Stabilization of the Metastable Pre-Fusion Conformation of the SARS-CoV-2 Spike Glycoprotein through N-Linked Glycosylation of the S2 Subunit

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the novel coronavirus responsible for the coronavirus disease 2019 (COVID-19) pandemic, represents a serious threat to public health. The spike (S) glycoprotein of SARS-CoV-2 mediates viral entry into host cells and is heavily glycosylated. In this study, we systemically analyzed the roles of 22 putative N-linked glycans in SARS-CoV-2 S protein expression, membrane fusion, viral entry, and stability. Using the α-glycosidase inhibitors castanospermine and NB-DNJ, we confirmed that disruption of N-linked glycosylation blocked the maturation of the S protein, leading to the impairment of S protein-mediated membrane fusion. Single-amino-acid substitution of each of the 22 N-linked glycosylation sites with glutamine revealed that 9 out of the 22 N-linked glycosylation sites were critical for S protein folding and maturation. Thus, substitution at these sites resulted in reduced S protein-mediated cell-cell fusion and viral entry. Notably, the N1074Q mutation markedly affected S protein stability and induced significant receptor-independent syncytium (RIS) formation in HEK293T/hACE2-KO cells. Additionally, the removal of the furin cleavage site partially compensated for the instability induced by the N1074Q mutation. Although the corresponding mutation in the SARS-CoV S protein (N1056Q) did not induce RIS in HEK293T cells, the N669Q and N1080Q mutants exhibited increased fusogenic activity and did induce syncytium formation in HEK293T cells. Therefore, N-glycans on the SARS-CoV and SARS-CoV-2 S2 subunits are highly important for maintaining the pre-fusion state of the S protein. This study revealed the critical roles of N-glycans in S protein maturation and stability, information that has implications for the design of vaccines and antiviral strategies.

Induction Chemotherapy and Toripalimab for Larynx Preservation in Resectable Locally Advanced Laryngeal/Hypopharyngeal Carcinoma: Preliminary Results of INSIGHT Study

PURPOSE/OBJECTIVE(S)

Previous studies have demonstrated excellent pathological response of induction PD-1 inhibitor with chemotherapy for locally advanced head and neck cancer. To our knowledge, there is scarce evidence on induction chemotherapy (ICT) and PD-1 inhibitor in organ preservation for patients (pts) with laryngeal/hypopharyngeal carcinoma. Hence, the aim of this study is to evaluate the efficacy and toxicities of ICT and PD-1inhibitor (Toripalimab) followed by radiotherapy or surgery, for pts with resectable locally advanced laryngeal/hypopharyngeal carcinoma.

MATERIALS/METHODS

This isa single-arm phase II study. Pts with histopathologic confirmed, resectable locally advanced laryngeal/hypopharyngeal squamous cell carcinoma and ECOG PS 0-1 were eligible. Three cycles of ICT (paclitaxel 175 mg/m d1, cisplatin 25 mg/m d1-3) combined with PD-1 inhibitor (Toripalimab 240 mg d0) were given. Response assessment (RECIST 1.1) was performed post-ICT. Patients with complete response (CR)/partial response (PR) of primary tumor received concurrent chemoradiation, followed by maintenance therapy of Toripalimab for eight cycles. Otherwise, patients were referred to surgery, followed by adjuvant radiation (RT)/chemoradiation (CRT), and then maintenance therapy of Toripalimab. The primary endpoint is larynx-preservation (LP) rate at 3 months post-RT. Forty-two patients were planned. Based on a two-stage Fleming design (one-sided α:10%, power: 80%), if at least 22 patients attained LP of the first 27 patients in stage I or at least thirty-two pts attained LP of the 42 patients at the end of stage II, the null hypothesis would be rejected. The cohort would enroll 15 more pts in stage II if 19-21 pts in stage I observed LP, and the study would be terminated if the number of pts with LP were less than 18 in stage I.

RESULTS

A total of 27 pts were enrolled. By the cut-off date Feb 8, 2023, all reached at least 3 months of follow-up post-RT. Median age was 63 (53-74) years with 92.6% male. Hypopharyngeal cancer accounted for 66.7%. There were 74.1% who were T3 to T4, and 77.7% were N2 to N3. Six cases had primary invasion of esophagus and five pts underwent pretreatment tracheostomy. ORR of ICT was 85.2%. Afterward, 21 pts were treated with concurrent CRT, while 6 pts received surgery of primary tumor. At 3 months post-RT, 23 pts attained organ preservation and the LP rate was 85.2%. With a median follow-up of 13.5 months, 1-year OS rate, PFS rate and LP survival rate was 83.1%, 79.5% and 79.4%, respectively. During ICT, 22.2% of pts experienced grade 3-4 treatment-related AEs (TRAEs). The most common grade 3-4 TRAEs were nausea and neutrophil count decreased.

CONCLUSION

The primary endpoint LP rate was met. In this cohort of extensive locally advanced laryngeal/hypopharyngeal carcinoma, ICT and Toripalimab followed by radiotherapy or surgery resulted in satisfactory short-term LP rate and encouraging survival.

DTI of Opioid-Exposed Fetuses Using ComBat Harmonization: A Bi-Institutional Study

BACKGROUND AND PURPOSE

The underlying mechanisms leading to altered cognitive, behavioral, and vision outcomes in children with prenatal opioid exposure are yet to be fully understood. Some studies suggest WM alterations in infants and children with prenatal opioid exposure; however, the time course of WM changes is unknown. We aimed to evaluate differences in diffusion tensor imaging MRI parameters in the brain between opioid exposed fetuses and normal controls.

MATERIALS AND METHODS

This is a pilot, prospective cohort study in which subjects in the third trimester of pregnancy underwent fetal DTI of the brain with 20 noncolinear diffusion directions and a b-value of 500 s/mm2 at 2.5-mm isotropic resolution.

