Morphology and rheology of an immiscible polymer blend subjected to a step electric field under shear flow

We have investigated the structural change of an immiscible polymer blend in shear flow when subjected to a step electric field. During the process three-dimensional images were successfully constructed with a confocal scanning laser microscope and at the same time the transient shear stress was also measured. The interface tensor was calculated from the images. Several factors are incorporated into the shear stress, such as the bulk viscosity, the interfacial tension and the Maxwell stress. We performed an experiment to separate the Maxwell stress from the total shear stress. The results are discussed in terms of the interface tensor.

Changes of ROS during a two-day ultra-marathon race

To assess oxidative stress (OS) induced by endurance exercise, concentrations of serum reactive oxygen species (ROS) were determined in 70 Japanese male amateur runners completing a two-day ultra-marathon race. Serum ROS levels were analyzed at three time points: before the race (baseline), after the 1st day race (mid-race), and after the 2nd day race (goal) (post-race). The means (SE) of ROS were 151.4(3.7) (U. CARR.), 168.7(4.4), and 156.8(4.4), respectively. Significant positive trends were noted between age and serum ROS concentrations at the three race points (p<0.05 for all). After adjusting for age, BMI and average monthly running distance, the baseline serum ROS concentrations were positively associated with completion times of the first-day race, in particular (p<0.05), suggesting that the concentrations may predict physical performance. The ROS production increased at mid-race (p<0.05), but the levels returned to baseline levels at post-race, indicating that an antioxidant defense system may develop post-race to reduce OS.

Increases in body mass index, even within non-obese levels, raise the risk for Type 2 diabetes mellitus: a follow-up study in a Japanese population

AIMS

Obesity, the strongest risk factor for Type 2 diabetes mellitus, is less prevalent in Japanese than in other populations. We investigated the effects of body mass index (BMI, kg/m(2)) on the incidence of diabetes mellitus in a Japanese population.

METHODS

A follow-up study in 16 829 men and 8370 women who were apparently healthy at baseline (age 30-59 years, BMI 14.9-43.2 kg/m(2)). Incident diabetes mellitus was identified by 'fasting serum glucose > or = 7.00 mmol/l (126 mg/dl)' and/or 'under medical treatment for diabetes mellitus'. Hazard ratio, as an index for risk ratio, for incident diabetes mellitus according to BMI was estimated using Cox's proportional hazard models. Baseline age, smoking, drinking, exercise and education were computed as confounders.

RESULTS

During mean follow-up periods of 7.4 years for men and 7.1 years for women, 869 men and 224 women had incident diabetes mellitus. Although the subjects were averagely non-obese [mean (sd) BMI 23.1 (2.6) kg/m(2) for men, 22.3 (2.7) kg/m(2) for women], hazard ratio for incident diabetes mellitus increased in parallel with increases in BMI. Multivariate-adjusted hazard ratios (95% confidence intervals) for increases in BMI of 1 kg/m(2) were 1.26 (1.24, 1.29) for men and 1.24 (1.20, 1.29) for women.

CONCLUSION

BMI, even within the non-obese level, is a dose-dependent risk factor for diabetes mellitus in middle-aged Japanese. Increases in BMI of 1 kg/m(2) (= body-weight gain of 2.4-2.9 kg) may raise the risk by about 25%.

Spinal epidural metastasis from pineal germinoma

A 16-year-old boy first presented with a pineal tumour identified by neuroimaging but without positive serum or cerebrospinal fluid markers. The tumour disappeared after 50 Gy cranial irradiation. One year later he returned with spinal epidural metastasis from the pineal germinoma and required emergency surgery. Intraoperative findings showed that the spinal tumour had originated from cerebrospinal fluid dissemination and had passed through the spinal nerve sleeve. The pathologic diagnosis of the tumour was of a pure germinoma metastasis. An epidural tumour frequently requires emergency diagnosis and treatment. Attention should be paid to the possibility of this rare but serious clinical situation caused by a metastasis from a pineal germinoma.

