COVID-19 reopening strategies at the county level in the face of uncertainty: Multiple Models for Outbreak Decision Support

Policymakers make decisions about COVID-19 management in the face of considerable uncertainty. We convened multiple modeling teams to evaluate reopening strategies for a mid-sized county in the United States, in a novel process designed to fully express scientific uncertainty while reducing linguistic uncertainty and cognitive biases. For the scenarios considered, the consensus from 17 distinct models was that a second outbreak will occur within 6 months of reopening, unless schools and non-essential workplaces remain closed. Up to half the population could be infected with full workplace reopening; non-essential business closures reduced median cumulative infections by 82%. Intermediate reopening interventions identified no win-win situations; there was a trade-off between public health outcomes and duration of workplace closures. Aggregate results captured twice the uncertainty of individual models, providing a more complete expression of risk for decision-making purposes.

Explaining the Bomb-Like Dynamics of COVID-19 with Modeling and the Implications for Policy

Using a Bayesian approach to epidemiological compartmental modeling, we demonstrate the "bomb-like" behavior of exponential growth in COVID-19 cases can be explained by transmission of asymptomatic and mild cases that are typically unreported at the beginning of pandemic events due to lower prevalence of testing. We studied the exponential phase of the pandemic in Italy, Spain, and South Korea, and found the R0 to be 2.56 (95% CrI, 2.41-2.71), 3.23 (95% CrI, 3.06-3.4), and 2.36 (95% CrI, 2.22-2.5) if we use Bayesian priors that assume a large portion of cases are not detected. Weaker priors regarding the detection rate resulted in R0 values of 9.22 (95% CrI, 9.01-9.43), 9.14 (95% CrI, 8.99-9.29), and 8.06 (95% CrI, 7.82-8.3) and assumes nearly 90% of infected patients are identified. Given the mounting evidence that potentially large fractions of the population are asymptomatic, the weaker priors that generate the high R0 values to fit the data required assumptions about the epidemiology of COVID-19 that do not fit with the biology, particularly regarding the timeframe that people remain infectious. Our results suggest that models of transmission assuming a relatively lower R0 value that do not consider a large number of asymptomatic cases can result in misunderstanding of the underlying dynamics, leading to poor policy decisions and outcomes.

A Two-Step GRIN Lens Coating for In Vivo Brain Imaging / 神经科学通报·英文版

The complex spatial and temporal organization of neural activity in the brain is important for information-processing that guides behavior. Hence, revealing the real-time neural dynamics in freely-moving animals is fundamental to elucidating brain function. Miniature fluorescence microscopes have been developed to fulfil this requirement. With the help of GRadient INdex (GRIN) lenses that relay optical images from deep brain regions to the surface, investigators can visualize neural activity during behavioral tasks in freely-moving animals. However, the application of GRIN lenses to deep brain imaging is severely limited by their availability. Here, we describe a protocol for GRIN lens coating that ensures successful long-term intravital imaging with commercially-available GRIN lenses.

Growth factor composite scaffolds for bone defect repair via immediate implantation of bone defects / 中国组织工程研究

BACKGROUND:Nerve growth factor has been shown to play an important role in bone healing, but little is reported on the effect of growth factor composite scaffolds via the immediate implantation in the repair of canine bone defects. OBJECTIVE:To analyze the effect of nerve growth factor composite scaffolds via the immediate implantation for the repair of canine bone defects. METHODS:Nerve growth factor composited strontium apatite scaffolds were prepared. Canine mandibular defect models were established and divided into three groups, fol owed by implanted with composite scaffold (experimental group), strontium apatite (positive control group), or nothing (blank control group). The three-dimensional CT reconstruction and hematoxylin-eosin staining of canine mandibular bone defects were observed. RESULTS AND CONCLUSION:In the blank control group, there were few new bones surrounding bone defect. Trabecular bones spread from the defect center to the surrounding tissues in the experimental and positive control groups. The bone density, volume, thickness, and implant-bone contact were significantly increased, while the trabecular separation was significantly decreased in the experimental group compared with the positive control and blank control groups (P<0.05), and al above indicators in the positive contro group were significantly higher than those in the blank control group (P<0.05). Hematoxylin-eosin staining showed that in the experimental group, there were a large number of new bones that contacted with the surrounding bones closely, and trabecular bones arranged regularly. In the positive control group, newborn osteoid, trabeculare, and a smal amount of debris were found. In the blank control group, few new bones were connected with the surrounding bones untightly and trabecular bone arranged irregularly. These results indicate that the nerve growth factor composite scaffold can promote the bone regeneration in the canine bone defects after immediate implantation.

