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To evaluate hematological effects of direct current (DC) and alternating current (AC) extremely low frequency (ELF) electric field exposure, this study investigated red blood cell (RBC) movement in whole blood. Video images of RBCs were recorded under a microscope using specially designed electrode systems. Video analysis software was then used to measure the RBC velocity. The noise level and measurement system stability were confirmed based on results of a no-field exposure experiment. Using the electrode system to produce a non-homogeneous electric field, different movements were found to occur in DC and AC field exposure. The RBCs moved in the directions of the electric field and the gradient of field distribution, respectively, in the DC and AC fields. Dependences of the RBC velocity on the field strength were, respectively, linear and quadratic in the DC and AC fields. These results suggest that electrophoretic and dielectrophoretic movements were, respectively, dominant in the DC and AC fields. The magnitude of the electric field necessary to cause these effects was found to be 10

Delivering ions and molecules into living cells has become an important challenge in medical and biological fields. Conventional molecular delivery, however, has several issues such as physical and chemical damage to biological cells. Here, we present a method of directly delivering molecules into adhesive cells with an Au-based nanostraw membrane stamp that can physically inject a target molecule into the cytoplasm through a nanostraw duct. We successfully delivered calcein target molecules into adhesive cells with high efficiency (85%) and viability (90%). Furthermore, we modeled the molecular flow through Au nanostraws and then demonstrated the control of calcein flow by changing the concentration and geometry of Au nanostraws. Our Au membrane stamping provides a new way of accessing the cytoplasm to modulate cellular functions via injected molecules.

Protons (H

To realize direct power generation from biofuels in natural organisms, we demonstrate a needle-type biofuel cell (BFC) using enzyme/mediator/carbon nanotube (CNT) composite fibers with the structure Osmium-based polymer/CNT/glucose oxidase/Os-based polymer/CNT. The composite fibers performed a high current density (10 mA/cm2) in 5 mM artificial blood glucose. Owing to their hydrophilicity, they also provided sufficient ionic conductivity between the needle-type anode and the gas-diffusion cathode. When the tip of the anodic needle was inserted into natural specimens of grape, kiwifruit, and apple, the assembled BFC generated powers of 55, 44, and 33 μW from glucose, respectively. In addition, the power generated from the blood glucose in mouse heart was 16.3 μW at 0.29 V. The lifetime of the BFC was improved by coating an anti-fouling polymer 2-methacryloyloxyethyl phosphorylcholine (MPC) on the anodic electrode, and sealing the cathodic hydrogel chamber with medical tape to minimize the water evaporation without compromising the oxygen permeability.

Natural biological composites often couple light weight with tunable and spatially controlled mechanical properties including stiffness, toughness, and hardness. Examples include the toughness of seashells, the hardness of the chiton tooth, and the stiffness gradient of the squid beak. While seashells and the chiton tooth have a mineralized inorganic component, the squid beak is entirely organic. The squid beak is known as one of the hardest fully organic materials. The hydrated squid beak has a large stiffness gradient from soft, at the interface with the squid mouth, to hard at the tip. This gradient occurs from the spatially controlled cross-linking of chitin nanofibers with a protein matrix aided by catecholamines. Here, we introduce a water processable deacetylated chitin composite with tunable mechanical properties from spatially controlled cross-linking assisted by catecholamines. Given the natural abundance of chitin and the ease of water processing, this composite can find applications for bridging mechanically mismatched materials.

As for the diagnosis and treatment of eye diseases, an ideal fundus imaging system is expected to be portability, low cost, and high resolution. Here, we demonstrate a non-mydriatic near-infrared fundus imaging system with light illumination from an electronic contact lens (E-lens). The E-lens can illuminate the retinal and choroidal structures for capturing the fundus images when voltage is applied wirelessly to the lens. And we also reconstruct the images with a depth-dependent point-spread function to suppress the scattering effect that eventually visualizes the clear fundus images.

