scholarly journals Poor Uncorrected Visual Acuity and Association With Sleep Duration and Screen Time: A Dose–Response Relationship Study

Dose-Response ◽  
2021 ◽  
Vol 19 (4) ◽  
pp. 155932582110421
Author(s):  
Yueyang Hu ◽  
Qiaoyi Xu ◽  
Jikang Shi ◽  
Xinli Lin ◽  
Junsong Fei ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Sleep Duration ◽  
Dose Response ◽  
Screen Time ◽  
Response Curve ◽  
Dose Response Curve ◽  
Residential Areas ◽  
Cross Sectional ◽  
Uncorrected Visual Acuity ◽  
Nighttime Sleep

Background We aimed to investigate the prevalence of poor uncorrected visual acuity and the difference among students with different ages and residential areas in the Northeast of China. The relationships between screen time, nighttime sleep duration, and poor uncorrected visual acuity would be explored. Methods It was a cross-sectional study using multi-stage stratified random sampling method to recruit participants. 2149 students have completed questionnaires and underwent visual acuity examinations. The dose–response curve method was applied to examine the non-linear associations between sleep duration and poor uncorrected visual acuity under different screen time subgroups. Results The overall prevalence of poor uncorrected visual acuity and severe poor uncorrected visual acuity was 84.7% and 63.3%, respectively. The dose–response curve showed the odds ratios (ORs) of sleep duration for the poor uncorrected visual increased relatively slowly when screen time <1 hour, then increased dramatically in screen time ≥1 hours. The ORs of sleep time and poor uncorrected visual acuity showed a U-shaped change trend among students with 2 or more hours of screen time every day. Conclusion We found associations between nighttime sleep duration and poor uncorrected visual acuity in adolescents. However, these associations were not consistent across all screen time categories.

OVARIAN ASCORBIC ACID DEPLETION TEST FOR LUTEINIZING HORMONE

1967 ◽  
Vol 56 (4) ◽  
pp. 619-625 ◽  
Author(s):  
Hans Jacob Koed ◽  
Christian Hamburger
Keyword(s):  
Ascorbic Acid ◽  
Luteinizing Hormone ◽  
Dose Response ◽  
Response Curve ◽  
Dose Response Curve ◽  
Human Origin ◽  
Response Curves ◽  
Significant Difference ◽  
The Mean ◽  
Different Levels

ABSTRACT Comparison of the dose-response curves for LH of ovine origin (NIH-LH-S8) and of human origin (IRP-HMG-2) using the OAAD test showed a small, though statistically significant difference, the dose-response curve for LH of human origin being a little flatter. Two standard curves for ovine LH obtained with 14 months' interval, were parallel but at different levels of ovarian ascorbic acid. When the mean ascorbic acid depletions were calculated as percentages of the control levels, the two curves for NIH-LH-S8 were identical. The use of standards of human origin in the OAAD test for LH activity of human preparations is recommended.

HYPERTROPHIC ADRENALS AND THEIR RESPONSE TO STRESS AFTER LESIONS IN THE MEDIAN EMINENCE OF TOTALLY HYPOPHYSECTOMIZED PIGEONS

1961 ◽  
Vol 37 (4) ◽  
pp. 565-576 ◽  
Author(s):  
Richard A. Miller
Keyword(s):  
Dose Response ◽  
Median Eminence ◽  
Response Curve ◽  
Liver Parenchyma ◽  
Dose Response Curve ◽  
Pars Distalis ◽  
Adrenal Enlargement ◽  
Response To Stress ◽  
Lethal Doses ◽  
Chromaffin Tissue

