Salivary Alpha-Amylase Activity and Mild Cognitive Impairment among Japanese Older Adults: The Toon Health Study.

BACKGROUND: There is growing interest in examining objective markers for early identification and behavioral intervention to prevent dementia and mild cognitive impairment in clinical and community settings. OBJECTIVE: To investigate the association between salivary alpha-amylase as an objective measure of psychological stress response and mild cognitive impairment for the implication of psychological stress in the development of mild cognitive impairment. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study involved 865 participants aged ≥ 65 years. A saliva sample was collected in the morning, and the levels of salivary alpha-amylase were assayed. Mild cognitive impairment was evaluated using the Japanese version of the Montreal Cognitive Assessment; a score < 26 was indicative of mild cognitive impairment. A multivariable logistic regression model was used to examine the association of salivary alpha-amylase and mild cognitive impairment after adjusting for age, sex, current drinking status, current smoking status, body mass index, hypertension, diabetes mellitus, physical activity, education, social support, social network, and heart rate variability. RESULTS: Salivary alpha-amylase was associated with mild cognitive impairment (the multivariable-adjusted odds ratio [95% confidence interval] for the 1-standard deviation increment of log-transformed salivary alpha-amylase was 1.24 [1.07-1.44]). This significant association persisted after adjusting for various confounding factors. CONCLUSION: Elevation of salivary alpha-amylase was associated with mild cognitive impairment among Japanese community-dwelling older adults. This suggests that salivary alpha-amylase is a useful objective marker of psychological stress responses associated with mild cognitive impairment.

Association of salivary lactate dehydrogenase level with systemic inflammation in a Japanese population.

BACKGROUND AND OBJECTIVE: Salivary lactate dehydrogenase (LDH) was reported to be a useful parameter for the screening of periodontal disease. We performed a cross-sectional study to verify the usefulness of salivary LDH as a biomarker of periodontitis and to investigate the association of severity of periodontitis with systemic inflammation by measuring salivary LDH and serum high sensitive C-reactive protein (hs-CRP) levels in a community-based middle-aged and elderly population in Japan. MATERIAL AND METHODS: We recruited 644 men and 1171 women, aged 30-79 years, who participated in the Toon Health Study during 2011-15. Periodontal condition was assessed by full-mouth examination including mean value of probing depth, percentage of probing depth of ≥4 mm and ≥6 mm, and bleeding on probing. Saliva and blood serum samples were collected for measurement of salivary LDH level and hs-CRP, respectively. A linear trend across quartiles of salivary LDH was calculated using linear regression. Interaction of salivary LDH and overweight status (body mass index of ≥25 kg/m2 ) was tested using the cross-product term of log-transformed continuous salivary LDH and overweight status. RESULTS: Analysis of covariance adjusted for potential confounders revealed strong associations between salivary LDH level and the indicators of periodontal condition (P < .01) in both men and women. Sex- and age-adjusted mean values of hs-CRP according to salivary LDH quartiles were 0.40, 0.45, 0.45 and 0.50 mg/L (P for trend <.01). Although the association was attenuated after further adjustment for body mass index, hypertension, diabetes mellitus, dyslipidemia, alcohol intake, smoking status and physical activity. When stratified by overweight status, the association remained significant in overweight individuals (P = .03). The multivariable adjusted odds ratio of hs-CRP level of ≥1 mg/L for the highest vs lowest quartile of salivary LDH was 1.93 (95% CI, 1.01-3.69) in overweight individuals, but not significant in non-overweight individuals. CONCLUSION: Salivary LDH appears to be a promising biomarker for the mass screening of periodontitis in local community health settings. High salivary LDH levels, particularly in overweight individuals might contribute to prevention of cardiovascular disease, through measuring systemic inflammatory burdens as well as traditional cardiovascular risk factors.

Scalloped tongue is associated with nocturnal intermittent hypoxia among community-dwelling Japanese: the Toon Health Study.