RESULTS

The study included a total of 26 fetuses, 11 opioid-exposed (mean gestational age, 32.61 [SD, 2.35] weeks) and 15 unexposed controls (mean gestational age, 31.77 [SD, 1.68] weeks). After we adjusted for gestational age, fractional anisotropy values were significantly higher in opioid-exposed fetuses relative to controls in 8 WM tracts: the bilateral lemniscus (left: P = .017; right: P = .020), middle cerebellar peduncle (P = .027), left inferior cerebellar peduncle (P = .026), right sagittal stratum (P = .040), right fornix stria terminalis (P = .022), right inferior fronto-occipital fasciculus (P = .011), and the right uncinate fasciculus (P = .033). Significant alteration was also identified in other DTI indices involving a series of brain regions.

CONCLUSIONS

Our data demonstrate initial evidence of cerebral WM microstructural differences between opioid-exposed fetuses and unexposed controls. Further studies in larger patient populations will be needed to fully understand these findings.

Host susceptibility and structural and immunological insight of S proteins of two SARS-CoV-2 closely related bat coronaviruses

The bat coronaviruses (CoV) BANAL-20-52 and BANAL-20-236 are two newly identified severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) closely related coronaviruses (SC2r-CoV) and the genome of BANAL-20-52 shares the highest homology with SARS-CoV-2. However, the risk of their potential zoonotic transmission has not been fully evaluated. Here, we determined their potential host susceptibility among 13 different bat species and 26 different animal species, and found that both might have extensive host ranges, indicating high zoonotic transmission potential. We also determined the cryo-EM structures of BANAL-20-52 and BANAL-20-236 S proteins at pH 5.5 and the complex of BANAL-20-236 S1 and Rhinolophus affinis ACE2, and found that both trimeric S proteins adopt all three receptor binding domains (RBDs) in "closed" conformation and are more compact than SARS-CoV-2. Strikingly, the unique sugar moiety at N370 of bat SC2r-CoVs acts like a "bolt" and crosses over two neighboring subunits, facilitating the S proteins in the locked conformation and underpinning the architecture stability. Removal of the glycosylation at N370 by a T372A substitution substantially enhances virus infectivity but becomes highly sensitive to trypsin digestion at pH 5.5, a condition roughly mimicking the insectivorous bat's stomach digestion. In contrast, WT S proteins of SC2r-CoVs showed considerable resistance to trypsin digestion at pH 5.5, indicating that the highly conserved T372 in bat CoVs might result from the selective advantages in stability during the fecal-oral transmission over A372. Moreover, the results of cross-immunogenicity among S proteins of SARS-CoV-2, BANAL-20-52, and BANAL-20-236 showed that A372 pseudoviruses are more sensitive to anti-S sera than T372, indicating that immune evasion might also play a role in the natural selection of T372 over A372 during evolution. Finally, residues 493 and 498 of the S protein affect host susceptibility, and residue 498 also influences the immunogenicity of the S protein. Together, our findings aid a better understanding of the molecular basis of CoV entry, selective evolution, and immunogenicity and highlight the importance of surveillance of susceptible hosts of these viruses to prevent potential outbreaks.

Effect of polymorphism in Rhinolophus affinis ACE2 on entry of SARS-CoV-2 related bat coronaviruses

Bat coronavirus RaTG13 shares about 96.2% nucleotide sequence identity with that of SARS-CoV-2 and uses human and Rhinolophus affinis (Ra) angiotensin-converting enzyme 2 (ACE2) as entry receptors. Whether there are bat species other than R. affinis susceptible to RaTG13 infection remains elusive. Here, we show that, among 18 different bat ACE2s tested, only RaACE2 is highly susceptible to transduction by RaTG13 S pseudovirions, indicating that the bat species harboring RaTG13 might be very limited. RaACE2 has seven polymorphic variants, RA-01 to RA-07, and they show different susceptibilities to RaTG13 S pseudovirions transduction. Sequence and mutagenesis analyses reveal that residues 34, 38, and 83 in RaACE2 might play critical roles in interaction with the RaTG13 S protein. Of note, RaACE2 polymorphisms have minimal effect on S proteins of SARS-CoV-2 and several SARS-CoV-2 related CoVs (SC2r-CoVs) including BANAL-20-52 and BANAL-20-236 in terms of binding, membrane fusion, and pseudovirus entry. Further mutagenesis analyses identify residues 501 and 505 in S proteins critical for the recognition of different RaACE2 variants and pangolin ACE2 (pACE2), indicating that RaTG13 might have not been well adapted to R. affinis bats. While single D501N and H505Y changes in RaTG13 S protein significantly enhance the infectivity and minimize the difference in susceptibility among different RaACE2 variants, an N501D substitution in SARS-CoV-2 S protein displays marked disparity in transduction efficiencies among RaACE2 variants with a significant reduction in infectivity on several RaACE2 variants. Finally, a T372A substitution in RaTG13 S protein not only significantly increases infectivity on all RaACE2 variants, but also markedly enhances entry on several bat ACE2s including R. sinicus YN, R. pearsonii, and R. ferrumeiqunum. However, the T372A mutant is about 4-fold more sensitive to neutralizing sera from mice immunized with BANAL-20-52 S, suggesting that the better immune evasion ability of T372 over A372 might contribute to the natural selective advantage of T372 over A372 among bat CoVs. Together, our study aids a better understanding of coronavirus entry, vaccine design, and evolution.

Negatively charged phospholipids accelerate the membrane fusion activity of the plant-specific insert domain of an aspartic protease

Various plants use antimicrobial proteins/peptides to resist phytopathogens. In the potato, Solanum tuberosum, the plant-specific insert (PSI) domain of an aspartic protease performs this role by disrupting phytopathogen plasma membranes. However, the mechanism by which PSI selects target membranes has not been elucidated. Here, we studied PSI-induced membrane fusion, focusing on the effects of lipid composition on fusion efficiency. Membrane fusion by the PSI involves an intermediate state whereby adjacent liposomes share their bilayers. We found that increasing the concentration of negatively charged phosphatidylserine (PS) phospholipids substantially accelerated PSI-mediated membrane fusion. NMR data demonstrated that PS did not affect the binding between the PSI and liposomes but had seminal effects on the dynamics of PSI interaction with liposomes. In PS-free liposomes, the PSI underwent significant motion, which was suppressed on PS-contained liposomes. Molecular dynamics simulations showed that the PSI binds to PS-containing membranes with a dominant angle ranging from −31° to 30°, with respect to the bilayer, and is closer to the membrane surfaces. In contrast, PSI is mobile and exhibits multiple topological states on the surface of PS-free membranes. Taken together, our data suggested that PS lipids limit the motion of the anchored PSI, bringing it closer to the membrane surface and efficiently bridging different liposomes to accelerate fusion. As most phytopathogens have a higher content of negatively charged lipids as compared with host cells, these results indicate that the PSI selectively targets negatively charged lipids, which likely represents a way of distinguishing the pathogen from the host.