ABSTRACT Four per cent formaldehyde, insulin, or epinephrine in oil was injected for 5 days into pigeons subjected to varying degrees of hypophysectomy alone or together with large lesions in the median eminence and hypothalamus. Adrenals atrophied after the removal of the pars distalis alone or together with the neurohypophysis in untreated pigeons but showed markedly hypertrophic interrenal tissue (cortex in mammals) after treatment with formaldehyde or insulin. The slope of the dose-response curve was similar in operated and unoperated pigeons. The accumulation of bile in the liver parenchyma, which may occur after removal of the pars distalis, is an endogenous stress which was associated regularly with adrenal hypertrophy. After very large lesions of the median eminence and ventral hypothalamus in addition to total hypophysectomy, adrenals hypertrophied rather than atrophied, and the response to formaldehyde paralleled that in intact and »hypohysectomized« pigeons. Interrenal tissue was stimulated regularly; chromaffin tissue was partially degranulated, sometimes showed hyperplasia with colchicine, but only occasionally appeared hypertrophied. Epinephrine in nearly lethal doses caused only minimal adrenal enlargement. After adrenal denervation followed by hypophysectomy, the adrenals were still stimulated by formaldehyde. It appears that the interrenal tissue of the pigeon responds to a humoral stimulus not of hypophyseal origin in the absence of the hypophyseal-hypothalamic system.

ANTI-OVULATORY ACTIVITY OF STEROIDS ADMINISTERED BY GAVAGE IN THE ADULT OESTRUS RABBIT

1963 ◽  
Vol 42 (2_Suppl) ◽  
pp. S17-S30
Author(s):  
Fred A. Kind ◽  
Ralph I. Dorfman
Keyword(s):  
Dose Response ◽  
Active Compound ◽  
Subcutaneous Injection ◽  
Response Curve ◽  
Parent Compound ◽  
Dose Response Curve ◽  
Relative Potency ◽  
Reference Standard ◽  
Highly Active ◽  
Dose Levels

ABSTRACT Thirty-seven steroids have been studied as orally effective inhibitors of ovulation in the mated oestrus rabbit. Norethisterone served as the reference standard and a dose response curve was established between the 0.31 and 1.25 mg dose levels. Nine highly active anti-ovulatory compounds are described listed in a decreasing order of potency with norethisterone having the arbitrary value of one: 6-chloro-Δ6-dehydro-17α-acetoxyprogesterone (35), 6α-methyl-Δ1-dehydro-17α-acetoxyprogesterone (≥ 10), 6-fluoro-Δ6-dehydro-17α-acetoxyprogesterone(9), 6-methyl-Δ6-dehydro-17α-acetoxyprogesterone (5), Δ6-dehydro-17α-acetoxyprogesterone (≥ 3), 6α-methyl-17α-acetoxyprogesterone (2.6), 6-chloro-Δ1,6-bisdehydro-17α-acetoxyprogesterone (≥ 2), 2-hydroxymethyl-17α-methyl-17β-hydroxyandrostan-3-one (≥ 2), and 6α-fluoro-16α-methyl-17α-acetoxyprogesterone (≥ 1.25). The anti-ovulatory activity of a compound was not related necessarily to the progestational activity of a compound nor to the anti-gonadotrophic activity as measured in parabiotic rats. 6-Chloro-Δ60dehydro-17-acetoxyprogesterone was as effective by gavage as previously shown by subcutaneous injection. 2-Hydroxymethyl-17α-methyl-17β-hydroxyandrostan-3-one was at least 2.5 times more active by gavage than by injection. While 17α-acetoxyprogesterone was a very weak anti-ovulatory steroid, modifications of the structure by addition of methyl or halogen at the 6α position with or without unsaturation greatly increased the activity. 6-Chloro-Δ6-dehydro-27α-acetoxyprogesterone was the most active compound in this series showing a relative potency of 3500 times that of the parent compound 17α-acetoxyprogesterone.

scholarly journals Compliance with the 24-Hour Movement Behavior Guidelines and Associations with Adiposity in European Preschoolers: Results from the ToyBox-Study

2021 ◽  
Vol 18 (14) ◽  
pp. 7499
Author(s):  
Marga Decraene ◽  
Vera Verbestel ◽  
Greet Cardon ◽  
Violeta Iotova ◽  
Berthold Koletzko ◽  
...  
Keyword(s):  
Sleep Duration ◽  
Screen Time ◽  
Total Sample ◽  
Cross Sectional Study ◽  
World Health ◽  
Movement Behavior ◽  
Cross Sectional ◽  
Guideline Compliance ◽  
Z Scores ◽  
Health Organization

