光照度对豚鼠屈光发育的影响

目的探讨豚鼠在不同光照度照明条件下(10 000,500,5 lx,白色光,色温6000 K)的屈光发育状况,以比较光照度对豚鼠屈光发育的影响。方法 30只3周龄的豚鼠(英国种三色豚鼠),随机分为强光组10只、对照组10只和弱光组10只,分别置于10 000、500、5 lx三种光照度环境下,光照周期为12/12 h(早6:00～晚6:00)。于实验前及光照12周末分别用带状检影计、A超测定仪、角膜曲率计对豚鼠右眼重复进行眼球的生物学测量(包括屈光度、眼轴、角膜曲率)。光照12周结束后处死豚鼠取右眼球行高效液相色谱分析,对不同时间点的组间测量数据采用单因素方差分析,以P<0.05为差异有统计学意义。结果光照前不同组间生物学测量参数差异无显著性(P>0.05)。光照12周后,强光组屈光度为(4.03±1.59)D,同光照前相比发生(0.45±1.65)D的变化,对照组屈光度为(2.15±2.01)D,发生(2.28±0.66)D的变化,强光组同对照组相比远视度数偏高约1.50 D,两者差异有显著性(P<0.05);强光组眼轴增长(0.54±0.10)mm,对照组为(0.76±0.05)mm,强光组较对照组眼轴长度延长较慢,差异有显著性(P<0.05);光照后不同组角膜曲率半径均增加,但组间变化差异无显著性(P>0.05);强光组视网膜多巴胺含量平均为(148.70±22.44)nmol/g,对照组为(44.50±12.45)nmol/g,两者差异有显著性(P<0.001)。光照12周后弱光组较对照组相比,无论是屈光度、曲率、眼轴以及视网膜多巴胺含量均无统计学差异(P>0.05)。结论强光可以引起豚鼠眼球眼轴增长减缓,正视化进展减慢,屈光度数偏远视,弱光对豚鼠的屈光发育没有影响。强光照射后可以引起豚鼠视网膜多巴胺含量增加,可能为强光引起豚鼠正视化进展减缓的机制之一。     

Effects of changing illuminance on somatosensory function

Artificial sources of illumination can be easily used, regardless of the time and place, to improve visibility at night and in dark places. Illuminance and color temperature are particularly important factors since they are known to elicit physiological effects. However, the relationship between changes in illuminance and somatosensory function has not been sufficiently clarified. Thus, the purpose of this study was to construct a laboratorial model to examine the effects of lowering or raising illuminance on somatosensory function. Three illuminance levels (200 lx, 50 lx, and 0 lx), which were changed using all combinations, and an artificial sensory stimulus maintained at a constant intensity were presented to the subjects of this study. Objective sensory function in response to the sensory stimulus was investigated by somatosensory evoked potential (SEP), and subjective sensory evaluation in response to the stimulus was investigated using a visual analogue scale (VAS) and by interview. In many cases, the SEP amplitude and VAS value tended to decrease when illuminance was lowered and tended to increase when illuminance was raised. However, in a few cases, SEP amplitude and VAS value tended to increase in spite of the low illuminance. The occurrence of attention responses and unpleasant emotional responses caused by lowering the illuminance seems to be related to this study finding.     

Phototaxis in the flagellates,Euglena gracilis and Ochromonas danica

Oriented movement with respect to laterally impinging white light of the flagellates Euglena gracilis and Ochromonas danica has been analyzed in an individual cell study with a microvideographic technique. Using the deviation of track segments (in given time intervals of 1 s) from the light direction as raw data allowed a computer based analysis of the direction distribution. A number of statistical methods employed to test the significance of the obtained results demonstrated an obvious phototactic orientation in Ochromonas which was positive (toward the light source) in low illuminance (1.25 lx=5.3×10^-3 Wm^-2) and negative in higher illuminance (>12.5 lx=5.3×10^-2 Wm^-2). Since in this flagellate the threshold for negative phototaxis is much lower than that for the step-up photophobic response, the hypothesis that negative phototaxis may be brought about by repetitive step-up phobic responses can be rejected for at least this organism. In Euglena positive phototaxis was observed in 50 lx (=0.21 Wm^-2), while an illuminance of 500 lx (=2.1 Wm^-2) caused a negative phototaxis.The experiments were carried out in this laboratory     