Scalloped tongue is considered as a possible clinical finding of obstructive sleep apnoea (OSA). There are few evidence of the association between scalloped tongue and OSA. To examine the association between scalloped tongue and nocturnal intermittent hypoxia (NIH), a surrogate marker of OSA, among a general Japanese population. Study participants were 398 men and 732 women aged 30-79 years who participated in the Toon Health Study from 2011 to 2014. Scalloped tongue was classified into three categories: none, mild and moderate-to-severe. Moderate-to-severe NIH was defined as the 3% oxygen desaturation index of ≥15 events/h during sleep for one night with pulse oximetry. The multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for moderate-to-severe NIH were calculated according to scalloped tongue categories using a logistic regression model. There were 69 (6·1%) moderate-to-severe NIH cases in this population. The multivariable-adjusted ORs (95% CIs) of moderate-to-severe NIH were 1·59 (0·85-2·95) for mild and 2·39 (1·10-5·17) for the moderate-to-severe scalloped tongue group compared with the group without scalloped tongues. When stratified by overweight status (BMI <25 or ≥25 kg m-2 ), the respective ORs (95% CIs) were 2·83 (1·06-7·55) and 4·74 (1·28-17·49) among overweight individuals, and 0·94 (0·40-2·70) and 1·52 (0·57-4·05) among non-overweight individuals. Scalloped tongue was associated with higher prevalence of moderate-to-severe NIH among the general Japanese population and this association was more evident in overweight individuals.

The effect of peer support groups on self-care for haemophilic patients with HIV in Japan.

Experienced peer support groups (EPSG) are expected to improve self-care and complement professional health care for haemophilic patients, even those living in inconvenient clinical setting. However, these benefits have not been verified quantitatively. The structural equation modelling (SEM) was used to evaluate the effects of contact with EPSG on self-care for haemophilic patients in the Japanese clinical settings. Factors affecting self-care were compared between groups with and without EPSG contact. Self-reported questionnaires were mailed to 652 haemophilic patients with HIV in Japan (September 2005-January 2006). SEM demonstrated significant associations between EPSG contact, self-care scores and other social and individual factors. The total effect of EPSG contact on self-care was calculated. The structural differences between models were analysed in a multi-group analysis. Of the 257 respondents (response rate, 39.4%), 109 reported having contact with an EPSG (EPSG+ group) and 139 reported no contact (EPSG- group). EPSG contact was significantly associated with better self-care. In the multi-group analysis, the total effect of inconvenient access to medical services on self-care in the EPSG+ group was 10% of that in the EPSG- group and was significantly associated with poor illness-related knowledge and high anxiety level only in the EPSG- group. In the EPSG+ group, patient age was strongly associated with self-care than in the EPSG- group. These findings suggest that EPSG contact may alleviate inconvenience in medical services. Factors associated with self-care differed between groups. Health care professionals must carefully assess self-care behaviours and service accessibility based on these results.

Selective photoreceptor damage in four species of insects induced by experimental exposures to UV-irradiation.

Damage to photoreceptive cells of insect compound eyes exposed to abnormally high doses of UV-radiation of 350nm peak wavelength manifests itself in at least two different ways. In the butterflies Papilio xuthus and Pieris napi from Japan and northern Finland, respectively, only the cell bodies of retinula cells 1 and 2, (identified as short wavelength receptors), but not their corresponding rhabdomeres, exhibit damage with apoptotic features. In the eye of UV-irradiated adult crickets, however, cell bodies and cytoplasm remain normal, while the rhabdomeres of cells 7 and 8 exhibit signs of severe membrane disruptions. No signs of damage whatsoever occurred in the eyes of northern Finnish bumblebees exposed to UV. It is suggested that metabolic shortfalls in the UV-sensitive cells of the butterfly eyes result in cellular shut-down, but that in the cricket receptors UV-induced changes of the membrane lipids dominate, leading to membrane instability without concomittant cell death. The strong resistance of the bumblebee eye to UV-induced damage requires further investigation, but since preconditioning to light can reduce photic damage in the rat eye, the 24h daylight experienced by northern Finnish bumblebees during the summer season could be involved.

Effects of light and darkness on cell deaths in damaged retinal ganglion cells of the carp retina.