Wearable devices that generate power using sweat have garnered much attention in the field of skin electronics. These devices require high performance with a small volume and low production rate of sweat by living organisms. Here we demonstrate a high-power biofuel cell bracelet based on the lactate in human sweat. The biofuel cell was developed by using a lactate oxidase/osmium-based mediator/carbon nanotube fiber for lactate oxidation and a bilirubin oxidase/carbon nanotube fiber for oxygen reduction; the fibers were woven into a hydrophilic supportive textile for sweat storage. The storage textile was sandwiched between a hydrophobic textile for sweat absorption from the skin and a hydrophilic textile for water evaporation to improve sweat collection. The performance of the layered cell was 74 μW at 0.39 V in 20 mM artificial sweat lactate, and its performance was maintained at over 80% for 12 h. Furthermore, we demonstrated a series-connection between anode/cathode fibers by tying them up to wrap the bracelet-type biofuel cell on the wrist. The booster six-cell bracelet generated power at 2.0 V that is sufficient for operating digital wrist watches.

In nature, protons (H+) play an important role in biological activities such as in mitochondrial ATP synthesis, which is driven by a H+ gradient across the inner membrane, or in the activation of acid sensing ion channels in neuron cells. Bioprotonic devices directly interface with the H+ concentration (pH) to facilitate engineered interactions with these biochemical processes. Here we develop a H+ biotransducer that changes the pH in a mitochondrial matrix by controlling the flow of H+ between a conductive polymer of sulfonated polyaniline and solution. We have successfully modulated the rate of ATP synthesis in mitochondria by altering the solution pH. Our H+ biotransducer provides a new way to monitor and modulate pH dependent biological functions at the interface between the electronic devices and biological materials.

A sheet-type, stretchable biofuel cell was developed by laminating three components: a bioanode textile for fructose oxidation, a hydrogel sheet containing fructose as fuel, and a gas-diffusion biocathode textile for oxygen reduction. The anode and cathode textiles were prepared by modifying carbon nanotube (CNT)-decorated stretchable textiles with fructose dehydrogenase (FDH) and bilirubin oxidase (BOD), respectively. Enzymatic reaction currents of anode and cathode textiles were stable for 30 cycles of 50% stretching, with initial loss of 20-30% in the first few cycles due to the partial breaking of the CNT network at the junction of textile fibers. The assembled laminate biofuel cell showed power of ~0.2 mW/cm(2) with 1.2 kΩ load, which was stable even at stretched, twisted, and wrapped forms.

The ability of bioelectronic devices to conduct protons and other ions opens up opportunities to interface with biology. In this research highlight, we report on our recent efforts in bioprotonic devices. These devices monitor and modulate a current of protons with an applied voltage. Voltage-controlled proton flow mimics semiconductor devices with complementary transistors or biological behaviors such as synaptic-like memories and enzyme logic.

Wound healing on skin involves cell migration and proliferation in response to endogenous electric current. External electrical stimulation by electrical equipment is used to promote these biological processes for the treatment of chronic wounds and ulcers. Miniaturization of the electrical stimulation device for wound healing on skin will make this technology more widely available. Using flexible enzymatic electrodes and stretchable hydrogel, a stretchable bioelectric plaster is fabricated with a built-in enzymatic biofuel cell (EBFC) that fits to skin and generates ionic current along the surface of the skin by enzymatic electrochemical reactions for more than 12 h. To investigate the efficacy of the fabricated bioelectric plaster, an artificial wound is made on the back skin of a live mouse and the wound healing is observed for 7 d in the presence and absence of the ionic current of the bioelectric plaster. The time course of the wound size as well as the hematoxylin and eosin staining of the skin section reveals that the ionic current of the plaster leads to faster and smoother wound healing. The present work demonstrates a proof of concept for the electrical manipulation of biological functions by EBFCs.

A completely organic iontophoresis patch is reported. A built-in biofuel cell is mounted on the patch that generates transdermal iontophoretic administration of compounds into the skin. The amplitude of transdermal current is tuned by integrating a conducting polymer-based stretchable resistor of predetermined resistance.

