation represents a promising strategy for developing next-generation antiviral drugs to combat infectious diseases. Here we leverage the proteolysis targeting chimera (PROTAC) technology to develop a new class of small-molecule antivirals that induce the degradation of SARS-CoV-2 M Pro . Our previously developed M Pro inhibitors MPI8 and MPI29 were used as M Pro ligands to conjugate a CRBN E3 ligand, leading to compounds that can both inhibit and degrade SARS-CoV-2 M Pro . Among them, MDP2 was demonstrated to effectively reduce M Pro protein levels in 293T cells (DC 50 = 296 nM), relying on a time-dependent, CRBN-mediated, and proteasome-driven mechanism. Furthermore, MPD2 exhibited remarkable efficacy in diminishing M Pro protein levels in SARS-CoV-2-infected A549-ACE2 cells, concurrently demonstrating potent anti-SARS-CoV-2 activity (EC 50 = 492 nM). This proof-of-concept study highlights the potential of PROTAC-mediated targeted protein degradation of M Pro as an innovative and promising approach for COVID-19 drug discovery.

A Systematic Survey of Reversibly Covalent Dipeptidyl Inhibitors of the SARS-CoV-2 Main Protease

SARS-CoV-2, the COVID-19 pathogen, relies on its main protease (MPro) for replication and pathogenesis. MPro is a demonstrated target for the development of antivirals for SARS-CoV-2. Past studies have systematically explored tripeptidyl inhibitors such as nirmatrelvir as MPro inhibitors. However, dipeptidyl inhibitors especially those with a spiro residue at their P2 position have not been systematically investigated. In this work, we synthesized about 30 dipeptidyl MPro inhibitors and characterized them on enzymatic inhibition potency, structures of their complexes with MPro, cellular MPro inhibition potency, antiviral potency, cytotoxicity, and in vitro metabolic stability. Our results indicated that MPro has a flexible S2 pocket to accommodate inhibitors with a large P2 residue and revealed that dipeptidyl inhibitors with a large P2 spiro residue such as (S)-2-azaspiro [4,4]nonane-3-carboxylate and (S)-2-azaspiro[4,5]decane-3-carboxylate have favorable characteristics. One compound, MPI60, containing a P2 (S)-2-azaspiro[4,4]nonane-3-carboxylate displayed high antiviral potency, low cellular cytotoxicity, and high in vitro metabolic stability.

An Azapeptide Platform in Conjunction with Covalent Warheads to Uncover High-Potency Inhibitors for SARS-CoV-2 Main Protease

Main protease (M _Pro ) of SARS-CoV-2, the viral pathogen of COVID-19, is a crucial nonstructural protein that plays a vital role in the replication and pathogenesis of the virus. Its protease function relies on three active site pockets to recognize P1, P2, and P4 amino acid residues in a substrate and a catalytic cysteine residue for catalysis. By converting the P1 Cα atom in an M _Pro substrate to nitrogen, we showed that a large variety of azapeptide inhibitors with covalent warheads targeting the M _Pro catalytic cysteine could be easily synthesized. Through the characterization of these inhibitors, we identified several highly potent M _Pro inhibitors. Specifically, one inhibitor, MPI89 that contained an aza-2,2-dichloroacetyl warhead, displayed a 10 nM EC ₅₀ value in inhibiting SARS-CoV-2 from infecting ACE2 ₊ A549 cells and a selectivity index of 875. The crystallography analyses of M _Pro bound with 6 inhibitors, including MPI89, revealed that inhibitors used their covalent warheads to covalently engage the catalytic cysteine and the aza-amide carbonyl oxygen to bind to the oxyanion hole. MPI89 represents one of the most potent M _Pro inhibitors developed so far, suggesting that further exploration of the azapeptide platform and the aza-2,2-dichloroacetyl warhead is needed for the development of potent inhibitors for the SARS-CoV-2 M _Pro as therapeutics for COVID-19.

