[Sensitivity and specificity of nucleic acid testing in close contacts of COVID-19 cases in Guangzhou]

Objective: To analyze the sensitivity and specificity of SARS-CoV-2 nucleic acid testing in 20 348 close contacts of COVID-19 cases in different prevention and control stages in Guangzhou and to provide scientific evidence for optimizing epidemic response strategies. Methods: A total of 20 348 close contacts of COVID-19 cases in Guangzhou were traced between February 21 and September 22,2020. All the close contacts were tested for the nucleic acid of SARS-CoV-2. The sensitivity and specificity of nucleic acid testing and diagnosis in the different prevention and control stages were compared. Results: In 20 348 close contacts, 12 462 were males (61.24%), the median (P₂₅,P₇₅) of age of them was 31.0 years (23.0,43.0), the median number (P₂₅,P₇₅) of nucleic acid testing for them was 2.0 (1.0,3.0), and the median (P₂₅,P₇₅) of their quarantine days was 12.0 (8.0,13.0) days, respectively. A total of 256 COVID-19 cases were confirmed in the close contacts after seven nucleic acid tests. In the 1^st, 2^nd, 3^rd and 7^th nucleic acid testing, the sensitivity and specificity were 69.14% and 99.99% (177 cases confirmed), 89.84% and 99.99% (230 cases confirmed), 97.27% and 99.99% (249 cases confirmed), and 100.00% and 99.98%, respectively. In the three stages of COVID-19 prevention and control in China: domestic case stage, imported case stage, and imported case associated local epidemic stage, the sensitivity of the 1^st nucleic acid testing was 70.68%, 68.00% and 67.35%, and the specificity was 99.98%, 100.00% and 100.00%, respectively. Conclusions: The sensitivity of nucleic acid testing in the close contacts at the different stages were consistent with slight decrease, which might be related to the increased proportion of asymptomatic infections in the late stage of epidemic prevention and control with COVID-19 in Guangzhou. It is suggested to give three nucleic acid tests to improve the sensitivity and reduce false negative risk.

[Effects of oxygen saturation on all-cause mortality among the elderly over 65 years old in 9 longevity areas of China]

Objective: To investigate the association between oxygen saturation (SpO₂) and risk of 3-year all-cause mortality among Chinese older adults aged 65 or over. Methods: The participants were enrolled from Healthy Aging and Biomarkers Cohort Study in year of 2012 to 2014 in 9 longevity areas in China. In this prospective cohort study, 2 287 participants aged 65 or over were enrolled. Data on SpO₂ and body measurements were collected at baseline in 2012, and data on survival outcome and time of mortality were collected at the follow-up in 2014. Participants were divided into two groups according to whether SpO₂ was abnormal (SpO₂<94% was defined as abnormal). Results: The 2 287 participants were (86.5±12.2) years old, 1 006 were males (44.0%), and 315 (13.8%) were abnormal in SpO₂. During follow-up in 2014, 452 were died, 1 434 were survived, and 401 were lost to follow-up. The all-cause mortality rate was 19.8%, and the follow-up rate was 82.5%. The mortality rate of SpO₂ in normal group was 21.1%, and that of abnormal group was 41.6% (P<0.001). After adjusting for confounding factors, compared to participants with normal SpO₂, participants with abnormal SpO₂ had increased risk of all-cause mortality with HR (95%CI) of 1.62 (1.31-2.02); HR (95 % CI) was 1.49 (0.98-2.26) for males and 1.71 (1.30-2.26) for females in abnormal SpO₂ group, respectively; HR (95%CI) was 2.70 (0.98-7.44) for aged 65-79 years old, 1.22 (0.63-2.38) for aged 80-89 years old, and 1.72 (1.35-2.19) for aged over 90 years old in abnormal SpO₂ group, respectively. Conclusion: Abnormal SpO₂ was responsible for increased risk of 3-year all-cause mortality among Chinese elderly adults.