In 2019, the World Health Organization (WHO) published 24 h movement behavior guidelines for preschoolers with recommendations for physical activity (PA), screen time (ST), and sleep. The present study investigated the proportion of preschoolers complying with these guidelines (on a total week, weekdays and weekend days), and the associations with adiposity. This cross-sectional study included 2468 preschoolers (mean age: 4.75 years; 41.9% boys) from six European countries. The associations were investigated in the total sample and in girls and boys separately. PA was objectively assessed by step counts/day. Parent-reported questionnaires provided ST and sleep duration data. Generalized estimating equations were used to analyze the association between guideline compliance and adiposity indicators, i.e., body mass index (BMI) z-score and waist to height ratio (WHR). Only 10.1% of the preschoolers complied with the 24 h movement behavior guidelines, 69.2% with the sleep duration guideline, 39.8% with the ST guideline and 32.7% with the PA guideline. No association was found between guideline compliance with all three movement behaviors and adiposity. However, associations were found for isolated weekday screen time (BMI z-scores and WHR: p = 0.04) and weekend day sleep duration (BMI z-scores and WHR: p = 0.03) guideline compliance with both lower adiposity indicators. The latter association for sleep duration was also found in girls separately (BMI z-scores: p = 0.02; WHR: p = 0.03), but not in boys. Longitudinal studies, including intervention studies, are needed to increase preschoolers’ guideline compliance and to gain more insight into the manifestation of adiposity in children and its association with 24 h movement behaviors from a young age onwards.

scholarly journals Enhancement of morphine-induced antinociception after electroconvulsive shock in mice

2021 ◽  
Vol 17 ◽  
pp. 174480692199262
Author(s):  
Ken Iwata ◽  
Yukio Takamatsu ◽  
Nagafumi Doi ◽  
Kazutaka Ikeda
Keyword(s):  
Dose Response ◽  
Response Curve ◽  
Antinociceptive Effect ◽  
Dose Response Curve ◽  
Expression Level ◽  
Morphine Injection ◽  
Hot Plate ◽  
Hot Plate Test ◽  
Plate Test ◽  
Pain Patients

Electroconvulsive therapy (ECT) has been applied for chronic pain for decades. The amounts of opioids to treat pain are sometimes reduced after a series of ECT. The effect of ECT on morphine-induced analgesia and its mechanism underlying the reduction of morphine requirement has yet to be clarified. Therefore, we administered electroconvulsive shocks (ECS) to mice and investigated the antinociceptive effect of morphine in a hot plate test. We examined the expression level of µ-opioid receptor in the thalami of mice 25 h after administration of ECS compared to the thalami of mice without ECS administration using western blotting. ECS disturbed the development of a decrease in the percentage of maximal possible effect (%MPE), which was observed 24 h after a morphine injection, when ECS was applied 25, 23, 21, and 12 h before the second administration of morphine. We also examined the effect of ECS on the dose-response curve of %MPE to morphine-antinociception. Twenty-five hours after ECS, the dose-response curve was shifted to the left, and the EC50 of morphine given to ECS-pretreated mice decreased by 30.1% compared to the mice that were not pretreated with ECS. We also found that the expression level of µ-opioid receptors was significantly increased after ECS administration. These results confirm previous clinical reports showing that ECT decreased the required dose of opioids in neuropathic pain patients and suggest the hypothesis that this effect of ECT works through the thalamus.

Method for testing antiserum titer and avidity in nephelometric systems.