Maternal Obesity during Pregnancy is Associated with Lower Cortical Thickness in the Neonate Brain

BACKGROUND AND PURPOSE

Recent studies have suggested that maternal obesity during pregnancy is associated with differences in neurodevelopmental outcomes in children. In this study, we aimed to investigate the relationships between maternal obesity during pregnancy and neonatal brain cortical development.

MATERIALS AND METHODS

Forty-four healthy women (28 normal-weight, 16 obese) were prospectively recruited at <10 weeks' gestation, and their healthy full-term neonates (23 boys, 21 girls) underwent brain MR imaging. All pregnant women had their body composition (fat mass percentage) measured at ∼12 weeks of pregnancy. All neonates were scanned at ∼2 weeks of age during natural sleep without sedation, and their 3D T1-weighted images were postprocessed by the new iBEAT2.0 software. Brain MR imaging segmentation and cortical surface reconstruction and parcellation were completed using age-appropriate templates. Mean cortical thickness for 34 regions in each brain hemisphere defined by the UNC Neonatal Cortical Surface Atlas was measured, compared between groups, and correlated with maternal body fat mass percentage, controlled for neonate sex and race, postmenstrual age at MR imaging, maternal age at pregnancy, and the maternal intelligence quotient and education.

RESULTS

Neonates born to obese mothers showed significantly lower (P ≤ .05, false discovery rate-corrected) cortical thickness in the left pars opercularis gyrus, left pars triangularis gyrus, and left rostral middle frontal gyrus. Mean cortical thickness in these frontal lobe regions negatively correlated (R = -0.34, P = .04; R = -0.50, P = .001; and R = -0.42, P = .01; respectively) with the maternal body fat mass percentage measured at early pregnancy.

CONCLUSIONS

Maternal obesity during pregnancy is associated with lower neonate brain cortical thickness in several frontal lobe regions important for language and executive functions.

The Rhinolophus affinis bat ACE2 and multiple animal orthologs are functional receptors for bat coronavirus RaTG13 and SARS-CoV-2

Bat coronavirus (CoV) RaTG13 shares the highest genome sequence identity with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among all known coronaviruses, and also uses human angiotensin converting enzyme 2 (hACE2) for virus entry. Thus, SARS-CoV-2 is thought to have originated from bat. However, whether SARS-CoV-2 emerged from bats directly or through an intermediate host remains elusive. Here, we found that Rhinolophus affinis bat ACE2 (RaACE2) is an entry receptor for both SARS-CoV-2 and RaTG13, although the binding of RaACE2 to the receptor-binding domain (RBD) of SARS-CoV-2 is markedly weaker than that of hACE2. We further evaluated the receptor activities of ACE2s from additional 16 diverse animal species for RaTG13, SARS-CoV, and SARS-CoV-2 in terms of S protein binding, membrane fusion, and pseudovirus entry. We found that the RaTG13 spike (S) protein is significantly less fusogenic than SARS-CoV and SARS-CoV-2, and seven out of sixteen different ACE2s function as entry receptors for all three viruses, indicating that all three viruses might have broad host rages. Of note, RaTG13 S pseudovirions can use mouse, but not pangolin ACE2, for virus entry, whereas SARS-CoV-2 S pseudovirions can use pangolin, but not mouse, ACE2 enter cells efficiently. Mutagenesis analysis revealed that residues 484 and 498 in RaTG13 and SARS-CoV-2 S proteins play critical roles in recognition of mouse and human ACE2s. Finally, two polymorphous Rhinolophous sinicus bat ACE2s showed different susceptibilities to virus entry by RaTG13 and SARS-CoV-2 S pseudovirions, suggesting possible coevolution. Our results offer better understanding of the mechanism of coronavirus entry, host range, and virus-host coevolution.

Clinical epidemiology and outcome of HIV-associated talaromycosis in Guangdong, China, during 2011-2017

OBJECTIVES

Talaromycosis is an invasive mycosis endemic to Southeast Asia. This study aimed to investigate the epidemiology, clinical features and prognostic factors of HIV-associated talaromycosis in Guangdong, China.

METHODS

We retrospectively evaluated HIV patients hospitalized with histopathology- or culture-confirmed talaromycosis between 2011 and 2017. Factors associated with poor prognosis were identified using logistic regression.

RESULTS

Overall, 1079 patients with HIV-associated talaromycosis were evaluated. Both the number and prevalence of talaromycosis among HIV admissions increased from 125 and 15.7% in 2011 to 253 and 18.8% in 2017, respectively, reflecting the increase in HIV admissions. Annual admissions peaked during the rainy season between March and August. Common clinical manifestations included fever (85.6%), peripheral lymphadenopathy (72.3%), respiratory symptoms (60.8%), weight loss (49.8%), skin lesions (44.5%) and gastrointestinal symptoms (44.3%). Common laboratory abnormalities were hypoalbuminaemia (98.6%), anaemia (95.6%), elevated aspartate aminotransferase level (AST) (76.9%), elevated alkaline phosphatase level (55.8%) and thrombocytopenia (53.7%). The median CD4 count was 9 cells/μL. Talaromyces marneffei was isolated from blood and bone marrow cultures of 66.6% and 74.5% of patients, respectively. The rate increased to 86.6% when both cultures were performed concurrently. At discharge, 14% of patients showed worsening conditions or died. Leucocytosis, thrombocytopenia, elevated AST, total bilirubin, creatinine and azole monotherapy independently predicted poor prognosis.