Discrepancies in dietary intakes and plasma concentrations of fatty acids according to age among Japanese female dietitians

OBJECTIVE

To clarify the influences of age on dietary intakes and plasma concentrations of fatty acids (FAs) in Japanese female dietitians.

SUBJECTS AND METHODS

In autumn 1996, we estimated dietary FA intakes based on 7 day weighed diet records and analyzed plasma FA concentrations in 79 healthy Japanese female dietitians, and investigated their relationships with age, dividing into three age groups (young (32-42 y), middle-aged (43-50 y) and elderly (51-66 y)).

RESULTS

Dietary intakes of total FA, saturated FAs, monounsaturated FAs, n-3 polyunsaturated FAs (PUFAs) and alpha-linolenic acid (18:3n-3) were significantly highest in the middle-aged group, and lowest in the elderly. Similar trends were observed for dietary intakes of n-6 PUFAs and linoleic acid (18:2n-6), but there were no differences with regard to eicosapentaenoic acid (EPA; 20:5n-3), docosahexaenoic acid (DHA; 22:6n-3) and n-3 highly unsaturated FAs (HUFAs=EPA+22:5n-3+DHA). On the other hand, plasma concentrations of all FAs except for arachidonic acid (20:4n-6) demonstrated positive correlations with age. Moreover, plasma concentrations of EPA in all age groups, DHA in the elderly and n-3 HUFAs in the middle-aged and the elderly were all positively correlated with dietary intakes.

CONCLUSIONS

We should take into account the influence of age on dietary habit and lipid metabolism when interpreting associations between dietary FA intakes and plasma FA concentrations.

Perturbation transfer from the front to rear surface of laser-irradiated targets

We present experimental results on the perturbation transfer of laser irradiated planar foils. Perturbed polystyrene foils were irradiated directly by laser at intensity of 6 x 10(13) W/cm(2). We measured perturbations on the foils by side-on x-ray backlighting technique. Perturbations on the rear surface due to the rippled shock front were observed just after the shock breakout. We also observed feed-through of perturbations on the laser-irradiated surface that grows due to the Rayleigh-Taylor instability.

Changes in mRNA levels of alkaline phosphatase and tartrate-resistant acid phosphatase in femur of ovariectomized rats: effects of estrogen and unloading

Our previous studies demonstrated that estrogen (E2) prevents the development of disuse atrophy of the femur in tail-suspended rats. To elucidate the mechanisms of this E2 action, we investigated the effects of E2 on the expression of alkaline phosphatase (ALP, a marker for bone formation) and tartrate-resistant acid phosphatase (TRAP, a marker for bone resorption) in the femur of ovariectomized and tail-suspended rats. One group of ovariectomized rats received estradiol dipropionate (OVX-E2), and the other the vehicle alone (OVX). Each group was subjected to tail-suspension. After 1, 3, 5 or 7 days of suspension, ALP and TRAP mRNA levels were determined by Northern blot analysis. The ALP mRNA level was not altered by suspension in the OVX group, but it gradually increased in the OVX-E2 group, the highest level being observed at day 5 of suspension. In contrast, TRAP mRNA significantly increased at days 5 and 7 in the OVX group, while it is decreased significantly from day 3 to 7 in the OVX-E2 group. These results indicate that E2 prevents disuse atrophy of the femur in an ovariectomized and tail-suspended rat model by stimulating bone formation and by inhibiting bone resorption.

Relative validity of a semi-quantitative food frequency questionnaire versus 28 day weighed diet records in Japanese female dietitians

OBJECTIVE

To assess the relative validity of a semi-quantitative food frequency questionnaire (SQFFQ) against 28 day weighed diet records (WDRs).

SUBJECTS AND METHODS

The SQFFQ was administered to 106 (21 male and 85 female) Japanese dietitians in Aichi Prefecture in autumn, 1996 and four-season consecutive 7 day WDRs were carried out during 1996-1997. We evaluated validity of intakes of 15 foods and 31 macro- and micro-nutrients based on the SQFFQ against those according to 28 day WDRs among 79 Japanese female dietitians.

