Effect of drinking green tea on age-associated accumulation of Maillard-type fluorescence and carbonyl groups in rat aortic and skin collagen.

Tea catechins and other flavonoids have been shown to potentially protect against chronic cardiovascular diseases such as coronary heart disease and atherosclerosis. In this study, 6-month-old female Sprague-Dawley rats were fed green tea extract (50 mg/100 ml in drinking water) up to the age of 22 months, and the age-associated changes in Maillard-type fluorescence and carbonyl groups in the aortic and skin collagen were compared with those occurring in the water-fed control animals. Collagen-linked Maillard-type fluorescence was found to increase in both the aortic and skin tissues as animals aged. The age-associated increase in the fluorescence in the aortic collagen was remarkably inhibited by the green tea extract treatment, while that occurring in the skin collagen was not significantly inhibited by the treatment. The collagen carbonyl content also increased in both the aortic and skin tissues as animals aged. In contrast with the case of Maillard-type fluorescence, however, the age-associated increase in the carbonyl content was not inhibited by the green tea extract treatment either in the aortic or skin collagen. These results suggest that the inhibition of AGE formation in collagen is an important mechanism for the protective effects of tea catechins against cardiovascular diseases.     

Age-associated increase of spontaneous mutant frequency and molecular nature of mutation in newborn and old lacZ-transgenic mouse

Accumulation of mutation has long been hypothesized to be a cause of aging and contribute to many of the degenerative diseases, which appear in the senescent phase of life. To test this hypothesis, age-associated changes in spontaneous mutation in different tissues of the body as well as the molecular nature of such changes should be examined. This kind of approach has become feasible only lately with a development of new transgenic mice suitable for mutation assay. Here, using one of these transgenic mice harboring lacZ gene, we have shown that the age-associated increase in spontaneous mutant frequency is common to all tissues examined; spleen, liver, heart, brain, skin and testis, while the rates of increase in mutant frequency differed among the tissues. DNA sequencing of the 496 lacZ mutants recovered from the tissues of newborn and old mice has revealed that spectra of mutations are similar at the two age points with G:C to A:T transition at CpG site being a predominant type of mutation. Furthermore, some mutations in old tissues are complex type and not found in tissues of newborn mice. These results suggest that similar mechanisms may be operating for mutation induction in fetal and postnatal aging process. In addition, the appearance of complex types of mutations in the old tissues suggests a unique cause for these mutations in aging tissues.     

Update on olfactory mucosal metabolic enzymes: age-related changes and N-acetyltransferase activities

We have expanded previous observations on olfactory metabolic enzymes by examining the content of various metabolic enzymes in the olfactory mucosa of the male Long-Evans rat at different ages. Age-related changes in metabolic enzyme content may be related to changes in susceptibility to toxicants with age and may also contribute to altered odorant perception in the elderly. While some enzymes did not vary over the age range examined, decreases in the microsomal content of other enzymes were observed. While mRNA for acetyltransferase enzymes has previously been described in olfactory mucosa, the markedly higher activity of olfactory acetyltransferases compared to liver had not previously been described. Acetyltransferases are important in the metabolism of drugs and toxicants that are aromatic amine derivatives and may contribute to the bioactivation of rodent olfactory mucosal carcinogens such as 2,6-dimethylaniline and alachlor. These studies show that the olfactory mucosa varies in its metabolic capacity with age, and characterize another class of metabolic enzymes in the olfactory mucosa, both of which may impact significantly on responses to toxicants and therapeutic agents in the nasal cavity.     

A method for parallel determination of choline acetyltransferase and muscarinic cholinergic receptors: Application in aged-rat brain

We have devised a method for the parallel determination of choline acetyltransferase (CAT) and muscarinic cholinergic receptor (mCh-R) in the same brain tissue. The method for CAT activity determination is more rapid, simplified, stable, and economical than the usual Fonnum's method. With our method, age-associated changes in CAT activity and mCh-R levels were examined. Although CAT activity hardly changed with age except in a few areas, mCh-R binding of aged-rats was markedly reduced in all areas. These results suggest that the change in mCh-R represents an age-associated biochemical change in the brain and that determination of CAT activity is not sufficient for the study of age-associated changes in the brain cholinergic system.     