Effects of light and darkness on the apoptosis of retinal ganglion cells (RGCs) in young carp were measured by TUNEL method after transection of the optic nerve. Following the operation, the fish were kept under one of four regimens; constant darkness (DD), constant light (LL), 12 hr light and 12 hr dark (LD) and 3 hr of flickering light followed by 21 hr in the dark (FL). On day 3, the highest ratio of apoptotic RGCs was seen under conditions of DD, followed by LL, LD, and FL. On day 6, the percentages of apoptotic RGCs were lower under every experimental condition than what they had been earlier on day 3, but the same ranking order was maintained. Immunohistochemically it could be shown that phosphorylated ERKs were more intensively localized in FL rather than DD retinas. The results suggest that illumination regimens, and in particular cyclic diurnal light/dark changes, have an influence on the degree of apoptosis of damaged RGCs, and that inhibition of apoptosis is correlated with the higher expression of phosphorylated ERKs.

Light activation of phospholipase A2 in the photoreceptor of the crayfish (Procambarus clarkii).

Retinal lipids of crayfish, kept at 4 degrees C under continuous darkness for 3 weeks, consisted mainly of phosphatidylcholine (PC) and phosphatidylethanolamine (PE); sphingomyelin (SM), phosphatidylinositol (PI) and phosphatidylserine (PS) were minor contributors. PI, involved in the phototransduction cascade, never reached greater concentrations than 7% of the total. High concentrations of polyunsaturated fatty acids (PUFA) such as 20:4n-6, 20:5n-3 and 22:6n-3 (DHA, docosahexaenoic acid) were present in PC, PE and PS, but scarce in SM and PI. In retinae of crayfish kept at 4 degrees C in darkness for 3 weeks and then exposed to white light (6 h; ca. 4,500 lx), SM and PS remained seemingly unaffected. PC, however, significantly decreased within 10 min to 65% of the initial value and 50% at 180 min. To study the reduction of PC, lipids of retinae suspended in physiological solution with/without phospholipase C (PLC) and phospholipase A2 (PLA2) inhibitors such as DMDA (= DEDA), manoalide, ET-18-OCH3, and U-73122 were measured. Only free fatty acids (FFA) of retinae with inhibitors of PLA2 like DMDA and manoalide decreased. Retinae irradiated by white light for 3 h displayed a significant reduction of PC, compared with those that had remained in continuous darkness. However, the PC of retinae with PLA2-inhibitors was not decreased by light. Our results provide evidence that not only photoreceptor cell PLC, but also PLA2 is activated by light.

Fine structural correlates of sensitivity in the eyes of the ctenid spider, Cupiennius salei Keys.

We studied fine structural correlates of sensitivity in the principal and secondary eyes of the nocturnal hunting spider Cupiennius salei. In night-adapted eyes the four rhabdomeres of the principal eye photoreceptors are 58 microm long and occupy together 234 microm(2) in cross-section (average), whereas the two rhabdomeres of the secondary eye photoreceptors are about 49 microm long and measure 135-183 microm(2) in cross-section (average). The rhabdoms (photosensitive structures) consist of tightly packed microvilli (diameter 0.1 microm, maximum length 3.5 microm) and occupy up to 63% of the cross-sectional area of the retina. When calculating the amount of light the eyes of Cupiennius are able to capture according to their morphological characteristics, the values for sensitivity S(see Land, 1981, 1985) are between 78 and 109 microm(2). Cupiennius is more sensitive than any other hunting spider examined except Dinopis whose posterior median eyes are the most sensitive ones of all terrestrial arthropod eyes studied. In day-adapted eyes the rhabdomeral microvilli are almost completely degraded. The remaining microvillar surface amounts to only about one-tenth compared with the night-adapted state. Efferent synaptoid terminals have been found to contact the photoreceptors in all eyes of C. salei. The present fine structural data are compared to previous electrophysiological research and underline the significance of vision in Cupiennius.

Compound Eye Fine Structure in Paralomis multispina Benedict, an Anomuran Half-Crab From 1200 m Depth (Crustacea; Decapoda; Anomura).