Phototaxis inEuglena gracilis: Effect of sodium azide and triphenylmethyl phosphonium ion on the photosensory transduction chain

Phototaxis in the flagellateEuglena gracilis was studied by means of a microvideographic analysis, and the light-induced directional movement was determined by computer-based statistical treatments. Lateral white light with an illuminance of 25 lx (0.105 Wm^–2) caused the cells to preferentially swim toward the light source (positive phototaxis), while an illuminance of 1,000 lx (4.2 Wm^–2) induced negative phototaxis. The lipophilic membranepenetrating cation triphenylmethyl phosphonium ion (TPMP⁺) specifically inhibited positive phototaxis, while it hardly affected negative phototaxis. The uncoupler sodium azide, on the other hand, impaired negative phototaxis substantially.     

Simplicity, function, and legibility in an enhanced ambigraphic nucleic acid notation

We previously showed that an ambigraphic nucleic acid notation, based on symmetrical lowercase Roman characters, permits users to complement DNA by physically rotating the sequence text 180 degrees . This article describes an enhanced ambigraphic notation, which uses concept-related symbol design, rather than the arbitrary set of symbols that constitute the Roman alphabet, to logically encode the four DNA bases and 11 ambiguity characters. As ambigrams, the symbols continue to permit the rapid derivation of complementary sequences and visualization of palindromic DNA. In addition, the new AmbiScript notation uses legibility principles to support the identification of sequence polymorphism and improves writing efficiency by requiring fewer strokes per character than the International Union of Pure and Applied Chemistry (IUPAC) notation.     

Melanopsin Gene Polymorphism I394T Is Associated with Pupillary Light Responses in a Dose-Dependent Manner

Background

Melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) play an important role in non-image forming responses to light, such as circadian photoentrainment, light-induced melatonin suppression, and pupillary light response. Although it is known that there are some single nucleotide polymorphisms (SNPs) in the melanopsin (OPN4) gene in humans, the associations of the SNPs with non-image forming responses to light remains unclear. In the present study, we examined the associations of melanopsin gene polymorphisms with pupillary light response.

Methods

Japanese university students (mean age: 21.0±1.7 years) with the genotypes of TT (n = 38), TC (n = 28) and CC (n = 7) at rs1079610 (I394T) located in the coding region participated in the present study. They were matched by age and sex ratio. Dark-adapted pupil size (<1 lx) was first measured. Then steady-state pupil size was measured during exposure to five lighting conditions (10 lx, 100 lx, 1000 lx, 3000 lx, 6000 lx in the vertical direction at eye level).

Results

Significant interaction between the genotype of I394T (TT versus TC+CC) and luminance levels was found in pupil size. Under high illuminance levels (1000 lx, 3000 lx and 6000 lx), pupil sizes in subjects with the C allele were significantly smaller than those in subjects with the TT genotype. On the other hand, pupil size in subjects with the C allele under low illuminance (<1 lx) was significantly larger than that in subjects with the TT genotype. Percentages of pupil constriction under high illuminance levels were significantly greater in subjects with the C allele than in subjects with the TT genotype.

Conclusions

Human melanopsin gene polymorphism I394T interacted with irradiance in association with pupil size. This is the first evidence suggesting a functional connection between melanopsin gene polymorphism and pupillary light response as an index of non-image forming response to light.     

The truth about doctors' handwriting: a prospective study.