CONCLUSIONS

The incidence of HIV-associated talaromycosis has increased in Guangdong with the high HIV burden in China. Skin lesions were seen in less than half of patients. Induction therapy with azole alone is associated with higher mortality. Findings from this study should help to improve treatment of the disease.

Maternal Anxiety and Depression during Late Pregnancy and Newborn Brain White Matter Development

BACKGROUND AND PURPOSE

Anxiety and depression during pregnancy have been associated with an increased risk of adverse neurodevelopmental outcomes in offspring. We aimed to study the in utero effects of maternal anxiety and depression on early brain development.

MATERIALS AND METHODS

Pregnant women were recruited at ∼36 weeks of gestation for this prospective study. They were assessed for anxiety symptoms by the State-Trait Anxiety Inventory and for depression symptoms by the Beck Depression Inventory, 2nd Edition. After delivery, infant underwent an MR imaging examination of the brain without sedation, including DTI, for evaluation of white matter (WM) development. Infant fractional anisotropy values, a putative marker of WM integrity, were correlated with the mothers' State-Trait Anxiety Inventory and Beck Depression Inventory scores by using both tract-based spatial statistics and ROI methods.

RESULTS

Thirty-four infants were included in this study. Both maternal State-Anxiety and Trait-Anxiety scores negatively correlated (P < .05, corrected) with fractional anisotropy values in widespread brain WM regions; Beck Depression Inventory scores also negatively correlated (P < .05) with fractional anisotropy values in one cluster in the brain. Further ROI analyses confirmed significant negative correlations between average fractional anisotropy values in ROIs including left and right prefrontal WM, left and right middle frontal gyrus WM, and the fornix, and State-Anxiety (R values, -0.47 to -0.67; P values, .008 to <.001), Trait-Anxiety (R, -0.37 to -0.59; P, .04 to <.001), and Beck Depression Inventory (R values, -0.36 to -0.55; P, .05 to .002) scores.

CONCLUSIONS

Higher maternal anxiety and depression symptom scores during late pregnancy were associated with lower estimated infant brain WM development, which indicated in utero influences of maternal mental health during pregnancy on the developing brain.

Insights into the mechanism of membrane fusion induced by the plant defense element, plant-specific insert

In plants, many natural defense mechanisms include cellular membrane fusion as a way to resist infection by external pathogens. Several plant proteins mediate membrane fusion, but the detailed mechanism by which they promote fusion is less clear. Understanding this process could provide valuable insights into these proteins' physiological functions and guide bioengineering applications (i.e. the design of antimicrobial proteins). The plant-specific insert (PSI) from Solanum tuberosum can help reduce certain pathogen attack via membrane fusion. To gain new insights into the process of PSI-induced membrane fusion, a combined approach of NMR, FRET, and in silico studies was used. Our results indicate that (i) under acidic conditions, the PSI experiences a monomer-dimer equilibrium, and the dimeric PSI induces membrane fusion below a certain critical pH; (ii) after fusion, the PSI resides in a highly dehydrated environment with limited solvent accessibility, suggesting its capability in reducing repulsive dehydration forces between liposomes to facilitate fusion; and (iii) as shown by molecular dynamics simulations, the PSI dimer can bind stably to membrane surfaces and can bridge liposomes in close proximity, a critical step for the membrane fusion. In summary, this study provides new and unique insights into the mechanisms by which the PSI and similar proteins induce membrane fusion.

Brain Cortical Structure and Executive Function in Children May Be Influenced by Parental Choices of Infant Diets

BACKGROUND AND PURPOSE

While it is known that breastfeeding promotes healthy brain development in children, the potential effects of formulas substantially differing in composition (ie, milk-based versus soy-based) during infancy on brain development are unclear.

MATERIALS AND METHODS

Seventy-one 8-year-old children who were predominantly breastfed, milk formula fed, or soy formula fed during infancy were recruited for an MR imaging examination of the brain and a Behavior Rating Inventory of Executive Function assessment (completed via a questionnaire to the parents). Brain cortical features measured from MR imaging such as cortical thickness and surface area were extracted and compared among groups and correlated with Behavior Rating Inventory of Executive Function test scores.

RESULTS

Clusters in the frontal and occipital lobes showed significant differences (cluster-wise P  ≤  .05, corrected for multiple comparisons) in cortical thickness or surface area among the 3 diet groups. The effects were more prominent for boys, particularly for comparison of the milk formula fed versus soy formula fed boys. Assessments of executive function and behavior showed significantly lower Behavior Rating Inventory of Executive Function test scores in soy formula fed versus milk formula fed groups, which were mostly attributed to differences in boys. There were no differences between milk formula fed and breastfed groups for either sex. Mean cortical thickness for several of the clusters in the brain showing infant diet-associated effects significantly correlated with Behavior Rating Inventory of Executive Function scores.

CONCLUSIONS

Choices of infant diets (ie, breastfed, milk formula fed, soy formula fed) may have long-term and sex-specific effects on the cortical development and executive function and behavior of children's brains.

[Real-world efficacy and safety of lopinavir/ritonavir and arbidol in treating with COVID-19 : an observational cohort study]

Objective: To evaluate the efficacy and safety of lopinavir/ritonavir (LPV/r) and arbidol in the treatment of COVID-19 in the real world. Methods: The clinical data of 178 patients diagnosed with COVID-19 admitted to Guangzhou Eighth People's Hospital were retrospectively analyzed from January 21 to February 9, 2020. According to the patient's antiviral treatment regimen, 178 patients were divided into 4 groups including LPV/r group (59 patients), arbidol group (36 patients), combination therapy with LPV/r plus arbidol group (25 patients) and the conventional treatment group without any antiviral drugs (58 patients). The main observation end points of the study was the negative conversion time of nucleic acid of the novel coronavirus (2019-nCoV) in pharyngeal swab. Results: The baseline of 4 groups before treatment was consistent and comparable. The negative conversion time of nucleic acid of the 2019-nCoV in pharyngeal swab was (10.20 ± 3.49), (10.11 ± 4.68), (10.86 ± 4.74), (8.44 ± 3.51) days separately in the LPV/r group, the arbidol group, the combination therapy group, and the conventional treatment group without significant difference (F = 2.556, P = 0.058). There was also no significant difference in the rate of negative conversion rate of 2019-nCoV nucleic acid, the improvement ration in clinical symptoms, and the improvement ration of pulmonary infection in the lung CT imaging (P> 0.05). However, a statistically significant difference was found in the proportion of deterioration changing from mild/moderate to severe/critical type at day 7 (χ(2) = 9.311, P = 0.017) as follows: the combination therapy group (24.0%, 6/25), the arbidol group ( 16.7%, 6/36), LPV/r group (5.4%, 3/56) and conventional treatment group (5.2%, 3/58). Moreover, the frequency of adverse reactions in the three groups receiving antiviral drugs was significantly higher than that in the conventional treatment group (χ(2) = 14.875, P = 0.002). Conclusions: No evidences could prove that LPV/r and arbidol could shorten the negative conversion time of novel coronavirus nucleic acid in pharyngeal swab nor improve the symptoms of patients. Furthermore, the combination usage of LPV/r and arbidol may not benefit for improving the disease. Noteworthy, the adverse reactions of the antiviral drugs should be paid careful attention during the treatment.