Inhibition of the Na+,K(+)-ATPase pump during induction of experimental colon cancer.

During the development of large bowel cancer alterations in colonic epithelial ion transport have been observed some of which result in altered intracellular ionic composition. In many tumors intracellular sodium and potassium become elevated and depressed, respectively. This observation suggests that mechanisms governing intracellular homeostasis for sodium and potassium are no longer tightly regulated. Changes in cell membrane permeability, sodium, potassium-ATPase K(+)-ATPase) pump activity, or both may be responsible for these alterations. It is not known when during initiation and development of cancer such changes may occur. To assess whether there are changes in the Na+, K(+)-ATPase pump early during the induction of large bowel cancer and prior to any notable histological changes, we measured the kinetics of the Na+, K(+)-pump in distal colonic mucosa of CF1 mice one week following only four weekly injections of the carcinogen 1,2-dimethyhydrazine (DMH). The kinetics of the pump were found to be best described by a model of highly cooperative binding. The VMAX of the pump in premalignant mucosa was lower for both sodium and potassium substrate activation (55-65% of control) with little change in other kinetic parameters. Depression of VMAX could not be attributed to an increased barium blockable potassium conductance of the basolateral membrane. Na+,K(+)-ATPase activity was also decreased by 50% in the distal colon of DMH treated mice, but was not affected in the less cancer susceptible proximal colon. These data demonstrate that alterations occur in the Na+,K(+)-pump in premalignant mucosa months before gross tumors develop, and these changes may partially explain the altered levels of Na+ and K+ in the cytoplasm of pre-malignant and malignant colonocytes.     

DNA repair and aging in mouse liver: 8-oxodG glycosylase activity increase in mitochondrial but not in nuclear extracts

8-oxo-deoxyguanosine (8-oxodG) is one of the major DNA lesions formed upon oxidative attack of DNA. It is a mutagenic adduct that has been associated with pathological states such as cancer and aging. Base excision repair (BER) is the main pathway for the repair of 8-oxodG. There is a great deal of interest in the question about age-associated accumulation of this DNA lesion and its intracellular distribution, particularly with respect to mitochondrial or nuclear localization. We have previously shown that 8-oxodG-incision activity increases with age in rat mitochondria obtained from both liver and heart. In this study, we have investigated the age-associated changes in DNA repair activities in both mitochondrial and nuclear extracts obtained from mouse liver. We observed that 8-oxodG incision activity of mitochondrial extracts increases significantly with age, from 13.4 + or - 2.2 fmoles of oligomer/100 microg of protein/16 h at 6 to 18.6 + or - 4.9 at 14 and 23.7 + or - 3.8 at 23 months of age. In contrast, the nuclear 8-oxodG incision activity showed no significant change with age, and in fact slightly decreased from 11.8 + or - 3 fmoles/50 microg of protein/2 h at 6 months to 9.7 + or - 0.8 at 14 months. Uracil DNA glycosylase and endonuclease G activities did not change with age in nucleus or mitochondria. Our results show that the repair of 8-oxodG is regulated differently in nucleus and mitochondria during the aging process. The specific increase in 8-oxodG-incision activity in mitochondria, rather than a general up-regulation of DNA metabolizing enzymes in those organelles, suggests that this pathway may be up regulated during aging in mice.     

Skin and diabetes mellitus: what do we know?

Diabetes mellitus (DM) is becoming increasingly prevalent worldwide. Although major complications of this condition involve kidney, retina and peripheral nerves, the skin of diabetic patients is also frequently injured. Hence, interest is mounting in the definition of the structural and molecular profile of non-complicated diabetic skin, i.e., before injuries occur. Most of the available knowledge in this area has been obtained relatively recently and, in part, derives from various diabetic animal models. These include both insulin-dependent and insulin-resistant models. Structural work in human diabetic skin has also been carried out by means of tissue samples or of non-invasive methods. Indications have indeed been found for molecular/structural changes in diabetic skin. However, the overall picture that emerges is heterogeneous, incomplete and often contradictory and many questions remain unanswered. This review aims to detail, as much as possible, the various pieces of current knowledge in a systematic and synoptic manner. This should aid the identification of areas in which key questions are still open and more research is needed. A comprehensive understanding of this field could help in determining molecular targets for the prevention and treatment of skin injuries in DM and markers for the monitoring of cutaneous and systemic aspects of the disease. Additionally, with the increasing development of non-invasive optics-based deep-tissue-imaging diagnostic technologies, precise knowledge of cutaneous texture and molecular structure becomes an important pre-requisite for the use of such methods in diabetic patients.     