OBJECTIVES: To determine whether doctors have worse handwriting than other health professionals. DESIGN: Comparison of handwriting samples collected prospectively in a standardised 10 seconds'' task. SETTING: Courses on quality improvement. SUBJECTS: 209 health care professionals attending the courses, including 82 doctors. MAIN OUTCOME MEASURES: Legibility rated on a four-point scale by four raters. RESULTS: The handwriting of doctors was no less legible than that of non-doctors. Significantly lower legibility than average was associated with being an executive and being male. Overall legibility scores were normally distributed, with median legibility equivalent to a rating between "fair" and "good." CONCLUSION: This study fails to support the conventional wisdom that doctors'' handwriting is worse than others.'' Illegible writing is, however, an important cause of waste and hazard in medical care, but efforts to improve the safety and efficiency of written communication must approach the problem systemically- and assume that the problems are in inherent in average human writing-rather than treating doctors as if they were a special subpopulation.     

The effect of ecologically relevant variations in light level on the performance of Mongolian gerbils on two visual tasks

Tests of rodent visual capacities are typically performed under standard laboratory illumination. However, light level can have subtle and complex effects on behavior in rodents. We tested Mongolian gerbils (Meriones unguiculatus) – a species that shows individual differences in activity pattern – on visual tasks at three ecologically relevant levels of ambient illuminance: approximating moonlight (1 lx), dawn or dusk (10 lx), and low daylight (100 lx). A jumping task and a grating discrimination quantified depth perception and grating acuity, respectively. Illuminance variations had important effects on behavior. Gerbils jumped faster in lower light on the depth discrimination task, but were also less accurate than in bright light. Daytime activity levels (possibly reflecting variations in activity pattern) mediated these effects, with animals that were awake during a lower proportion of daytime hours exhibiting a trend toward jumping faster with lower light level as compared to more day-active gerbils. Moreover, while illuminance did not affect acuity overall, it interacted with activity levels in a complex way: in both the darkest and lowest light levels, animals that were awake during a greater proportion of daytime hours showed higher acuity levels than animals that were less active during the day. These results indicate that gerbils show behavioral profiles in vision tasks that represent an interaction between visual ability and illuminance-sensitive motivational or emotional actors, perhaps including chronotype. Thus, the most ecologically relevant assessments of the visual performance of rodents will likely be achieved by testing at species-specific preferred light levels.     

Range of entrainment of rat circadian rhythms to sinusoidal light-intensity cycles

The range of entrainment of the circadian behavioral rhythm was compared between two groups of Sprague-Dawley rats (each n = 10) exposed to daily cycles of rectangular light-dark alternation (LD) and sinusoidal fluctuations of light intensity (SINE), respectively. The maximum illuminance (20 lx), the minimum illuminance (0.01 lx), and the total amount of light exposure per cycle were the same under the two lighting conditions. The periods (Ts) of both lighting cycles were lengthened stepwise from 24 through 25, 26, 26.5, 27, 27. 5, and 28 h to 28.5 h in experiment 1 and were shortened stepwise from 24 through 23.5, 23, and 22.5 h to 22 h in experiment 2. Each T cycle lasted for 30 cycles. In experiment 1, 60% of rats under the LD condition entrained up to T = 28.5 h, whereas 50% of rats under the SINE condition entrained up to T = 28.5 h. In experiment 2, no animal under the LD condition entrained to T < 23.5 h, whereas 40% of rats under the SINE condition entrained down to T = 23 h and 20% of rats remained to entrain down to T = 22 h cycles. The phase angle of entrainment was systematically changed, depending on T under both conditions. These results suggest that the lower limit of entrainment is expanded under the SINE condition compared with the LD condition.     

Preference of growing pigs for illuminance

This experiment investigated the preference of juvenile pigs for illuminance, and indirectly photoperiod, at two ages. The animals were equally familiar with all illuminances prior to testing. Four groups, each of four pigs, occupied a four-compartment preference chamber in which a different illuminance was applied to each compartment: minimum (2.4), 4, 40 and 400 lx. Illuminances were rearranged every 2 days to avoid positional bias. The pigs significantly preferred the dimmest illuminance (mean occupancy 7 h 20 min per 24 h, backtransformed data) and spent the least time in the brightest (4 h 49 min per 24 h), with an intermediate and similar length of time spent in the other illuminances (6 h 25 min and 5 h 25 min in 4 and 40 lx, respectively, F_3,127 = 8.93, P < 0.001). The most common behaviours of the pigs when in the darkest compartment were resting and sleeping. The EU directive 2001/88 requires a minimum illuminance of 40 lx for pig production; this illuminance was neither aversive nor strongly preferred by the pigs. Our findings also suggest that pigs should be provided with an appropriate period of rest at an illuminance of 2.4 lx for at least 6 h per day. The only active behaviour affected by illuminance was defecation; the pigs preferred to defecate in the brighter illuminances. Spatial provision of minimal illuminance could potentially improve pig welfare by providing a preferred light environment for resting and also by creating a resting area distinct from dunging areas, thus improving hygiene.     