A Systematic Survey of Reversibly Covalent Dipeptidyl Inhibitors of the SARS-CoV-2 Main Protease

SARS-CoV-2 is the coronavirus pathogen of the currently prevailing COVID-19 pandemic. It relies on its main protease (M Pro ) for replication and pathogenesis. M Pro is a demonstrated target for the development of antivirals for SARS-CoV-2. Past studies have systematically explored tripeptidyl inhibitors such as nirmatrelvir as M Pro inhibitors. However, dipeptidyl inhibitors especially those with a spiro residue at their P2 position have not been systematically investigated. In this work, we synthesized about 30 reversibly covalent dipeptidyl M Pro inhibitors and characterized them on in vitro enzymatic inhibition potency, structures of their complexes with M Pro , cellular M Pro inhibition potency, antiviral potency, cytotoxicity, and in vitro metabolic stability. Our results indicated that M Pro has a flexible S2 pocket that accommodates dipeptidyl inhibitors with a large P2 residue and revealed that dipeptidyl inhibitors with a large P2 spiro residue such as ( S )-2-azaspiro[4,4]nonane-3-carboxylate and ( S )-2-azaspiro[4,5]decane-3-carboxylate have optimal characteristics. One compound MPI60 containing a P2 ( S )-2-azaspiro[4,4]nonane-3-carboxylate displayed high antiviral potency, low cellular cytotoxicity, and high in vitro metabolic stability and can be potentially advanced to further preclinical tests.

A systematic exploration of boceprevir-based main protease inhibitors as SARS-CoV-2 antivirals

Boceprevir is an HCV NSP3 inhibitor that was explored as a repurposed drug for COVID-19. It inhibits the SARS-CoV-2 main protease (MPro) and contains an α-ketoamide warhead, a P1 β-cyclobutylalanyl moiety, a P2 dimethylcyclopropylproline, a P3 tert-butylglycine, and a P4 N-terminal tert-butylcarbamide. By introducing modifications at all four positions, we synthesized 20 boceprevir-based MPro inhibitors including PF-07321332 and characterized their MPro inhibition potency in test tubes (in vitro) and 293T cells (in cellulo). Crystal structures of MPro bound with 10 inhibitors and cytotoxicity and antiviral potency of 4 inhibitors were characterized as well. Replacing the P1 site with a β-(S-2-oxopyrrolidin-3-yl)-alanyl (Opal) residue and the warhead with an aldehyde leads to high in vitro potency. The original moieties at P2, P3 and the P4 N-terminal cap positions in boceprevir are better than other tested chemical moieties for high in vitro potency. In crystal structures, all inhibitors form a covalent adduct with the MPro active site cysteine. The P1 Opal residue, P2 dimethylcyclopropylproline and P4 N-terminal tert-butylcarbamide make strong hydrophobic interactions with MPro, explaining high in vitro potency of inhibitors that contain these moieties. A unique observation was made with an inhibitor that contains a P4 N-terminal isovaleramide. In its MPro complex structure, the P4 N-terminal isovaleramide is tucked deep in a small pocket of MPro that originally recognizes a P4 alanine side chain in a substrate. Although all inhibitors show high in vitro potency, they have drastically different in cellulo potency to inhibit ectopically expressed MPro in human 293T cells. In general, inhibitors with a P4 N-terminal carbamide or amide have low in cellulo potency. This trend is reversed when the P4 N-terminal cap is changed to a carbamate. The installation of a P3 O-tert-butyl-threonine improves in cellulo potency. Three molecules that contain a P4 N-terminal carbamate were advanced to cytotoxicity tests on 293T cells and antiviral potency tests on three SARS-CoV-2 variants. They all have relatively low cytotoxicity and high antiviral potency with EC50 values around 1 μM. A control compound with a nitrile warhead and a P4 N-terminal amide has undetectable antiviral potency. Based on all observations, we conclude that a P4 N-terminal carbamate in a boceprevir derivative is key for high antiviral potency against SARS-CoV-2.

Evaluation of SARS-CoV-2 Main Protease Inhibitors Using a Novel Cell-Based Assay

As an essential enzyme of SARS-CoV-2, main protease (M^Pro) triggers acute toxicity to its human cell host, an effect that can be alleviated by an M^Pro inhibitor. Using this toxicity alleviation, we developed an effective method that allows a bulk analysis of the cellular potency of M^Pro inhibitors. This novel assay is advantageous over an antiviral assay in providing precise cellular M^Pro inhibition information to assess an M^Pro inhibitor. We used this assay to analyze 30 known M^Pro inhibitors. Contrary to their strong antiviral effects and up to 10 μM, 11a, calpain inhibitor II, calpain XII, ebselen, bepridil, chloroquine, and hydroxychloroquine showed relatively weak to undetectable cellular M^Pro inhibition potency implicating their roles in interfering with key steps other than just the M^Pro catalysis in the SARS-CoV-2 life cycle. Our results also revealed that MPI5, MPI6, MPI7, and MPI8 have high cellular and antiviral potency. As the one with the highest cellular and antiviral potency among all tested compounds, MPI8 has a remarkable cellular M^Pro inhibition IC₅₀ value of 31 nM that matches closely to its strong antiviral effect with an EC₅₀ value of 30 nM. Therefore, we cautiously suggest exploring MPI8 further for COVID-19 preclinical tests.