Lower expression of catalytic and structural subunits of the proteasome contributes to decreased proteolysis in peripheral blood T lymphocytes during aging

Aging, in the immune system, is characterized by a decreased ability to respond to exogenous insults, resulting in increased susceptibility to infections and blunted response to vaccination. While significant age-associated deficits in immune function have been documented, the underlying molecular mechanisms are still being investigated. A consistent decline in the proteolytic activity of the proteasome has been demonstrated with advancing age, implicating an important role for the proteasome in immune senescence, by studies that largely employed proteasome-enriched preparations from cell lysates. With the availability of novel cell permeable active site probes designed specifically for assaying proteasomal activity in live cells, we now confirm our earlier data demonstrating lower catalytic activity of the proteasome in primary human T cells obtained from the elderly when compared to those from young donors. Loss in proteasomal catalytic activity translated into a loss in functional activity, as was observed in a degradation assay employing an ubiquitinated protein substrate, Ub-IkappaBalpha. Unlike fluorogenic peptide substrates, use of ubiquitinated protein substrates not only confer greater stringency in terms of proteasomal hydrolysis, but also involve the participation of the 19S regulatory component. This age-associated loss in proteasomal activity is accompanied by alteration in the levels of catalytic, structural and regulatory subunits, with no change in that of the 11S activator or the inhibitor PAAF1. Oxidative modification, such as carbonylation and lipid-peroxidation, of proteasomal subunits was also detected in T cells from the elderly. Thus, oxidative modification and lower levels of proteasomal subunits contribute to decreased proteolytic activity during immune-senescence.     

Effect of aging on response to induction and metabolizing activity of the hepatic mixed-function oxidase system of male Sprague-Dawley rats

The composition and activity of the rat hepatic mixed-function oxidase system were investigated, in male rats 17 to 127 weeks old, with respect to content of its various components and their response to induction by phenobarbital and beta-naphthoflavone. There were decreases in many of the components of this enzyme system in older rats which could not be fully compensated by phenobarbital induction. However, there appeared to be no age-related loss of response to induction by beta-naphthoflavone. Decreases in mixed-function oxidase enzymes with age did not occur at the same rate or to the same extent. Metabolic studies with ethylmorphine and aniline demonstrated some age-associated changes which did not necessarily parallel reductions in the enzyme system. For example, there was a reduction in apparent Km as a function of age for the hydroxylation of aniline in rats treated with beta-naphthoflavone, even though they showed no apparent change in the amount of cytochrome P-450. There was also a trend to altered Km for the demethylation of ethylmorphine in saline or corn oil treated rats in older animals. We feel that these changes are a reflection of differential reductions in the various isoenzymes of cytochromes P-450. Further studies are planned to confirm this hypothesis.     

Aldehyde dehydrogenases and their role in carcinogenesis.

