Association between social network and dietary variety among community-dwelling older adults

OBJECTIVE

Social networks are critical social health factors for older adults. This study examined the association between social networks and dietary variety among community-dwelling older adults.

DESIGN

A cross-sectional study, using the dietary variety score (DVS) developed for older Japanese people to assess dietary variety and the Lubben Social Network Scale (LSNS-6) to assess social networks.

SETTING

N City, H Prefecture, Japan.

PARTICIPANTS

Community-dwelling older adults aged ≥ 65 years (n 1229).

RESULTS

The LSNS-6 score in the low DVS group was lower than that in the middle and high DVS groups (12·2 ± 5·6 v. 13·4 ± 5·4 and 14·4 ± 5·7, P < 0·001). The population of social isolation (LSNS-6, < 12) in the low DVS group was higher than that in the middle and high DVS groups (43·5 % v. 35·8 % and 31·0 %, P = 0·005). Multivariate linear regression analysis showed that the LSNS-6 score was positively correlated with DVS (standardised coefficient, 0·092; P = 0·002). Social isolation was also significantly associated with a low DVS in the multivariate-adjusted logistic analysis model (OR, 1·30; 95 % CI 1·00, 1·68; P = 0·048). Stratified analysis results revealed the LSNS-6 and DVS were significantly associated in participants with the following characteristics: younger age (< 75 years), women and those living with someone.

CONCLUSIONS

Social networks were associated with dietary variety; social isolation was related to poor dietary variety among community-dwelling older adults. An association between social networks and dietary variety was observed among young-old older adults, women and those living with someone.

Association between asymmetric dimethylarginine and sarcopenia in community-dwelling older women

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of endothelium nitric oxide synthesis and causes endothelial dysfunction that may be related to sarcopenia. However, the association between ADMA and sarcopenia has not been studied. We evaluated the correlations between plasma ADMA levels and sarcopenia in community-dwelling older women. In total, 144 community-dwelling older women participated in this study. Plasma ADMA levels were measured using a competitive enzyme-linked immunosorbent assay. Skeletal muscle mass, measured in terms of bioimpedance and grip strength, was used to assess sarcopenia. Plasma ADMA levels were significantly higher in participants with sarcopenia than in those without sarcopenia. Through receiver-operating characteristic curve analysis, the cutoff value of plasma ADMA level for sarcopenia was estimated at 0.57 μM. Sarcopenia was significantly more prevalent in participants with higher plasma ADMA levels than in those with lower plasma ADMA levels. According to logistic regression analysis, the crude odds ratio of higher plasma ADMA levels in participants with sarcopenia was 4.57 (95% confidence interval, 1.82-11.47; p = 0.001). Reductions in the skeletal muscle mass index over 2 years were significantly greater in participants with higher plasma ADMA levels. In conclusion, plasma ADMA levels were significantly associated with sarcopenia in community-dwelling older women.

Breakfast Skipping and Declines in Cognitive Score Among Community-Dwelling Older Adults: A Longitudinal Study of the HEIJO-KYO Cohort

Previous studies outlined the correlation of adverse effects of breakfast skipping with cognitive function. However, the majority of these studies have focused on the short-term effects; to date, the long-term effect of breakfast skipping on cognitive function among older adults remains unclear. In this prospective cohort study of 712 older adults (mean age, 70.8 years), breakfast skipping was defined as skipping breakfast one or more times per week, and declines in cognitive score was defined as decreases in Mini-Mental State Examination (MMSE) score of two or more in the observed period. During follow-up (median, 31 months), 135 of 712 participants developed declines in cognitive score. Poisson regression models revealed that the incidence rate for declines in cognitive score was significantly higher in breakfast skipper (n = 29) than breakfast eaters (n = 683) [incidence rate ratio (IRR), 2.10; 95% CI, 1.28-3.44]. Additional propensity score adjustments related to breakfast skipping from baseline parameters (age, gender, smoking and drinking status, BMI, household income, educated level, depressive symptoms, hypertension, diabetes, sleep medication, physical activity, caloric intake, and baseline cognition) produced consistent results (IRR, 2.21; 95% CI, 1.33-3.68). Sensitivity analysis, when the cut-off value of decreases in MMSE score was changed to three points, suggested a significant and stronger association (IRR, 3.03; 95% CI, 1.72-5.35). Regarding daily intakes of food groups, breakfast skippers consumed a significantly lower amount of vegetables, fruits, and fish than breakfast eaters. In conclusion, our findings suggest that breakfast skipping is longitudinally associated with declines in cognitive score among older adults.

Social contact impacts physical activity and sedentary behavior among older adults in Japan due to COVID-19

Background

The coronavirus disease 2019 (COVID-19) has adversely affected social contact and physical activity. This study investigated the correlation between physical activity, social contact, and sedentary time among adults aged 65 years and above during the COVID-19 pandemic.

Methods

This study was conducted in N City, H Prefecture, Japan. The authors randomly selected 4,996 adults, aged 65 years and above (mean age 74.1 ± 6.1 years), living in N City, and survey forms were distributed by mail in mid-August 2020. Altogether, 1,925 participants were included in this study. The survey comprised questions concerning the participants’ sex, height, weight, age, smoking and drinking habits, living arrangements, social contact assessments, physical activity levels, and sedentary time. Moreover, linear regression analysis was utilized to investigate the associations between the variables.