The P3 O - Tert -Butyl-Threonine is Key to High Cellular and Antiviral Potency for Aldehyde-Based SARS-CoV-2 Main Protease Inhibitors

As an essential enzyme to SARS-CoV-2, main protease (M ^Pro ) is a viable target to develop antivirals for the treatment of COVID-19. By varying chemical compositions at both P2 and P3 sites and the N -terminal protection group, we synthesized a series of M ^Pro inhibitors that contain β -(S-2-oxopyrrolidin-3-yl)-alaninal at the P1 site. These inhibitors have a large variation of determined IC ₅₀ values that range from 4.8 to 650 nM. The determined IC ₅₀ values reveal that relatively small side chains at both P2 and P3 sites are favorable for achieving high in vitro M ^Pro inhibition potency, the P3 site is tolerable toward unnatural amino acids with two alkyl substituents on the α -carbon, and the inhibition potency is sensitive toward the N -terminal protection group. X-ray crystal structures of M ^Pro bound with 16 inhibitors were determined. All structures show similar binding patterns of inhibitors at the M ^Pro active site. A covalent interaction between the active site cysteine and a bound inhibitor was observed in all structures. In M ^Pro , large structural variations were observed on residues N142 and Q189. All inhibitors were also characterized on their inhibition of M ^Pro in 293T cells, which revealed their in cellulo potency that is drastically different from their in vitro enzyme inhibition potency. Inhibitors that showed high in cellulo potency all contain O - tert -butyl-threonine at the P3 site. Based on the current and a previous study, we conclude that O - tert -butyl-threonine at the P3 site is a key component to achieve high cellular and antiviral potency for peptidyl aldehyde inhibitors of M ^Pro . This finding will be critical to the development of novel antivirals to address the current global emergency of concerning the COVID-19 pandemic.

The N -Terminal Carbamate is Key to High Cellular and Antiviral Potency for Boceprevir-Based SARS-CoV-2 Main Protease Inhibitors

Boceprevir is an HCV NSP3 inhibitor that has been explored as a repurposed drug for COVID-19. It inhibits the SARS-CoV-2 main protease (M ^Pro ) and contains an α-ketoamide warhead, a P1 β-cyclobutylalanyl moiety, a P2 dimethylcyclopropylproline, a P3 tert -butyl-glycine, and a P4 N -terminal tert -butylcarbamide. By introducing modifications at all four positions, we synthesized 20 boceprevir-based M ^Pro inhibitors including PF-07321332 and characterized their M ^Pro inhibition potency in test tubes ( in vitro ) and human host cells ( in cellulo ). Crystal structures of M ^Pro bound with 10 inhibitors and antiviral potency of 4 inhibitors were characterized as well. Replacing the P1 site with a β-(S-2-oxopyrrolidin-3-yl)-alanyl (opal) residue and the warhead with an aldehyde leads to high in vitro potency. The original moieties at P2, P3 and the P4 N -terminal cap positions in boceprevir are better than other tested chemical moieties for high in vitro potency. In crystal structures, all inhibitors form a covalent adduct with the M ^Pro active site cysteine. The P1 opal residue, P2 dimethylcyclopropylproline and P4 N -terminal tert -butylcarbamide make strong hydrophobic interactions with M ^Pro , explaining high in vitro potency of inhibitors that contain these moieties. A unique observation was made with an inhibitor that contains an P4 N -terminal isovaleramide. In its M ^Pro complex structure, the P4 N -terminal isovaleramide is tucked deep in a small pocket of M ^Pro that originally recognizes a P4 alanine side chain in a substrate. Although all inhibitors show high in vitro potency, they have drastically different in cellulo potency in inhibiting ectopically expressed M ^Pro in human 293T cells. All inhibitors including PF-07321332 with a P4 N -terminal carbamide or amide have low in cellulo potency. This trend is reversed when the P4 N -terminal cap is changed to a carbamate. The installation of a P3 O-tert -butyl-threonine improves in cellulo potency. Three molecules that contain a P4 N -terminal carbamate were advanced to antiviral tests on three SARS-CoV-2 variants. They all have high potency with EC ₅₀ values around 1 μM. A control compound with a nitrile warhead and a P4 N -terminal amide has undetectable antiviral potency. Based on all observations, we conclude that a P4 N -terminal carbamate in a boceprevir derivative is key for high antiviral potency against SARS-CoV-2.