Induction of apoptosis by Xiakemycin A in human hepatoma HepG2 cells

Xiakemycin A (XKA), a new antibiotic in the pyranonaphthoquinone family, shows antitumor activity. However, the type of cell death induced by XKA remains elusive. In this study, we aim to investigate the type of death induced by XKA in hepatic cancer.The apoptotic features, such as chromatic agglutination, reactive oxygen species generation and membrane potential of mitochondria, in HepG2 cells treated by XKA were measured by Hoechst 33342 staining and flow cytometry. Apoptosis of HepG2 cells treated with XKA was determined by Annexin V-FITC/propidium iodide double staining and Western blot analysis, respectively.XKA had a significant dose-dependent elevation of chromatic agglutination, reactive oxygen species generation, Annexin V and propidium iodide staining, decrease of membrane potential. Meanwhile, in apoptotic HepG2 cells induced by XKA, robust increment was noticed in p53 expression, cleavage of PARP, caspase-3, and caspase-9.XKA showed potent inhibitory effects on the proliferation of HepG2 cells. Such phenomenon may be related to activation of the apoptotic pathway.

Characterization of spike glycoprotein of SARS-CoV-2 on virus entry and its immune cross-reactivity with SARS-CoV

Since 2002, beta coronaviruses (CoV) have caused three zoonotic outbreaks, SARS-CoV in 2002-2003, MERS-CoV in 2012, and the newly emerged SARS-CoV-2 in late 2019. However, little is currently known about the biology of SARS-CoV-2. Here, using SARS-CoV-2 S protein pseudovirus system, we confirm that human angiotensin converting enzyme 2 (hACE2) is the receptor for SARS-CoV-2, find that SARS-CoV-2 enters 293/hACE2 cells mainly through endocytosis, that PIKfyve, TPC2, and cathepsin L are critical for entry, and that SARS-CoV-2 S protein is less stable than SARS-CoV S. Polyclonal anti-SARS S1 antibodies T62 inhibit entry of SARS-CoV S but not SARS-CoV-2 S pseudovirions. Further studies using recovered SARS and COVID-19 patients' sera show limited cross-neutralization, suggesting that recovery from one infection might not protect against the other. Our results present potential targets for development of drugs and vaccines for SARS-CoV-2.

A Protocol for Transverse Cardiac Slicing and Optical Mapping in Murine Heart

Thin living tissue slices have recently emerged as a new tissue model for cardiac electrophysiological research. Slices can be produced from human cardiac tissue, in addition to small and large mammalian hearts, representing a powerful in vitro model system for preclinical and translational heart research. In the present protocol, we describe a detailed mouse heart transverse slicing and optical imaging methodology. The use of this technology for high-throughput optical imaging allows study of electrophysiology of murine hearts in an organotypic pseudo two-dimensional model. The slices are cut at right angles to the long axis of the heart, permitting robust interrogation of transmembrane potential (Vm) and calcium transients (CaT) throughout the entire heart with exceptional regional precision. This approach enables the use of a series of slices prepared from the ventricles to measure Vm and CaT with high temporal and spatial resolution, allowing (i) comparison of successive slices which form a stack representing the original geometry of the heart; (ii) profiling of transmural and regional gradients in Vm and CaT in the ventricle; (iii) characterization of transmural and regional profiles of action potential and CaT alternans under stress (e.g., high frequency pacing or β-adrenergic stimulation) or pathological conditions (e.g., hypertrophy). Thus, the protocol described here provides a powerful platform for innovative research on electrical and calcium handling heterogeneity within the heart. It can be also combined with optogenetic technology to carry out optical stimulation; aiding studies of cellular Vm and CaT in a cell type specific manner.

Cesarean Delivery Impacts Infant Brain Development

BACKGROUND AND PURPOSE

The cesarean delivery rate has increased globally in the past few decades. Neurodevelopmental outcomes associated with cesarean delivery are still unclear. This study investigated whether cesarean delivery has any effect on the brain development of offspring.

MATERIALS AND METHODS

A total of 306 healthy children were studied retrospectively. We included 3 cohorts: 2-week-old neonates (cohort 1, n = 32/11 for vaginal delivery/cesarean delivery) and 8-year-old children (cohort 2, n = 37/23 for vaginal delivery/cesarean delivery) studied at Arkansas Children's Hospital, and a longitudinal cohort of 3-month to 5-year-old children (cohort 3, n = 164/39 for vaginal delivery/cesarean delivery) studied independently at Brown University. Diffusion tensor imaging, myelin water fraction imaging, voxel-based morphometry, and/or resting-state fMRI data were analyzed to evaluate white matter integrity, myelination, gray matter volume, and/or functional connectivity, respectively.

RESULTS

While not all MR imaging techniques were shared across the institutions/cohorts, post hoc analyses showed similar results of potential effects of cesarean delivery. The cesarean delivery group in cohort 1 showed significantly lower white matter development in widespread brain regions and significantly lower functional connectivity in the brain default mode network, controlled for a number of potential confounders. No group differences were found in cohort 2 in white matter integrity or gray matter volume. Cohort 3 had significantly different trajectories of white matter myelination between groups, with those born by cesarean delivery having reduced myelin in infancy but normalizing with age.

