Characterization and structural basis of a lethal mouse-adapted SARS-CoV-2

The ongoing SARS-CoV-2 pandemic has brought an urgent need for animal models to study the pathogenicity of the virus. Herein, we generated and characterized a novel mouse-adapted SARS-CoV-2 strain, named MASCp36, that causes severe acute respiratory symptoms and mortality in standard laboratory mice. Particularly, this model exhibits age and gender related skewed distribution of mortality akin to severe COVID-19, and the 50% lethal dose (LD50) of MASCp36 was 58 PFU in 9-month-old, male BALB/c mice. Deep sequencing identified three amino acid substitutions, N501Y, Q493H, and K417N, subsequently emerged at the receptor binding domain (RBD) of MASCp36, during in vivo passaging. All three mutations in RBD significantly enhanced the binding affinity to its endogenous receptor, mouse ACE2 (mACE2). Cryo-electron microscopy (cryo-EM) analysis of human ACE2 (hACE2) or mACE2 in complex with the RBD of MASCp36 at 3.1 to 3.7 angstrom resolution elucidates molecular basis for the receptor-binding switch driven by specific amino acid substitutions. Interestingly, N501Y and Q493H enhanced the binding affinity to human ACE2 (hACE2); while triple mutations N501Y/Q493H/K417N decreased affinity to hACE2, thus led to the reduced infectivity of MASCp36 to human cells. Our study not only provides a robust platform for studying the pathogenesis of severe COVID-19 and rapid evaluation of coutermeasures against SARS-CoV-2, but also unveils the molecular mechanism for the rapid adaption and evolution of SARS-CoV-2 in human and animals. One sentence summaryA mouse adapted SARS-CoV-2 strain that harbored specific amino acid substitutions in the RBD of S protein showed 100% mortality in aged, male BALB/c mice.

Effects of Acute Sacral Neuromodulation at Different Pulse Widths on Bladder Overactivity in Pigs / 대한배뇨장애요실금학회지

PURPOSE: Sacral nerve stimulation has been used to treat overactive bladder. This study evaluated the effects of stimulation using different pulse widths on the inhibition of bladder overactivity by sacral nerve stimulation (SNM) in pigs. METHODS: Implant-driven stimulators were used to stimulate the S3 spinal nerve in 7 pigs. Cystometry was performed by infusing normal saline (NS) or acetic acid (AA). SNM at pulse widths of 64 μsec to 624 μsec was conducted at the intensity threshold at which observable perianal and/or tail movement was induced. Multiple cystometrograms were performed to determine the effects of different pulse widths on the micturition reflex. RESULTS: AA-induced bladder overactivity reduced the bladder capacity to 46.9%±7.1% of the NS control level (P0.05). The actual intensity threshold varied from 0.7 to 8 V. The mean intensity threshold (T visual) for pulse widths of 64 μs, 204 μs, and 624 μs were 5.64±0.76 V, 3.11±0.48 V, and 2.52±0.49 V. T visual for pulse widths of 64 μsec was larger than the other two T visual for pulse widths of 204 μsec and 624 μsec (P0.05). CONCLUSIONS: This study indicated that different pulse widths could play a role in inhibiting bladder overactivity. It is not yet certain which pulse widths increased bladder capacity compared with AA levels, to minimize energy consumption and maintain patient comfort during stimulation, 204 μsec may be an appropriate pulse width for SNM.

Intravesical injection of botulinum toxin A for treatment of interstitial cystitis/bladder pain syndrome: 13 years of experience / 中华泌尿外科杂志

Objective To evaluate the efficacy of the intravesical injection of botulinum toxin A (BTX-A) and bladder hydrodistention plus sodium hyaluronate (Cystistat) instillation in patients with interstitial cystitis/bladder pain syndrome (IC/BPS).Methods We retrospectively reviewed 153 women with IC/BPS from January 2003 to December 2015.Of the 153 patients,77 were treated with BTX-A(group A),the average age was (56.0 ± 4.1) years old.76 underwent bladder hydrodistention plus sodium hyaluronate (Cystistat) instillation (group B),the average age was (58.0 ± 3.3) years old.The patients were evaluated using the O'Leafy-Saint score,visual analog scale pain score,urinary frequency record and quality of life questionnaire before treatment and 1 week,1,3,6 and 12 months after treatment.Results In group A,only 2 had acute urinary retention,27 received a repeat injection,and 28 were lost to follow-up.In group B,3 had urinary tract infection,15 switched to BTX-A injection at 6 months because the treatment of hydrodistention plus Cystistat instillation is not good.31 were lost to follow-up.BTX-A was shown to remain effective for up to 6 months after treatment.After repeated Chinese BTX-A injections,symptoms improved significantly.Hydrodistention plus Cystistat remained effective for up to 3 months after treatment.Conclusions Intravesical injection of BTX-A is a effective therapeutic option for patients with IC/BPS.The average duration of the effect of one dose of Chinese BTX-A was 6 months.Repeated injection of BTX-A is effective.

A resting-state functional MRI study on brain control of bladder storage function / 中华泌尿外科杂志

Objective In order to observe central responses during naturally occurring urinary bladder storage in healthy subjects,we examined brain areas that control strong bladder sensation by resting-state functional magnetic resonance imaging (rs-fMRI).Methods 44 healthy subjects (19 men and 25 women,between 22 and 50 years of age) were screened in the study from October 2014 to October 2016.All subjects were right-handed and scanned twice under the following two conditions:empty bladder (bladder volume ＜ 10 ml)and full bladder (‘strong desire to void’,bladder volume between 200 and 400 ml)without the use of filling with a catheter.Brain imaging softwares (SPM8,DPABI,REST) were adopted to analyze the difference in brain-blood perfusion between these two conditions.Voxel-based analysis of the regional homogeneity (ReHo) was performed to analyze rs-fMRI data including the main excitatory regions and inhibitory areas,peak value (X-axis,Y-axis,Z-axis),clusters size (active volume unit:number of voxel),T value (the excitatory and inhibitory extent of brain active regions).Results The rs-fMRI scans of 44 healthy subjects were analyzed.Nine subjects were excluded because of excessive head movements of more than 1.5 mm and 1.5° in rotation.Data sets were obtained from 35 subjects in two states of bladder,empty bladder and strong desires to void.Increased activity during strong desire to void was observed in the prefrontal cortex (PFC),anterior cingulate cortex (ACC),hypothalamus,temporal lobes and left caudate nucleus.Conclusions There are significant changes in the brain's ReHo during the strong sensation to void.The results suggest that the PFC,the ACC,hypothalamus,temporal lobes and left caudate nucleus play a role in the cerebral control of bladder storage without artificial bladder filling in healthy people.