RESULTS

Mean daily intakes of selected foods and nutrients determined by the SQFFQ were generally equivalent to those measured by 28 day WDRs. Pearson's de-attenuated correlation coefficients (CCs) with log-transformation and energy-adjustment between intakes of selected foods and nutrients quantified by the SQFFQ and 28 day WDRs (minimum-median-maximum) ranged from 0.17 (beverages)-0.52 to 0.74 (rice), and Spearman's rank CCs with energy-adjustment ranged from 0.28 (confectionery)-0.42 to 0.68 (rice). Respective Pearson's CCs for intakes of nutrients were 0.28 (PUFAs)-0.51 to 0.73 (magnesium), and Spearman's rank CCs ranged from 0.23 (n-3 PUFAs)-0.45 to 0.71 (magnesium). Favorably higher agreement for intakes of foods/nutrients was achieved along with lower disagreement.

CONCLUSIONS

Satisfactorily higher relative validity was attained in Japanese female dietitians with the SQFFQ. This calibrated questionnaire seems therefore appropriate for administration to Japanese dietitians to clarify associations between diet and health/disease.

SPONSORSHIP

A grant-in-aid from the Ministry of Education, Science, Sports and Culture (06454242).

Interplay of physical activity and vitamin D receptor gene polymorphism on bone mineral density

The interplay of physical activity and vitamin D receptor (VDR) gene polymorphism in their effects on bone mineral density (BMD) was studied for 120 Japanese girls aged 18-19 years. BMD at distal radius in the group with the VDR genotype at the Apal site of Aa was significantly higher than that in the aa group, but this association disappeared in a group having the habit of physical activity. The Aa genotype gave a higher BMD than the aa genotype only in the group without the habit of physical activity. The habit of physical activity was associated with a higher BMD only in the aa genotype group. The similar interplay was observed in the VDR genotype at the TaqI site. We thus suggest that physical activity and VDR genotypes affect BMD in independent mechanism to give a saturated level of BMD. Higher dietary calcium intake tended to be associated with higher BMD only in the Aa genotype, suggesting that the calcium intake and VDR genotype affect BMD in a synergistic mechanism.

Effects of sedentary work on physical fitness and serum cholesterol profile in middle-aged male workers

OBJECTIVES

To evaluate independent and interactive health effects of physical activity at work (PAW) and physical activity at habitual exercise (PAHE).

METHODS

A cross-sectional study on 1,117 male workers aged 29 to 46 years with a mean of 37.0 years. Using a self-administered questionnaire, the subjects were classified into 'High'/'Low' (n = 338/779) on PAW, and into 'Yes'/'No' (n = 353/764) on PAHE. As outcome indices, physical fitness expressed as maximal oxygen uptake (VO2max) was estimated, and serum total cholesterol (TC), HDL-cholesterol (HDLC) and TC/HDLC ratio were determined. Age, body mass index (kg/m2), alcohol-drinking and smoking were used as confounding factors.

RESULTS

The 'High' PAW group had a significantly higher level of VO2max than the 'Low' PAW group (+ 1.0 ml/kg min; 34.4 vs. 33.4 ml/ kg min in adjusted means). The 'High' PAW group also had a better profile of serum cholesterol than the 'Low' PAW group, but it was not significant. The 'Yes' PAHE group had significantly higher levels of VO2max (+ 2.0 ml/kg min; 34.9 vs. 32.9 ml/kg min) and serum HDLC (+0.09 mmol/l; 1.48 vs. 1.39 mmol/l), and a significantly lower TC/HDLC ratio (-0.29; 3.90 vs. 4.19) than the 'No' PAHE group. Among PAW PAHE subgroups, the 'High-Yes' group (n = 110), most physically active, had the best profile of VO2max and serum cholesterol, and the 'Low-No' group (n = 536), least physically active, had the worst one. Interactive effects of PAW and PAHE were not found either on VO2max or on serum cholesterol profile. All the results were not influenced by statistical adjustments for the four confounding factors used here.