Fully grown, unsexed specimens of the anomuran half-crab Paralomis multispina Benedict were obtained from a depth of 1200 m, and the eyes of three individuals were prepared for light and electron microscopy. In their outer appearance the compound eyes of Paralomis resemble those of common shallow-water half-crabs (e.g., Petrolisthes), but facets in Paralomis were about 3 times larger in diameter (i.e., 60 {mu}m) and at least twice as long. Interommatidial angles ranged from 3{deg} to 5{deg}. The proximal width of the crystalline cone in Paralomis was 10 times that of its equivalent in the Petrolisthes eye, and the rhabdom--although only twice as long--had a radius that was 7 times greater distally and 4 times greater proximally. A clear-zone between cones and rhabdom was not developed, and cross sections of crystalline cones revealed rounded rather than square profiles. A distal retinula cell (R8) was absent, and all regular retinula cells (R1-R7) protruded microvilli of about 0.11 {mu}m diameter in many (and not only two) directions. A maximum rhabdom occupation ratio of 85% was found in the Paralomis retinula, whereas in the shallow-water half-crabs the comparable figure was 35%. Paralomis featured a wide, rhabdomless space between basement membrane and proximal rhabdom ends; the space was occupied by reflecting cells. Primary screening pigment cells and their dark granules were present; secondary screening pigment cells, however, were replaced by reflecting cells. The anatomical modifications in the Paralomis eye are consistent with habitat-related adaptations seen in the eyes of other benthic and slow-moving deep-water crustaceans, but not with those of euphausiids. We conclude that the eye of Paralomis functions as an apposition eye, designed to maximize photon capture, especially from point sources (i.e., bioluminescence) rather than extended sources. We estimate that the Paralomis eye is at least 150 times more sensitive to light than the eye of shallow-water Petrolisthes.

Two opsins from the compound eye of the crab Hemigrapsus sanguineus

The primary structures of two opsins from the brachyuran crab Hemigrapsus sanguineus were deduced from the cDNA nucleotide sequences. Both deduced proteins were composed of 377 amino acid residues and included residues highly conserved in visual pigments of other species, and the proteins were 75 % identical to each other. The distribution of opsin transcripts in the compound eye, determined by in situ hybridization, suggested that the mRNAs of the two opsins were expressed simultaneously in all of the seven retinular cells (R1-R7) forming the main rhabdom in each ommatidium. Two different visual pigments may be present in one photoreceptor cell in this brachyuran crab. The spectral sensitivity of the compound eye was also determined by recording the electroretinogram. The compound eye was maximally sensitive at about 480 nm. These and previous findings suggest that both opsins of this brachyuran crab produce visual pigments with maximal absorption in the blue-green region of the spectrum. Evidence is presented that crustaceans possess multiple pigment systems for vision.

Morphogenesis of the photoreceptive site and development of the electrical responses in the butterfly genital photoreceptors during the pupal period.

This paper describes the process of morphogenesis of the photoreceptive site of the butterfly genital photoreceptors. Associated development of the electrical responses is also described. The photoreceptor is a sensory neuron whose cell body is located in the genitalia and has a photoreceptive site of the phaosome-type. This consists of the distal processes and the tubular membranes, which protrude from the tip of distal processes. Phaosome morphogenesis was studied using electron microscopy. The results indicate that morphogenesis occurs in the latter half of the pupal period and that the process is divided into five phases. First, the tubular membranes appear as small membrane protrusions (phase I). The short tubular membranes emerge from several portions of the cell body forming several membrane clusters (phase II). The clusters then collect to form a small phaosome. Short distal processes become evident (phase III). The phaosome volume increases, mainly due to the extensive elongation and bifurcation of both tubular membranes and distal processes (phase IV). Phase V achieves final adult morphology. The photoreceptors of phase II are already able to produce spikes in response to light stimulation, although the sensitivity was about one tenth of the adult. The sensitivity increase occurred in parallel with the increase in the phaosome volume.

Synthesis of 3-hydroxyretinal in the cytosol of the butterfly compound eye.

The metabolism of 3-hydroxyretinoids in the cytosol of the compound eyes of a species of butterfly, Papilio xuthus, was investigated. The cytosol was found to contain 25-30% of the total 3-hydroxyretinal and 70-82% of the total 3-hydroxyretinol in the eye. These percentages of 3-hydroxyretinoids in the cytosol were found to be constant regardless of whether the eyes are light-adapted or dark-adapted. 3-Hydroxyretinal can be newly synthesized in the cytosol of light-adapted eyes. Blue light specifically increases the amount of 11-cis and all-trans 3-hydroxyretinal ca 2.5 and 1.8 times respectively, compared to pre-irradiation. When 3-hydroxyretinal was synthesized, 3-hydroxyretinol was decreased or disappeared in the cytosol. When retinol (non-native chemical) was added to the cytosol, it was converted into retinal. This result indicates that an oxidative system exists in the compound eye which can convert 3-hydroxyretinol to 3-hydroxyretinal.

