Nurses' workload associated with 16-h night shifts. II: Effects of a nap taken during the shifts.

This study aimed at examining the effects on the subjective symptoms in nurses of both timing and length of a 2-h nap during a 16-h night shift. Compared to pre-nap levels, sleepiness, fatigue, and dullness increased immediately after napping. Afterwards, sleepiness decreased significantly, and the other symptoms returned to the pre-nap values.

Nurses' workload associated with 16-h night shifts on the 2-shift system. I: Comparison with the 3-shift system.

To assess nurses' workload with 16-h night shifts on a 2-shift system, we investigated the differences between workloads with each shift on the 2- and 3-shift systems with questionnaires on subjective symptoms and measuring heart rate and physical activity. It was found that the 2-shift nurses during the 16-h night shifts complained of fatigue less frequently and showed general decreases in heart rate and physical activity compared with the 3-shift nurses during 8-h evening and night shifts. The results suggest that a 2-h nap, an increase of staff, and a day off may reduce the nurses' workload when they have 16-h night shifts.

Development of an analytical method for beryllium in airborne dust by micellar electrokinetic chromatography.

The separation of diacetylacetonato-beryllium [Be(acac)2] from acetylacetone was achieved with micellar electrokinetic chromatography (MEKC) followed by subsequent beryllium analysis carried out using capillary electrophoresis. Analysis using a separation and absorption detector, with a 50 microns capillary cell, could detect approximately 1000 ppb of beryllium in the final sample. Be(acac)2 is a promising reagent for absorption spectrophotometry, because its molar absorption coefficient, (32,000 l mol-1 cm-1) is very large.

Differential metal response and regulation of human heavy metal-inducible genes.

A number of heavy metal-inducible genes have been reported, but their ranges of response to various metal species are not well known. It is also unclear if these genes are regulated through common mechanisms. To answer these questions, we compared induction kinetics of human metal-inducible genes including the MT-IIA (coding for a metallothionein isoform), hsp70 (coding for the 70-kDa heat-shock protein), and c-fos genes in HeLa cells exposed to Zn, Cd, Ag, Hg, Cu(II), Co, or Ni ions.

Shift work-related problems in 16-h night shift nurses (2): Effects on subjective symptoms, physical activity, heart rate, and sleep.

We compared the shift work-related problems between 16-h night shift and 8-h evening/night shifts among nurses in a university hospital with respect to subjective symptoms, physical activity, heart rate (HR), and sleep. The nurses of one group (n = 20) worked a 16-h night shift under a rotating two-shift system, while those of the other group (n = 20) worked an 8-h evening or night shift under a rotating three-shift system. The 16-h night shift was staffed by three or four nurses who alternately took a 2-h nap during the shift, and had at least one day off after each shift.

Shift work-related problems in 16-h night shift nurses (1): Development of an automated data processing system for questionnaires, heart rate, physical activity and posture.

To assess the shift work-related problems associated with a 16-h night shift in a two-shift system, we took the following important factors into consideration; the interaction between circadian rhythms and the longer night shift, the type of morningness and eveningness experienced, the subjective sleep feeling, the subjects' daily behavior, the effectiveness of taking a nap during the long night shift, and finally the effectiveness of using several different kinds of measuring devices. Included among the measuring devices used were a standard questionnaire, repetitive self-assessment of subjective symptoms and daily behavior at short intervals, and a continuous recording of such objective indices as physical activity and heart rate. A potential problem lies in the fact that field studies that use such measures tend to produce a mass of data, and are thus faced with the accompanying technical problem of analyzing such a large amount of data (time, effort and cost).

Rapid and simple analysis of urinary vanilmandelic acid by high-performance liquid chromatography with electrochemical detection.

We examined an analytical method for urinary vanilmandelic acid (VMA) by high-performance liquid chromatography with electrochemical detection from the viewpoint of practical analysis and application. The sample pretreatment in our method is only the dilution of urine samples with citrate buffer. The calibration curve for VMA was linear within the range 0.

Trichloroethylene inhibits aldehyde dehydrogenase only for aliphatic aldehydes of short chains in rats.

The effects of trichloroethylene (TCE) administration on aldehyde dehydrogenase (ALDH) and cytochrome P450 isozymes were studied in rats and compared with those of methanol. Intragastric administration of TCE to rats at 0.05 or 0.

Transcriptional activity and regulatory protein binding of metal-responsive elements of the human metallothionein-IIA gene.

Multiple copies of a cis-acting DNA element, metal-responsive element (MRE) are required for heavy metal-induced transcriptional activation of mammalian metallothionein genes. To approach the regulatory mechanism mediated by these multiple elements, we studied the properties of seven MREs located upstream of the human metallothionein-IIA (hMT-IIA) gene in detail. Transfection assays of reporter gene constructs each containing one of these MREs as the promoter element revealed that only four MREs can mediate zinc response.

An animal exposure system using ultrasonic nebulizer that generates well controlled aerosols from liquids.

Various aerosol generators have been developed for animal inhalation experiments and the performance tests of measuring instruments and respirators. It has been, however, difficult to generate aerosols from an aqueous solution or suspension keeping the concentration and particle size distribution constant for a long time. Resolving such difficulties, the present study developed an animal exposure system that generates well-controlled and stable aerosols from liquids.

Effect of working hours on cardiovascular-autonomic nervous functions in engineers in an electronics manufacturing company.

A field survey of 147 engineers (23-49 years) in an electronics manufacturing company was conducted to investigate the effect of working hours on cardiovascular-autonomic nervous functions (urinary catecholamines, heart rate variability and blood pressure). The subjects were divided into 3 groups by age: 23-29 (n = 49), 30-39 (n = 74) and 40-49 (n = 24) year groups. Subjects in each age group were further divided into shorter (SWH) and longer (LWH) working hour subgroups according to the median of weekly working hours.