CONCLUSIONS

Both sedentary work and lack of habitual exercise are very common in Japanese workers. Sedentary work, independently from lack of habitual exercise, may increase the risk of diseases related to physical inactivity by affecting physical fitness and serum cholesterol profile.

Thyrotropin modifies activation of nuclear factor kappaB by tumour necrosis factor alpha in rat thyroid cell line

We have recently demonstrated that nuclear factor kappaB (NF-kappaB) mediates the tumour necrosis factor alpha (TNF-alpha)-dependent expression of the gene encoding interleukin 6 (IL-6) in rat thyroid FRTL-5 cells cultured in the presence of thyrotropin (TSH). In the present study we investigated how TSH is involved in the activation of NF-kappaB by TNF-alpha in the cells. Electrophoretic mobility-shift assay revealed that, in the absence of TSH, TNF-alpha activated a single protein-DNA complex containing the p50 subunit but not other NF-kappaB subunits such as p65. In contrast, two distinct protein-DNA complexes were activated in the presence of TSH: the faster-migrating complex contained only p50 subunit; the slower-migrating complex consisted of p65-p50 heterodimer. This TSH effect was mimicked by forskolin and thyroid-stimulating antibodies obtained from patients with Graves's disease, suggesting that an increase in intracellular cAMP is responsible for the induction of different NF-kappaBs by TNF-alpha. A transient transfection study with a luciferase reporter gene driven by multimerized NF-kappaB sites demonstrated that TNF-alpha increased the luciferase activities only in the presence of TSH, and that this increase was inhibited by the co-transfection of mutant p65, which prevented the function of wild-type p65 in a dominant-negative manner. Accordingly, TNF-alpha activated the expression of the IL-6 gene in the presence of TSH but not in its absence. Although the expression of the p105 gene, another known target for NF-kappaB, was increased by TNF-alpha in the absence of TSH, the presence of TSH further increased the mRNA level. Taken together, these observations indicate that the presence of TSH is crucial for the NF-kappaB-mediated actions of TNF-alpha on thyroid follicular cells.

Effects of lifestyle factors on ultrasonographically determined bone health in Japanese women

The objective of this study was to determine by ultrasonographic measurements, an inexpensive and radiation-free technique, the association between bone health and lifestyle factors among a large population of Japanese women. Two hundred and fifty-six pre-menopausal women and 585 post-menopausal women who underwent a voluntary medical check-up for osteoporosis in 1996-1997 were analyzed. There were significant positive correlations between the bone density (designated as the stiffness value) vs the weight, the height and the body mass index of the subjects only in the post-menopausal group. Negative correlations were also found between the bone density vs the age and the years since menopause. Our data using ultrasonographic technique agree well with previous studies using other devices. In both groups, subjects with current or past exercise habits had higher stiffness values. Dietary habits had no effects on the stiffness value. Smoking habits had a trend towards negative effects and alcohol consumption seemed to have a trend towards positive effects on the stiffness value in post-menopausal women, but these effects did not reach statistical significance. Positive effects of current exercise on bone density were maintained after adjustment for past exercise habits. These results support the effectiveness of exercise begun in adulthood. Having a good exercise habit is one of the most effective ways of maintaining good bone health.