Titanium core/bone morphogenetic protein composite materials used to repair alveolar bone defects after immediate implant placement / 中国组织工程研究

BACKGROUND:Now experimental and clinical research on suitable bone substitutes for alveolar bone defects after dental implantation is an issue of concern.OBJECTIVE:To study the therapeutic effect of titanium core/bone morphogenetic protein (BMP) composite material on alveolar bone defects after immediate implant placement.METHODS:Twenty-four New Zealand rabbits were randomly assigned into normal group (no intervention),experimental group or control group.Animal models of bone femoral greater trochanter defect were made in the experimental and control groups.Dental implant and titanium core/BMP composite material were implanted in the experimental group,while dental implant and titanium core were implanted in the control group.Percentage of CD4+,CD8+ T lymphocytes,natural killer cell activity and interleukin 2 level were detected at postoperative 4 weeks;bone mineral density and osteogenesis around the implant were detected at postoperative 16 weeks through X-ray and histological examinations.RESULTS AND CONCLUSION:X-ray results showed that the bone mineral density in the experimental group was significantly higher than that in the control group (P ＜ 0.05).Histological results showed that in the experimental group,different degrees of cell lysis around the composite,more bone cells and bone matrices were found,implant-bone osseointegration formed well,and red-dyed mature bone tissues were detective inside the implant.Compared with the experimental group,lower number of bone cells and fibrocytes were found in the control group.Additionally,the percentage of CD4+ and CD8+ T lymphocytes,natural killer cell activity and interleukin 2 level in the experimental group were significantly lower than those in the control group (P ＜ 0.05).To conclude,the titanium core/BMP composite material can effectively repair alveolar bone defects after immediate implant placement to guide the growth of bone cells.

Effects of the aqueous extract of Schizandra chinensis fruit on ethanol withdrawal-induced anxiety in rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>We previously demonstrated that the aqueous extract of the Schizandra chinensis fruit (AESC) ameliorated Cd-induced depletion of monoamine neurotransmitters in the brain through antioxidant activity. In the present study, we investigated the effect of AESC on anxiety-like behavior and the levels of norepinephrine and 3-methoxy-4-hydroxy-phenylglycol (a metabolite of norepinephrine) in different brain regions during ethanol withdrawal in rats.</p><p><b>METHODS</b>Male Sprague-Dawley rats were treated with 3 g/kg of ethanol (20%, w/v) or saline by daily intraperitoneal injection for 28 days followed by three days of withdrawal. During withdrawal, rats were given AESC (100 mg × kg(-1)× d(-1) or 300 mg × kg(-1)× d(-1), P.O.) once a day for three days. Thirty minutes after the final dose of AESC, the anxiogenic response was evaluated using an elevated plus maze, and the plasma corticosterone levels were examined by radioimmunoassay. Meanwhile, the concentrations of norepinephrine and 3-methoxy-4-hydroxy-phenylglycol in the hypothalamic paraventricular nucleus and hippocampus were also measured by high performance liquid chromatography.</p><p><b>RESULTS</b>Rats undergoing ethanol withdrawal exhibited substantial anxiety-like behavior, which was characterized by both the decrease in time spent in the open arms of the elevated plus maze and the increased level of corticosterone secretion, which were greatly attenuated by doses of AESC in a dose-dependent manner. The high performance liquid chromatography analysis revealed that ethanol withdrawal significantly increased norepinephrine and 3-methoxy-4-hydroxy-phenylglycol levels in the hypothalamic paraventricular nucleus, while not significantly altering them in the hippocampus. Similar to the results from the elevated plus maze test, the AESC significantly inhibited the elevation of norepinephrine and its metabolite in the hypothalamic paraventricular nucleus in a dose-dependent manner.</p><p><b>CONCLUSIONS</b>These results suggest that AESC attenuates anxiety-like behavior induced by ethanol withdrawal through modulation of the hypothalamic norepinephrine system in the brain.</p>