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1.
Neural Plast ; 2020: 8876230, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33029124

RESUMO

Background: Visceral hypersensitivity is a common occurrence of gastrointestinal diseases such as irritable bowel syndrome (IBS), wherein early-life stress (ELS) may have a high predisposition to the development of visceral hypersensitivity in adulthood, with the specific underlying mechanism still elusive. Herein, we assessed the potential effect of small-conductance calcium-activated potassium channel subtype 2 (SK2) in the spinal dorsal horn (DH) on the pathogenesis of visceral hypersensitivity induced by maternal separation (MS) in mice. Methods: Neonatal mice were subjected to the MS paradigm, an established ELS model. In adulthood, the visceral pain threshold and the abdominal withdrawal reflex (AWR) were measured with an inflatable balloon. The elevated plus maze, open field test, sucrose preference test, and forced swim test were employed to evaluate the anxiety- and depression-like behaviors. The expression levels of SK2 in the spinal DH were determined by immunofluorescence and western blotting. The mRNA of SK2 and membrane palmitoylated protein 2 (MPP2) were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Electrophysiology was applied to evaluate the neuronal firing rates and SK2 channel-mediated afterhyperpolarization current (I AHP). The interaction between MPP2 and SK2 was validated by coimmunoprecipitation. Results: In contrast to the naïve mice, ethological findings in MS mice revealed lowered visceral pain threshold, more evident anxiety- and depression-like behaviors, and downregulated expression of membrane SK2 protein and MPP2 protein. Moreover, electrophysiological results indicated increased neuronal firing rates and decreased I AHP in the spinal DH neurons. Nonetheless, intrathecal injection of the SK2 channel activator 1-ethyl-2-benzimidazolinone (1-EBIO) in MS mice could reverse the electrophysiological alterations and elevate the visceral pain threshold. In the naïve mice, administration of the SK2 channel blocker apamin abated I AHP and elevated spontaneous neuronal firing rates in the spinal DH neurons, reducing the visceral pain threshold. Finally, disruption of the MPP2 expression by small interfering RNA (siRNA) could amplify visceral hypersensitivity in naïve mice. Conclusions: ELS-induced visceral pain and visceral hypersensitivity are associated with the underfunction of SK2 channels in the spinal DH.

2.
Neuropharmacology ; : 108351, 2020 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-33031806

RESUMO

The widely abused prescription opioid oxycodone is a mu-opioid receptor (MOP-r) agonist and addiction to such opioids is a relapsing disorder. The human MOP-r gene (OPRM1) has an important functional single nucleotide polymorphism (SNP), A118G, which affects risk of severe opioid use disorders. A112G (G/G) knock-in mice are models of human A118G carriers. We examined oxycodone self-administration (SA) in male and female G/G versus wild type (A/A) mice in SA sessions and in relapse-like behavior. Adult male and female G/G and A/A mice self-administered oxycodone (0.25 mg/kg/infusion, FR1) for 10 consecutive days. Following 10-day home cage drug free withdrawal, the mice were re-exposed to oxycodone SA for a further 10 days. MOP-r receptor mRNA in various brain regions were examined immediately after the last re-exposure session. We found that G/G mice had greater oxycodone SA than A/A mice in the initial and in re-exposure sessions. Mice of both genotypes had greater oxycodone intake during the re-exposure period than during the initial exposure. We also detected differences in MOP-r gene expression due to genotype, sex and oxycodone SA history in the dorsal striatum, hippocampus, and prefrontal cortex. These studies may improve our understanding of MOP-r-agonist self-exposure and relapse in human carriers of the A118G SNP.

3.
Chem Asian J ; 2020 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-33034939

RESUMO

The activatable off-on near-infrared QCy7-based fluorogenic probes have emerged as powerful modalities for detecting and monitoring biological analytes and understanding their biological processes in cells and organisms. The use of biomarker-activated QCy7-based probes enables simple synthesis, minimum photo-damage to biological samples, and minimum background interference from biological systems. In this minireview, we aim to provide a rigorous but concise overview of activatable QCy7-based fluorogenic probes by reporting the significant progress made in recent years. The design strategies and the main applications of accurate detection and imaging of disease-related biomarkers (including ROS/RSS, enzymes, metal ions, and other related species) were reasonably analyzed and discussed. The potential challenges and prospects of activatable QCy7-based fluorogenic probes are also emphasized to further advance the development of new methods for biomarker detection and bioimaging.

