Byung-Pal Yu

The effect of age on cyclooxygenase-2 gene expression: NF-κB activation and IκBα degradation

Increased oxidative stress resulting in the activation of NF-kappaB is thought to play a crucial role in the expression of the cyclooxygenase-2 (COX-2), which is the key enzyme in proinflammatory prostanoid synthesis. In the current study, we investigated whether the aging process affects the status of the redox-sensitive NF-kappaB in rat kidney, and how this age-related modulation is related to COX-2 gene expression and COX-derived reactive oxygen species (ROS). We found that the aging process strongly enhanced the activation of NF-kappaB and its DNA-binding activity with an increased ROS status. Accompanied with the change in the NF-kappaB activity was a decreased IkappaBalpha as confirmed by the increased nuclear p65 protein. Thus, these data strongly indicated that the aging process increases NF-kappaB activity by downregulating IkappaBalpha. A closer examination further revealed that age-related oxidative status correlated with the increased COX-derived prostanoid biosynthetic process is mediated by the increased NF-kappaB-regulated COX activity. This increase in NF-kappaB activity was accompanied by the increased COX-2 mRNA and protein levels. Based on these data, we concluded that the age-related increase in redox-sensitive NF-kappaB translocation and binding activities are associated with increased ROS, and further that this transactivation was modulated by the age-related decrease of IkappaBalpha.

Relationship between osteocalcin and glucose metabolism in postmenopausal women

BACKGROUND Recently, osteocalcin was found to regulate blood glucose, insulin secretion, and fat deposition in mice. However, the relationship between osteocalcin levels and factors related to glucose metabolism in humans has not yet been investigated. We investigated the relationship between osteocalcin and glucose metabolism in postmenopausal women. METHODS Three hundred thirty-nine postmenopausal women were recruited for this study. Glucose metabolism related substance and serum osteocalcin were assayed. RESULTS There was a significant reduction in osteocalcin levels among type 2 diabetes mellitus patients compared with the normal glucose and impaired fasting glucose groups. Next, the subjects in the highest quartile for osteocalcin were observed to have significantly decreased fasting glucose and HbA1c levels compared with subjects in the lowest quartile. In addition, osteocalcin levels were inversely correlated with glucose, insulin, HbA1c, and insulin resistance. Moreover, multivariate analysis showed that serum osteocalcin was found to be an independent factor associated with glucose and HbA1c. CONCLUSIONS There is a potential role of osteocalcin in regulating blood glucose levels in postmenopausal women. This finding indicates that in humans the skeleton may be involved in energy metabolism by functioning as part of the endocrine system.

Physical activity as a factor in the action of dietary restriction on aging: Effects in Fischer 344 rats

Dietary restriction (DR) slows the rate of aging in laboratory rodents but the mechanism of action is unknown. DR is known to induce beneficial effects in a variety of tissues and organ systems. DR also maintains high levels of physical activity over the life span. We tested the hypothesis that lifelong physical activity is an important component of the anti-aging action of DR. Male specific pathogen-free Fischer 344 rats were divided into 4 groups at 6 weeks of age: A: fed ad libitum; AE: fed ad libitum and in cages with running wheels; B: fed 60% ad libitum; BE: fed 60% ad libitum and in cages with running wheels. Running activity and spontaneous cage activity were measured over 24 hours and over the life span. Metabolic rate was measured indirectly by analysis of air entering and leaving cages. AE rats exhibited low levels of running activity and ran very little beyond 6 months of age. In contrast, BE rats sustained high running levels even after all A and AE rats had died. High levels of wheel running did not decrease spontaneous cage activity. Median life span (50% survival) was in the order A = AE < B < BE. Ten percent survival was in the order A = AE < B = BE. BE rats had greatest median life span and also highest specific metabolic rate. Exercise and DR altered pathology: At death BE rats had a high incidence of cardiomyopathy, whereas A and AE rats had high incidence of chronic nephropathy and pituitary tumors. The data indicate that increased physical activity is probably not an important factor in the action of DR on aging.