Effect of estrogen and tail-suspension on expression of osteocalcin mRNA in femur of ovariectomized rats

We investigated the effect of estrogen (E2) and tail-suspension on expression of osteocalcin (OC) mRNA in the femur of ovariectomized rats. Five-week-old female Wistar rats were ovariectomized and divided into two groups: one group received estradiol dipropionate (OVX-E2), and the other received the vehicle (OVX). Each group was further divided into two subgroups, tail-suspended (S) and non-suspended (N), giving a total of four groups: OVX-E2-S, OVX-E2-N, OVX-S and OVX-N. After a 7-day suspension, femurs were excised, and OC mRNA levels were determined by Northern blot analysis. A significant decrease of OC mRNA in OVX-E2-N was observed when compared with that of OVX-N, indicating that E2 decreases the OC expression. Interestingly, tail-suspension further decreased the mRNA levels in both OVX-S and OVX-E2-S when compared with the levels of OVX-N and OVX-E2-N, respectively. Since glucocorticoids have been shown to decrease OC expression, we also measured the urinary excretion of corticosterone during the suspension period that reflects the serum levels of corticosterone, and found that it was increased by E2 and further increased by tail-suspension. These results indicate that estrogen and glucocorticoids exert additive effects in inhibiting OC expression in the rat femur.

A potential role of activated NF-kappa B in the pathogenesis of euthyroid sick syndrome

Euthyroid sick syndrome, characterized by low serum 3,5, 3'-triiodothyronine (T(3)) with normal L-thyroxine levels, is associated with a wide variety of disorders including sepsis, malignancy, and AIDS. The degree of low T(3) in circulation has been shown to correlate with the severity of the underlying disorders and with the prognosis. Elevated TNF-alpha levels, which accompany severe illness, are associated with decreased activity of type I 5'-deiodinase (5'-DI) in liver, leading us to speculate that high levels of this factor contribute to euthyroid sick syndrome. Here we demonstrate that the activation of NF-kappa B by TNF-alpha interferes with thyroid-hormone action as demonstrated by impairment of T(3)-dependent induction of 5'-DI gene expression in HepG2 cells. Inhibition of NF-kappa B action by a dominant-negative NF-kappa B reversed this effect and allowed T(3) induction of 5'-DI. Furthermore, we show that an inhibitor of NF-kappa B activation, clarithromycin (CAM), can inhibit TNF-alpha-induced activation of NF-kappa B and restore T(3)-dependent induction of 5'-DI mRNA and enzyme activity. These results suggest that NF-kappa B activation by TNF-alpha is involved in the pathogenesis of euthyroid sick syndrome and that CAM could help prevent a decrease in serum T(3) levels and thus ameliorate euthyroid sick syndrome.

Rotation in clinostat results in apoptosis of osteoblastic ROS 17/2.8 cells

Clinostat is an effective, ground-based tool which can be used to verify data from space flight, and to test hypotheses and experimental conditions for eventual space flights. Rotation in clinostat appears to mimic the microgravity environment by nulling the gravitational vector by continuous averaging. In the present study, we exposed osteoblast-like ROS 17/2.8 cells to a vector-averaged gravity environment in a clinostat and found that the cells undergo apoptotic death during the first 24 hr of clino-rotation. We suggest that apoptosis might be one of the mechanisms for reduced bone formation as observed in actual space flights.

Feed-out of rear surface perturbation due to rarefaction wave in laser-irradiated targets

We report experimental results on hydrodynamic perturbation transfer from the rear to the front of laser-irradiated targets. Flat polystyrene foils with rear-surface perturbations were irradiated by partially coherent light. We observed phase inversion of the rear surface after the shock breakout at the rear surface. Perturbations on the laser-irradiated surface arose due to the rippled rarefaction wave. Experimental results were well reproduced by a simple model with unperturbed hydrodynamic quantities calculated from the one-dimensional simulation.

