Since animals are under constant threat of starvation, storage of energy sources inside the body is essential for various activities. Therefore, animals exhibit highly sophisticated mechanisms for storing energy inside their bodies in adipose tissue. However, in humans it has been clarified that fat cell (adipocyte, which comprises adipose tissues) dif-ferentiation and the extent of subsequent fat accumulation (hypertrophy of cells) are closely associated with the occurrence and advancement of various diseases resulting from obesity. Moreover, progress in biochemical studies with respect to adipocyte in recent years has rap-idly clarified new functions and differentiation mechanisms of adipocytes. Interesting points, in particular, are the function of white adipocytes as “secreting cells” and the molec-ular mechanism of adipocyte differentiation via the nuclear receptors. Consequently, adi-pose tissue is being targeted to prevent or treat many common diseases. This paper summa-rizes recent knowledge on characteristics, differentiation and proliferation of adipocytes and the mechanisms by which adipocytes are regulated.

View full abstract

In 1909 Moreschi observed that tumors transplanted into underfed mice did not grow as well as those transplanted into mice fed ad libitum. His finding stimulated a decade of research which showed that caloric restriction also affected negatively the growth of spontaneous tumors. Between 1920 and 1940 little work was done in this area, possibly because of limiting methodology. In the 1940s the laboratories of Tannenbaum (Chicago) and Baumann (Wisconsin) were able to design studies using defined diets and showed that the observed effect was due to caloric content of the diet independently of the source of calo-ries. After another active decade research activity in the calorie-cancer area declined until it was reborn in the 1980s. By the 1980s knowledge of physiology and molecular biology had advanced enough to allow investigators to probe mechanisms underlying the calorie-cancer phenomenon. We now know that caloric expenditure (as work or exercise) will lead to re-duced risk. Energy restriction enhances DNA repair and moderates oxidative damage to DNA. Energy restriction reduces oncogene expression as well. Over a half century ago, Boutwell noted that energy restriction in female rats resulted in adrenal hypertrophy and reduced weight of ovaries and uterus. He suggested that energy restriction resulted in “pseudohypophysectomy.” We now know that adrenalectomy can negate the effects of caloric restriction. Caloric restriction also affects insulin metabolism and may influence gene expression. These recent observations should help us understand some of the basic mechanisms involved in establishment and proliferation of tumors.

View full abstract

To investigate the vitamin status of young Japanese women, dietary intakes of vitamin A, E, C, B₁, B₂, B₆, B₁2, niacin, folate, and β-carotene were assessed by a 3-d weighed food record in 150 female students aged 21-22. Whole blood levels of vitamin B₁, B₂, and nicotinic acid, and serum levels of retinol, α-tocopherol, vitamin B₆, and β-carotene were determined by HPLC. Vitamin B₁2 and folate in serum were measured by chemilumi-nescence immunoassay, and serum vitamin C was done by dinitrophenylhydrazine method. When the 6th revision RDAs for the Japanese (physical activity level I) were applied, 46.7% of the females showed sufficient intake for vitamin A, 28.7% for E, 80.7% for B₁, 92.7% for B₂, 54.7% for B₆, 99.3% for niacin, 76.0% for B₁2, 34.0% for folate, and 54.0% for C. Fifty-nine percent of total vitamin A (μgRE) intakes were derived from β-carotene. The mean ±SD of energy intakes was low, 1, 572±315 kcal. Significant correlations among intakes of en-ergy and all these vitamins were found. Serum folate and ascorbic acid levels in the females with corresponding vitamin intakes above the RDA were significantly higher than in those with intakes below the RDA. There were significant correlations between blood vitamin lev-els and vitamin intakes in vitamin B₁2 (r=0.185), folate (r=0.255), vitamin C (r=0.272), and β-carotene (r=0.319). Mean blood levels of folate, ascorbic acid, vitamin B₂, B₁2, and β-carotene were higher in the highest quartile of intake than in the lowest. The 95% confi-dence intervals of blood vitamin levels obtained from the females with sufficient vitamin in-takes were nearly equal to those obtained from all subjects. Only a few females (0.7-4.7%) had their blood vitamin levels below the lower limits. Serum α-tocopherol levels were signif-icantly correlated with serum levels of retinol, β-carotene, and vitamin C. This data sug-gested that young women should increase suitable dietary food intakes in order to maintain good status of vitamin. Moreover, sufficient amount of physical activity would be expected for prevention of excessive energy intake.