Colour discrimination in dim light by the larvae of the African catfish <Emphasis Type="Italic">Clarias gariepinus</Emphasis>

Many demersal fish species undergo vertical shifts in habitats during ontogeny especially after larval metamorphosis. The visual spectral sensitivity shifts with the habitat, indicating a change in colour vision. Colour vision depends on sufficient ambient light and becomes ineffective at a particular low light intensity. It is not known how fishes see colour in dim light. By means of a behavioural experiment on larval African catfish Clarias gariepinus in the laboratory, we determined colour vision and colour discrimination in dim light. Light-adapted larvae were subjected to classical conditioning to associate a reward feed with a green or a red stimulus placed among 7 shades of grey. The larvae learned this visual task after 70 and 90 trials. A different batch of larvae were trained to discriminate between green and red and then tested for the ability to discriminate between these colours, as the light intensity was reduced. The larvae learned this visual task after 110 trials in bright light and were able to discriminate colours, as light was dimmed until 0.01 lx, the minimal illuminance measurable in this study, and similar to starlight. The retinae of the larvae were found to be light adapted at 0.01 lx; thus indicating cone-based colour vision at this illuminance. For comparison, three human subjects were tested under similar conditions and showed a colour vision threshold at between 1.5 and 0.1 lx. For the larvae of C. gariepinus, the ability of colour discrimination in dim light is probably due to its retinal tapetum, which could increase the sensitivity of cones.     

Design of a high-power collimating optical system based on Fresnel lenses

In light-emitting diode (LED) illumination (e.g., LED maritime lighting for ships), creating a uniform light environment for optical systems is an important challenge. In this study, we present a high-power collimating system based on Fresnel lenses, which allows high-brightness LED illumination in the earlier-mentioned remote distance. The work presented in this article focuses on improving the power, compacting the optical structure, and promoting the brightness of the spot. To prove the claims, the system with a total power of 1 kW is designed. The system consists of a 27 W LED array, a freeform surface lens array, and a confocal Fresnel lens array. In comparison with the traditional optical system, the optical structure shortens from 390 to 120 mm, and the divergent angle decreases from 3° to 2 $$. Meanwhile, the illuminance of the system is obtained as high as 230 lx at the near field of 200 m and 3.0 lx at the far field of 1.5 nautical miles. This new method provides a practical and effective way to solve the problem of low power, insufficient illuminance, and long optical structure for LED array illumination, which is suitable for remote illumination and guidance of ships.     

New evidence for the mechanism of phototactic orientation ofEuglena gracilis

When rotated horizontally in a cuvette in a strong lateral light beam, the flagellateEuglena gracilis effectively corrects its course and shows negative phototaxis, provided the angular velocity does not exceed 20⁰s^–1. Faster rotations cannot be corrected effeciently. In two strong light beams of equal illuminance perpendicular to each other, the cells move along the resultant away from the light beams. Decreasing the illuminance of one beam causes increasing numbers of the organisms to orient with respect to the stronger light source. In two perpendicular low illuminance beams (>200lx), the population splits into two components moving towards either light source. The percentage of cells in each component depends on the relative illuminances. The results can be explained by the shading hypothesis combined with a dichroic orientation of the photoreceptor molecules perpendicular to the long axis of the cells. Externally applied electric dc fields have no effect on positive or negative phototaxis; this supports the hypothesis that electrical potential changes are not involved in the sensory transduction chain of photoorientation inEuglena.     