4.
Front Immunol ; 11: 526965, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33013922

RESUMO

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory illness, particularly in infants, the elderly, and immunocompromised adults. There is no licensed commercial vaccine against RSV. Importantly, formalin-inactivated RSV vaccines mediate enhanced respiratory disease. RSV fusion (F) protein with pre-fusion conformation is a promising candidate subunit vaccine. However, some problems remain to be solved, such as low immunogenicity and humoral immunity bias. Adjuvants can effectively enhance and adjust vaccine immune responses. In this study, we formulated pre-fusion RSV-F protein with the adjuvants, Alhydrogel, MF59, AS03, AS02, and glycol chitosan (GCS). We then conducted head-to-head comparisons of vaccine-induced immune responses in BALB/c mice. All adjuvanted vaccines enhanced antigen-specific and neutralizing antibody titers and viral clearance and gave an order of adjuvant activity: AS02 > AS03, MF59 > GCS, and Alhydrogel. Among them, AS02 elicited the highest antibody expression, which persisted until week 18. Moreover, AS02 significantly enhanced Th1 type immune response in immunized mice. Mice in the AS02 group also showed faster recovery from viral attacks in challenge tests. Further transcriptome analysis revealed that AS02 regulates immune balance by activating TLR-4 and promotes Th1-type immune responses. These results suggest that AS02 may be an excellent candidate adjuvant for RSV-F subunit vaccines. This study also provides valuable information regarding the effect of other adjuvants on immune responses of RSV-F subunit vaccines.

5.
Artigo em Inglês | MEDLINE | ID: mdl-33017806

RESUMO

We investigate the radiation of energy and angular momentum from 2D topological systems with broken inversion symmetry and time reversal symmetry. A general theory of far-field radiation is developed using the linear response of 2D materials to the thermal fluctuation of electric currents. Applying the theory to the Haldane model, we verify that the heat radiation complies with Planck's law only at low temperature and deviates from it as temperature becomes high. In contrast to normal metals, angular momentum radiation is possible for this system and exhibits saturation as temperature increases. Parameters crucial to the radiation are investigated and optimized. This research enlightens the possibility of transposing the quantum information to the angular momentum degree of freedom.

6.
Chem Rec ; 2020 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-33021040

RESUMO

Gas sensors based on metal oxides semiconductor (MOS) have attracted extensive attention from both academic and industry. ZnO, as a typical MOS, exhibits potential applications in toxic gas detection, owning to its wide band gap, n-type transport characteristic and excellent electrical performance. Meanwhile, doping is an effective way to improve the sensing performance of ZnO materials. In this review, the effects of different types of doping on morphology, crystal structure, band gap and depletion layer of ZnO materials are comprehensively discussed. Theoretical analysis on the strategies for enhancing the sensing properties of ZnO is also provided. This review puts forward the reasonable insight for designing efficient n-type ZnO-based semiconductor oxide sensing materials.

7.
Inorg Chem ; 2020 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-33030016

RESUMO

The most critical aspect in the assembly of phosphor-converted white light-emitting diodes (pc-WLEDs) is how to stabilize the device in a practical environment. The high applied currents can generate enormous heat up to more than 100 °C, and such a continuous illumination process will lead to serious effects concerning the stability of the device. Therefore, the new search for examples to fully suppress thermal quenching effect is a real challenge. In this study, a novel Eu3+-activated CaMgGeO4 (CMGO) phosphor of olivine type is developed via a conventional solid-state reaction. The results reveal that Eu3+ occupies the low symmetric Ca2+ site of this host. Upon visible-light sensitization at 464 nm, a dominant red emission band with maximum at 612 nm is witnessed. Its full width at half-maximum (fwhm) is merely ∼4.37 nm, and a high color purity of around 94% is achieved. Their corresponding Commission Internationale de L'Eclairage (CIE) coordinates are very close to standard red color coordinates (0.666, 0.333). The influence of concentration and temperature on the optical property has been explored. It has been discovered that the optimized sample (CMGO:0.01Eu3+) is not influenced by the thermal quenching effect and its fluorescent intensity is improved even up to 473 K, which is mainly attributed to the incorporation of abundant trap sites generated by the nonequivalent substitution Eu3+ for Ca2+. After it is integrated into commercially available YAG:Ce3+ phosphor-based pc-WLEDs, the excellent optical parameters of the fabricated WLEDs are evaluated. The correlated color temperature (CCT) varies from cool white (6458 K) to warm (4370 K), and the color rendering index (CRI) increases from 78 to 86 under a high flux operating current of 200 mA. Furthermore, the chromaticity coordinates remain almost stable with the increasing drive current from 200 mA to 1000 mA. It is highly expected that CaMgGeO4:0.01Eu3+ will become a suitable red phosphor for the preparation of white LEDs with high efficiency.