View full abstract

Peroxidatively modified low-density lipoprotein (LDL) may contribute to ath-erosclerotic processes; therefore, protecting LDL. against peroxidation may thus reduce or re-tard the progression of atherosclerosis. We have evaluated the protective effects of ascorbic acid on copper-catalyzed LDL peroxidative modification. The protective effects of ascorbic acid on copper-catalyzed LDL peroxidative modification were examined by measurement of concentration of lipid hydroperoxides in LDL and by the provision of LDL cholesterol to lym-phocytes via LDL receptor-mediated pathway. The measurement of concentration of lipid hydroperoxides in LDL showed that ascorbic acid inhibited peroxidative modification of LDL. Also, ascorbic acid preserved the ability of LDL to be recognized by LDL receptors in periph-eral blood lymphocytes to the same extent as native LDL. These findings indicate that ascor-bic acid may protect LDL against peroxidative modification, maintaining its ability to act as a ligand for LDL receptors in vivo.

View full abstract

The purpose of this study is to examine the carotenoid effects on lung tumori-genesis induced by intratracheal instillation of diesel exhaust particles (DEP) into mice weekly for 20 wk. It was suggested that active oxygen radicals might play an important role in DEP-induced lung tumorigenesis. Mice were divided to 4 groups of diet containing 0.02% of palm oil carotene, 0.02% of β-carotene, or no carotenoid with or without DEP. The BF group (4% fat) and the HF group (16% fat) were prepared for each diet group. The experi-mental period was 12 mo. By the administration of palm oil carotene, neither adenocarci-noma nor adenoma was found in the BF group. In the HF group with palm oil carotene, no adenocarcinoma was observed, and adenoma was reduced. Adenoma in the HF group was not greatly reduced by β-carotene, but rather increased in the BF group. No adenocarci-noma was found in either the BF or the HF groups with β-carotene. The 8-hydroxy-deoxyguanosine/deoxyguanosine ratio in palm carotene groups was lower than in the other groups, while that in β-carotene groups was not. From these results, palm oil carotene was suggested to prevent lung tumorigenesis by its protective effect on DNA from active oxygen. Beta-carotene was supposed to have different effects from palm oil carotene on lung tumori-genesis. Besides the chemopreventive effect, the growth of mice was inhibited by the admin-istration of palm oil carotene. Further studies are necessary to elucidate the mechanisms of carotenoid effects.

View full abstract

The present experiment was conducted to study the effects of dietary vitamin E on plasma corticosterone (CTC) concentration and adrenal steroid syntheses in chickens treated with adrenocorticotropic hormone (ACTH). Chickens were divided into ACTH (-) and ACTH (+) groups, and each group was further divided into three subgroups adminis-tered with vitamin E (500 or 5, 000 mg/kg diet) and without the vitamin. Vitamin E (DL-α-tocopheryl acetate) was mixed with the basal diet at levels of 500 and 5, 000 mg/kg and fed for 6 d. ACTH (20 IU/kg body weight) was given daily by intraperitoneal injection for 5 d. α-Tocopherol levels in the plasma and adrenal gland were markedly elevated by vitamin E feeding, and the level of adrenal free cholesterol (CHOL), which is used for steroid synthesis, was significantly decreased by vitamin E feeding in a dose-dependent manner. However, the level of adrenal CHOL ester was unchanged by any treatment. The elevations of preg-nenolone, progesterone and CTC levels in the adrenal gland of chickens with ACTH treat-ment were decreased by vitamin E administration. The elevation of plasma CTC concentra-tion in the ACTH (+) group was dramatically decreased by vitamin E administration, while that concentration was not influenced by the vitamin administration in the ACTH (-) group. These findings indicate that vitamin E suppresses the elevation of the plasma CTC concentration due to ACTH in chickens, possibly by inhibiting the conversion of CHOL ester to free CHOL in the adrenal gland.

View full abstract

Lack of adequate food and in particular high quality protein, is one of the causes of malnutrition in children which could result in retarded growth. Iron deficiency is common in populations where protein sources are of vegetable origin; however in northern Mexico where the bean consumption is high, anemia is not a problem. The primary staples in the Mexican diet are corn tortillas and beans. The objective of this study was to evaluate the anthropometric condition of children 4-6 years old living in the city of Oaxaca, Oaxaca, Mexico and to determine the prevalence of anemia. Mean Z scores for children 4-6 years old living in poor conditions in the city of Oaxaca, Oaxaca, Mexico showed significant differ-ences between socioeconomic groups (p<0.002) for height/age (H/A) and weight/age (W/A) (p<0.001) after adjusting for age and sex. Weight/height (W/H) was not different (p<0.30). By using the Waterlow classification system, 28.8% of the pre-school children of this study were stunted and only 0.9% were classified as wasted. There were no children that presented both stunting and wasting. Iron deficiency was very prevalent in both boys and girls, ranging from 56-79% depending on the indicator used. When classified by the combination of serum ferritin, % transferrin saturation and hemoglobin values, 23.7% of the children were classified as anemic, 11.9% in a state of iron deficiency and 13.6% with low iron reserves.