Dim artificial light at night reduces the cellular immune response of the black field cricket,Teleogryllus commodus

A functioning immune system is crucial for protection against disease and illness, yet increasing evidence suggests that species living in urban areas could be suffering from immune suppression, due to the presence of artificial light at night (ALAN). This study examined the effects of ecologically relevant levels of ALAN on three key measures of immune function (haemocyte concentration, lytic activity, and phenoloxidase activity) using a model invertebrate species, the Australian black field cricket, Teleogryllus commodus. We reared crickets under an ecologically relevant daily light‐cycle consisting of 12 hr bright daylight (2600 lx) followed by either 12 h darkness (0 lx) or dim environmentally relevant ALAN (1, 10, 100 lx), and then assessed immune function at multiple time points throughout adult life using haemolymph samples. We found that the presence of ALAN had a clear negative effect on haemocytes, while the effects on lytic activity and phenoloxidase activity were more complex or largely unaffected by ALAN. Furthermore, the effects of lifelong exposure to ALAN of 1 lx were comparable to those of 10 and 100 lx. Our data suggest that the effects of ALAN could be large and widespread, and such reductions in the core immune response of individuals will likely have greater consequences for fitness and survival under more malign conditions, such as those of the natural environment.     

Grip force variability and its effects on children's handwriting legibility, form, and strokes

A comprehensive understanding of the underlying biomechanical processes during handwriting is needed to accurately guide clinical interventions. To date, quantitative measurement of such biomechanical processes has largely excluded measurements of the forces exerted radially on the barrel of the writing utensil (grip forces) and how they vary over time during a handwriting task. An instrumented writing utensil was deployed for a direct measurement of kinematic and temporal information during a writing task, as well as forces exerted on the writing surface and on the barrel of the pen. The writing utensil was used by a cohort of 35 students (19 males), 16 in first grade and 19 in second grade, as they performed the Minnesota Handwriting Assessment (MHA) test. Quantitative grip force variability measures were computed and tested as correlates of handwriting legibility, form, and strokes. Grip force variability was shown to correlate strongly with handwriting quality, in particular for students classified by the MHA as nonproficient writers. More specifically, static grip force patterns were shown to result in poor handwriting quality and in greater variation in handwriting stroke durations. Grip force variability throughout the writing task was shown to be significantly lower for nonproficient writers (t-test, p<0.01) while the number of strokes and per-stroke durations were shown to be higher (p<0.03). The results suggest that grip force dynamics play a key role in determining handwriting quality and stroke characteristics. In particular, students with writing difficulties exhibited more static grip force patterns, lower legibility and form scores, as well as increased variation in stroke durations. These findings shed light on the underlying processes of handwriting and grip force modulation and may help to improve intervention planning.     

Innate immunity,oxidative stress and body indices of Eurasian perch Perca fluviatilis after two weeks of exposure to artificial light at night

Artificial light at night (ALAN) can disrupt biological rhythms of fish and other vertebrates by changing the light information of the nocturnal environment. Disrupted biorhythms can impair the immune system of vertebrates as it has been shown for conditions with continuous illumination or long-day photoperiod in many vertebrates, including fish. Nonetheless, this has not been shown so far for typical ALAN scenarios with high light intensities during day and low light intensities at night. Therefore, in this study, proxies for the innate immune system and oxidative stress as well as body indices of Eurasian perch Perca fluviatilis were measured under a wide range of intensities of nocturnal illumination. The authors found no changes in parameters of the innate immune system and no significant changes in proxies for oxidative stress after 2-week exposures to nocturnal illuminance ranging from 0.01 lx to 1 lx in one experiment or from 1 lx to 100 lx in a second experiment. A decrease in the hepato-somatic index at the highest tested light intensity of 100 lx compared to the dark control was the only significant difference in all parameters among treatments. After 2 weeks of exposure, ALAN does not seem to seriously challenge the innate immune system and seems to cause less oxidative stress than expected. The results of this study contradict the findings from other studies applying continuous illumination or long-day photoperiod and highlight the importance of further research in this field. Because ALAN represents a sustained modulation of the environment that may have cumulative effects over time, long-term studies are required for a better understanding of how ALAN modulates the health of fish.     