8.
Int J Mol Sci ; 21(19)2020 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-33023038

RESUMO

Glucose-6-phosphate dehydrogenase (G6PDH) plays an important role in plant stress responses. Here, five FaG6PDH sequences were obtained in strawberry, designated as FaG6PDH-CY, FaG6PDH-P1, FaG6PDH-P1.1, FaG6PDH-P2 and FaG6PDH-P0, which were divided into cytosolic (CY) and plastidic (P) isoforms based on the bioinformatic analysis. The respective FaG6PDH genes had distinct expression patterns in all tissues and at different stages of fruit development. Notably, FaG6PDH-CY was the most highly expressed gene among five FaG6PDH members, indicating it encoded the major G6PDH isoform throughout the plant. FaG6PDH positively regulated cold tolerance in strawberry. Inhibition of its activity gave rise to greater cold-induced injury in plant. The FaG6PDH-CY transcript had a significant increase under cold stress, similar to the G6PDH enzyme activity, suggesting a principal participant in response to cold stress. Further study showed that the low-temperature responsiveness (LTR) element in FaG6PDH-CY promoter can promote the gene expression when plant encountered cold stimuli. Besides, FaG6PDH-CY was involved in regulating cold-induced activation of antioxidant enzyme genes (FaSOD, FaCAT, FaAPX and FaGR) and RBOH-dependent ROS generation. The elevated FaG6PDH-CY enhanced ROS-scavenging capability of antioxidant enzymes to suppress ROS excessive accumulation and relieved the oxidative damage, eventually improving the strawberry resistance to cold stress.

9.
Inflammation ; 2020 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-33006074

RESUMO

Acute liver injury (ALI) refers to abnormalities in liver function caused by various causes and accompanied by poor prognosis and high mortality. Common predisposing factors for the disease are viral hepatitis, bacteria, alcohol, and certain hepatotoxic drugs. Inflammatory response and oxidative stress are critical for the pathogenesis of ALI. Pterostilbene (Pte), a natural polyphenol product extracted from blueberries and grapes, has been reported that exerted multiple biological activities, including antioxidative, anti-inflammatory, anti-carcinogenic, and anti-apoptotic properties. However, there is very little data showing the hepatoprotective effect of Pte on lipopolysaccharide/D-galactosamine (LPS/D-Gal)-induced ALI in mice. In this study, the possible protective effect and potential mechanisms of Pte on ALI are being investigated. It has been found that Pte markedly ameliorates LPS/D-Gal-induced inflammatory infiltration, hemorrhage, and dissociation of the hepatic cord, reducing the myeloperoxidase (MPO) activity in liver tissues and serum levels of alanine transaminase (ALT) and aspartate aminotransferase (AST) in ALI. Pte also inhibits LPS/D-Gal-induced secretion of pro-inflammatory cytokine tumor necrosis factor-a (TNF-α), interleukin 6 (IL-6), and interleukin 1ß (IL-1ß) in liver tissues. Furthermore, the western blot analysis reveals that LPS/D-Gal-activated nuclear factor-kappa B (NF-κB) is significantly inhibited by Pte, and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 (HO-1) are upregulated by Pte. In conclusion, our results suggest that Pte exerts anti-inflammatory and antioxidative effects, which might contribute to ameliorating LPS/D-Gal-induced ALI in mice. Pte has the potential to be a preventive hepatoprotective agent.