[Analysis on detection status of cardio-metabolic related risk factors in women aged 15-49 years in 15 provinces in China]

Objective: To analyze the prevalence, co-prevalence of cardiovascular metabolic (CM) risk factors in women aged 15-49 years in China, and describe the influence of social economic factors on them. Methods: The project data of Nutritional Status and Health Transition of Chinese Residents in 2015 were used. The changes in epidemiological characteristics of central obesity, elevated blood pressure, FPG and TG, decreased HDL-C and co-prevalence of the risk factors in women aged 15-49 years were analyzed. According to the definition of the metabolic syndrome released by the International Diabetes Federation in 2005, five cardio-metabolic risk factors appeared as central obesity, increased triglycerides, decreased HDL-C, increased blood pressure and increased plasma glucose. Co-prevalence of risk factors was defined as detecting 2 or more risk factors in a person at the same time. Multivariate logistic regression model was used to analyze the relationship between socioeconomic factors and metabolic risk factors. Results: In 2015, in women aged 15-49 years in 15 provinces, the detection number (rates) of central obesity, elevated blood pressure, FPG and TG, decreased HDL-C, at least one CM risk factor and co-detection rate of CM risk factors were 944 (47.4%), 464 (23.3%), 123 (6.2%), 327 (16.4%), 1 025 (51.5%), 1 501 (75.4%), and 874 (43.9%), respectively. Compared with women aged 15-19 years, the women in age group of 25-, 30-, 35-, 40-, and 45-49 years were more likely to have central obesity (P<0.05), the women in age group of 30- 35-, 40-, and 45-49 years were more likely to have elevated blood pressure (P<0.05), the women aged 45-49 years were more likely to be affected by one or more CM risk factors (P<0.05), but the women in age group 25-29 years group had lower risk for elevated FPG (P<0.05). The odds of having central obesity, elevated blood pressure, FPG and TG, decreased HDL-C, at least one CM risk factor and co-prevalence of CM risk factors in women with BMI≥24.0 kg/m(2) were 14.16, 3.05, 2.46, 2.49, 2.42, 9.79 and 7.39 times higher than those in the women with BMI of 18.5-24.0 kg/m(2), respectively. The odds of having elevated FPG and TG in women aged 15-49 years in western China and the odds of having elevated blood pressure and FPG in women aged 15-49 years in eastern China were significantly higher than those in central China. No significant correlations were found between the prevalence and co-prevalence of CM risk factors and income level or urban and rural area residences in women aged 15-49 years. Conclusions: Age, BMI level and living area were the major influencing CM risk factors. The precise prevention and control measures should be taken in time for the adverse changes in CM risk factor prevalence.

[Effects of estimated glomerular filtration rate on all-cause mortality in the elderly aged 65 years and older in 8 longevity areas in China]

Objective: To investigate the association between estimated glomerular filtration rate (eGFR) and all-cause mortality in the elderly aged 65 years and older in longevity areas in China. Methods: Data used in this study were obtained from Healthy Aging and Biomarkers Cohort Study, a sub-cohort of the Chinese Longitudinal Healthy Longevity Survey, 1 802 elderly adults were collected in the study during 2012-2017/2018. In this study, the elderly were classified into 4 groups, moderate-to-severe group [<45 ml·min(-1)·(1.73 m(2))(-1)], mild-to-moderate group [45- ml·min(-1)·(1.73 m(2))(-1)], mild group [60- ml·min(-1)·(1.73 m(2))(-1)] and normal group [≥90 ml·min(-1)·(1.73 m(2))(-1)] according to their eGFR levels. Results: After 6 years of follow-up, 852 participants died, with a mortality rate of 47.3%. Multivariate Cox regression analysis showed that the levels of eGFR were negatively correlated with all-cause mortality risk in the elderly (the HR of elderly was 0.993 and the 95%CI was 0.989-0.997 for every unit of eGFR increased, P=0.001), while compared with the group with normal eGFR, the HRs (95%CI) of the elderly in the moderate-to-severe group, mild-to-moderate group, and mild group were 1.690 (1.224-2.332, P=0.001), 1.312 (0.978-1.758, P=0.070), 1.349 (1.047-1.737, P=0.020) respectively [trend test P<0.001]. Conclusion: The decrease in eGFR was associated with higher mortality risk among the elderly in longevity areas in China.

[Method for developing mouse model of endometrios is based on estrogen-releasing thermo-sensitive hydrogel system]

