SKIN POTENTIAL, HEART RATE, AND THE SPAN OF IMMEDIATE MEMORY

Relations between orienting response and span of immediate memory were studied by measuring skin potential responses (SPR) and heart rate (HR). Four conditions were studied by presenting letters in a tachistoscope and a 1000 cycle, 100 db tone simultaneous on some but not all trials. The conditions (15 Ss in each) were: tone and letters for 10 trials, then letters alone for 10 trials; tone and letters for 20 trials; only letters for 10 trials, followed by letters and tone for 10 trials; and only letters for 20 trials. The results showed: (1) positive SPR habituated and negative did not, (2) tone produced more SP activity, (3) HR showed a shift from acceleration to deceleration over 20 trials, but tone had no influence, (4) tone had no direct influence on span scores, (5) Ss showed improvement in number ol letters reported correctly. There was a significant correlation between span and negative SPR when tone was sounded (r =. 36).     

Effect of influenza A virus on leukocyte histamine release

Viral respiratory infections provoke asthma in many patients. In the following study we examined the effect of an in vitro incubation of influenza A on leukocyte histamine release. After incubation with a live influenza A (H3N2) virus, calcium ionophore A23187 (0.5, 1.0, and 1.5 microgram/ml)-induced leukocyte histamine release (HR) was enhanced (p less than 0.05). This effect was also found with heat- or ether-inactivated virus. Similarly, influenza A-exposed leukocytes had augmented leukocyte HR during subsequent incubation with ragweed AgE. Incubation of the leukocyte suspension with interferon (800 IU/ml) for 24 hr was also associated with enhanced HR to ragweed AgE. In contrast, interferon did not alter the calcium ionophore A23187 HR. Therefore, although interferon may mediate the enhanced leukocyte HR when ragweed AgE is the inciting stimulus, it does not change HR to the calcium ionophore.     

Development of allergy in children. I. Association with virus infections.

Children born into allergic families, with two allergic parents, are at high risk of developing allergy within the first 5 years of life. In order to observe possible external factors in the sensitization process, a prospective study of 13 such children was done, in which serial clinical and immunologic observations were made at 3- to 6-month intervals over a period of 1 to 4 yr. Eleven of these children are now clinically allergic; 5 have asthma. Immunologic evidence for allergic sensitization was observed in these 11 children by RAST, antigen-induced leukocyte histamine release, lymphoblastogenesis, and rise in serum IgE. Upper respiratory infections (URI) occurred in these 11 allergic children 1 to 2 months prior to the onset of allergic sensitization. In 10 of these 11 URI children, complement-fixing antibodies to viruses (parainfluenza, RSV, CMV) increased in the same blood samples in which immunologic allergic sensitization was first evidenced. This coincidence suggests that certain viruses may contribute to the allergic sensitization process.     

扶桑花抗生育成分对早孕小鼠黄体影响的定量研究

本文处用图像分析仪 ,以核浆比和数密度为指标 ,研究了不同浓度的扶桑花提取物—HR 1对早孕小鼠黄本组织学的影响。结果表明 :(1)小鼠黄体细胞的核浆比和数密度 ,随给药剂量 (0、 4、 10、 10 0、10 0 0mg/kg/d)的增加而增加 ,其中 10 0和 10 0 0mg/kg/d两组的黄体细胞核浆比和数密度明显高于对照组(p <0 .0 5) ;(2 )黄体组织学的定性观察显示 ,给药各组的黄体细胞明显退化 ,细胞缩小 ,细胞界限不清。这些结果提示 ,扶桑花提取物的抗早孕作用与妊娠黄体受损有关。     

Autonomic nervous system mediates the cardiovascular effects of Rhodiola sacra radix in rats