Wearable biofuel cells with flexible enzyme/carbon nanotube (CNT) fibers were designed on a cotton textile cloth by integrating two components: bioanode fibers for glucose oxidation and O2-diffusion biocathode fibers for oxygen reduction. The anode and cathode fibers were prepared through modification with glucose dehydrogenase and bilirubin oxidase, respectively, on multi-walled carbon nanotube-coated carbon fibers. Both biofibers woven on the cloth generated a power density of 48 μW/cm2 at 0.24 V from 0.1 mM glucose (human sweat amount), and of 216 μW/cm2 at 0.36 V, when glucose was supplied from a hydrogel tank containing 200 mM glucose. Our fiber-based biofuel cell deformed to an S-shape without a significant loss in cell performance. Furthermore, we demonstrated a series-connection involving the tying of biofibers on a cloth with batik-based ionic isolation. The booster four cells generate power at 1.9 V that illuminated an LED on the cloth.

Controlling the flow of ions and electrons at the device/biological interface has become an important challenge in broad fields such as bioelectronics and medical biology. These devices provide a new way to translate bidirectionally between the ionic language of biology and the electronic language of circuitry. The current strategy to develop such ion and electron controlling devices is to use new functional materials at the device/biological interface. For example, silicon nanowire and carbon nanotube based transistors use ions to read out biological functions. Aluminum nanostraws and carbon nanotube porins can selectively deliver molecules such as cations, DNA, and nicotine into biological materials. Since conductive polymers allow the transport of both ions and electrons, there are many conductive polymer based examples including organic field effect transistors for biosensing and organic ion pumps for locally delivering ions and neurotransmitters into cells and the brain. Along with ions and small molecules, protons (H+) play an important role in biology. Examples include the homeostatic pH regulation in body and bacteria, acid sensing ion channels activating in neuron cells, proton activated bioluminescence in dinoflagellates, and pH responsive flagella in bacteria. Mitochondria in particular are a noteworthy organelle that utilize the transport of protons and electrons across a membrane to synthesize adenosine triphosphate (ATP) molecules. To translate H+ signals from biological environments into measureable electronic signals, Rolandi and co-workers developed a prototype bioprotonic device using a Pd/PdHx protode. In his group, the metallic protode was used to measure the protonic conductivity in biological materials such as chitosan and jelly from in the ampullae of Lorenzini of sharks, and to integrate electronic signals with an enzymatic flip flop circuit, ion channels, and light-sensitive bacteriorhodopsin. Gorodestky and co-workers have separately demonstrated high proton conductivity in reflectin squid proteins and Pd/PdHx based transistors. All attempts however focused on the interfacing between Pd-based metal and biological materials, even though the Pd protode may occur side reactions such as oxygen conversion (PdO, PdO2 and Pd(OH)x) at the potentials beginning at 0.9 V vs. NHE and toxic hydrogen peroxide production. Here, we develop an organic biotransducer using a high H+-coupling conductive polymer of sulfonated polyaniline (SPA) that monitors and modulates the pH in the vicinity of the SPA electrode, even in solutions with the high buffering capacity typical of mitochondrial environments (Fig.1). We integrate this biotransducer with mitochondria isolated from pig hearts to translate the H+ signal from the activated mitochondria into a measureable protonic current, and also to control the activity of ATP synthase through electrochemical pH modulation at the SPA surface. Figure 1