Ultrastructure of the extraocular photoreceptor in the genitalia of a butterfly, Papilio xuthus.

This paper describes the ultrastructure of a sensory neuron found in the extraocular photoreceptive site on the butterfly genitalia. Our previous studies have shown that there are two pairs of the photoreceptive sites in a butterfly (four per individual). Each photoreceptive site is recognizable by a transparent area in the pigmented cuticle of the genitalia. From the nerve that extends from the transparent cuticle to the last abdominal ganglion, a sustained train of single unit spikes can be recorded in response to a light flash. The single unit spikes disappear when the transparent cuticle is covered, thus indicating that a single photoreceptor exists close to it. Here, we examined complete serial semithin sections of plastic-embedded photoreceptive sites of both male and female, and observed an ovoid structure close to the transparent cuticle. The structure contained the cell body of a sensory neuron whose axon was in the nerve branch from which the photoresponse had been recorded. Further electron microscopy revealed that the cell body extended a few distal processes that protrude tubular membrane from the tip, forming a structure resembling the phaosome (from Greek; phaos = light, some = body) which was first described in the earthworm dermal photoreceptors. The sensory neuron was also found in a surgically isolated nerve-photoreceptor preparation that responded to the light. We therefore propose that the phaosome-containing sensory neuron is the butterfly genital photoreceptor.

Intrinsic control of rhabdom size and rhodopsin content in the crab compound eye by a circadian biological clock.

Under conditions of constant darkness, rhabdom volume and the amount of visual pigment chromophore show circadian changes in the compound eye of the crab Hemigrapsus sanguineus. The present results indicate that an intrinsic circadian biological clock is involved in the control of the changes.

Retinyl and 3-dehydroretinyl esters in the crayfish retina.

We have studied chemical nature and localization of retinyl esters stored in the retina of the crayfish, Procambarus clarkii, which has a rhodopsin-porphyropsin visual pigment system. The crayfish kept at 10 degrees C in the constant dark had 3-dehydroretinal along with retinal in the retina as the chromophore of visual pigment. Both retinyl and 3-dehydroretinyl esters were found in the retina, more than 95% of them in the 11-cis configuration. Of three kinds of fatty acid detected in the esters, the major component (about 80%) was the polyunsaturated fatty acid, docosahexaenoic acid (C22 = 6). Observations with electron and fluorescence microscopy and the results of fractionation experiments showed that the esters were stored in photoreceptor cells as oil droplets. The ratio of 3-dehydroretinal/retinal as visual pigment chromophore was always higher than that of 3-dehydroretinol/retinol in the stored esters. This result suggests a mechanism of selective utilization of 3-dehydroretinol for the chromophore of visual pigment in the crayfish retina.

Daily changes of structure, function and rhodopsin content in the compound eye of the crab Hemigrapsus sanguineus.