CONCLUSIONS

Cesarean delivery may influence infant brain development. The impact may be transient because similar effects were not observed in older children. Further prospective and longitudinal studies may be needed to confirm these novel findings.

Lower endogenous p53 levels and degradation of AKT protein contribute to potent suppression of the new antibiotic Xiakemycin A on tumor cells

Xiakemycin A (XKA), a new pyranonaphthoquinone antibiotic, is isolated from the fermentation broth of Streptomyces sp. CC8-201. It exerts potent suppression of cell proliferation on some types of tumor cells. In the present study, its underlying mechanism on tumor cells has been investigated. In contrast to the specific AKT inhibitor triciribine hydrate, XKA demonstrated a weak inhibition of the AKT kinase activity in vitro. Knockdown of AKT protein levels reduced XKA-inhibitory action on prostate carcinoma PC-3 cells. Degradation of AKT protein was markedly observed in the XKA-treated PC-3 cells in comparison with triciribine hydrate treatment. There was no typical apoptosis induced by XKA in PC-3 cells. The propidium iodide-stained cells increased concentration-dependently when the cells were treated with XKA. Degradation of apoptosis-related proteins, such as p53 and PARP-1, was also detected in the XKA-treated PC-3 cells. Knockdown of p53 protein levels potentiated XKA action on non-small lung cancer A549 cells. Collectively, the mechanism of XKA potent inhibition was due to degradation of AKT protein and low endogenous p53 levels. As a leading compound, new derivatives based on XKA will be developed to precisely treat tumor cells which have high AKT and low p53 protein levels.

Gestational Age at Birth and Brain White Matter Development in Term-Born Infants and Children

BACKGROUND AND PURPOSE

Studies on infants and children born preterm have shown that adequate gestational length is critical for brain white matter development. Less is known regarding how variations in gestational age at birth in term infants and children affect white matter development, which was evaluated in this study.

MATERIALS AND METHODS

Using DTI tract-based spatial statistics methods, we evaluated white matter microstructures in 2 groups of term-born (≥37 weeks of gestation) healthy subjects: 2-week-old infants (n = 44) and 8-year-old children (n = 63). DTI parameters including fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were calculated by voxelwise and ROI methods and were correlated with gestational age at birth, with potential confounding factors such as postnatal age and sex controlled.

RESULTS

Fractional anisotropy values, which are markers for white matter microstructural integrity, positively correlated (P < .05, corrected) with gestational age at birth in most major white matter tracts/regions for the term infants. Mean diffusivity values, which are measures of water diffusivities in the brain, and axial and radial diffusivity values, which are markers for axonal growth and myelination, respectively, negatively correlated (P < .05, corrected) with gestational age at birth in all major white matter tracts/regions excluding the body and splenium of the corpus callosum for the term infants. No significant correlations with gestational age were observed for any tracts/regions for the term-born 8-year-old children.

CONCLUSIONS

Our results indicate that longer gestation during the normal term period is associated with significantly greater infant white matter development (as reflected by higher fractional anisotropy and lower mean diffusivity, axial diffusivity, and radial diffusivity values); however, similar associations were not observable in later childhood.

Crystal structure of the receptor binding domain of the spike glycoprotein of human betacoronavirus HKU1

Human coronavirus (CoV) HKU1 is a pathogen causing acute respiratory illnesses and so far little is known about its biology. HKU1 virus uses its S1 subunit C-terminal domain (CTD) and not the N-terminal domain like other lineage A β-CoVs to bind to its yet unknown human receptor. Here we present the crystal structure of HKU1 CTD at 1.9 Å resolution. The structure consists of three subdomains: core, insertion and subdomain-1 (SD-1). While the structure of the core and SD-1 subdomains of HKU1 are highly similar to those of other β-CoVs, the insertion subdomain adopts a novel fold, which is largely invisible in the cryo-EM structure of the HKU1 S trimer. We identify five residues in the insertion subdomain that are critical for binding of neutralizing antibodies and two residues essential for receptor binding. Our study contributes to a better understanding of entry, immunity and evolution of CoV S proteins.

Effects of acute aerobic exercise on neural correlates of attention and inhibition in adolescents with bipolar disorder

Executive dysfunction is common during and between mood episodes in bipolar disorder (BD), causing social and functional impairment. This study investigated the effect of acute exercise on adolescents with BD and healthy control subjects (HC) to test for positive or negative consequences on neural response during an executive task. Fifty adolescents (mean age 16.54±1.47 years, 56% female, 30 with BD) completed an attention and response inhibition task before and after 20 min of recumbent cycling at ~70% of age-predicted maximum heart rate. 3 T functional magnetic resonance imaging data were analyzed in a whole brain voxel-wise analysis and as regions of interest (ROI), examining Go and NoGo response events. In the whole brain analysis of Go trials, exercise had larger effect in BD vs HC throughout ventral prefrontal cortex, amygdala and hippocampus; the profile of these effects was of greater disengagement after exercise. Pre-exercise ROI analysis confirmed this 'deficit in deactivation' for BDs in rostral ACC and found an activation deficit on NoGo errors in accumbens. Pre-exercise accumbens NoGo error activity correlated with depression symptoms and Go activity with mania symptoms; no correlations were present after exercise. Performance was matched to controls and results survived a series of covariate analyses. This study provides evidence that acute aerobic exercise transiently changes neural response during an executive task among adolescents with BD, and that pre-exercise relationships between symptoms and neural response are absent after exercise. Acute aerobic exercise constitutes a biological probe that may provide insights regarding pathophysiology and treatment of BD.

Skin image retrieval using Gabor wavelet texture feature

OBJECTIVE

Skin imaging plays a key role in many clinical studies. We have used many skin imaging techniques, including the recently developed capacitive contact skin imaging based on fingerprint sensors. The aim of this study was to develop an effective skin image retrieval technique using Gabor wavelet transform, which can be used on different types of skin images, but with a special focus on skin capacitive contact images.