ETHNOPHARMACOLOGICAL RELEVANCE: Rhodiola sacra (Crassulaceae) exhibits cardiovascular bioactivities and is used in Tibetan medicine for promoting circulation and preventing hypertension. However, the underlying mechanisms of its cardiovascular effects are poorly understood. AIM OF THE STUDY: The aim of this study was therefore to evaluate the cardiovascular activity of water-soluble fraction (WtF) and n-butanol-soluble fraction (BtF) of Rhodiola sacra radix and to explore its mechanism of action in propofol anesthetized Sprague-Dawley rats. MATERIALS AND METHODS: The changes of blood pressure, heart rate and cardiac contractility after systemic administration of the extracts (10-75mg/kg) were examined for at least 40min. Different antagonists were used to evaluate the mechanisms of cardiovascular effects of the extracts. RESULTS: Intravenous injection of the WtF (10, 25, 35, 50 or 75mg/kg) exhibited dose-dependent hypotension and increases in heart rate and cardiac contractility. In contrast, mild alterations in the same cardiovascular parameters were detected only at high dose (75mg/kg) BtF. The WtF-induced hypotensive, positive inotropic and chronotropic effects were significantly abolished by pretreatment with hexamethonium (30mg/kg, i.v.) or reserpine (5mg/kg, i.v.), whereas the hypotensive, but not the positive inotropic or chronotropic effect was potentiated by captopril (2.5mg/kg, i.v.). Pretreatment with methylatropine (1mg/kg, i.v.), on the other hand, reversed the positive inotropic and chronotropic but not the hypotensive effects of WtF. The WtF-induced cardiovascular responses were not affected in rats pretreated with N(G)-nitro-l-arginine methyl ester (20mg/kg, i.v.). CONCLUSIONS: We conclude that systemic administration of the WtF of Rhodiola sacra radix elicited a potent hypotensive effect that was mediated by the withdrawal of sympathetic vasomotor tone and interaction with the circulatory angiotensin system. The positive inotropic and chronotropic effects of WtF may result from a direct vagal inhibition on the heart.     

Temporal effect of Guanxin No. 2 on cardiac function, blood viscosity and angiogenesis in rats after long-term occlusion of the left anterior descending coronary artery

AIM: Cardiac infarction is one of the main causes of death in both developing and developed countries over past decades. Currently available approaches for treating patients with this disease are not satisfactory. Traditional Chinese medicines have been increasingly paid attention to. The aim of this study was to characterize the dynamic protective effects of Guanxin No. 2 decoction (GX II) on cardiac dysfunction combined with the blood viscosity and myocardial hypertrophy parameters in myocardial infarction (MI) rats. METHODS: Male Sprague-Dawley rats (180-200 g) were randomly divided into three groups: sham-operated, coronary artery ligation (CAL), and CAL plus GX II (GX II, 10.0 g raw materials/kg/d, bid, p.o.). The experiment was carried out at 4 time points as the 3rd, 7th, 14th, and 28th day after ligation. RESULT: It was found that on the one hand, GX II could significantly improve the heart function, and remarkably decrease infarct size and inhibit ventricular remodeling. On the other hand, GX II showed some unique effects such as angiogenesis which was induced in the left ventricular tissue. This result was consistent with the finding of an augmented vascular endothelial growth factor (VEGF) expression in this area. CONCLUSIONS: The studies demonstrated that GX II exerted extensively beneficial cardioprotective effect on CAL rats, it might stimulate angiogenesis of ischemic region to compensate blood supply to the heart via upregulated VEGF expression.     