The euphoria from drinking alcoholic beverages makes them popular worldwide. Abuse in alcohol (ethanol) consumption leads to dependence, behavioral problems, and fatal accidents1. In 2013, 10,076 people lost their lives in alcohol-related-driving accidents in the United States alone, accounting for nearly 31% of all traffic related deaths1. Driving under the influence is illegal and the maximum allowed blood alcohol concentration (BAC) is 0.05–0.08%, in most countries2. A breathalyzer measures the concentration of ethanol in the breath to estimate the BAC of an individual. The first generation of breathalyzers uses a liquid dye sensitive to ethanol exposure, potassium dichromate, and a photodetector3. Reliability of these detectors is a challenge and potassium dichromate is environmentally toxic3. A new generation of breathalyzers uses the ethanol in the breath to power a fuel cell whose output is proportional to the ethanol concentration4. These breathalyzers are connected directly to smart phones to test one’s alcohol level before attempting to drive. However, these breathalyzers are still impractical because they require constant recalibration4. To-date the most reliable BAC tests and the only one that is admissible in court is the blood test, which is difficult to administer on site or for preventative purposes. A breathalyzer as easy to use as an inexpensive and disposable glucose paper-strip sensor would greatly simplify BAC testing5. Organic electrochemical transistors (OECTs) are excellent candidates for disposable biosensors because they are inexpensive, they can be made on flexible substrates, and they can be printed on paper6,7. OECTs are typically made with poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) PEDOT:PSS. PEDOT:PSS is a p-type organic semiconductor with several applications in bioelectronics8,9. Coupled with enzymes in the electrolyte, PEDOT:PSS OECTs are able to detect micro molar glucose concentration in human blood and sweat10. OECTs sensors are amenable to screen-printing11 and inkjet printing12 for rapid and inexpensive manufacturing. Here, we demonstrate an early stage proof-of-concept OECT-breathalyzer on paper by integrating a PEDOT:PSS OECT with the enzyme alcohol dehydrogenase. This proof-of-concept OECT-breathalyzer may aid the development of a breathalyzer that is easy-to-use, inexpensive, easily calibrated, and can be coupled with a cell-phone or a smart watch for BAC self-testing to reduce alcohol related traffic accidents.

A strip of carbon fabric (CF) electrode modified with multiwalled carbon nanotubes and subsequently fructose dehydrogenase (FDH) showed an oxidation current density of ∼11 mA cm−2 in stirred 200 mM fructose solution. Obtaining a sufficient dispersion of the nanotubes during its modification was found to be critical to ensure such a performance of the FDH anode. For use with this anode, a CF strip modified with ketjenblack (KB) and bilirubin oxidase (BOD) served as a gas-diffusion cathode for the reduction of O2 from air at a current density of ∼2 mA cm−2. The FDH-modified CF strip and the BOD-modified CF strip were stacked with an agarose film that retained an electrolyte solution and fuel (fructose) to construct a totally flexible sheet-shaped biofuel cell. This assembly allowed bending of 44° without affecting the maximum output power density, 550 μW cm−2 obtained at 0.4 V.

Molecularly ordered composites of polyvinylimidazole-[Os(bipyridine)2Cl] (PVI-[Os(bpy)2Cl]) and glucose oxidase (GOD) are assembled inside a film of aligned carbon nanotubes. The structure of the prepared GOD/PVI-[Os(bpy)2Cl]/CNT composite film is entirely uniform and stable; more than 90% bioelectrocatalytic activity could be maintained even after storage for 6 d. Owing to the ideal positional relationship achieved between enzyme, mediator, and electrode, the prepared film shows a high bioelectrocatalytic activity for glucose oxidation (ca. 15 mA cm−2 at 25 °C) with an extremely high electron-transfer turnover rate (ca. 650 s−1) comparable to the value for GOD solutions, indicating almost every enzyme molecule entrapped within the ensemble (ca. 3 × 1012 enzymes in a 1 mm × 1 mm film) can work to the fullest extent. This free-standing, flexible composite film can be used by winding on a needle device; as an example, a self-powered sugar monitor is demonstrated.

We report the fabrication of totally organic hydrogel-based microelectrodes of poly(3,4-ethylenedioxythiophene) (PEDOT), which exhibit a lowered sheet resistivity of about 100 Ω/□. The preparation process starts with the electrodeposition of conductive PEDOT (ca. 20 S cm

We have combined a topographically patterned agarose microstamp with an electrode substrate to develop a novel printing device that internally contains an electrochemical system for a controlled supply of reactive ink to the stamp surface. The 10 wt % agarose gel containing 0.1 M PBS + 25 mM KBr showed suitable elasticity for forming stamps and served as the electrolytic medium for the electrochemical oxidation of Br(-) to generate HBrO. The electrode substrate patched with an agarose stamp having 50-microm-high bumps was used for the spatially confined detachment of heparin/polyethyleneimine precoated on glass substrates, followed by micropatterned adsorption of fibronectin. Using the microelectrode array, the addressable micropatterning of protein by the controlled delivery of HBrO to each bump was demonstrated.