Results

The reported median physical activity was 1272 metabolic equivalent of task-min/week (interquartile range 528–2628), and the reported median sedentary time was 360 min/week (interquartile range 240–600). COVID-19 “somewhat,” “quite a lot,” or “completely” hindered the frequency of in-person contact with friends among 75.5% of the respondents and hampered the frequency of virtual contact with friends among 38.8% of the respondents. Physical activity was associated significantly with in-person contact indicators: “interaction with friends” (B = -0.111; 95%CI: -0.187, -0.035; p = 0.004) and “social participation” (B = -0.163; 95%CI: -0.248, -0.079; p < 0.001). These associations remained significant for both multivariate analysis Models 1 (sex and age) and 2 (addition of body mass index [BMI], alcohol use, smoking, living alone, and the number of illnesses to Model 1). Additionally, sedentary time was significantly associated with the social contact variable of “interaction with friends” (B = 0.04; 95%CI: 0.016, 0.064; p = 0.001). This association remained significant in both multivariate analysis models.

Conclusions

Significant associations were confirmed between reduced social contact, decreased physical activity, and more sedentary behavior among older adults due to COVID-19. Hence, continuous monitoring and support for social activities among susceptible older adults in extraordinary circumstances are essential.

Relationship Between Social Activity and Frailty in Japanese Older Women During Restriction on Outings due to COVID-19

Background

This study investigated the relationship between social activities and frailty during the restriction on outings due to COVID-19.

Design

A cross-sectional study.

Setting and Subjects

This study was conducted in City Nishinomiya of Prefecture Hyogo, in Japan. A mail survey was carried out among women aged 65 years or older in May 2020. A population of 293 women aged 65 years or older living in the community was recruited for the study and 213 of them were analyzed.

Measurements

The survey included questions on sex, age, height, weight, and social activity. Social activity consisted of participation in social organizations and their frequency, as well as frequency of interaction with family and friends. The survey also asked if regular social activity had been impeded by COVID-19.

Results

A significant association was found between frailty and hindered interaction with friends (β: 0.176, p = .014). Multivariate linear regression analysis confirmed that this association was also significant in Model 1 (β: 0.158, p = .025), and Model 2 (β: 0.148, p = .034).

Conclusions

No association between being hindered in social activity and frailty was found in older women living in the community during the restriction on outings due to COVID-19.

Relationship Between Dietary Variety and Frailty in Older Japanese Women During the Period of Restriction on Outings Due to COVID-19

Objective

This study investigated the relationship between diet and frailty in community-dwelling older adults during the period of restriction on outings due to COVID-19. A population of 322 women aged 65 years or older living in the community was recruited for the study, of whom 253 were analyzed.

Method

A mail survey was carried out in May 2020, targeting adults aged 65 years or older. The survey included questions regarding sex, age, height, weight, and social participation. Dietary variety score and frailty score were also calculated.

Results

Mean age for the 253 participants was 80.0±6.4 years. Dietary variety score and frailty score were significantly correlated under linear regression analysis (β :-0.224, P < 0.001). In multivariate regression analysis, these factors remained significantly correlated in Model 2 , which was adjusted for age (β :-0.229, P < 0.001), and Model 3, which was adjusted for age, BMI, and other confounding factors (β :-0.208, P = 0.001).

Conclusion

Diet was correlated with frailty in older adults living in the community during the period of restriction on outings due to COVID-19.

Associations between Dietary Variety and Frailty in Community-Dwelling Older People Who Live Alone: Gender Differences

OBJECTIVES

This study aimed to investigate the influences of living arrangements on the association between dietary variety and frailty by gender in community-dwelling older people.

DESIGN

A cross-sectional study.

SETTING

Nishinomiya city, Hyogo prefecture, Japan.

PARTICIPANTS

A total of 4,996 randomly selected community-dwelling older people aged 65 years and older and living in Nishinomiya City.

MEASUREMENTS

Survey questionnaires were distributed via mail. The frailty score was evaluated by the 5-item frailty screening index. Dietary variety was assessed using the dietary variety score developed for the general older Japanese population.

RESULTS

A total of 2,764 community-dwelling participants aged ≥ 65 years responded to the questionnaires. After excluding missing data, 1,780 participants were included in the study analysis. The frailty scores in older men living alone were significantly higher than those in older men living with someone (P < 0.001). The dietary variety scores in older men living alone were significantly lower than those in older men living with someone (P < 0.001). However, differences in the frailty and dietary variety scores between living alone and living with someone were not were observed in older women (P = 0.360 and P = 0.265, respectively). In the multivariable regression analysis, the associations between dietary variety score and frailty score in living alone (β= -0. 271, P = 0.011) were stronger than those in living with someone in the case of older men (β= -0.131, P = 0.045). Similar associations between dietary variety and frailty were presented in older women living alone than in those living with someone (β -0.114, P = 0.002; β -0.088, P = 0.012, respectively).

CONCLUSIONS

Older men who live alone had higher frailty score and lower dietary variety. The associations between dietary variety and frailty were different according to living arrangements in both older men and older women.