10.
Neurotoxicology ; 2020 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-33053366

RESUMO

Vincristine (VCR), an alkaloid extracted from vinca, is often used in combination with other chemotherapeutic drugs to treat a variety of cancers, such as acute lymphoblastic leukaemia (ALL), malignant lymphoma, and neuroblastoma. However, VCR possesses dose-dependent neurotoxicity, which is the main factor restricting its application. Vincristine-induced peripheral neuropathy (VIPN) not only limits the dose of VCR and leads to the discontinuation of treatment but also triggers serious damage to the physical and mental health of patients. In addition, VIPN brings huge healthcare costs to patients and society. Individuals with VIPN often exhibit mechanical allodynia, sensory/tactile disorders, and numbness in the hands and feet. Unfortunately, VIPN is easily ignored due to its variable symptoms, which gives rise to insufficient research on the aetiology and pathogenesis of this disease, thereby resulting in a lack of appropriate preventive and therapeutic management. We performed a comprehensive review of the latest findings on VIPN in terms of symptoms, risk factors, potential mechanisms, and prevention and treatment measures. The purpose was to help clinicians better understand and accurately diagnose VIPN, select appropriate intervention measures and reduce the damage to cancer patients.

11.
Ann Palliat Med ; 9(5): 3462-3471, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33065797

RESUMO

BACKGROUND: Hepatic cysts in located posterior segments close to the diaphragm (IVa, VII, and VIII) reportedly have a high recurrence rate. Presently, laparoscopic omentoplasty is the accepted technique; developed from laparoscopic deroofing, which places a viable pedicle flap of omentum to prevent cyst closure. However, potential adhesions have made laparoscopic omentoplasty less favorable. In this paper, we report on an improved surgical technique involving lauromacrogol sclerosis directly under laparoscopic fenestration. We also review and evaluate the efficacy and feasibility of this refined surgical approach. METHODS: Data from 49 patients admitted to the Department of Hepatobiliary Surgery at the Affiliated Hospital of Jiangnan University from October 2015 to June 2020 with simple hepatic cysts located in the IVa, VII, and VIII segments were retrospectively analyzed. All patients were symptomatic before admission. They were separated into two groups based on the surgical approach they had received; refined laparoscopic lauromacrogol sclerotherapy or laparoscopic omentoplasty, and were compared and evaluated in terms of the postoperative cyst volume and quality of life. RESULTS: No significant differences in sex, age, preoperative cyst volume, surgery duration, hospital stay, and bleeding volume were reported. There were no deaths or major complications in both groups. The postoperative cyst volume was significantly reduced in the laparoscopic lauromacrogol sclerotherapy group (2.48 cm) compared to the laparoscopic omentoplasty group (3.90 cm). This study evaluated both the immediate and medium-term results with a 3-12 months follow-up period for all patients. The cyst volume change in the laparoscopic lauromacrogol sclerotherapy group was found to be significantly greater than that of the laparoscopic omentoplasty group. The feedback regarding quality of life did not vary significantly between the two groups, except for general health and health change, where patients who received laparoscopic sclerotherapy responded with higher scores. CONCLUSIONS: Our results indicate that laparoscopic lauromacrogol sclerotherapy surgery was safe and effective in patients with IVa, VII and VIII segment simple hepatic cysts.

12.
Rev Sci Instrum ; 91(9): 095004, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-33003781

RESUMO

A novel piezoelectric rotary motor (PRM) on the basis of synchronized switching control was designed, fabricated, and tested to achieve high speed, high efficiency, and high torque. The new motor mainly consists of a vibrator working in the resonance state as the driving element of the PRM and a clutch working in the quasi-static state to control the shaft for unidirectional rotation. The finite element method software COMSOL Multiphysics 5.4 was used to design the structure of the motor and determine the feasibility of the design mechanism of the PRM. Moreover, an experimental setup was built to validate the working principles and evaluate the performance of the PRM. The prototype motor outputted a no-load speed of 7.21 rpm and a maximum torque of 54.4 N mm at a vibrator driving voltage of 120 Vp-p and a clutch driving voltage of 200 Vp-p. The motor achieved a net efficiency of 15.6% under the preload torque of 3 N mm. The average stepping angle of the motor with no-load was 0.068°, when the voltages applied to the clutch and the vibrator were 200 Vp-p and 120 Vp-p, respectively, with the frequency of 512 Hz.