Molecular exploration of age-related NF-κB/IKK downregulation by calorie restriction in rat kidney

Accumulating evidence strongly suggests that oxidative stress underlies aging processes, and that in a variety of organisms, calorie restriction (CR) retards these processes, thereby extending their lifespan. Recent studies revealed that the anti-aging action of CR depends on its anti-oxidative mechanism. In previous papers, we reported that aging activates the redox-sensitive transcription factor, NF-kappaB, and further reported that age-related NF-kappaB activation correlates with age-related oxidative stress. In the present paper, we present evidence that increased NF-kappaB binding activity during aging is elicited through the phosphorylation of IkappaB kinase (IKK), causing a degradation of IkappaBalpha and IkappaBbeta. We further show that CR inhibits IKK activation, down-regulating NF-kappaB activation as evidenced by increased bound IkappaBalpha and IkappaBbeta proteins in cytoplasm. These findings led to the conclusions that age-related oxidative stress may be a primary cause of up-regulated and altered NF-kappaB activity in aged kidney, and that the anti-oxidative action of CR is a major force responsible for the maintenance of a properly functioning NF-kappaB/IkappaB-IKK signaling pathway, which might be involved in CRs life-prolonging action.

Recent advances in calorie restriction research on aging

The extension of both median and maximum lifespan and the suppression of age-related diseases in laboratory animals by reduced food intake, i.e., calorie restriction (CR) are regarded as hallmarks of CRs anti-aging action. The diverse efficacy of CR to counteract aging effects and its experimental reproducibility has made it the gold standard of many aging intervention studies of recent years. Although CR originally was used as a tool to perturb the aging process of laboratory animals as to uncover clues of underlying mechanisms of aging processes, current CR research interests have shifted to the retardation of aging-related functional decline and the prevention of age-related diseases. Advances in CR research on non-human primates and recent endeavors using human subjects offer a promising outlook for CRs beneficial effects in healthy human aging. In this review, several major issues related to CRs anti-aging mechanisms are discussed by highlighting the importance of modulating deleterious chronic inflammation at molecular levels and the impact of epigenetic chromatin and histone modifications by CR at the ultimate control sites of gene expression. The recent research on rapamycin as a CR mimetic is summarized and a brief description of intermittent feeding patterns is reviewed in comparison to the CR effect.

Detoxification of reactive aldehydes in mitochondria: Effects of age and dietary restriction

Previously, we proposed that reactive aldehydic products generated from lipid peroxidation might be the deleterious cause of mitochondrial dysfunction during aging. Our present study focuses on the roles that aging and dietary restriction (DR) play in the elimination of 4-hydroxynonenal (HNE) in rat liver by exploring three enzymatic systems: aldehyde dehydrogenase (ALDH), glutathione S-transferase (GST), and alcohol dehydrogenase (ADH). Results show that the main pathways of HNE elimination in mitochondria are through ALDH-catalyzed oxidation, and the GSTcatalyzed conjugation of HNE. Findings also show that age reduces both ALDH and GST activities; mitochondrial HNE oxidation by ALDH declines at 18 and 24 months of age, and the glutathione conjugation of HNE reduces at 24 months of age. However, these enzymatic processes were found to be well-preserved in DR animals throughout their life span, supporting the evidence of less HNE accumulation in the membranes of restricted rats. These findings are consistent with our earlier proposal that indicates an age-associated decrease in mitochondrial detoxification as a major underlying process for malondialdehyde and lipofuscin accumulation in older animals. They also indicate that the prevention of the age-associated decrease in aldehyde detoxification by DR may be an important mechanism underlying enhanced aldehyde elimination, thus minimizing the functional deterioration observed in mitochondria of old animals.

Influence of dietary components on occurrence of and mortality due to neoplasms in male F344 rats

The influence of dietary components on the occurrence of, and mortality from spontaneous neoplasms in male F344 rats was investigated. The dietary regimens studied included restriction of specific dietary components (energy, fat, protein and mineral), as well as different sources of dietary protein (casein, soy protein and lactalbumin). A statistical approach based on contributing causes of death was used to obtain the mortality due to all neoplasms, and the relative onset rate of frequently observed neoplasms, e.g., leukemia, pituitary adenoma, testicular interstitial cell tumor, etc. Only the regimen involving energy restriction reduced the mortality due to all neoplasms. Neither reduction of individual components without energy restriction, nor replacement of casein with soy protein or lactalbumin as the protein source affected mortality. Analyses of the relative onset rate of selected neoplasms also indicated that only a reduction of energy intake suppressed the occurrence of most of these neoplasms. Other dietary regimens, at most, suppressed a few types of neoplasm. It is concluded that a reduction in energy intake is a key dietary factor for the prevention of neoplastic diseases in rats.