METHODS

Content-based image retrieval (CBIR) is a useful technology to retrieve stored images from database by supplying query images. In a typical CBIR, images are retrieved based on colour, shape, texture, etc. In this study, texture feature is used for retrieving skin images, and Gabor wavelet transform is used for texture feature description and extraction.

RESULTS

The results show that the Gabor wavelet texture features can work efficiently on different types of skin images. Although Gabor wavelet transform is slower compared with other image retrieval techniques, such as principal component analysis (PCA) and grey-level co-occurrence matrix (GLCM), Gabor wavelet transform is the best for retrieving skin capacitive contact images and facial images with different orientations. Gabor wavelet transform can also work well on facial images with different expressions and skin cancer/disease images.

CONCLUSION

We have developed an effective skin image retrieval method based on Gabor wavelet transform, that it is useful for retrieving different types of images, namely digital colour face images, digital colour skin cancer and skin disease images, and particularly greyscale skin capacitive contact images. Gabor wavelet transform can also be potentially useful for face recognition (with different orientation and expressions) and skin cancer/disease diagnosis.

Voxel-Based Morphometry and fMRI Revealed Differences in Brain Gray Matter in Breastfed and Milk Formula-Fed Children

BACKGROUND AND PURPOSE

Infant diets may have significant impact on brain development in children. The aim of this study was to evaluate brain gray matter structure and function in 8-year-old children who were predominantly breastfed or fed cow's milk formula as infants.

MATERIALS AND METHODS

Forty-two healthy children (breastfed: n = 22, 10 boys and 12 girls; cow's milk formula: n = 20, 10 boys and 10 girls) were studied by using structural MR imaging (3D T1-weighted imaging) and blood oxygen level-dependent fMRI (while performing tasks involving visual perception and language functions). They were also administered standardized tests evaluating intelligence (Reynolds Intellectual Assessment Scales) and language skills (Clinical Evaluation of Language Fundamentals).

RESULTS

Total brain gray matter volume did not differ between the breastfed and cow's milk formula groups. However, breastfed children had significantly higher (P < .05, corrected) regional gray matter volume measured by voxel-based morphometry in the left inferior temporal lobe and left superior parietal lobe compared with cow's milk formula-fed children. Breastfed children showed significantly more brain activation in the right frontal and left/right temporal lobes on fMRI when processing the perception task and in the left temporal/occipital lobe when processing the visual language task than cow's milk formula-fed children. The imaging findings were associated with significantly better performance for breastfed than cow's milk formula-fed children on both tasks.

CONCLUSIONS

Our findings indicated greater regional gray matter development and better regional gray matter function in breastfed than cow's milk formula-fed children at 8 years of age and suggested that infant diets may have long-term influences on brain development in children.

Impaired white matter development in extremely low-birth-weight infants with previous brain hemorrhage

BACKGROUND AND PURPOSE

Brain hemorrhage is common in premature infants. The purpose of the study is to evaluate white matter development in extremely low-birth-weight infants with or without previous brain hemorrhage.

MATERIALS AND METHODS

Thirty-three extremely low-birth-weight infants were prospectively enrolled and included in this institutional review board-approved study. Another 10 healthy term infants were included as controls. The medical records of the extremely low-birth-weight infants were reviewed for sonography diagnosis of intraventricular hemorrhage. All infants had an MR imaging examination at term-equivalent age for detection of previous hemorrhage, and their white matter was scored and compared among different groups. DTI measured fractional anisotropy values were also compared voxelwise by tract-based spatial statistics.

RESULTS

Compared with controls, the white matter score was not significantly different in extremely low-birth-weight infants without blood deposition on MR imaging (P = .17), but was significantly worse in extremely low-birth-weight infants with blood deposition on MR imaging but no intraventricular hemorrhage diagnosis by sonography (P = .02), in extremely low-birth-weight infants with grade 1 or 2 intraventricular hemorrhage on sonography (P = .003), and in extremely low-birth-weight infants with grade 3 or 4 intraventricular hemorrhage on sonography (P = .0001). Extremely low-birth-weight infants without blood deposition on MR imaging did not show any white matter regions with significantly lower fractional anisotropy values than controls. Extremely low-birth-weight infants with blood deposition on MR imaging, but no intraventricular hemorrhage diagnosis, did show white matter regions with significantly lower fractional anisotropy values, and extremely low-birth-weight infants with intraventricular hemorrhage diagnosis had widespread white matter regions with lower fractional anisotropy values.

CONCLUSIONS

Previous brain hemorrhage is associated with abnormal white matter in extremely low-birth-weight infants at term-equivalent age, and sonography is not sensitive to minor hemorrhages that are sufficient to cause white matter injury.

Potentiation of resveratrol-induced apoptosis by matrine in human hepatoma HepG2 cells

Resveratrol, a natural polyphenolic phytochemical, has received considerable attention due to its potential chemopreventive and chemotherapeutic properties. In the present study, we first evaluated the growth-inhibitory effect of resveratrol on HepG2 cells and explored the underlying molecular mechanisms. Resveratrol inhibited proliferation and induced apoptosis in HepG2 cells via activation of caspase-9 and caspase-3, upregulation of the Bax/Bcl-2 ratio and induction of p53 expression. Cell cycle analysis demonstrated that resveratrol arrested cell cycle progression in the G1 and S phase. We further focused on the combination of matrine, a natural component extracted from the traditional Chinese medical herb Sophora flavescens Ait., as a mechanism to potentiate the growth-inhibitory effect of resveratrol on HepG2 cells. Both MTT and colony formation assay results indicated that the combined treatment of resveratrol and matrine exhibited a synergistic antiproliferative effect. In addition, resveratrol-induced apoptosis was significantly enhanced by matrine, which could be attributed to activation of caspase-3 and caspase-9, downregulation of survivin, induction of reactive oxygen species (ROS) generation and disruption of mitochondria membrane potential (Δψm). Our findings suggest that the combination treatment of resveratrol and matrine is a promising novel anticancer strategy for liver cancer; it also provides new insights into the mechanisms of combined therapy.