We have studied the coimmobilization of glucose dehydrogenase (GDH) and its cofactor, oxidized nicotinamide adenine dinucleotide (NAD+), on a ketjenblack (KB) electrode as a step toward a biofuel cell anode that works without mediators. A KB electrode was first treated with a sulfuric acid/nitric acid/water mixture to lower the overvoltage for NADH oxidation, and was next chemically modified with NAD+ and GDH. The improved GDH/NAD+/KB electrode is found to oxidize glucose around 0 V vs. Ag/AgCl. A biofuel cell constructed with a bilirubin oxidase-immobilized KB cathode showed a maximum power density of 52 μW/cm2 at 0.3 V.

To elucidate the exact role of the C-terminal region of GroEL in its functional cycle, the C-terminal 20-amino acid truncated mutant of GroEL was constructed. The steady-state ATPase rate and duration of GroES binding showed that the functional cycle of the truncated GroEL is extended by approximately 2 s in comparison with that of the wild type, without interfering with the basic functions of GroEL. We have proposed a model for the functional cycle of GroEL, which consists of two rate-limiting steps of approximately 3- and approximately 5-s duration (Ueno, T., Taguchi, H., Tadakuma, H., Yoshida, M., and Funatsu, T. (2004) Mol. Cell 14, 423-434 g). According to the model, detailed kinetic studies were performed. We found that a 20-residue truncation of the C terminus extends the time until inorganic phosphate is generated and the time for arresting protein folding in the central cavity, i.e. the lifetime of the first rate-limiting step in the functional cycle, to an approximately 5-s duration. These results suggest that the integrity of the C-terminal region facilitates the transition from the first to the second rate-limiting state.

Three types of self-assembled monolayers (SAMs) are employed for the investigation of protein adsorption. An octadecylsilane (ODS) SAM, a fluoroalkylsilane (FAS) SAM, and a polyethylene glycol (PEG) SAM are selected as examples. The amount of adsorbed protein is measured by fluorescent microscopy. A molecular dynamics (MD) simulation is carried out for modeling both the molecular structures of the SAMs and the water structure on the SAMs. A hydrophilic PEG SAM prevents protein adsorption, while a large amount of adsorption is observed on a hydrophobic ODS SAM. In spite of the hydrophobicity, an FAS SAM prevents protein adsorption as well as a PEG SAM. MD calculation suggests that the existence of surface-bound water on an ODS SAM induces protein adsorption. In the case of the FAS SAM, owing to the electrostatic interaction and the flexibility of the precursor, the water molecule is not bound to the surface and protein adsorption is suppressed.

Objective. This study was conducted to estimate the prevalence of smoking among pregnant women living in Japan and to analyze the factors associated with their smoking behavior. Method. Five hundred institutions with maternity services were randomly sampled from a list of the Japan Association of Obstetricians and Gynecologists. Of these institutions, 260 participated in the survey which was conducted in February 2002. Using a self-reported anonymous questionnaire, a survey on smoking behavior, drinking behavior and sleep status was conducted on pregnant women. Chi-square tests and logistic regression analyses were used to examine the factors associated with their smoking behavior. Results. Data were obtained from a total of 16,414 pregnant women. The prevalence of smoking during pregnancy was 9.9% [95% confidence interval (CI) 9.4%, 10.4%]. The quit rate of smoking among pregnant woman was 61.9% [95% CI 60.4%, 63.4%]. The odds ratios for smoking during pregnancy were significantly higher in women with relatively young age, less schooling, multiparous, exposure to passive smoking, short sleep duration and in women who drank. Conclusion. Smoking among pregnant women remains an important public health problem in Japan. It is necessary to promote antismoking measures based on the results of this study.