Culture in vector-averaged gravity under clinostat rotation results in apoptosis of osteoblastic ROS 17/2.8 cells

Space flight experiments and studies carried out in altered gravity environments have revealed that exposure to altered gravity conditions results in (mal)adaptation of cellular function. In the present study, we used a clinostat to generate a vector-averaged gravity environment. We then evaluated the responses of osteoblast-like ROS 17/2.8 cells subsequent to rotation at 50 revolutions per minute (rpm) for 6-24 h. We found that the cells started to detach from the substrate between 12 h and 24 h of rotation in clinostat but not in stationary cultures or after horizontal rotation (the latter serving as a motion control for turbulence, shear forces, and vibrations). At 24 h, 35% of clinorotated cells had detached and the cells underwent apoptotic death as evidenced by DNA fragmentation analysis, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) staining, and flow cytometry with Annexin V staining. The apoptotic death was associated with perinuclear distribution of cell-surface integrin beta1 and disorganization of actin cytoskeleton. These results suggest that vector-averaged gravity causes apoptosis of osteoblasts by altering the organization of the cytoskeleton. We hypothesize that apoptotic death of osteoblasts might play an important role in the pathogenesis of osteoporotic bone loss as observed in actual space flights.

Culture in vector-averaged gravity environment in a clinostat results in detachment of osteoblastic ROS 17/2.8 cells

Studies carried out in space flights and in altered gravitational environments have shown that exposure to altered gravity conditions results in alterations in cellular structure and function. In the present study, we used a clinostat to generate a vector-averaged gravity environment, and evaluated the responses of osteoblast-like ROS 17/2.8 cells subsequent to rotation at 50 r.p.m from 24 to 72 hr. We found that the cells started to detach during the first 24 hr of culture in clinostat, but not in stationary and horizontal rotation (the latter serving as a control for turbulence, shear forces and vibrations). At 24 hr, there was a significant decrease in the number of adherent cells under clino-rotation (2.75 +/- 0.5 x 10(5) in stationary culture versus 2.02 +/- 0.27 x 10(5) under clino-rotation), and 19.8% of adherent cells were trypan-blue positive when cultured in 2% fetal bovine serum. All the detached cells were trypan-blue positive. At 72 hr, the cells became confluent in all three groups. These results suggest that vector-averaged gravity could cause the death of osteoblasts during the first 24 hr of clino-rotation. We hypothesize that this cell death might play a role in the pathogenesis of osteoporotic bone loss as observed in actual space flight.

Inhibition of nuclear factor-kappaB activation confers sensitivity to tumor necrosis factor-alpha by impairment of cell cycle progression in human glioma cells

Tumor necrosis factor (TNF)-alpha has been shown to exert cytotoxic or cytostatic effects on tumor cells, but susceptibility to TNF-alpha varies among different types of cells. TNF-alpha activates a transcription factor, nuclear factor-kappaB (NF-kappaB), which induces a wide variety of genes and causes pleiotrophic responses. In this study, the relationship between susceptibility to TNF-alpha and activation of NF-kappaB was investigated in six human malignant glioma cell lines. Cell proliferation analysis revealed that only one cell line, SK-MG-1, was sensitive to TNF-alpha and that the other five, including U-251MG, were resistant. Electrophoretic mobility-shift assay showed that TNF-alpha strongly activated a subtype of NF-kappaB, the p50-p65 heterodimer, in all of the resistant cell lines tested. However, this activation was weak in the sensitive cell line, SK-MG-1. Activation of NF-kappaB by TNF-alpha in the resistant cell lines resulted in a significant increase of a reporter gene expression driven by NF-kappaB site, suggesting a possibility that activation of p50-p65 confers resistance to TNF-alpha. To test this hypothesis, we established a stable cell line that expresses an inducible dominant negative NF-kappaB (p65 DN) protein in one of the TNF-alpha-resistant cell lines, U-251MG. In the established clone, induction of p65 DN protein decreased TNF-alpha-dependent increase in the DNA binding of p50-p65 heterodimer and NF-kappaB-dependent reporter gene activity. Although no growth inhibition of this clone was observed by TNF-alpha treatment, induction of p65 DN together with TNF-alpha resulted in a significant decrease in cell number. Cell cycle analysis revealed that this growth inhibition was due to the impairment of cell cycle progression. These results indicate that an active NF-kappaB complex, such as the p50-p65 heterodimer, plays a crucial role in the progression of cell cycle in malignant glioma cells. Refractoriness to TNF-alpha treatment could be prevented by inhibiting NF-kappaB activation.