View full abstract

The details of calcium flux during growth were examined in female rats. Twenty-eight 53-d-old rats were equally divided into 4 groups. Rats were given a purified diet (0.5% Ca and 0.35 % Pi) throughout the experiment. Calcium balance and ⁴⁵Ca kinetics studies using an open two-compartment model were performed over a 3-d period when rats were 60 (control), 74, 88 and 116 d old. A simple calcium balance study, using the last group, was carried out at the age of 102 d. Compared with the control group, true intestinal calcium absorption was significantly increased at 74 d, but then decreased in a time-de-pendent manner up to 116 d. The apparent intestinal calcium absorption began to decrease at 88 d, and decreased further with age. An increase in urinary calcium output was ob-served at 74 and 88 d in phase with calcium excretion into the intestine, and both variables returned to the control level at 116 d. Calcium into bone was decreased at 74 and 116 d. Calcium from bone similarly changed with V_o⁺ at 74 d; however the highest value was ob-served at 88 d. Thereafter, V_o^- reached the control level at 116 d. Calcium balance rapidly decreased at 88, 102 and 116 d, but still remained positive. Calcium intake remained steady until 102 d, but was significantly decreased at the end of the experiment. The changes in calcium flux with age can be summarized as follows: 1) bone turnover decreased, calcium excretion into the urine and feces began to increase, and true intestinal calcium absorption increased, 2) apparent intestinal calcium absorption decreased, while calcium from bone and calcium excretion into the urine and feces increased, and 3) calcium intake and cal-cium into bone decreased.

View full abstract

We have previously reported that rats with diabetes induced by injecting streptozotocin into neonates showed remarkably lower blood glucose, urine volume, and glucosuria after administration of Maitake (Grifola frondosa). In the present study, we investi-gated the effects of Maitake on insulin concentration, organ weight, serum composition, and islets of Langerhans in streptozotocin-induced diabetic rats using the same method. The diabetic rats were produced by injecting 80 mg/kg B.W. streptozotocin into 2-d-old neonates. From the age of 9 wk, the rats were given experimental diets for 100 d. The dia-betes and control groups were given either diets containing 20% Maitake (DM and CM groups) or control diets (D and C groups). During administration of the experimental diets, we measured body weight, food intake, amount of feces, and serum insulin concentration at glucose loading. The glucose tolerance test was performed at the 10th week after the start of the experimental diets. The D group had an initial fasting blood glucose of 225±49 mg/dL, and a maximum blood glucose of 419±55 mg/dL at 60 min. In the DM group, however, the initial fasting blood glucose was 170±23 mg/dL, and the maximum blood glucose was 250±41 mg/dL at 15 min. Both values were markedly lower than those in the D group (p<0.05). The insulin concentration at 15 min. after glucose loading in the DM group was 41±16 μU/mL, which was significantly higher than that in the D group (15±7 μU/mL) (p<0.05). After the 100-d experimental period, blood samples were collected. The fruc-tosamine level was significantly lower in the DM group (152±21 mmol/L) than in the D group (185±13mmol/L). The concentration of 1.5-A.G. (1.5-anhydro glucitol) was signifi-cantly higher in the DM group (9.33±2.42, μg/mL) than in the D group (1.33±0.52 μg/mL). Observation of insulin antibody stain in the Langerhans cells of the pancreas using ABC method showed a decrease insulin antibody stain in the D group. The cells of the DM group were stained more darkly than those of the D group. From these results, we pos-tulated that the bioactive substances present in Maitake can ameliorate the symptoms of di-abetes.

View full abstract

In order to have basic data for dietary preventive measures against some vas-cular diseases caused by disorder of lipid metabolism, food intake and lipid status were inves-tigated in three Vietnamese populations with different per capita income levels. Totally, 299 people aged over 18 were involved in this study. Among them, 98 subjects were selected from one commune with low income, 100 and 101 subjects from two urban areas with medium and high income respectively. Food intake was assessed by 24-h recall method and lipid status was evaluated by measuring serum concentration of triglyceride, total choles-terol and its subfractions. The results showed that food consumption, dietary habits and lipid status varied with income levels. In general, diet was still unbalanced in all three groups, and low in fat and protein. In the rural, fat and protein intakes were lower than in the urban. The high prevalence of low serum cholesterol was observed in all three groups, the highest in the rural (45.3%) and the lowest in the urban (11.2%). On the contrary, the prevalence of high serum cholesterol was the lowest in the rural (2%) and the highest in the urban (16%). From these data, it is suggested that the majority of the Vietnamese might be vulnerable to some vascular diseases such as stroke if the situation of low fat intake and low serum cholesterol is not a problem of concern.