Structural conservation among variants of the SARS-CoV-2 spike postfusion bundle

Variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) challenge currently available COVID-19 vaccines and monoclonal antibody therapies due to structural and dynamic changes of the viral spike glycoprotein (S). The heptad repeat 1 (HR1) and heptad repeat 2 (HR2) domains of S drive virus–host membrane fusion by assembly into a six-helix bundle, resulting in delivery of viral RNA into the host cell. We surveyed mutations of currently reported SARS-CoV-2 variants and selected eight mutations, including Q954H, N969K, and L981F from the Omicron variant, in the postfusion HR1HR2 bundle for functional and structural studies. We designed a molecular scaffold to determine cryogenic electron microscopy (cryo-EM) structures of HR1HR2 at 2.2–3.8 Å resolution by linking the trimeric N termini of four HR1 fragments to four trimeric C termini of the Dps4 dodecamer from Nostoc punctiforme. This molecular scaffold enables efficient sample preparation and structure determination of the HR1HR2 bundle and its mutants by single-particle cryo-EM. Our structure of the wild-type HR1HR2 bundle resolves uncertainties in previously determined structures. The mutant structures reveal side-chain positions of the mutations and their primarily local effects on the interactions between HR1 and HR2. These mutations do not alter the global architecture of the postfusion HR1HR2 bundle, suggesting that the interfaces between HR1 and HR2 are good targets for developing antiviral inhibitors that should be efficacious against all known variants of SARS-CoV-2 to date. We also note that this work paves the way for similar studies in more distantly related viruses.