13.
Nucleic Acids Res ; 2020 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-33010163

RESUMO

RNA endowed with both protein-coding and noncoding functions is referred to as 'dual-function RNA', 'binary functional RNA (bifunctional RNA)' or 'cncRNA (coding and noncoding RNA)'. Recently, an increasing number of cncRNAs have been identified, including both translated ncRNAs (ncRNAs with coding functions) and untranslated mRNAs (mRNAs with noncoding functions). However, an appropriate database for storing and organizing cncRNAs is still lacking. Here, we developed cncRNAdb, a manually curated database of experimentally supported cncRNAs, which aims to provide a resource for efficient manipulation, browsing and analysis of cncRNAs. The current version of cncRNAdb documents about 2600 manually curated entries of cncRNA functions with experimental evidence, involving more than 2,000 RNAs (including over 1300 translated ncRNAs and over 600 untranslated mRNAs) across over 20 species. In summary, we believe that cncRNAdb will help elucidate the functions and mechanisms of cncRNAs and develop new prediction methods. The database is available at http://www.rna-society.org/cncrnadb/.

15.
Aging (Albany NY) ; 122020 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-33040050

RESUMO

Cognitive dysfunction caused by chronic cerebral hypoperfusion is a common underlying cause of many cognition-related neurodegenerative diseases. The mechanisms of cognitive dysfunction caused by CCH are not clear. Long non-coding RNA is involved in synaptic plasticity and cognitive function, but whether lncRNA is involved in cognitive dysfunction caused by CCH has not yet been reported. In the present study, we identified the altered lncRNAs and mRNAs by deep RNA sequencing. A total of 128 mRNAs and 91 lncRNAs were up-regulated, and 108 mRNAs and 98 lncRNAs were down-regulated. Real-time reverse transcription-polymerase chain reaction verified the reliability of the lncRNA and mRNA sequencing. Gene Ontology and KEGG pathway analyses showed that differentially-expressed mRNAs were related to peptide antigen binding, the extracellular space, the monocarboxylic acid transport, and tryptophan metabolism. The co-expression analysis showed that 161 differentially expressed lncRNAs were correlated with DE mRNAs. By predicting the miRNA in which both DE lncRNAs and DE mRNAs bind together, we constructed a competitive endogenous RNA network. In this lncRNAs-miRNAs-mRNAs network, 559 lncRNA-miRNA-mRNA targeted pairs were identified, including 83 lncRNAs, 67 miRNAs, and 108 mRNAs. Through GO and KEGG pathway analysis, we further analyzed and predicted the regulatory function and potential mechanism of ceRNA network regulation. Our results are helpful for understanding the pathogenesis of cognitive dysfunction caused by CCH and provide direction for further research.

17.
Brain Behav ; : e01885, 2020 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-33047489

RESUMO

INTRODUCTION: Our study was designed to examine the relationship between Brain-Derived Neurotrophic Factor (BDNF) genotypes (rs6265, Val66Met), BDNF plasma levels, and cognitive impairment in Chinese patients with panic disorder (PD). METHODS: Total 85 patients with PD and 91 healthy controls finally completed all assessments. The severity of panic symptoms and whole anxiety of PD was measured by Panic Disorder Severity Scale-Chinese Version (PDSS-CV) and Hamilton Anxiety Scale (HAMA-14). Montreal Cognitive Assessment (MoCA) and some neurocognitive measures were conducted to evaluate the cognitive performance. All participants were detected for the plasma BDNF levels and BDNF Val66Met polymorphism before assessment and treatment. RESULTS: No significant differences were found in the BDNF allele frequencies and the BDNF genotype distributions between healthy controls and PD patients. BDNF Met/Met genotype was associated with lower BDNF plasma levels in PD patients, and PD patients with BDNF Met/Met genotype had the lower scores in the attention and speed of processing domains compared to those with Val/Val and Met/Val genotype (p's < .05). Among PD patients, the BDNF plasma levels showed moderate positive correlations with Stroop interference (r = .60, p < .001). Using the MoCA data, the BDNF plasma levels were correlated with delayed memory (r = .50, p < .001), verbal learning (r = .45, p < .001), and total scores of MoCA (r = .51, p < .001). CONCLUSIONS: The BDNF Met/Met genotype may be associated with lower BDNF plasma levels and cognitive impairments in PD patients.