Responsiveness to thyroid hormone is enhanced in rat hepatocytes cultured as spheroids compared with that in monolayers: altered responsiveness to thyroid hormone possibly involves complex formed on thyroid hormone response elements

We previously reported that the expression of type I iodothyronine 5'-deiodinase (5'DI) gene was increased by 3,3,',5-triiodothyronine (T3) in isolated rat hepatocytes when cultured as spherical aggregates (spheroids), whereas this effect was greatly attenuated in conventional monolayer cultures. In the current study, we examined whether the enhanced T3 responsiveness in spheroid cultures extends to other T3-responsive genes. As observed for 5'DI, T3 increased spot 14, malic enzyme and fibronectin messenger RNAs (mRNAs) by fourfold to fivefold in spheroid cultures, while the effect in monolayer cultures was blunted. This difference in T3 responsiveness was also observed when T3-responsive reporters consisting of the luciferase gene under the control of triiodothyronine response element (TRE) were introduced into hepatocytes using a replication-defective adenovirus vector. These results suggest that the factors required for T3-dependent transcriptional activation are preserved in spheroid cultures and that they must exert their effect by interacting with TRE. Maximal binding capacity of nuclear T3 receptor was not different between monolayer and spheroid cultures while the expression of retinoid X receptor-alpha (RXR alpha) mRNA was higher in spheroid cultures compared with that in monolayers. The difference in RXR alpha mRNA expression, together with enhanced proteolytic cleavage in monolayers that we demonstrated recently, may account for the difference in T3 responsiveness between the two hepatocyte culture systems.

9-cis-retinoic acid decreases the level of its cognate receptor, retinoid X receptor, through acceleration of the turnover

In this study, we investigated the ligand-mediated regulation of retinoid X receptor (RXR) in two human cell lines (HepG2 and JEG-3 cells), which have been reported to express RXRalpha predominantly. Western blot analysis revealed that a treatment with 1 microM 9-cis-retinoic acid (9-cis RA) for 24 h decreased RXRalpha protein level to 72 +/- 9 and 75 +/- 7% in HepG2 and JEG-3 cells, respectively, when the levels in the non-treated cells were expressed as 100%. The decrease was not due to the changes in steady-state level of RXRalpha mRNA or its stability as revealed by Northern blot analysis. However, the 9-cis RA treatment decreased the half-life of RXRalpha protein as determined by pulse-chase analysis. It was thus demonstrated that 9-cis RA downregulates RXRalpha by increasing the turnover of the protein in the two cell lines. The ligand-dependent downregulation of RXRalpha protein may be important for several hormonal signalings, in which the receptors heterodimerize with RXR.

Body mass index (weight/height2) or percentage body fat by bioelectrical impedance analysis: which variable better reflects serum lipid profile?

We present population data on percentage body fat (%BF) by bioelectrical impedance analysis (BIA) in 12,287 men and 6657 women aged 30-69 y. In addition, we examined relationships among BMI, %BF and serum lipids (total-cholesterol (TC), HDL-cholesterol (HDLC), TC/HDLC ratio, LDL-cholesterol (LDLC) and triglycerides (TG)) in order to determine whether body mass index (BMI, kg/m2) or %BF by BIA better reflected lipid metabolism. Women had larger %BF than men in all age groups. On the other hand, women aged < 60 y had smaller BMI than corresponding men. Regardless of age, BMI was obviously correlated with %BF (r = 0.743-0.924). As previously reported, high BMI and high %BF were strongly associated with high serum TC/HDLC ratio and TG, and low serum HDLC rather than high serum TC and LDLC. Compared with BMI, %BF by BIA was better correlated with the serum indices except for serum HDLC. These results were found in both sexes, and there was a trend in which younger subjects had stronger correlations among BMI, %BF and serum lipids. Consequently, %BF by BIA (an index of body composition) better reflects serum lipid profile than BMI.