Development and validation of nutrient estimates based on a food-photographic record in Japan

Background

Previous studies have reported that estimates of portion size, energy, and macronutrients such as carbohydrates, proteins, and fat based on the food-photographic record closely correlate with directly weighed values. However, the correlation based on a large sample of the test meal with the evidence of many nutrients is yet to be determined. We conducted this study to assess the correlation and difference between the food-photographic record and weighed results for 44 nutrients based on a larger number of test meals than those in previous studies.

Methods

We assessed the nutrients of test meals using a food-photographic record and direct weighing and compared the results of the two methods. Twenty participants prepared a total of 1163 test meals. Each participant cooked 28–29 different kinds of dishes. Five participants cooked the same dish with their own recipes. For the most commonly consumed 41 dishes, 20 participants served a meal with their usual portion size. For the remaining 73 dishes, five participants served a meal with their usual portion size. An independent researcher weighed each ingredient and calculated the nutrients of the test meals. The participants took photographs of the test meals using a digital camera. Two independent, trained analysts measured the longitudinal and transverse diameters of the food area on the photographs of the test meals, compared the portion size with the reference photographs, and calculated the nutrients based on a database that contained reference photographs.

Results

Rank correlation coefficients between estimates from the food-photographic record of each test meal and weighed results were high for portion size (r = 0.93), energy (r = 0.93), protein (r = 0.90), fat (r = 0.92), and carbohydrate (r = 0.94), and those for the 44 nutrients ranged from 0.78 to 0.94. We found high reproducibility between the two analysts for all the nutrients (r > 0.90).

Conclusions

We found a high correlation and small difference between the food-photographic record method and weighed results of a large number of nutrients in many test meals.

Relationship between Economic Security and Self-Rated Health in Elderly Japanese Residents Living Alone

OBJECTIVES

The purpose of this study was to assess the relationship between economic security and self-rated health for elderly Japanese residents living alone.

DESIGN

A secondary analysis of a cross-sectional study.

SETTING

N City, H. Prefecture, Japan.

PARTICIPANTS

Survey questionnaires were distributed to 2,985 elderly residents living alone, aged ≥70 years, of which, 1,939 (65.0%) were returned and treated as valid responses.

MEASUREMENTS

The survey included questions about gender, age, number of years spent in N City, self-rated health, economic security, number of years spent living alone, reason for living alone, life satisfaction, cooking frequency, frequency of seeing a doctor, long-term care service usage, as well as whether they enjoyed their lives, participated in social organizations.

RESULTS

Of the respondents, 1,563 (80.6%) reported that they were economically secure, and 376 (19.4%) responded that they were insecure. The odds ratio predicting poor self-rated health for the economically insecure participants was significantly high (odds ratio: 3.19, 95%, Confidence Interval (CI): 2.53-4.02, and P < 0.001). Similarly, the adjusted odds ratio for poor self-rated health was significantly high for the economically insecure participants in multivariate analyses controlling for factors such as age, gender, cooking frequency, and social participation (adjusted odds ratio: 2.21, 95%, CI: 1.70-2.88, and P < 0.001). Furthermore, a similar trend was observed in stratified analyses based on gender and age groups.

CONCLUSION

Economic security predicted self-rated health independently of confounders, including social participation and cooking frequency, among the elderly Japanese living alone in communities.

Relationship between Breakfast Skipping and Obesity among Elderly: Cross-Sectional Analysis of the HEIJO-KYO Study

OBJECTIVE

Breakfast skipping is reported to be associated with obesity in children and younger populations; however, few studies report the association among elderly. The purpose of this study was to investigate the relationships between breakfast skipping and obesity prevalence among elderly.

DESIGN

Cross-sectional study.

SETTING

Community-dwelling elderly in Nara, Japan.

PARTICIPANTS

1052 elderly participants (mean age: 71.6 years).

MEASUREMENTS

Obesity and breakfast skipping were defined as body mass index of ≥25 kg/m2 and skipping breakfast one or more times per week, respectively.

RESULTS

Two hundred and seventy-two participants (25.9%) were classified as obese and forty-one (3.9%) were as breakfast skippers. Obesity prevalence was significantly higher in breakfast skippers than in breakfast eaters (43.9% vs. 25.1%, P = 0.007). In multivariable logistic regression analysis adjusted for potential confounders (age, sex and alcohol consumption), breakfast skippers showed significantly higher odds ratio (OR) for obesity than breakfast eaters (OR, 2.23; 95% confidence interval, 1.17-4.27; P = 0.015), which continued to be significant after further adjustment for socioeconomic status. In addition, breakfast skippers showed significantly lower daily potassium (P <0.001) and dietary fibre intakes (P = 0.001) and lower subjective physical activity (P = 0.035) than breakfast eaters.

CONCLUSIONS

Breakfast skipping was significantly associated with obesity among elderly. Poor diet quality and physical inactivity may be potential intermediators underlying the association between breakfast skipping and obesity.