Aldehydes are highly reactive molecules that may have a variety of effects on biological systems. They can be generated from a virtually limitless number of endogenous and exogenous sources. Although some aldehyde-mediated effects such as vision are beneficial, many effects are deleterious, including cytotoxicity, mutagenicity, and carcinogenicity. A variety of enzymes have evolved to metabolize aldehydes to less reactive forms. Among the most effective pathways for aldehyde metabolism is their oxidation to carboxylic acids by aldehyde dehydrogenases (ALDHs). ALDHs are a family of NADP-dependent enzymes with common structural and functional features that catalyze the oxidation of a broad spectrum of aliphatic and aromatic aldehydes. Based on primary sequence analysis, three major classes of mammalian ALDHs--1, 2, and 3--have been identified. Classes 1 and 3 contain both constitutively expressed and inducible cytosolic forms. Class 2 consists of constitutive mitochondrial enzymes. Each class appears to oxidize a variety of substrates that may be derived either from endogenous sources such as amino acid, biogenic amine, or lipid metabolism or from exogenous sources, including aldehydes derived from xenobiotic metabolism. Changes in ALDH activity have been observed during experimental liver and urinary bladder carcinogenesis and in a number of human tumors, including some liver, colon, and mammary cancers. Changes in ALDH define at least one population of preneoplastic cells having a high probability of progressing to overt neoplasms. The most common change is the appearance of class 3 ALDH dehydrogenase activity in tumors arising in tissues that normally do not express this form. The changes in enzyme activity occur early in tumorigenesis and are the result of permanent changes in ALDH gene expression. This review discusses several aspects of ALDH expression during carcinogenesis. A brief introduction examines the variety of sources of aldehydes. This is followed by a discussion of the mammalian ALDHs. Because the ALDHs are a relatively understudied family of enzymes, this section presents what is currently known about the general structural and functional properties of the enzymes and the interrelationships of the various forms. The remainder of the review discusses various aspects of the ALDHs in relation to tumorigenesis. The expression of ALDH during experimental carcinogenesis and what is known about the molecular mechanisms underlying those changes are discussed. This is followed by an extended discussion of the potential roles for ALDH in tumorigenesis. The role of ALDH in the metabolism of cyclophosphamidelike chemotherapeutic agents is described. This work suggests that modulation of ALDH activity may an important determinant of the effectiveness of certain chemotherapeutic agents.(ABSTRACT TRUNCATED AT 400 WORDS)     

Getting under the skin: the immunogenetics of psoriasis

Psoriasis is a chronic inflammatory disorder of the skin that is mediated by T cells, dendritic cells and inflammatory cytokines. We now understand many of the cellular alterations that underlie this disease, and genomic approaches have recently been used to assess the alterations of gene expression in psoriatic skin lesions. Genetic susceptibility factors that contribute to predisposition to psoriasis are now also being identified. It is hoped that we will soon be able to correlate the cellular pathogenesis that occurs in psoriasis with these genetic factors. In this Review article, we describe what is known about genes that confer increased susceptibility to psoriasis, and we integrate this with what is known about the molecular and cellular mechanisms that occur in other inflammatory and autoimmune disorders.     

Age-associated increase in heterochromatic marks in murine and primate tissues

Chromatin is highly dynamic and subject to extensive remodeling under many physiologic conditions. Changes in chromatin that occur during the aging process are poorly documented and understood in higher organisms, such as mammals. We developed an immunofluorescence assay to quantitatively detect, at the single cell level, changes in the nuclear content of chromatin-associated proteins. We found increased levels of the heterochromatin-associated proteins histone macro H2A (mH2A) and heterochromatin protein 1 beta (HP1β) in human fibroblasts during replicative senescence in culture, and for the first time, an age-associated increase in these heterochromatin marks in several tissues of mice and primates. Mouse lung was characterized by monophasic mH2A expression histograms at both ages, and an increase in mean staining intensity at old age. In the mouse liver, we observed increased age-associated localization of mH2A to regions of pericentromeric heterochromatin. In the skeletal muscle, we found two populations of cells with either low or high mH2A levels. This pattern of expression was similar in mouse and baboon, and showed a clear increase in the proportion of nuclei with high mH2A levels in older animals. The frequencies of cells displaying evidence of increased heterochromatinization are too high to be readily accounted for by replicative or oncogene-induced cellular senescence, and are prominently found in terminally differentiated, postmitotic tissues that are not conventionally thought to be susceptible to senescence. Our findings distinguish specific chromatin states in individual cells of mammalian tissues, and provide a foundation to investigate further the progressive epigenetic changes that occur during aging.     

X-Ray-Radiation-Induced Cooperative Atomic Movements in Protein

X-rays interact with biological matter and cause damage. Proteins and other macromolecules are damaged primarily by ionizing X-ray photons and secondarily by reactive radiolytic chemical species. In particular, protein molecules are damaged during X-ray diffraction experiments with protein crystals, which is, in many cases, a serious hindrance to structure solution. The local X-ray-induced structural changes of the protein molecule have been studied using a number of model systems. However, it is still not well understood whether these local chemical changes lead to global structural changes in protein and what the mechanism is.We present experimental evidence at atomic resolution indicating the movement of large parts of the protein globule together with bound water molecules in the early stages of radiation damage to the protein crystal. The data were obtained from a crystal cryocooled to ~ 100 K and diffracting to 1 ?. The movement of the protein structural elements occurs simultaneously with the decarboxylation of several glutamate and aspartate residues that mediate contacts between moving protein structural elements and with the rearrangement of the water network. The analysis of the anisotropy of atomic displacement parameters reveals that the observed atomic movements occur at different rates in different unit cells of the crystal. Thus, the examination of the cooperative atomic movement enables us to better understand how radiation-induced local chemical and structural changes of the protein molecule eventually lead to disorder in protein crystals.     