An electron microscopic examination of age-related changes in the rat kidney: the influence of diet.

The changes with age in the ultrastructure of the kidneys were explored in ad libitum fed rats with restricted food intake started soon after weaning or started in young adult life or limited to early life and in rats restricted in protein but not caloric intake. Many ultrastructural changes occurred with age both in the glomeruli and the tubules. Food restriction started soon after weaning or in adult life modulated most of these age changes. By providing detailed information on basement membrane and tubular cell structure, these findings complement previous light microscopic and functional studies in regard to the effects of food restriction on progressive kidney disease in the rat. Food restriction limited to early life and protein restriction without caloric restriction were less effective in modulating these age changes in kidney ultrastructure than food restriction initiated at 6 weeks or 6 months of age and continued for the rest of the life span.

Inhibition of endothelial cell adhesion by the new anti-inflammatory agent α-iso-cubebene

The current study explored if alpha-iso-cubebene, a novel cubebene sesquiterpene compound purified from Schisandra chinensis, could attenuate the activities of adhesion molecules in tumor necrosis factor-alpha (TNF-alpha)-stimulated human umbilical vein endothelial cells (HUVECs). The study was performed on HUVECs that were pretreated with 25 microg/ml of alpha-iso-cubebene before TNF-alpha treatment. Treatment of HUVECs with alpha-iso-cubebene for 6 h significantly inhibited TNF-alpha-induced reactive oxygen species (ROS) formation. HUVECs treated with alpha-iso-cubebene showed markedly suppressed TNF-alpha-induced mRNA expression of VCAM-1 and E-selectin, but little alteration in ICAM-1 mRNA expression. alpha-iso-Cubebene treatment also significantly decreased the TNF-alpha-induced cell surface and total protein expression of VCAM-1 and E-selectin without affecting ICAM-1 expression. In addition, treatment of HUVECs with alpha-iso-cubebene markedly reduced U937 monocyte adhesion to TNF-alpha-stimulated HUVECs. alpha-iso-Cubebene treatment did not affect translocation of NF-kappaB transcription factor from the cytosol into the nucleus. However, alpha-iso-cubebene significantly inhibited NF-kappaB transcription factor activation in TNF-alpha-stimulated HUVECs. The new anti-inflammatory agent alpha-iso-cubebene attenuates TNF-alpha-stimulated endothelial adhesion to monocytes by inhibiting intracellular ROS production, the activation of redox-sensitive NF-kappaB transcription factor and expression of VCAM-1 and E-selectin. Based on these findings, alpha-iso-cubebene is proposed as an effective new anti-inflammatory agent that may have a potential therapeutic use for the prevention and treatment of vascular diseases.

Effects of Aloe vera ingestion in the rat. I. Growth, food and fluid intake and serum chemistry

This study was designed to examine the effects of long‐term (1.5 and 5.5 months) Aloe vera (Aloe barbadensis) ingestion on the growth, food intake and serum chemistry of Fischer 344 male rats. Aloe vera powders, produced by two different methods, were mixed with rat chow at selected concentrations. Process A aloe was prepared from skinned aloe filets by homogenization followed by lyophilization and grinding to a fine powder; Process B aloe was prepared similarly except that the homogenate was charcoal filtered prior to lyophilization. Ingestion of Process A aloe at concentrations greater than 1% was associated with diarrhoea and a decrease in weight gain. Ingestion of 1% Process A and both 1% and 10% Process B aloe had no adverse effect on body weight gain, food intake, gastrointestinal transit time and gross pathology. Serum chemistry was minimally affected. The rats ingesting 10% Process B aloe exhibited a slight, but significant increase in fluid intake. The results indicate that, although high concentrations of aloe should be avoided, ingestion of moderate levels (1%) of aloe from either process causes no apparent adverse effects in the rat.