Association of Serum Asymmetric Dimethylarginine With Muscle Strength and Gait Speed: A Cross-Sectional Study of the HEIJO-KYO Cohort

Muscle strength and gait speed are related with functional limitations and disabilities and also predict cardiovascular and all-cause mortality. Nitric oxide (NO) plays an important role in regulating physiological process in skeletal muscles; however, the association between serum asymmetric dimethylarginine (ADMA) level, an endogenous competitive inhibitor of NO synthesis, and physical performance has not yet been studied. We investigated the associations of serum ADMA level with muscle strength and usual gait speed in a cross-sectional study of 550 elderly individuals (mean age, 71.2 ± 6.6 years). Mean ADMA level was 0.45 ± 0.06 µmol/L; mean grip and quadriceps strengths were 27.7 ± 8.4 kg and 165.1 ± 81.6 Nm, respectively; and mean gait speed was 1.37 ± 0.30 m/s. In multivariate linear regression analysis adjusted for potential confounding factors (age, gender, body weight, smoking and drinking status, household income, hypertension, diabetes, renal function, and physical activity), higher serum ADMA level was significantly associated with lower grip and quadriceps strengths and slower gait speed (grip strength: β, -1.257; 95% confidence interval [CI], -1.990 to -0.525; p = 0.001; quadriceps strength: β, -11.730; 95% CI, -20.924 to -2.536; p = 0.012; gait speed: β, -0.065; 95% CI, -0.108 to -0.022; p = 0.003). Our findings indicate the significant association between serum ADMA level and physical performance among elderly individuals, which was independent of the important potential confounders. © 2015 American Society for Bone and Mineral Research.

Distribution and major sources of flavonoid intakes in the middle-aged Japanese women

We estimated the intake of individual flavonoids in a cross sectional study and clarified the major sources contributing to the flavonoid levels in the middle-aged Japanese women by a 24-h weighed dietary record study. The subjects included in the study were 516 free-living women. Each subject completed a 24-h weighed dietary record and received a health check-up. We used the Functional Food Factor database for estimating the intake of 5 major flavonoid intakes, i.e. flavan-3-ols, isoflavones, flavonols, flavanones and flavones. The mean intake of flavan-3-ols, isoflavones, flavonols, flavanones and flavones was 1277, 216, 58, 31 and 15 µmol/d, respectively. The richest source of flavan-3-ols was green tea. The 3 major food sources of isoflavone were the processed soy foods and those of flavonol were the onion, moroheiya (nalta jute) and Japanese radish leaves. Grapefruit and citrus fruit juices were the major sources of flavanones, and tsurumurasaki (malabar spinach), green pepper and grapefruit were the main sources of flavone. Furthermore, analysis of sub-samples from middle-aged Japanese women indicated that there may be an association between flavonoid intake and the levels of oxidized LDL, which might be related to the incidence of cardiovascular diseases.

Rapid identification of metallothionein isoforms in liver cytosol fraction by capillary zone electrophoresis using EDTA

Identification of metallothionein (MT) isoforms on capillary zone electrophoresis (CZE) analysis was studied using a linear polyacrylamide-coated capillary at pH 7.4 and EDTA. The CZE system was able to separate standard (purified and commercially available) MT specimens into their isoforms within 10 min. The peaks of MT-1 and MT-2 isoforms disappeared on addition of EDTA to the specimen, and the disappearance was shown to be time-dependent and dose-dependent, although the reason why the peaks decreased is still unclear. A heat-treated cytosol fraction prepared from Zn-injected mouse liver showed many major and minor peaks on CZE analysis. Two major peaks were identified to be MT-1 and MT-2, respectively, by co-injection with the purified MT isoforms. When EDTA was added to the cytosol fraction, the two major peaks, MT-1 and MT-2, and three other minor peaks disappeared time-dependently. Therefore, each MT isoform in the cytosol fraction can be identified by the addition of EDTA, also the peaks are identified by the corresponding migration times of purified MTs. Unknown substances like MT sub-isoforms may also be detected, although this question warrants clarification. From these results, it was concluded that the addition of EDTA is useful for identification of MT isoforms in cytosol fractions on CZE analysis.

Identification of metallothionein isoforms on capillary zone electrophoresis by adding anti-metallothionein antibody

The aim of this study was to identify metallothionein (MT) isoforms in mouse liver by using capillary zone electrophoresis (CZE). Purified MT-1 and MT-2 isoforms were completely separated by CZE using a polyacrylamide-coated tube at physiologic pH. There were two peaks in the cytosol fraction prepared from zinc-injected mouse liver, in which the migration times corresponded with those of purified MT-1 and MT-2 isoforms. When anti-MT monoclonal antibody was added with the purified MT-1 or MT-2 solution, the peaks decreased. Furthermore, the two peaks in the cytosol prepared from Zn-injected mouse liver decreased in a time-dependent manner from the electropherogram after the addition of the antibody. Therefore, those peaks were identified as MT-1 and MT-2 isoforms, respectively. In conclusion, the addition of anti-MT monoclonal antibody to the cytosol fraction of tissues is an effective method for identification of MT isoforms after separation using CZE.