Objective: This study will explore and optimize the conditions for the construction of the mouse model of endometriosis using the estrogen-releasing thermo-sensitive hydrogel system. Methods: (1) The mice were injected subcutaneously with a gradient concentration of estrogen-releasing thermo-sensitive hydrogel systems, and the blood estrogen concentration was measured 3 days later. And then we draw the curve between mouse blood estrogen concentration and thermo-sensitive hydrogel systems concentration, selecting the most appropriate concentration of estrogen-releasing thermo-sensitive hydrogel systems. (2) To explore the release pattern of estrogen-releasing thermo-sensitive hydrogel system, the mice were injected subcutaneously with the optimal concentration of estrogen-releasing thermo-sensitive hydrogel system, and the blood estrogen concentration was measured on the 1st, 3rd, 5th, 7th and 10th day respectively. (3) We transplanted uteruses from donor mice into the abdominal cavities of recipient mice. The recipient mice were divided into three groups named a, b, and c. Group a was intraperitoneally injected with PBS everyday after transplantation, and group b was intraperitoneally injected with estrogen solution everyday after transplantation. And estrogen-releasing thermo-sensitive hydrogel systems mentioned above were injected subcutaneously to group c once a week. Mice were killed 21 days later to observe the success rate of the endometriosis models. Results: (1) The concentration of estrogen in mice was linear with the concentration of estrogenin the estrogen-releasing thermo-sensitive hydrogel systems. And 0.8 mg/ml was the most appropriate concentration of the estrogen-releasing thermo-sensitive hydrogel system. (2) The thermo- sensitive hydrogel systems including 0.8 mg/ml estrogen can release estrogen in mice for 7 days and can achieve effective blood estrogen concentration. (3) All mice in group a, b, and c survived. All mice in group b and c showed ectopic cysts, and no cyst was observed in group a. Conclusions: The construction of the mouse model of endometriosis requires exogenous estrogen. We have found that the novelestrogen-releasing thermo-sensitive hydrogel systems can slowly release estrogen after subcutaneously injection in mice, and the value of the subcutaneously injection of estrogen-releasing thermo-sensitive hydrogel system (0.8 mg/ml) per week to the construction of the mouse model is certain.The estrogen-releasing thermo-sensitive hydrogel system has high application value and is worthy of promotion.

Synergistic effect in treatment of C.I. Acid Red 2 by electrocoagulation and electrooxidation

An aqueous C.I. Acid Red 2 solution was decolorized by electrolysis using iron as anode. The decolorization mechanism was investigated through experimental observations on the electrochemical behavior of C.I. Acid Red 2 on Pt rotating disk electrode, UV-visible spectra of the solution and IR spectra of the coagulated mixtures. It is found that the decolorization efficiency is high, over 98.0% after 40 min, and this high decolorization efficiency can be ascribed to the synergistic effect of electrocoagulation and electrooxidation. The electrocoagulation results from the electrogenerated iron hydroxide and the electrooxidation results from electrogenerated ferric ions. The results obtained from IR spectra shows that the decolorization of C.I. Acid Red 2 by electrooxidation is due to the partial or complete cleavage of C-N bonds in C.I. Acid Red 2.

Postural control of the trunk in response to lateral support surface translations during trunk movement and loading

The postural response to translation of the support surface may be influenced by the performance of an ongoing voluntary task. This study was designed to test this proposal by applying lateral perturbations while subjects handled a load in the frontal plane. Measurements were made of medio-lateral displacement of the centre of pressure, angular displacement of the trunk and thigh in the frontal plane and intra-abdominal pressure. Subjects were translated randomly to the left and right in a variety of conditions that involved standing either quietly or with a 5 kg load in their left hand, which they were required either to hold statically or to lift or lower. The results indicate that when the perturbation occurred towards the loaded left side the subjects were able to return their centre of pressure, trunk and thigh rapidly and accurately to the initial position. However, when the perturbation occurred towards the right (away from the load) this correction was delayed and associated with multiple changes in direction of movement, suggesting decreased efficiency of the postural response. This reduced efficiency can be explained by a conflict between the motor commands for the ongoing voluntary task and the postural response, and/or by the mechanical effect of the asymmetrical addition of load to the trunk.

Intramuscular myoelectric activity and selective coactivation of trunk muscles during lateral flexion with and without load

STUDY DESIGN

Myoelectric activity of trunk muscles was measured intramuscularly in six healthy subjects as they maintained static trunk postures at 0 degrees, 15 degrees, and 30 degrees of lateral bending, unloaded or holding a 20-kg load in one hand alongside the body.

OBJECTIVE

To determine the position and load dependency of the agonistic and antagonistic myoelectric responses of deep and superficial trunk lateral flexor muscles.

SUMMARY OF BACKGROUND DATA

Loading of the trunk in lateral bending is associated with incidences of low back pain. The neuromotor control of muscles surrounding the spine may be decisive for its vulnerability. Earlier documentation of the activation pattern of trunk muscles, particularly those situated deeply, is incomplete.

METHODS

Trunk angle was measured between S1-C7 and the vertical with a protractor. Electromyographic activity was recorded unilaterally from eight trunk muscles using intramuscular fine-wire electrodes inserted under the guidance of ultrasound.