1981 ◽  
Vol 27 (11) ◽  
pp. 1838-1844 ◽  
Author(s):  
G A Hudson ◽  
R F Ritchie ◽  
J E Haddow
Keyword(s):  
Dose Response ◽  
Response Curve ◽  
Direct Evidence ◽  
Reaction Rates ◽  
Dose Response Curve ◽  
Antigen Concentration ◽  
Response Curves ◽  
Binding Strength ◽  
Antiserum Dilution ◽  
Antiserum Titer

Abstract Antiserum performance in a nephelometric system can be characterized by parameters derived from measuring reaction rates. The characterization process is derived from a series of dose-response curves (elicited nephelometric response vs antigen concentration) generated from various dilutions of the antiserum being tested. Antiserum titer can then be calculated by plotting the antigen concentration found at one-half the maximum nephelometric response (Hmax) of each dose-response curve (C50) vs the corresponding antiserum dilution. Antiserum avidity can be calculated by plotting Hmax against its corresponding antiserum concentration. After general expressions are determined for C50 and Hmax vs antiserum concentration, a single dose-response curve suffices for characterizing antisera with respect to titer and avidity. Direct evidence is provided for the validity of C50 and Hmax as measures of titer and avidity by correlating these parameters with antiserum binding strength and with the number of antibodies eluted from immobilized antigen. This method can be applied to evaluate and compare different antiserum lots having the same specificity, to identify reagent inadequacies by comparing antisera of different specificity, and to predict the optimal antiserum dilution to use in performing an assay.

scholarly journals Prevalence and correlates of adherence to movement guidelines among urban and rural children in Mozambique: a cross-sectional study

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Taru Manyanga ◽  
Joel D. Barnes ◽  
Jean-Philippe Chaput ◽  
Peter T. Katzmarzyk ◽  
Antonio Prista ◽  
...  
Keyword(s):  
Physical Activity ◽  
Sleep Duration ◽  
Screen Time ◽  
Cross Sectional Study ◽  
Rural Children ◽  
Sectional Study ◽  
Cross Sectional ◽  
Middle Income ◽  
Middle Income Countries ◽  
Low Middle Income Countries

Abstract Background Insufficient physical activity, short sleep duration, and excessive recreational screen time are increasing globally. Currently, there are little to no data describing prevalences and correlates of movement behaviours among children in low-middle-income countries. The few available reports do not include both urban and rural respondents, despite the large proportion of rural populations in low-middle-income countries. We compared the prevalence of meeting 24-h movement guidelines and examined correlates of meeting the guidelines in a sample of urban and rural Mozambican schoolchildren. Methods This is cross-sectional study of 9–11 year-old children (n = 683) recruited from 10 urban and 7 rural schools in Mozambique. Moderate- to vigorous-intensity physical activity (MVPA) and sleep duration were measured by waist-worn Actigraph GT3X+ accelerometers. Accelerometers were worn 24 h/day for up to 8 days. Recreational screen time was self-reported. Potential correlates of meeting 24-h movement guidelines were directly measured or obtained from validated items of context-adapted questionnaires. Multilevel multivariable logit models were used to determine the correlates of movement behaviours. Meeting 24-h movement guidelines was defined as ≥60 min/day of MVPA, ≤2 h/day of recreational screen time, and between 9 and 11 h/night of sleep. Results More rural (17.7%) than urban (3.6%) children met all three 24-h movement guidelines. Mean MVPA was lower (82.9 ± 29.5 min/day) among urban than rural children (96.7 ± 31.8 min/day). Rural children had longer sleep duration (8.9 ± 0.7 h/night) and shorter recreational screen time (2.7 ± 1.9 h/day) than their urban counterparts (8.7 ± 0.9 h/night and 5.0 ± 2.3 h/day respectively). Parental education (OR: 0.37; CI: 0.16–0.87), school location (OR: 0.21; CI: 0.09–0.52), and outdoor time (OR: 0.67; CI: 0.53–0.85) were significant correlates of meeting all three 24-h movement guidelines. Conclusions Prevalence and correlates of meeting movement guidelines differed between urban and rural schoolchildren in Mozambique. On average, both groups had higher daily MVPA minutes, shorter sleep duration, and higher recreational screen time than the 24-h movement guidelines recommend. These findings (e.g., higher than recommended mean daily MVPA minutes) differ from those from high-income countries and highlight the need to sample from both urban and rural areas.

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