Acute biological effects of intratracheally instilled titanium dioxide whiskers compared with nonfibrous titanium dioxide and amosite in rats

The dimensions of man-made mineral fiber whiskers are similar to those of some kinds of asbestos. Thus these mineral fibers raise the concern for potential health hazard for workers exposed in the occupational environments. This study was designed to define acute biological effects of intratracheally administered titanium dioxide whiskers (TO1) compared with nonfibrous titanium dioxide (TOP) and UICC amosite (Ams), and their relations to acute lung inflammation in rats. The observed geometric mean length (microm) and width (microm) and geometric standard deviation are: TO1(2.1[2.0], 0.14[1. 53]); Ams (4.3[3.3], 0.31[1.9]); and TOP (50 nm, 1-2 microm aggregates). Ten-week-old Wistar-Jcl male rats received a single tracheal injection of test materials at doses between 0.05 and 1.0 mg/rat. Control animals were injected with the same volume of saline. Lung tissue and bronchoalveolar lavage (BAL) fluid were collected from rats on days 1, 3, and 7 after administration. In the group injected with TO1, total protein, cytokine-induced neutrophil chemoattractant (CINC)/growth-regulated gene product (GRO), interleukin (IL) 1beta, and tumor necrosis factor (TNF) alpha increased on day 1. Subsequently, total elastolytic activity and fucose levels in BAL increased by day 3. All parameters, except for fucose in BAL, recovered to the normal levels. Animals in the Ams group showed increased total protein and CINC/GRO and decreased total elastolytic activity in a dose-dependent manner on day 1. The fucose level increased on day 3 in the Ams group. All parameters returned to their control levels on day 7. Animals in the TOP group did not show significant changes any of parameters during the experimental period. Gene expression of TNF-alpha and monocyte chemoattractant protein (MCP) 3 in the lung increased dose-dependently in the animals treated with the three materials. The mRNAs for eotaxin and MIP-1alpha were overexpressed in the lung of animals treated with Ams and TO1, while RANTES mRNA was overexpressed dose-dependently in the lung of animals treated with Ams on day 1. Onset of inflammatory response was more rapid in the Ams group than the TO1 group. Recovery of the fucose level in BAL was slower in the TO1 group than in the Ams group, though we observed similar histopathological changes in the lung of animals with TO1 or Ams. We conclude that whisker-induced acute biological effects in the lung may be related to the shape of the whiskers and not to their chemical composition or surface crystal structure, showing biological effects similar to those of UICC amosite.

Identification of metallothionein isoforms with capillary zone electrophoresis using a polyacrylamide-coated tube

Metallothionein (MT) isoforms from various liver tissues were separated with capillary zone electrophoresis (CZE) using a polyacrylamide-coated tube at neutral pH. The electrophoresis was performed on MT-1 and MT-2 purified from mouse, rat, rabbit and human livers. The retention times of mouse and rat MT-1 coincided, while the retention times of rabbit and human MT-1 were longer. The retention times of MT-2 purified from the four sources were the same. MT-1 and MT-2 separated more definitely with N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES)-Tris buffer (25 mM, pH 7.4) than with N-tris(hydroxymethyl)methyl-3-aminopropane sulfonic acid (TAPS)-Tris buffer (25 mM, pH 7.7) or with N-(2-acetamido)iminodiacetic acid (ADA)-Tris buffer (25 mM, pH 7.4). In addition, liver MT isoforms prepared from Zn- or Cd-administered mice could be separated.

Blocking effect of anti-mouse interleukin-6 monoclonal antibody and glucocorticoid receptor antagonist, RU38486, on metallothionein-inducing activity of serum from lipopolysaccharide-treated mice

Although there is much evidence to suggest that lipopolysaccharide (LPS)-induced elevation of hepatic metallothionein (MT) contents is mediated by cytokines, the presence of MT-inducing activity in the serum of LPS-treated animals has not been examined. It was found that serum from LPS-treated mice stimulated MT induction in a hepatoma cell culture. The MT-inducing activity in serum was highest 2 h after LPS injection. Tumor necrosis factor and interleukin (IL)-6 levels in the serum were highest 1 and 2 h, respectively, after LPS injection. Anti-mouse IL-6 monoclonal antibody neutralized MT-inducing activity in serum obtained from mice 2 h after LPS injection. The MT-inducing activity in serum was blocked by the glucocorticoid antagonist, RU38486. A similar requirement for glucocorticoid was also observed in an IL-6-stimulated culture. These results show that the LPS-induced elevation of hepatic MT is mediated by IL-6, and the expression of the stimulating activity of IL-6 is dependent on the presence of glucocorticoid.

Metallothionein in human seminal plasma

Metallothionein (MT) concentrations were measured in the seminal plasma of 4 fertile and 35 infertile men and in the hydrocele and spermatocele fluids. The relationship between MT content and sperm density, total number of sperm per ejaculate, sperm motility and abnormal form rates, leukocyte count and zinc levels in seminal plasma, as well as the relationship between MT and serum follicle-stimulating hormone, luteinizing hormone, testosterone, and prolactin were examined. MT was not detected in the hydrocele and spermatocele fluids. MT levels were related to zinc levels and to the leukocyte count in seminal plasma, but there was no correlation between MT and the other factors examined. This study supported previous findings that MT was secreted predominantly from the prostate and induced by inflammation of the prostate gland or seminal vesicles; the findings suggest that MT binds mainly to zinc and is one of the zinc-binding proteins in seminal plasma.

Metallothionein in developing human brain

Localization of metallothionein (MT) in the developing human brain was investigated by immunohistochemical techniques. Fetal brain at 21 weeks showed no MT expression. In 35-week-old fetuses, glial cells in the gray matter showed MT expression in the nucleus and perinuclear cytoplasm, but glial cells in the white matter showed MT not only in the nucleus and perinuclear cytoplasm but also in glial processes. At 40 weeks, glial cells in gray and white matter expressed immunoreactive MT in the nucleus, cytoplasm and glial processes. Blood vessels were positive for MT. In the infant brain, there were clear differences in glial cells between protoplasmic and fibrous astrocytes; their nuclei, cytoplasm and processes were positive for MT, but the MT-positive glial processes of protoplasmic astrocytes were fine. In the child, typical protoplasmic astrocytes in gray matter and fibrous astrocytes in white matter were observed and their nuclei, cytoplasm and glial processes were positive for MT. Pia mater and blood vessels expressed MT in infants and children.