18.
Nanoscale ; 2020 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-33048096

RESUMO

As one of the most intriguing elemental 2D materials beyond graphene, stanene is a unique material possessing strong quantum spin Hall effect and is promising for spintronics applications. Since most of these exotic phenomena are associated with the edge states of stanene and their responses under external stimuli, here, we first investigate the electronic and transport behavior of the edge states of stanene. Through examining the acoustic phonon-limited scattering of transporting carriers, we reveal a staggering behavior in the effective mass and mobility varying with the width of stanene nanoribbons. Remarkably, an opposite oscillating trend of the quantum confinement effect with respect to the electrons and holes is found and this trend is in sharp contrast to graphene. Moreover, through group-theory analysis, we further analyze the symmetry-permitted light absorptions and predict a much smaller band gap at Γ compared with other IV-group 2D materials like graphene and silicene, allowing for a red-shift of optical π-π* absorption in stanene. The presence of the narrow flat bands along the M-K path in stanene suggests appreciable density of states of low-energy carriers and a strong light-matter interaction for low-energy photons, which are beneficial for its applications in low-frequency optoelectronics.

19.
Reprod Domest Anim ; 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33001490

RESUMO

Steroid hormones and receptors play important roles in female reproduction, and their expression patterns affect follicular growth and development. To examine the expression of dihydrotestosterone (DHT) synthases (5α-reductase (5α-red)1 and 5α-red2) and androgen receptor (AR) during follicular development, and the regulation of DHT signaling by follicle-stimulating hormone (FSH) and luteinizing hormone (LH), we have used enzyme-linked immunosorbent assays, quantitative real time-polymerase chain reaction, immunohistochemical staining, and western blotting to examine DHT synthesis in small (≤2 mm), medium (2-5 mm), and large (≥5 mm) sheep follicles. Expression of 5α-red1, 5α-red2, and AR was observed in ovine ovaries, and with the development of follicles, the expressions of 5α-red1 and 5α-red2 mRNA and protein increased, but the levels of AR mRNA, protein and DHT level decreased. In addition, granulosa cells were treated with FSH (0.01, 0.1, and 1 international unit (IU)/mL), LH (0.01, 0.1, and 1 IU/mL), and testosterone (T, 10-7 M) to evaluate the effects of FSH and LH on DHT and estradiol (E2) synthesis and 5α-red1, 5α-red2, and AR expression. We found that FSH and LH up-regulated 5α-red1 and 5α-red2 in sheep granulosa cells, but down-regulated the concentration of DHT and expression of AR. Meanwhile, FSH and LH significantly up-regulated the expression of aromatase (P450arom) and secretion of E2. This result indicates that although FSH and LH promote the expression of 5α-red1 and 5α-red2, T is not transformed into DHT, but E2. This study reveals the reason why DHT concentration is down-regulated in large follicles and lays a foundation for further exploring the synthesis mechanism of DHT during follicular development.

20.
Euro Surveill ; 25(40)2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-33034281

RESUMO

BackgroundThe natural history of disease in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remained obscure during the early pandemic.AimOur objective was to estimate epidemiological parameters of coronavirus disease (COVID-19) and assess the relative infectivity of the incubation period.MethodsWe estimated the distributions of four epidemiological parameters of SARS-CoV-2 transmission using a large database of COVID-19 cases and potential transmission pairs of cases, and assessed their heterogeneity by demographics, epidemic phase and geographical region. We further calculated the time of peak infectivity and quantified the proportion of secondary infections during the incubation period.ResultsThe median incubation period was 7.2 (95% confidence interval (CI): 6.9‒7.5) days. The median serial and generation intervals were similar, 4.7 (95% CI: 4.2‒5.3) and 4.6 (95% CI: 4.2‒5.1) days, respectively. Paediatric cases < 18 years had a longer incubation period than adult age groups (p = 0.007). The median incubation period increased from 4.4 days before 25 January to 11.5 days after 31 January (p < 0.001), whereas the median serial (generation) interval contracted from 5.9 (4.8) days before 25 January to 3.4 (3.7) days after. The median time from symptom onset to discharge was also shortened from 18.3 before 22 January to 14.1 days after. Peak infectivity occurred 1 day before symptom onset on average, and the incubation period accounted for 70% of transmission.ConclusionThe high infectivity during the incubation period led to short generation and serial intervals, necessitating aggressive control measures such as early case finding and quarantine of close contacts.


Assuntos
Infecções por Coronavirus/transmissão , Coronavirus/patogenicidade , Período de Incubação de Doenças Infecciosas , Pneumonia Viral/transmissão , Adolescente , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Betacoronavirus , Criança , Pré-Escolar , China/epidemiologia , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/prevenção & controle , Estudos Epidemiológicos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pandemias , Pneumonia Viral/epidemiologia , Pneumonia Viral/prevenção & controle , Adulto Jovem
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