Discovery of Selective Small-Molecule Inhibitors for the ENL YEATS Domain

Eleven-nineteen leukemia (ENL) protein is a histone acetylation reader essential for disease maintenance in acute leukemias, in particular, the mixed-lineage leukemia (MLL)-rearranged leukemia. In this study, we carried out high-throughput screening of a small-molecule library to identify inhibitors for the ENL YEATS domain. Structure-activity relationship studies of the hits and structure-based inhibitor design led to two compounds, 11 and 24, with IC₅₀ values below 100 nM in inhibiting the ENL-acetyl-H3 interaction. Both compounds, and their precursor compound 7, displayed strong selectivity toward the ENL YEATS domain over all other human YEATS domains. Moreover, 7 exhibited on-target inhibition of ENL in cultured cells and a synergistic effect with the bromodomain and extraterminal domain inhibitor JQ1 in killing leukemia cells. Together, we have developed selective chemical probes for the ENL YEATS domain, providing the basis for further medicinal chemistry-based optimization to advance both basic and translational research of ENL.

MPI8 is Potent against SARS-CoV-2 by Inhibiting Dually and Selectively the SARS-CoV-2 Main Protease and the Host Cathepsin L*

A number of inhibitors have been developed for the SARS‐CoV‐2 main protease (M^Pro) as potential COVID‐19 medications but little is known about their selectivity. Using enzymatic assays, we characterized inhibition of TMPRSS2, furin, and cathepsins B/K/L by more than a dozen of previously developed M^Pro inhibitors including MPI1‐9, GC376, 11a, 10–1, 10–2, and 10–3. MPI1‐9, GC376 and 11a all contain an aldehyde for the formation of a reversible covalent hemiacetal adduct with the M^Pro active site cysteine and 10–1, 10–2 and 10–3 contain a labile ester to exchange with the M^Pro active site cysteine for the formation of a thioester. Our data revealed that all these inhibitors are inert toward TMPRSS2 and furin. Diaryl esters also showed low inhibition of cathepsins. However, all aldehyde inhibitors displayed high potency in inhibiting three cathepsins. Their determined IC₅₀ values vary from 4.1 to 380 nM for cathepsin B, 0.079 to 2.3 nM for cathepsin L, and 0.35 to 180 nM for cathepsin K. All aldehyde inhibitors showed similar inhibition levels toward cathepsin L. A cellular analysis indicated high potency of MPI5 and MPI8 in inhibiting lysosomal activity, which is probably attributed to their inhibition of cathepsins. Among all aldehyde inhibitors, MPI8 shows the best selectivity toward cathepsin L. With respect to cathepsins B and K, the selective indices are 192 and 150, respectively. MPI8 is the most potent compound among all aldehyde inhibitors in cellular M^Pro inhibition potency and anti‐SARS‐CoV‐2 activity in Vero E6 cells. Cathepsin L has been demonstrated to play a critical role in the SARS‐CoV‐2 cell entry. By selectively inhibiting both SARS‐CoV‐2 M^Pro and the host cathepsin L, MPI8 potentiates dual inhibition effects to synergize its overall antiviral potency and efficacy. Due to its high selectivity toward cathepsin L that reduces potential toxicity toward host cells and high cellular and antiviral potency, we urge serious consideration of MPI8 for preclinical and clinical investigations for treating COVID‐19.