In biological systems, intercellular communication is mediated by membrane proteins and ion channels that regulate traffic of ions and small molecules across cell membranes. A bioelectronic device with ion channels that control ionic flow across a supported lipid bilayer (SLB) should therefore be ideal for interfacing with biological systems. Here, we demonstrate a biotic–abiotic bioprotonic device with Pd contacts that regulates proton (H+) flow across an SLB incorporating the ion channels Gramicidin A (gA) and Alamethicin (ALM). We model the device characteristics using the Goldman–Hodgkin–Katz (GHK) solution to the Nernst–Planck equation for transport across the membrane. We derive the permeability for an SLB integrating gA and ALM and demonstrate pH control as a function of applied voltage and membrane permeability. This work opens the door to integrating more complex H+ channels at the Pd contact interface to produce responsive biotic–abiotic devices with increased functionality., Conventional electronics use electrons as charge carriers whereas biological systems use ions, confounding integration of electronics with biology. Here the authors show voltage-regulated flow of protons across a supported lipid bilayer using the ion channel Gramicidin A and the voltage-gated ion channel Alamethicin.

In Nature, protons (H+) can mediate metabolic process through enzymatic reactions. Examples include glucose oxidation with glucose dehydrogenase to regulate blood glucose level, alcohol dissolution into carboxylic acid through alcohol dehydrogenase and voltage-regulated H+ channels activating bioluminescence in firefly and jellyfish. Artificial devices that control H+ currents and H+ concentration (pH) are able to actively influence biochemical processes. Here, we demonstrate a biotransducer that monitors and actively regulates pH-responsive enzymatic reactions by monitoring and controlling the flow of H+ between PdHx contacts and solution. The present transducer records bistable pH modulation from an “enzymatic flip-flop” circuit that comprises glucose dehydrogenase and alcohol dehydrogenase. The transducer also controls bioluminescence from firefly luciferase by affecting solution pH.

The feasibility of using an octenyltrimethoxysilane (OCS) self-assembled monolayer (SAM) as a high-resolution electron beam (EB) resist is investigated. The vinyl groups of the OCS SAM can be modified into hydroxy groups, which are useful for biochip fabrication. The hydroxy-modified OCS SAM exhibits higher sensitivity than a vinyl-terminated one. By using the hydroxy-modified OCS SAM as an EB resist, a miniaturized pattern of 18 nm is achieved. Since the hydroxy-modified OCS SAM is repellent to many proteins, this methodology can be useful for the fabrication of protein-immobilizing templates of a molecular scale.

Objective Among the existing epidemiologic studies that have examined the relationship between depression and sleep disturbances, there are few nationwide studies that have been conducted on subjects representing the general population. The present study was therefore conducted to clarify the relationship between depression and sleep disturbances, in particular the relationship between depression and both sleep duration and subjective sleep sufficiency, using a large sample representative of the general population. Method The survey was conducted in June 2000, using self-administered questionnaires, targeting a population that was selected randomly from among 300 communities throughout Japan. Among the respondents, data from 24,686 individuals aged 20 years or older were analyzed. The Center for Epidemiologic Studies Depression Scale was used to assess the presence of depression. Sleep status, including sleep duration, subjective sleep sufficiency, and the presence or absence of insomnia symptoms, was evaluated. Results Those whose sleep duration was less than 6 hours and those whose sleep duration was 8 hours or more tended to be more depressed than those whose sleep duration was between 6 and 8 hours. Thus, sleep duration exhibited a U-shaped association with symptoms of depression. As subjective sleep sufficiency decreased, symptoms of depression increased, indicating a linear inverse-proportional relationship. Conclusion The fact that sleep duration and subjective sleep sufficiency exhibited different relationships with symptoms of depression indicates that these 2 sleep parameters each have their own significance with regard to depression. These findings may be useful in the medical management of mental diseases.