A new model rat with acute bronchiolitis and its application to research on the toxicology of inhaled particulate matter.

The aim of the present study was to establish a useful animal model that simulates humans sensitive to inhaled particulate matter (PM). We have developed a new rat model of acute bronchiolitis (Br) by exposing animals to NiCl2 (Ni) aerosols for five days. Three days following the Ni exposure, the animals developed signs of tachypnea, mucous hypersecretion, and bronchiolar inflammation which seemed to progress quickly during the fourth to fifth day.

Hexavalent chromium responsible for lung lesions induced by intratracheal instillation of chromium fumes in rats.

Lung toxicity of chromium fumes (Cr fumes) was examined by a single intratracheal instillation into rats of 10.6 mg and 21.3 mg Cr fumes/kg body weight and by repeated (3 times) instillations of 10.

A pilot study on the human body vibration induced by low frequency noise.

To understand the basic characteristics of the human body vibration induced by low frequency noise and to use it to evaluate the effects on health, we designed a measuring method with a miniature accelerometer and carried out preliminary measurements. Vibration was measured on the chest and abdomen of 6 male subjects who were exposed to pure tones in the frequency range of 20 to 50 Hz, where the method we designed was proved to be sensitive enough to detect vibration on the body surface. The level and rate of increase with frequency of the vibration turned out to be higher on the chest than on the abdomen.

The contribution of acute toxicity in animals to occupational exposure limits of chemical substances.

The correlations of lethal doses of various industrial chemicals for rats and mice with occupational exposure limit values were investigated. 50% lethal dose (LD50) values obtained by oral (p.o.

Effect of working hours on biological functions related to cardiovascular system among salesmen in a machinery manufacturing company.

A field survey of 71 salesmen (22-60 years) in a machinery manufacturing company was conducted to investigate the effect of working hours on biological functions related to the cardiovascular system. The subjects were divided into four groups by age, and those in each age group were further divided into shorter (SWH) and longer (LWH) working hour subgroups by weekly working hours. Rates of complaints of subjective fatigue for LWH were significantly higher than those for SWH on the whole.

Sleep inertia and autonomic effects on post-nap P300 event-related potential.

The objective of this study was to examine the relationship between post-nap measures of alertness and performance and non-rapid eye movement (NREM) sleep and parasympathetic activity during brief naps. Thirty healthy subjects were randomly assigned to no-nap, 15-min, and 45-min nap conditions after normal home sleep at prior night. Each nap was taken after lunch and monitored by electroencephalogram (EEG), electromyogram, electrooculogram, and electrocardiogram (ECG).

Influence of 2-bromopropane on reproductive system--2-bromopropane inhibits forced ovulation in mice.

The influence of 2-bromopropane, an alternative to freon, on ovulation was examined using superovulation induced by pregnant mare's serum gonadotropin and human chorionic gonadotropin (PMSG-hCG) treatment. Three groups of mice were injected intraperitoneally 8 times with 2-bromopropane (2-BP) at 500, 1,000 or 2,000 mg/kg and were induced to ovulate by PMSG-hCG treatment. Injection of 2-BP caused the number of ovulated ova in the 1,000 mg/kg and 2,000 mg/kg groups to decrease remarkably.

Ergonomic aspects of portable personal computers with flat panel displays (PC-FPDs): evaluation of posture, muscle activities, discomfort and performance.

The advent of compact and lightweight portable personal computers has offered its users mobility. Various sizes of PC-FPDs can now be seen in the occupational setting as an alternative to the desktop computers. However, the increasing popularity of this relatively new technology may not be without any accompanying problems.

Correlation of lethal doses of industrial chemicals between oral or intraperitoneal administration and inhalation exposure.

Correlations of lethal doses of industrial chemicals between oral or intraperitoneal administration and inhalation exposure in rats and mice were investigated. LC50 values for inhalation exposure and LD50 values for oral and intraperitoneal administration were obtained from the Registry of Toxic Effects of Chemical Substances. LC50 and LD50 values were plotted on ordinate and abscissa, respectively, using logarithmic scales.

Brief naps during post-lunch rest: effects on alertness, performance, and autonomic balance.

This study was designed to examine the effects of brief naps taken after lunch on alertness, performance, and autonomic balance. Three groups each comprising ten healthy subjects, who had slept normally at home the previous night, were randomly assigned to groups taking one of three 'lengths of nap (0, 15, and 45 min) after lunch. The P300, an event-related potential which is a neurophysiological correlate of cognitive function, subjective sleepiness (visual analogue scale), and electrocardiogram were measured before, 30 min after, and 3 h after the naps.

Prediction of TTS for hand intermittent vibration.

Temporary Threshold Shift (TTS) is often used as an indicator of the effect of hand-transmitted vibration on the human body. An experiment for the prediction of TTS in exposure to intermittent vibration was conducted in the present study to examine the exposure equivalent rule, as well as the equations for growth and recovery TTS. It was found that the prediction of TTS obtained here was in good agreement with measured TTS.

Urinary and salivary stress hormone levels while performing arithmetic calculation in a noisy environment.

The effects of environmental conditions on stress responses to mental work, were examined by measuring urinary catecholamine and cortisol excretion and salivary cortisol concentrations before, during and after an arithmetic calculation task under 90 dB(A) white noise and quiet conditions. Adrenaline excretion increased similarly during the task under both environmental conditions. The salivary cortisol level was significantly higher than the pre-task level during the task with noise, but not under quiet, conditions.