The transcription factors of tall fescue in response to temperature stress

Tall fescue (Festuca arundinacea) is an important grass species worldwide, but temperature stress severely affects its distribution and yield. Transcription factors (TFs), as the master switches in sophisticated regulatory networks, play essential roles in plant growth development and abiotic stress responses. In this study, the comparative transcriptome analysis was performed to explore the commonalities and differences in the response of TFs to the heat (40 °C), cold (10 °C) and control (22 °C) conditions. A total of 877 TF genes belonging to 35 families were identified. Most of them (784) were differentially expressed genes (DEG), indicating TF genes actively responded to temperature stress. The expression of bZIP and GTF family members was up-regulated when exposed to both heat and cold, but conversely, the expression of the most WRKY and NAC families members decreased. The HSF and GTE families and DREB2B were up-regulated upon heat, while bHLH, MYB, HD-ZIP and ERF families were elevated under cold stress. The TFs involved in 'Plant hormone signal transduction', 'Plant-pathogen interaction', 'Circadian rhythm' play major roles in responding to temperature stresses. The results showed the temperature threats up-regulated the expression of stress tolerance-related genes, and down-regulated those genes associated with growth and disease resistance, indicating TFs exert crucial roles in plant adaptation to an adverse environment. This study profiled the responsive pattern of TFs to temperature stresses, partially explained the mechanism of adaptations of cold-season forage crops and screened many candidate stress-tolerant TF genes.

A Quick Route to Multiple Highly Potent SARS-CoV-2 Main Protease Inhibitors*

The COVID-19 pathogen, SARS-CoV-2, requires its main protease (SC2M^Pro ) to digest two of its translated long polypeptides to form a number of mature proteins that are essential for viral replication and pathogenesis. Inhibition of this vital proteolytic process is effective in preventing the virus from replicating in infected cells and therefore provides a potential COVID-19 treatment option. Guided by previous medicinal chemistry studies about SARS-CoV-1 main protease (SC1M^Pro ), we have designed and synthesized a series of SC2M^Pro inhibitors that contain β-(S-2-oxopyrrolidin-3-yl)-alaninal (Opal) for the formation of a reversible covalent bond with the SC2M^Pro active-site cysteine C145. All inhibitors display high potency with K_i values at or below 100 nM. The most potent compound, MPI3, has as a K_i value of 8.3 nM. Crystallographic analyses of SC2M^Pro bound to seven inhibitors indicated both formation of a covalent bond with C145 and structural rearrangement from the apoenzyme to accommodate the inhibitors. Virus inhibition assays revealed that several inhibitors have high potency in inhibiting the SARS-CoV-2-induced cytopathogenic effect in both Vero E6 and A549/ACE2 cells. Two inhibitors, MPI5 and MPI8, completely prevented the SARS-CoV-2-induced cytopathogenic effect in Vero E6 cells at 2.5-5 μM and A549/ACE2 cells at 0.16-0.31 μM. Their virus inhibition potency is much higher than that of some existing molecules that are under preclinical and clinical investigations for the treatment of COVID-19. Our study indicates that there is a large chemical space that needs to be explored for the development of SC2M^Pro inhibitors with ultra-high antiviral potency.

A Speedy Route to Multiple Highly Potent SARS-CoV-2 Main Protease Inhibitors

The COVID-19 pathogen, SARS-CoV-2, requires its main protease (SC2M ^Pro ) to digest two of its translated polypeptides to form a number of mature proteins that are essential for viral replication and pathogenesis. Inhibition of this vital proteolytic process is effective in preventing the virus from replication in infected cells and therefore provides a potential COVID-19 treatment option. Guided by previous medicinal chemistry studies about SARS-CoV-1 main protease (SC1M ^Pro ), we have designed and synthesized a series of SC2M ^Pro inhibitors that contain β-( S -2-oxopyrrolidin-3-yl)-alaninal (Opal) for the formation of a reversible covalent bond with the SC2M ^Pro active site cysteine C145. All inhibitors display high potency with IC ₅₀ values at or below 100 nM. The most potent compound MPI3 has as an IC ₅₀ value as 8.5 nM. Crystallographic analyses of SC2M ^Pro bound to 7 inhibitors indicated both formation of a covalent bond with C145 and structural rearrangement from the apoenzyme to accommodate the inhibitors. Virus inhibition assays revealed that several inhibitors have high potency in inhibiting the SARS-CoV-2-induced cytopathogenic effect in both Vero E6 and A549 cells. Two inhibitors MP5 and MPI8 completely prevented the SARS-CoV-2-induced cytopathogenic effect in Vero E6 cells at 2.5-5 μM and A549 cells at 0.16-0.31 μM. Their virus inhibition potency is much higher than some existing molecules that are under preclinical and clinical investigations for the treatment of COVID-19. Our study indicates that there is a large chemical space that needs to be explored for the development of SC2M ^Pro inhibitors with extreme potency. Due to the urgent matter of the COVID-19 pandemic, MPI5 and MPI8 may be quickly advanced to preclinical and clinical tests for COVID-19.