Abnormal accumulation of copper-metallothionein in the liver and kidney of Long-Evans rats with a cinnamon-like coat color (LEC rats)

We determined the copper (Cu) and metallothionein (MT) concentrations in the liver and kidney supernatants of Long-Evans rats with a cinnamon-like coat color (LEC rats), and also measured the Cu and MT levels in the serum of these rats. Seven-week-old rats had abnormally high levels of both substances in the liver. The levels in the liver supernatant were over 80- and 16-fold higher, respectively, in LEC rats than in normal 7-week-old Wistar rats. LEC rats suffering from acute hepatitis or hepatoma had a much higher level of hepatic MT, but the Cu level was higher only in the liver of those with hepatoma. The serum levels of Cu and MT in LEC rats with acute hepatitis were more than 10-fold higher than those in normal LEC rats. These levels were decreased in the rats with chronic hepatitis or hepatoma. In the liver of LEC rats with hepatoma, the area of hepatocellular carcinoma and of noncancerous liver showed over twice higher Cu and MT levels than the area of cholangiofibrosis. The Sephadex G-75 elution profile from the liver supernatant of a normal LEC rat showed that the peak of Cu closely corresponded to that of MT recognized with anti-MT antiserum. The levels of Cu and MT in the kidney supernatant of LEC rats with acute hepatitis were more than 25-fold higher than in that of normal LEC rats. However, there were no marked increases in the levels in the kidney supernatant of LEC rats with chronic hepatitis or hepatoma.

Induction and subcellular localization of metallothionein in regenerating rat liver

A highly specific antiserum against rat liver metallothionein (MT) was raised in a Japanese white rabbit. Using this anti-MT antiserum, we found that MT was localized in the nuclei as well as in the cytoplasm of hepatocytes in newborn rats. Since it is known that these cells are growing actively, we suspected that there was a relationship between the localization of MT in cell nuclei and the cell proliferation. Therefore, the induction and subcellular localization of MT were examined in rat liver remaining after 70% removal. MT was induced in the remnant liver rapidly after the hepatectomy, its concentration being about 80-fold higher than that of the intact liver. Flow cytometric analysis revealed that MT was translocated into the nuclei from the cytoplasm of hepatocytes during liver regeneration after partial hepatectomy. The highest MT level in the nuclei was observed 24 h after hepatectomy. MT-stained positive nuclei were in S to G2M phases of the cell cycle of regenerating hepatocytes, and the nuclei in G1 phase were not stained with anti-MT antiserum. The increase in hepatic MT levels did not directly cause MT translocation into the nuclei. These results suggested that MT was a cell cycle-dependent, nuclear protein.

Localization of metallothionein in aged human brain

The localization of metallothionein (MT), a small molecular weight heavy metal binding protein in aged human brain, was investigated by immunohistochemical techniques. The amount of MT and heavy metals (Zn, Cu) were also assayed by radioimmunoassay and atomic absorption spectrophotometry, respectively. Immunohistochemically, MT was found in the pia mater, ependymal cells, protoplasmic astrocytes nand glial processes neuropil of the gray matter and fibrous astrocytes of the white matter of the telencephalon, whereas oligodendroglia and microglia did not show any positive immunostaining for MT. Cytoplasm, glial processes and some nuclei of protoplasmic and fibrous astrocytes showed strong MT immunostaining. Vascular feet and adventitia were also positive for MT immunostaining. Moreover, the pia mater, astrocytes and ependyma in the diencephalon, mesencephalon, pons, medulla oblongata and spinal cord showed the same positive immunostaining for MT as the telencephalon. In the cerebellum, Bergmann's glia, protoplasmic astrocytes of the granular layer and fibrous astrocytes of the white matter showed strongly positive immunostaining for MT. According to the radioimmunoassay, the amount of MT in the brain was relatively high at about 39.3 +/- 9.5 micrograms/g wet weight; of the heavy metals in the brain, zinc and copper were detected.

Copper-metallothionein distribution in the liver of Long-Evans cinnamon rats: studies on immunohistochemical staining, metal determination, gel filtration and electron spin resonance spectroscopy

Distribution of metallothionein (MT) and copper ion (Cu) in the liver of LEC (Long-Evans Cinnamon) rats was investigated to examine the relationship between Cu-MT induction and the development of hepatitis followed by hepatocellular carcinomas. Immunohistochemical studies on MT in the liver of LEC rats indicated that MT is accumulated in nuclei and cytosols. Both MT and Cu, estimated by radioimmunoassay and flameless atomic absorption spectrometry, respectively, in subcellular fractions of the liver were found to be concentrated highest in cytosols, followed by nuclei, mitochondria and microsomal fractions. Gel-filtration (Sephadex G-75) studies demonstrated that MT is induced as the Cu-MT form. Furthermore, the Cu-MT fragment purified by the gel-filtration contains the Cu(I)-MT form, as demonstrated by ESR (electron spin resonance) measurements at 77K. These results will be important for understanding the development of hepatitis in LEC rats.