The compound eye of the crab hemigrapsus sanguineus undergoes daily changes in morphology as determined by light and electron microscopy, both in the quantity of chromophore substances studied by HPLC and in visual sensitivity as shown by electrophysiological techniques. 1. At a temperature of 20 degrees C, the rhabdom occupation ratio (ROR) of an ommatidial retinula was 11.6% (maximum) at midnight, 8.0 times larger than the minimum value at midday (1.4%). 2. Observations by freeze-fracture revealed that the densities of intra-membranous particles (9-11 nm in diameter) of rhabdomeric membrane were ca. 2000/microns 2 and ca. 3000/microns 2 for night and daytime compound eyes, respectively. 3. Screening pigment granules migrated longitudinally and aggregated at night, but dispersed during the day. Reflecting pigment granules migrate transversally in the proximal half of the reticula layer i.e. cytoplasmic extensions containing reflecting pigment granules squeeze between neighbouring retinula cells causing optical isolation (Fig. 4). Thus the screening pigment granules within the retinula cells show longitudinal migration and radial movement so that the daytime rhabdoms are closely surrounded by the pigment granules. 4. At 20 degrees C, the total amount of chromophore of the visual pigment (11-cis and all-trans-retinal) was 1.4 times larger at night than during the day i.e. 46.6 pmol/eye at midnight and 33.2 pmol/eye at midday. Calculations of the total surface area of rhabdomeric membrane, total number of intra-membranous particles in rhabdomeric membrane and the total number of chromophore molecules in a compound eye, indicate that a considerable amount of chromophore-protein complex exists outside the rhabdom during the day. 5. The change in rhabdom size and quantity of chromophore were highly dependent on temperature. At 10 degrees C both rhabdom size and amount of chromophore stayed close to daytime levels throughout the 24 hours. 6. The intracellularly determined relative sensitivity of the dark adapted night eye to a point source of light was about twice as high as the dark-adapted day eye. Most of the increase in the sensitivity is attributed primarily to the effect of reflecting pigment migration around the basement membrane and, secondarily, to the changes in the amount and properties of the photoreceptive membrane. The results form the basis of a detailed discussion as to how an apposition eye can function possibly as a night-eye.

The effects of temperature and light on particles associated with crayfish visual membrane: a freeze-fracture analysis and electrophysiological study.

Depending on the pre-experimental treatment, densities as well as sizes of particles associated with the visual membranes in the eyes of Procambarus clarkii varied. The highest mean particle density (5268 +/- 969 microns -2) and the smallest mean particle diameter (5.57 +/- 1.35 nm) were found in crayfish which had been kept in the dark for 10 weeks in aerated fresh water of 10 degrees C. Crayfish kept under a 12 h dark/light regime in water of 10 degrees C or 30 degrees C for three weeks displayed particle densities of 1076 +/- 180 and 2899 +/- 249 microns -2, respectively; particle diameters were of the order of 8 nm. Temperature did not alter the shape or the slope of the V/log I curves, but ERG recordings show that maximum spectral sensitivity was shifted from lambda max = 560 nm in cold water crayfish (10 degrees C) to lambda max = 580 nm in crayfish from the 30 degrees C tank, and that the 10 degrees C curve was somewhat narrower than the 30 degrees C curve. It is suggested that the observed shift was caused by a combination of factors, of which the following may have played key roles: (1) The filter effect of screening pigment granules and other intracellular components such as vesicles, vacuoles, endoplasmic reticulum, and mitochondria, some of which were developed to a considerably greater extent in 30 degrees C material; (2) increased membrane fluidity due to higher temperature as well as the presence of photoproducts in the light, and the 'countermeasures' taken by the visual pigment molecules to stabilize the lipid bilayer, e.g. higher density, possible 12-s-cis linkages etc.; and (3) increased regeneration or synthesis of rhodopsin due to higher metabolic activity of retinula cells at higher temperatures. Temperature-induced changes of visual pigments in a variety of organisms are discussed and evidence for the rhodopsin-aggregate model of crayfish visual pigment is presented. It is concluded that the retinula cytoplasm is involved in restoring depleted stocks of photopigment, and that the biological sense of possessing an increase in red sensitivity during the warm summer months lies in the correlation of light penetration in the natural habitat of P. clarkii and optimal exploitation of the habitat.

3-Dehydroretinal (vitamin A2 aldehyde) in crayfish eye.

11-Cis-3-dehydroretinal was found in the eye of crayfish, Procambarus clarkii. The 11-cis-3-dehydroretinal was isomerized to all-trans isomer by light-illumination, as was also 11-cis-retinal. Irradiation with deep-red light (lambda greater than 680 nm) selectively isomerized the 11-cis-3-dehydroretinal. The 3-dehydroretinal was not extracted with petroleum ether from the tissue after freeze-drying. These facts suggest that the 11-cis-3-dehydroretinal is the chromophore of crayfish visual pigment. The 3-dehydroretinal content varied with season, high level in winter and low in summer. The crayfish may have a vitamin A1-A2 visual pigment system similar to those of freshwater fishes and amphibians.