Three previously unknown beta-coronaviruses have emerged in the first two decades of this century: severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003, Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in late 2019 (1). The most recent outbreak of SARS-CoV-2 that causes coronavirus disease 2019 (COVID-19) has claimed about 6 million lives in 2 y, and several variants of concern have emerged around the globe despite the relatively low mutation rate of coronaviruses (2). Some of these variants pose a challenge to currently available vaccines (3–6), likely due to structural changes of the target of these vaccines (7–11). Hence, there is an urgent need for new antiviral therapeutics (12) that target regions of viruses with conserved structural features that are less likely to be affected by mutations.SARS-CoV, MERS-CoV, and SARS-CoV-2 are enveloped viruses that rely on membrane fusion to deliver RNA to the host cell (13). In each case, the process of viral membrane fusion (14, 15) is mediated by the trimeric viral spike glycoprotein (S) that is cleaved into S1 and S2 subunits by multiple host proteases upon infection (16) (Fig. 1A). S1 recognizes the human angiotensin-converting enzyme 2 (ACE2) receptor and dissociates from S2. Subsequently, S2 undergoes substantial conformational changes that drive membrane remodeling. Similar to other enveloped viruses (14, 15), this process likely proceeds via an intermediate extended state that pulls together the two membranes via the transmembrane domain and fusion peptide of the S2 subunit (17). Two heptad repeat regions, HR1 and HR2, distant from each other in the prefusion S, drive membrane fusion by assembly into a six-helix bundle (18). This HR1HR2 bundle formation is thought to provide the energy for membrane fusion and is therefore a target for therapeutics, as exemplified by peptide inhibitors that disrupt infection by the HIV-1 (19, 20), SARS-CoV (21), MERS-CoV (22), SARS-CoV-2 (23–25), human parainfluenza virus 3 (26), and respiratory syncytial virus (26).Open in a separate windowFig. 1.Mutations of interest in the HR1HR2 bundle of SARS-CoV-2 variants. (A) Schematic diagram of the domain structures of the SARS-CoV-2 spike protein. The N and C termini are labeled on the left and right, respectively. FP, fusion peptide; HR1, heptad repeat 1; HR2, heptad repeat 2; TM, transmembrane region. (B) Locations of the five selected point mutations of SARS-CoV-2 variants (black spheres) and the three mutations of the SARS-CoV-2 Omicron variant (purple spheres) indicated in the crystal structure of the HR1HR2 bundle (PDB ID code 6lxt). Two HR2 residues, R1185 and N1187, that may be affected by the selected mutations are shown as red spheres. The HR1 and HR2 fragments are colored as light blue and light red, respectively. (C) Effects on fusion activity of these mutations. The fusion activity is shown as a percentage (Left)/fold change (Right) relative to that of the wild type (Materials and Methods). The Omicron construct used here for the fusion assay has three mutations—Q954H, N969K, and L981F—in the HR1 portion of the HR1HR2 bundle, but not other mutations from different regions of the spike found in the Omicron variant. *P < 0.05, **P < 0.01, ***P < 0.001, by a Student’s t test.Despite the established value of inhibitors targeting formation of the HR1HR2 bundle, the structural plasticity of this bundle upon mutation is largely unknown. Comparison with distantly related viruses suggests that the overall architecture is maintained despite vast differences in primary sequence (SI Appendix, Fig. S1). To what degree does the structure of the HR1HR2 bundle change upon mutation? To address this question, we surveyed mutations of all currently known variants (including Omicron) of SARS-CoV-2 S in the postfusion HR1HR2 bundle, selected eight mutations of potential interest, and investigated their effects on structure and function.Structural characterization of the HR1HR2 bundle has proven surprisingly challenging. To date, two successful approaches for determining structures of the HR1HR2 bundle have been employed. First, several HR1HR2 structures with the HR1 and HR2 domains synthetically linked were determined by X-ray crystallography (2.9 Å, Protein Data Bank [PDB] ID code 6lxt; 1.5 Å, PDB ID code 6m1v) (23, 25). Second, a sample of postfusion S2 was generated from a recombinant source (mammalian HEK-293F cells) expressing full-length S; as such, multiple states of S undergoing spontaneous transition from the prefusion to the postfusion state were present in the sample and the postfusion structure was determined by single-particle cryogenic electron microscopy (cryo-EM) (3.0 Å, PDB ID code 6xra) (18). Although the structures of the postfusion HR1HR2 bundle are similar, there are differences between these structures and the local resolution is quite variable or limited. More importantly, neither approach is particularly suited for efficient structure determination of multiple mutants at high resolution. Therefore, we decided to develop a platform for using single-particle cryo-EM to efficiently determine structures of HR1HR2 bundles at atomic resolution.The postfusion HR1HR2 bundle of SARS-CoV-2 is a 115 × 25 × 25 Å bundle consisting of six helices (PDB ID code 6lxt) (23). Its molecular weight is 40 kDa, close to the theoretical minimum size needed to achieve a reconstruction with near-atomic resolution by cryo-EM (27). To our knowledge, it has not yet been possible to determine structures of individual proteins <50 kDa to high resolution, with exception in the case of multimers (28, 29) or small RNA molecules (30). In addition, efforts extending the resolution limit of cryo-EM have largely focused on globular proteins (28, 29, 31, 32), perhaps because fibrous samples are more flexible, more susceptible to the issue of preferred orientation, and require thicker ice to bury the entire particle—all of which inevitably increase noise in the already extremely low-contrast and hard-to-align images. To overcome the size limit of single-particle cryo-EM, two strategies have been employed to increase the effective mass of the target protein, e.g. using antibodies/nanobodies/legobodies (33, 34) and molecular scaffolds (35–38). Since developing antibodies/nanobodies/legobodies can be time-consuming we resorted to the molecular scaffold approach. We first attempted to use existing scaffolds but were unable to engineer a linkage ensuring proper HR1HR2 bundle formation. We therefore designed a scaffold to efficiently determine structures of the postfusion HR1HR2 bundle and its mutants to near-atomic resolution by single-particle cryo-EM.Our high-resolution wild-type structure of the HR1HR2 bundle resolves uncertainties in some side-chain positions present in prior structures. Our HR1HR2 structures of SARS-CoV-2 variants reveal an overall architecture that is highly conserved, with only side-chain rearrangement for five point mutations and, for the Omicron variant containing three mutations in HR1, a slight shift of the HR2 backbone in a nonhelical region that interacts with HR1. These results suggest that interactions between HR1 and HR2 are excellent targets for disruption by broadly efficacious antiviral inhibitors. Moreover, our approach can be directly used to study the binding of potential HR2-based peptide inhibitors and adapted to study the postfusion bundles of other coronaviruses or other structurally similar viruses.     

HR神经元模型的放电节律分析

目的 研究HR神经元的复杂动力学行为.方法 运用非线性动力学方法,研究外界电流对神经元放电模式的影响.特别地,基于快慢动力学分析,探讨簇模式和峰模式不同的产生机理.结果 数值分析结果揭示了簇振荡和峰振荡模式存在的区域,此外,还发现了分岔序列结构.结论 为进一步研究外界激励对神经元复杂放电模式的影响提供了线索.