RESULTS

The electromyographic data showed that all muscles on the side contralateral to the load, except rectus abdominis, had their highest activity while loaded in the position most laterally flexed to the loaded side. The degree of bilateral coactivation was greater for the ventral than for the dorsal muscles.

CONCLUSIONS

The myoelectric responses of most lumbar trunk muscles to static lateral flexion were dependent on trunk position and loading. The abdominal muscles demonstrated more coactivation than the other trunk muscles, and thus appeared to contribute more to trunk stabilization in laterally bent and loaded trunk positions.

Trunk muscle strength in eccentric and concentric lateral flexion

The aim of this study was to investigate the position and velocity dependency of the strength (torque) output of lateral flexor muscles of the trunk. Twelve male volunteers with no history of back pain participated. Movement was constrained to the frontal plane and the velocity was controlled by an isokinetic dynamometer. The eccentric and concentric strength of lateral flexor muscles on the left side was measured in a supine position at velocities of 15, 30, 45 and 60 degrees x s(-1) and static strength at 20, 10, 0, -10 and -20 degrees of lateral trunk flexion. Average peak torque values ranged between 211 and 218 Nm (eccentric) and between 66 and 140 Nm (concentric) over all tested velocities, and the average static torque ranged between 80 and 172 Nm over all tested positions. The shape of the torque position curves was unaffected by speed and peak torque occurred at an average position of 11-15 degrees to the contralateral (right) side in both eccentric and concentric actions. In eccentric actions, torque output was significantly higher than that during concentric and static actions. Increasing the speed of contraction did not affect eccentric torque values, whereas both peak and angle-specific concentric torque decreased with increasing speed. These results are in general accordance with earlier findings from other muscle groups, such as the knee extensors. However, they are partially at variance with results obtained in studies of lateral lifting and lowering, indicating that there are other limiting factors in complex tasks that do not just involve the trunk muscles.

The visible human anatomy of the lumbar erector spinae

STUDY DESIGN

Image data of the male and female cadavers from the Visible Human Project were visualized and quantified.

OBJECTIVE

To clarify the anatomy of the lumbar part of the human lumbar erector spinae muscles.

SUMMARY OF BACKGROUND DATA

Recent studies have shown discrepancies in the description of the anatomy of the lumbar part of the lumbar erector spinae. The main differences concern whether lumbar fascicles of iliocostalis lumborum exist and whether the lumbar fascicles have direct attachments to the ilium or attach via the erector spinae aponeurosis. With the Visible Human Project from the U.S. National Library of Medicine, a new powerful basis for anatomic investigation has become available.

METHODS

Software was produced to visualize sections oriented in any direction and with maximum resolution of the Visible Human male and female. Three-dimensional coordinates of anatomic structures in the image space could be marked in the cross-sectional images. The geometry and the physiologic cross-sectional areas of the erector spinae fascicles of lumbar origin were thus derived.

RESULTS AND CONCLUSIONS

The study supports a classification of the lateral fascicles of the lumbar part of the lumbar erector spinae as part of iliocostalis lumborum. In both the male and the female, a large part of the erector spinae fibers of lumbar origin attached to the erector spinae aponeurosis. These results are of importance for biomechanical analysis of force transmission in the lumbar spine.

Pulling force in lateral lifting and lowering

This work investigated maximal voluntary lateral hand pulling force in 18 healthy, habitually active men. Measurements were made in standing at different static angles of lateral trunk flexion, as well as at different constant lifting and lowering velocities. Movement was constrained to the frontal plane, velocity was controlled by an isokinetic dynamometer, pulling force was measured with a strain gauge and overall lateral angular displacement of the trunk by an electrogoniometer. Mean peak pulling force values ranged from 478 to 658 N (static), 291 to 528 N (lifting), and 801 to 911 N (lowering), respectively. The static pulling forces were the highest in flexed positions to the loaded side (10 degrees and 20 degrees trunk angles). In lifting, peak and position-specific pulling force decreased with increasing velocity. Peak lifting force occurred in a flexed trunk position of 7 to 9 degrees to the loaded side. In lowering, pulling forces were significantly higher than during lifting at corresponding velocities and showed less changes with velocity. Peak lowering force occurred at a trunk angle of -7 to -11 degrees, that is towards the unloaded side. In conclusion, maximal voluntary pulling force in the frontal plane was found to be task dependent. Lowering was accompanied by higher forces and a different velocity and position dependency than lifting which, in addition to the fact that the trunk muscles act predominantly eccentrically during the lowering task, may impose an increased risk of injury.