View full abstract

Arachidonic acid (20:4 n-6) and its metabolic products, such as prosta-glandins and leukotrienes, have been known to be associated with skin inflammatory reac-tions. However, the mechanism of the competitive incorporation of 20:4 n-6 into ke-ratinocytes among polyunsaturated fatty acids (PUFAs) remains uncertain. To investigate the relationship between the molecular structure of PUFAs and the rate of incorporation of PUFAs into cells, a fetal rat skin keratinocyte (FRSK) cell line was used. The cells were incu-bated for 24 h with any two of the following arachidonic acid analogs: mead acid (20:3 n-9), dihomo-γ-linolenic acid (20:3 n-6), 11, 14, 17-cis-eicosatrienoic acid (20:3 n-3), arachi-donic acid (20:4 n-6), eicosapentaenoic acid (20:5 n-3) and 5, 8, 11, 14-cis-nonadecate-traenoic acid (19:4 n-5), at the ratio of 1:0, 0.5:0.5, or 0:1; and their incorporation into lipid was measured by capillary gas-liquid chromatography. The experiments indicated that 20:3 n-6 was preferentially incorporated into phospholipids of FRSK rather than 20:3 n-9 or 20:3 n-3, and 19:4 n-5 as well as 20:4 n-6 was preferentially incorporated into total cel-lular lipid and phospholipids rather than 20:3 n-9 or 20:5 n-3. When two PUFAs were added simultaneously to the medium, 19:4 n-5 most effectively reduced the competitive in-corporation of 20:4 n-6 into phospholipids. These results suggest that keratinocytes dis-criminate 20:4 n-6 from other arachidonic acid analogs by its double bond positions from the carboxyl group.

View full abstract

Onion is a major source of flavonoids and is cooked in various ways in the world. The major flavonoids in onion are two quercetin glycosides, quercetin 4'-O-β-gluco-side (Q4'G) and quercetin 3, 4'-Oβ-diglucosides (Q3, 4'G), which are recognized as bioac-tive substances that are good for our health. We have investigated the effect of cooking pro-cedures on the content of antioxidants. We selected quercetin conjugates, total phenol com-pounds, and ascorbic acid to estimate the amount of flavonoid ingestion from onion. We ex-amined the following cooking methods; boiling, frying with oil and butter, and microwave cooking. Various cooking methods do not consider the degradation of quercetin conjugates when cooking onion. Microwave cooking without water better retains flavonoids and ascor-bic acid. Frying does not affect flavonoid intake. The boiling of onion leads to about 30% loss of quercetin glycosides, which transfers to the boiling water. At that time, the effect of addi-tives on the quercetin conjugates is different according to the compounds. The hydrolysis of quercetin glycosides for daily cooking might occur with the addition of seasonings such as glutamic acid. Additional ferrous ions accelerated the loss of flavonoids.

View full abstract

Malnutrition, particularly protein undernutrition, contributes to the occur-rence of osteoporotic fracture by lowering bone mass. In this study, the effects of dietary pro-tein on bone mineral density and body weight in protein undernutrition were compared be-tween gelatin and milk casein. When mice were fed for 10 wk with a low protein diet con-taining 10% casein or 6% casein+4% gelatin, there was no significant difference in the final body weight between the 6% casein+4% gelatin group and the 10% casein group. In con-trast, bone mineral content and bone mineral density of the femur were significantly higher in the 6% casein+4% gelatin group than in the 10% casein group. Bone mineral content and bone mineral density did not differ significantly in 14% protein groups between 14% casein and 6% casein+8% gelatin. These results suggest that gelatin has differential effects on bone mineral density and body weight in protein undernutrition.

View full abstract

Leptin is a protein that is synthesized and secreted from adipose tissue. We ex-amined the changes in serum leptin level during the menstrual cycle in 5 normal and 5 obese Japanese women, and compared the data with those of serum estradiol (E2) and prog-esterone (P4) concentrations. Serum leptin levels were highly correlated with body mass index (BMI) and percent body fat, being higher in the obese group than in the normal group. In the obese group, serum leptin level increased in the luteal phase in parallel with the rise in the serum E2 level. In the normal group, however, there was no significant change in serum level during the menstrual cycle. These results suggested that the serum leptin levels were influenced by the phase of menstrual cycle, probably through the action of E2, in different ways for obese and non-obese women.

View full abstract