[Clinical features and outcomes in relapsing and monophasic patients with anti-leucine-rich glioma-inactivated 1 encephalitis]

Objective: To analyze the differences of clinical characteristics and outcomes between relapsing and monophasic patients with anti-leucine-rich glioma-inactivated 1 (anti-LGI1) encephalitis. Methods: Medical records of confirmed anti-LGI1 encephalitic patients who underwent immunotherapy were retrospectively collected from January 2015 to January 2019 in the first affiliated hospital of Zhengzhou University. Clinical data, treatment methods, duration of treatment and outcomes were analyzed between the relapsing and monophasic groups. Results: Among the 33 anti-LGI1 encephalitic patients, there were 12 and 21 cases in the relapsing and monophasic groups, respectively. No difference was found in age, sex, precipitating factors, intensive care unit (ICU) admission, symptoms and modified Rankin Scale (mRS) score in the acute phase (P>0.05). As to the lab test and image examination, no statistic difference was found in serum and cerebral spinal fluid (CSF) positive rate, hyponatremia, abnormal rate of electrocardiogram (ECG), electroencephalogram (EEG), CSF and magnetic resonance imaging (MRI) and lesion locations (P>0.05). No difference was found in time to diagnose the disease between the 2 groups (P>0.05). The median immunotherapy period was 102.5 days in relapsing group and 194.0 days in monophasic group, with a statistic difference (P=0.001). No patients had bad outcomes in the monophasic group at the last follow-up, while 6 patients had poor outcomes in the relapsing group (4 patients died). The patients in relapsing group had a worse prognosis compared to those in the monophasic group (P=0.007). Conclusions: Relapse is common in anti-LGI1 encephalitis. Patients in the relapsing group received a shorter term of immunotherapy and had worse outcomes than those in the monophasic group.

Spectral broadening in femtosecond pulse written filamentary waveguides in periodically poled lithium niobate

The authors report the filamentary waveguide formation and the significant spectral broadening based on periodically poled lithium niobate substrate. The modified morphology contributes to the combined effects of optical diffraction and self-focusing with the dependence on pulse intensity. Up to 4 times broadening of the FF wave and about 47 nm spanning of the SH wave with the pump power of 19.5 mW are achievable under 1550 nm excitation. Spectral evolution by cubic nonlinearity inside the waveguide has been obtained numerically, and provides a reasonable agreement with the experimental results.

Signed frequency offset measurement for direct detection DPSK system with a chromatic dispersion offset

We demonstrated a method for the measurement of signed frequency offset between optical source and delay interferometer (DI) for 10 Gb/s DPSK signals based on asynchronous delay-tap sampling technique with a chromatic dispersion (CD) offset. The demodulated DPSK signals show asymmetrical property and amplitude shoulder appears on the waveforms with frequency offset and a fixed CD offset together. The delay-tap sampling scatter plots also show the asymmetry related to the asymmetrical signal distortion. Our proposed method cannot only realize the measurement of the magnitude of frequency offset but also the polarity. The measurement range is from -2 GHz to +2 GHz and the sensitivity can reach ±100MHz. The simulation and experimental results are demonstrated and in good agreement.

Overexpression of WNT2 and TSG101 genes in colorectal carcinoma

Colorectal carcinoma (CRC) arises as a result of mutational activation of oncogenes coupled with inactivation of tumour suppressor genes. Mutations in APC, K-ras and p53 have been commonly reported. In a previous study by our group, the tumour susceptibility gene 101 (TSG101) were found to be persistently upregulated in CRC cases. TSG101 was reported to be closely related to cancers of the breast, brain and colon, and its overexpression in human papillary thyroid carcinomas and ovarian carcinomas had previously been reported. The wingless-type MMTV integration site family member 2 (WNT2) is potentially important in the Wnt/beta-catenin pathway and upregulation of WNT2 is not uncommon in human cancers. In this study, we report the investigation for mutation(s) and expression pattern(s) of WNT2 and TSG101, in an effort to further understand their role(s) in CRC tumourigenesis. Our results revealed no mutation in these genes, despite their persistent upregulation in CRC cases studied.