Analysis of mammalian metallothionein isoforms by high-resolution SDS-gel electrophoresis

Metallothioneins (MTs) are cysteine-rich heavy metal-binding proteins, whose possible functions are thought to be the protection against toxic metals as well as the regulation of essential metals. It is known that there are several MT isoforms, but the biological roles of the individual isoforms have not been elucidated. To facilitate the functional analysis of these isoforms, we improved an analytical method of MTs developed previously, which is based on a denaturing gel electrophoresis of chemically modified MTs. The established technique makes it possible not only to separate MT isoforms with a high resolution, but to estimate the levels of the individual isoforms by analyzing directly crude cell extracts. By this method, six MT isoforms were identified in the extracts of Cd-exposed human cells. It was also revealed that there is an apparent heterogeneity of the rat liver MT; five isoforms were identified in the liver extracts of Cd-injected rats. The present method will be useful in the functional analysis of the MT isoforms, as well as in a variety of aspects of the MT studies.

Induction of metallothionein by CdCl2 administration in rat prostate

Metallothionein (MT) induction in the rat prostate gland was investigated by means of cadmium chloride administration. Ten-week-old male Wistar rats housed with cadmium free food were divided into three groups of six rats each and castrated. After seven days, 1 mg of testosterone propionate per rat was injected subcutaneously once a day until the end of the experiment. After three weeks, rats were injected daily for six days with a physiological saline, 0.3 mg/kg CdCl2, and 0.9 mg/kg CdCl2. MT concentration of the ventral and dorsal lobes was significantly increased in the three groups in proportion to the dose of CdCl2. MT content of the lateral lobe in three groups was also increased, but was not significantly different. Immunohistochemically, MT was induced mainly in the ventral lobe in the basal cells, and in the lateral and dorsal lobes in the epithelial cells. The weights of the prostatic lobes were similar in the three groups, and no histological change was identified. These results suggested that MT in the prostate was induced by cadmium administration, and that it may prevent cellular damage from harmful metals.

Copper-metallothionein induction in the liver of LEC rats

Recently, copper (Cu) was found to be unusually accumulated, suggesting the induction of metallothionein (MT) in the liver of LEC rats (Long-Evans rats with a cinnamon-like coat color), which develop spontaneous jaundice with hereditary hepatitis. Thus, the direct relationship between the unusual Cu accumulation and the induction of Cu-MT was investigated by giving LEC rats Cu-overloaded or Cu-deficient diets. Results based on the determinations of Cu and MT levels in several organs, as well as the gel-filtration profiles of the cytosols of liver homogenates, showed that dietary Cu induced Cu-MT and development of hepatic injury associated with jaundice.

Immunohistochemical study of metallothionein in human seminal vesicles

Metallothionein (MT) in human seminal vesicles was examined by use of the avidin-biotin-peroxidase complex method. Tissues were obtained from six patients with prostate cancer who underwent luteinizing hormone-releasing hormone agonist or estrogen therapy before radical prostatectomy (group 1) and from 18 patients without hormone therapy (three with prostate cancer, three with urinary bladder cancer, and twelve free of urogenital diseases at autopsy) (group 2). MT was localized in the cytoplasm and nuclei of epithelial cells and also in secretory products in the lumen. The epithelial cells lacked uniformity in immunoreaction; for instance, some stained strongly while others stained weakly. Smooth muscle cells were found to have positive immunoreaction, but other connective tissues had no immunoreaction. The number of strongly positive cells in group 1 was fewer than that in group 2 (not significant), and the secretory products in group 1 had no immunoreaction. These results suggest that MT is synthesized in the epithelial cells of the seminal vesicles and secreted into the fluids, and that the synthesis of MT is suppressed by the hormone therapy.

Unusual accumulation of copper related to induction of metallothionein in the liver of LEC rats

Copper (Cu), iron (Fe), zinc (Zn) and manganese (Mn) levels in organs of LEC rats (Long-Evans rats with a cinnamon-like coat color), which develop spontaneous jaundice with hereditary hepatitis, were determined by instrumental neutron activation analysis method. Unusual accumulations of Cu in the liver of LEC rats were found, depending on the age of the animals, the metal concentration being more than approximately 20-40 times those of normal LEA rats (Long-Evans rats with an agouti coat color). Fe and Zn were also accumulated, in addition to Cu, significantly in the LEC rats. The unusual Cu accumulations in the liver of LEC rats were associated with the induction of metallothionein, estimated by radioimmunoassay method, in the liver of LEC rats, rather than that of superoxide dismutase, estimated by electron spin resonance -spin trapping method. These findings suggest that the unusual Cu accumulation in LEC rats is involved in the development of jaundice, hepatic injury and hepatocellular carcinoma.