There have been only a few studies on the relationship between sleep disturbances and somatic and psychological complaints in Japanese people. In this study, we analyzed this relationship using the data of the health and welfare survey performed in 2000 by the Ministry of Health, Labour and Welfare, Japan. The purpose of this study was to evaluate the relationship between sleep disturbances and somatic and psychological complaints among the Japanese general population. The survey was performed in members of households in 300 areas extracted randomly from all over the country using a self-reported questionnaire. The questionnaire items included somatic and psychological complaints (headache, dizziness, palpitation/dyspnea, epigastric discomfort, constipation/diarrhea, stiff neck/shoulder, backache, easy fatigability, persistent fatigue, irritability, anxiety, and worrying about health) and sleep disturbances. Data obtained from 28 714 subjects, aged 20 years or more, were analyzed. The prevalences of almost all complaints were significantly higher in the females than in the males. In the subjects who had a larger number of somatic and psychological complaints, the prevalence of symptom concerning sleep disturbances, such as difficulty initiating sleep, difficulty maintaining sleep, early morning awakening, insomnia, short sleep duration, and subjective insufficient sleep, were higher. Multivariate analysis demonstrated that individual somatic and psychological complaints were independently associated with each symptom of sleep disturbance. It is important to apply the results of this study to the treatment of sleep disturbances and sleep hygiene.

BACKGROUND: Benefits of breast-feeding are not only limited to nutrition and sanitation in developing countries but also extend to cost-saving health care and alleviation of anxiety related to childrearing in developed countries. This study aims to elucidate factors associated with exclusive breast-feeding in Japan and use this information to achieve child-rearing support worldwide by promoting breast-feeding.METHODS: This cross-sectional study used data from a survey conducted by Ministry of Health, Labour and Welfare of the Japanese government, the First Longitudinal Survey of Babies in 21st Century. All subjects were infants (n = 53,575) born in Japan in 2001 between January 10 and 17 and between July 10 and 17. According to the data, the exclusive breast-feeding rate in Japan during the first 6 months of life was 21.0%. We examined the factors associated with exclusive breast-feeding using univariate and multivariate logistic regression analyses.RESULTS: Among the factors examined, the adjusted odds ratio (OR) for exclusive breast-feeding was low for late childbearing, low birth weight infants, multiple births, smoking parents, living with grandparents, and feeling burdened by childrearing. The adjusted OR was high for factors that included sufficient childcare leave and consultation about childrearing with the spouse, a birth attendant and/or nurse, and a peer in a child-rearing circle.CONCLUSIONS: Exclusive breast-feeding is associated not only with medical factors but also with social factors. This study clarifies the necessity of social support to reduce the child rearing burden and a political system to promote paternal participation in childrearing and to improve the childcare leave system.J Epidemiol 2006; 16: 57-63.

Background. Pregnant women suffer from sleep disturbance, which may be aggravated by smoking and/or drinking. We investigate here the joint effect of smoking and drinking with respect to sleep disturbance during pregnancy. Methods. Survey of about 16,000 pregnant women in Japan, conducted in 2002 using a self-administered questionnaire. Results. Both smoking and drinking increased the odds of sleep disturbances, such as subjective insufficient sleep, difficulty in initiating or maintaining sleep, early-morning awakening, short sleep duration, excessive daytime sleepiness and restless legs syndrome. The joint odds ratios for smoking and drinking corresponded more or less to the products of the odds ratio for smoking or drinking. Conclusion. Smoking and drinking are independently associated with increased sleep disturbance during pregnancy, in addition to their other well-known side-effects.

This study sought to determine the relationship of job type differences to burnout level, the details of job characteristics for each job type, and the association between burnout and job factors in 189 social workers at all social welfare offices in a prefecture in Japan. Among the three job types, 32.9% of social workers involved with public assistance, 29.0% of social workers involved with public assistance, the elderly, the disabled and single mothers, and 15.2% of social workers involved with the elderly, the disabled and single mothers were scored in the "high burnout" category (p