Photorealistic image generation of molecular structure on PC screen using the ray-tracing technique

A PC version of three-dimensional molecular graphics package has been developed to run under MS-DOS environment on IBM PC-compatible computers equipped with a VGA graphics board. The program consists of two parts: a menu-driven interactive system module in EGA mode, and a ray-tracing module in VGA mode. In the 256-color VGA mode, ray-tracing images are represented with a 4-color map, with 64 levels for each color: 32 levels of illuminance and 32 levels of saturation. Molecular structure can be analyzed along various directions with various light sources. Ray-tracing images are also represented in a 16-color EGA mode with the half-toning method, which can display 76 gray levels for each color. To obtain good photo-realistic images in an efficient way, we have used two light sources, with an intensity ratio of 7:3, which are located in front of the top right and bottom left corners of the screen.     

Influences of diurnal bright or dim light exposure on urine volume in humans

We investigated with eight healthy females if 8 hr diurnal (0700 to 1500 h) bright rather than dim light (5,000 vs. 80 lx) influenced urine volume. Environmental illuminance was made identical at all other times besides 07:00 to 15:00 h. The participants spent time at strictly regulated schedules in a bioclimatic chamber (26 degrees C, relative humidity 60%) for 57 h. Blood was drawn (2 ml) just before lunch in order to calculate Creatinine clearance (Ccr). Urine volume was significantly higher during wakefulness and the 8-h sleep period with bright rather than dim light. Ccr was significantly higher after bright light. The results were discussed in terms of suppression of the sympathetic nerve system under the influence of diurnal bright light exposure. We also discussed these in terms of physiological polymorphisms.     

Light and magnetic fields in a neonatal intensive care unit

Effects of light and electromagnetic fields (EMFs) on pineal function could have implications for long-term risk of breast cancer, reproductive irregularities, or depression. Health-care workers in a neonatal intensive care unit (NICU) were interviewed to determine the tasks, work locations, and practices in their work environment as well as the care provided to the infants. After an initial visit, methods for measuring illuminance, luminance, and broadband resultant magnetic fields throughout the NICU were developed. Measurements were made of one nursery during a daytime (1:00 p.m.) and a night-time (12:30 a.m.) visit. Measurements relevant to both nurses and premature infants in the NICU were made. Some measurements could not be completed so as not to interfere with nurses' duties in the NICU. Illuminances measured during the daytime and nighttime averaged 184 and 34 lux (lx), respectively, much lower than those reported in other studies of illuminance in NICUs, with a maximum illuminance of 747 lx. Peak levels may be consistent with those thought to suppress melatonin. There was a high degree of variability in EMF levels, which exceeded 1,000 mG close to certain hospital equipment but averaged 1–2 mG at the nurses' workstation. Fields within incubators exceeded 10 mG. © 1996 Wiley-Liss, Inc.     

Variation patterns of bilateral characters: variation among characters and among populations in the White Sea herring, Clupea pallasi marisalbi (Berg) (Clupeidae, Teleosti)

Phenotypic variation in two populations of the White Sea herring Clupea pallasi marisalbi (Berg) (spring spawners and summer spawners), based on 21 meristic and 21 morphometric bilateral characters, has been studied. Total phenotypic variance was partitioned into a within-individual or stochastic component (fluctuating asymmetry) and an among-individual or factorial component, reflecting heterogeneity among individuals and resulting from the diversity of genotypes and environments. Both standardized stochastic and factorial components show clear negative correlations with means across characters. Negative correlation of the factorial components with means is in contradiction to the commonly accepted explanation of negative means-standardized variances association. Slopes of regression of standardized stochastic variances on means in meristic characters was significantly higher in summer spawners than in spring spawners, and results in discordance of stochastic variance across characters: it is higher in spring spawners for low and average variability characters and does not differ for both populations for high variability characters. The populations do not show notable differences in variation of morphometric characters. Consideration of other available data on these populations, such as spawning behaviour and salinity resistance of larvae, suggests that the lower slope of regression of stochastic variances on means is associated with the reduced viability of spring spawners