Metallothionein of prostatic tissues and fluids in rats and humans

We analyzed metallothionein (MT) in rat prostates by gel filtration and radioimmunoassay. The concentration of MT in the prostate, kidney and liver of cadmium-induced rats was measured. The concentration of MT was also measured in normal prostate, benign prostatic hyperplasia, prostate cancer and the prostatic fluids from various prostatic diseases in humans. MT was detected in rat prostates by gel filtration and radioimmunoassay. The concentration of MT (micrograms/g wet tissue) was 0.3 +/- 0.1 (S.D.) in the ventral lobe, 30.4 +/- 24.0 in the lateral lobe, 5.2 +/- 0.9 in the dorsal lobe, 25.0 +/- 6.4 in the kidney and 2.0 +/- 1.5 in the liver of the rat control group. Change in MT content in CdCl2-induced organs increased quantitatively with the dose administered. The concentration of MT (micrograms/g wet tissue) in human prostate was 99.3 +/- 121.8 in the peripheral zone (PZ), 12.0 +/- 8.5 in the preprostatic region (PR), 7.3 +/- 3.1 in the central zone (CZ), 17.5 +/- 15.0 in benign hyperplastic nodules (A) and 4.2 +/- 0.5 in cancer tissue (CA). MT concentration in PZ was very high and that of CA, low (p less than 0.05). MT concentration in prostatic fluids (ng/mg protein) was 11.5 +/- 5.7 in normal patients, 3.8 +/- 2.3 in acute prostatitis, 6.5 +/- 3.7 in chronic prostatitis with pyuria, 39.6 +/- 3.9 in chronic prostatitis without pyuria and 16.9 +/- 3.0 in benign prostatic hyperplasia. We concluded that MT in the prostate is induced by heavy metals and secreted into prostatic fluid. Possibly, it is a marker of secretory function in the prostate.

Localization of metallothionein in nuclei of growing primary cultured adult rat hepatocytes

In primary cultured adult rat hepatocytes stimulated by epidermal growth factor and insulin, dramatic changes in the subcellular distribution of metallothionein were clarified by indirect immunofluorescence using antisera specific for this protein. Metallothionein was detected only in the cytoplasm of cultured hepatocytes in the G0 and G1 phases, but was concentrated in the cell nuclei in the early S phase. The strongest staining pattern in the nuclei was observed 12 h after stimulation. Subsequently, the intensity of metallothionein staining in the nuclei decreased. These results suggest that primary cultured hepatocytes are suitable for examining the relation between subcellular localization of metallothionein and cell growth.

Cd2+-induced synthesis of metallothionein in HeLa cells

HeLa cells synthesize metallothioneins in response to Cd2+. The kinetics of thionein (apoprotein of metallothionein) synthesis was studied by pulse-labelling the cells with [35S]cysteine and measuring relative amounts of the labelled thioneins separated by electrophoresis. Thionein synthesis rapidly increases in the first 6-8 h after exposure to 0.5 micrograms of Cd2+/ml, and begins to decrease in a few hours after reaching the maximum. However, the rate of synthesis never returns to the basal value at least in 30 h after Cd2+ exposure; instead, the second increase in thionein synthesis occurs at 16-18 h. A possible regulatory mechanism of thionein synthesis is discussed from these results, together with the data on intracellular accumulation and subcellular distribution of 109Cd2+. The initial increase of thionein synthesis is accompanied by an increase of mRNA coding for thioneins (MT-mRNA). The induction of MT-mRNA is sensitive to Actinomycin D, but not to cycloheximide, suggesting transcriptional regulation without any mediating protein synthesis. Two thionein isomers are coded for by mRNA molecules of almost the same size, which is similar to that of hepatic MT-mRNA of mouse and rat.

Evidence for more than two metallothionein isoforms in primates

Two isoforms of metallothionein (MT) have in general been identified in mammalian cells. We have analyzed Cd2+-induced MTs of primate origin and demonstrated the presence of more than two isoforms. Four low molecular weight Cd2+-binding proteins were separated from Cd2+-exposed HeLa cells by gel filtration and ion-exchange chromatography and identified as MTs by amino acid analysis. These were carboxymethylated and analyzed by electrophoresis under denaturing conditions. Three of these proteins were found to be distinct molecules. We also analyzed hepatic MTs from Cd2+-exposed rhesus monkeys, which have previously been partially separated. In this case, five distinct isomers were detected.

Bone and kidney lesions in experimental cadmium intoxication

Young male rats were fed a diet containing cadmium (0, 10, 30, 100, and 300 ppm) so as to morphologically investigate the relationship between bone and kidney lesions caused by experimental cadmium intoxication. In the early stage of the experiment, before the occurrence of kidney lesions, ingeted cadmium caused osteoporotic changes in bone. In later stages, slight pathologic changes in the kdidney occurred in association with urinary excretion of cadmium. However, there was no evidence of osteomalacic change in bone during the 12-week experimental period. These findings suggest that cadmium may act primarily on bone, rather than secondarily through disturbances of the kidneys, which have some protective ability against cadmium intoxication in the early stage of ingestion of the metal.

Tyrosinase as glycoprotein

Purified tyrosinase T1 was incubated with neuraminidase. The catalytic activity of tyrosinase was essentially retained, after this treatment. The tyrosinase band (Dopa stained) was transformed into a new less anodic form, similar to tyrosinase T2, on disc electrophoresis. The band of protein was also converted to the same position as the Dopa stained. The other hand, the only one PAS stained band of native tyrosinase T1 was splitted into the three slower-moving bands. One was consistent with Dopa and protein stained bands. The other two were much more slower than the former band and completely free of peptide and enzymic activity. The PAS-densitometric value of native tyrosinase T1 was almost equal to those of three separated bands in total. These results suggest that mammalian tyrosinase is a kind of glycoprotein.