Association of XRCC5 polymorphisms with COPD and COPD-related phenotypes in the Han Chinese population: a case-control cohort study

Genome-wide association studies (GWAS) and integrative genomic approaches have demonstrated significant associations between chronic obstructive pulmonary disease (COPD) and polymorphisms of the X-ray repair cross-complementing protein 5 gene (XRCC5) in non-Asian populations. We investigated whether XRCC5 polymorphisms might be associated with COPD susceptibility and COPD-related phenotypes in the Chinese Han population. Nine single nucleotide polymorphisms (SNPs) (rs3821104, rs12470053, rs207936, rs3770498, rs6704622, rs3770492, rs4674066, rs7573191, and rs207906) in the XRCC5 gene were genotyped in a case-control study including 680 COPD patients and 687 controls. To estimate the strength of association, odds ratios (ORs) were calculated and the effects of potentially confounding variables were tested by logistic regression analysis. The association between haplotypes and COPD outcome was also assessed. Our data identified that the SNP rs207936 was associated with COPD with an adjusted P value of 0.038, which was also found when analyzing only data of current smokers (P=0.046). No significant associations were found between any of the SNPs and pulmonary function. Eight SNPs (rs3821104, rs12470053, rs207936, rs3770498, rs6704622, rs3770492, rs4674066, and rs7573191) showed strong linkage disequilibrium (R2≥0.9). Two major haplotypes were observed and showed a significant difference between case and control groups (P=0.0054 and 0.0081, respectively). The present study showed that the XRCC5 locus might be a contributor to COPD susceptibility in the Chinese Han population.

Identification of a novel C22-∆4-producing docosahexaenoic acid (DHA) specific polyunsaturated fatty acid desaturase gene from Isochrysis galbana and its expression in Saccharomyces cerevisiae

Isochrysis galbana, produces long chain polyunsaturated fatty acids including docosahexaenoic acid (DHA, 22:6n-3). A novel gene (IgFAD4-2), encoding a C22-∆4 polyunsaturated fatty acid specific desaturase, has been isolated and characterized from I. galbana. A full-length cDNA of 1,302 bp was cloned by LA-PCR technique. The IgFAD4-2 encoded a protein of 433 amino acids that shares 78 % identity with a previously reported ∆4-desaturase (IgFAD4-1) from I. galbana. The function of IgFAD4-2 was deduced by its heterologous expression in Saccharomyces cerevisiae, which then desaturated docosapentaenoic acid (DPA, 22:5n-3) to DHA. The conversion ratio of DPA to DHA was 34 %, which is higher than other ∆4-desaturases cloned from algae. However, IgFAD4-2 did not catalyze the desaturation or elongation reactions with other fatty acids. These results confirm that IgFAD4-2 has C22-∆4-PUFAs-specific desaturase activity.

[Cloning of delta8-fatty acid desaturase gene from Euglena gracilis and its expression in Saccharomyces cerevisiae]

Delta8 desaturase pathway, different from common delta6 desaturase pathway, is an alternate pathway of polyunsaturated fatty acids biosynthesis. Delta8-fatty acid desaturase is one of the key enzymes in delta8 desaturase pathway. Two specific fragments were separately cloned from genomic DNA and cDNA of Euglena gracilis by PCR with the primers designed according to the reported sequence. Comparison of the genomic and cDNA sequences revealed that there wasn't intron in this delta8-fatty acid desaturase gene. This gene has an open reading frame of 1 266 bp that encodes 421 amino acids. It is 6 bp longer than the reported gene sequence, and also showed certain difference from the reported sequence in the N-terminal. The recombinant expression plasmid pYEFD by subcloning delta8-fatty acid desaturase gene into the yeast-E. coli shuttle vector pYES2.0 was constructed and was transformed into the defective mutant INVSc1 of Saccharomyces cerevisiae by electrotransformation. The resulting strain YD8 harboring plasmid pYEFD was selected and was cultured in the induction medium with exogenous substrates omega6-eicosadienoic acid and omega3-eicosatrienoic acid for the expression of delta8-fatty acid desaturase gene. The results indicated that high level expressed As-fatty acid desaturase could convert omega6-eicosadienoic acid and omega3-eicosatrienoic acid to dihomo-gamma-linolenic acid and eicosatetraenoic acid with substrate conversion ratio 31.2% and 46.3%, respectively.

Central and peripheral arterial stiffness in patients after surgical repair of tetralogy of Fallot: implications for aortic root dilatation

OBJECTIVES

To test the hypotheses that (1) the central conduit arteries stiffen preferentially over the peripheral conduit arteries in patients with repaired tetralogy of Fallot (ToF); and (2) central arterial stiffening is related to aortic root dilatation.

DESIGN AND PATIENTS

Heart-femoral pulse wave velocity (PWV), femoral-ankle PWV, carotid augmentation index and body surface area-adjusted aortic sinotubular dimension were determined in 31 children after ToF repair and compared with those in 31 age-matched controls after left-to-right shunt repair. In addition, the PWVs and augmentation index were related to the sinotubular junction dimension.

SETTINGS

Tertiary paediatric cardiac centre.

RESULTS

Compared with controls, patients had significantly greater heart-femoral PWV (mean 666 (SD 151) v 587 (81) cm/s, p = 0.021) and carotid augmentation index (-14.1 (17.0)% v -25.2 (14.6)%, p = 0.016), whereas the right (888 (202) v 845 (207) cm/s, p = 0.42) and left (918 (227) v 851 (215) cm/s, p = 0.25) femoral-ankle PWVs were similar between the two groups. The sinotubular junction z score of patients was significantly greater than that of controls (4.7 (1.5) v 1.1 (1.4), p < 0.001). Univariate analysis showed that the sinotubular junction z score correlated positively with heart-femoral PWV (r = 0.43, p = 0.001) and carotid augmentation index (r = 0.46, p = 0.001). Multiple linear regression similarly identified heart-femoral PWV (beta = 0.30, p = 0.04) and carotid augmentation index (beta = 0.31, p = 0.04) (model R(2) = 0.26) as significant determinants of sinotubular junction z score.

CONCLUSIONS

The aorta stiffens in patients with repaired ToF, which may contribute to progressive dilatation of the aortic root in the long term.