The effects of aging on the intimal region of the human saphenous vein: insights from multimodal microscopy and quantitative image analysis

We hypothesized that structural remodeling associated with advancing age occurs in human saphenous veins. To address this hypothesis, we have identified structural remodeling in human saphenous veins by applying histochemistry, fluorescence staining and quantitative image analysis to specifically assess intimal area, intimal cellularity and intimal collagen content and organization. Saphenous veins were collected from patients undergoing coronary artery bypass graft surgery. Area measurements and cellularity were quantified using the image analysis software Stereo Investigator, employing planimetry and counting frames, respectively. Collagen content and organization were quantified in MetaMorph image analysis software based on measurements of color (hue, saturation, and intensity) from polarized light images. Intimal area and cellularity showed no statistically significant increases with age; in contrast, total collagen content showed a significant decrease with advancing age. Furthermore, collagen fiber types also demonstrated a statistically significant alteration with age; increases in age resulted in decreases in larger collagen fibers. No significant changes in small collagen fibers were identified. These results raise the possibility that age-associated structural alterations in total collagen content, specifically collagen fiber size, could be a factor in the etiology of age-associated venous diseases.     

The biochemical aspects of pineal gland functioning in the rat in ontogeny

We have studied metabolic pathways of serotonin in epiphysis of Wistar male rats at the age of 1; 1,5; 2; 3; 6; 12; 24 and 36 months. Epiphysis retains its functional activity throughout the life, however, serotonin metabolism in epiphysis undergoes marked changes. The main regulatory principle is the switch of serotonin metabolic pathways in the pineal gland. Most distinct changes between hydroxy- and methoxyindols in epiphysis have been observed during the periods of age-associated hormonal rearrangements like sexual maturation or involution of the gonad function at the old age.     

Pelvic ileo-anal reservoirs: a lectin histochemical study

Summary Pelvic ileo-anal reservoir (ileal pouch) formation is now a common surgical approach to the management of long-standing inflammatory bowel disease. The ileal mucosa in this new environment responds with changes in morphology and histochemical reactivity, as shown by conventional techniques. In this study, pre-pouch ileum and pouch ileal mucosa from 20 patients have been examined with a large panel of lectins using an avidin-biotin-peroxidase technique, with appropriate negative controls and sugar-inhibition studies. Changes were noted between pre-pouch ileum and the pouch mucosa which were complex, and no single alteration was seen in every case. Most variations related to saccharide sequences near the non-reducing termini of O- and N-linked glycans. Many of these were seen with lectins having requirements for terminal fucosyl residues, and to a lesser extent for galactosyl sequences, and were most obvious in the epithelium. Some of the changes occurred with such frequency as to suggest a direct response to surgery, but many of the variations were likely to be adaptive responses, possibly related to inflammation or infection. The changes in glycans were largely additive and could not be explained as a consequence of the actions of bacterial glycosidases. These alterations suggest that reservoir mucosa undergoes an adaptive response to the new intraluminal environment, without frank colonic metaplasia, and some changes occur to a greater degree in patients with pouchitis.     

Association of Structural Global Brain Network Properties with Intelligence in Normal Aging

Higher general intelligence attenuates age-associated cognitive decline and the risk of dementia. Thus, intelligence has been associated with cognitive reserve or resilience in normal aging. Neurophysiologically, intelligence is considered as a complex capacity that is dependent on a global cognitive network rather than isolated brain areas. An association of structural as well as functional brain network characteristics with intelligence has already been reported in young adults. We investigated the relationship between global structural brain network properties, general intelligence and age in a group of 43 cognitively healthy elderly, age 60–85 years. Individuals were assessed cross-sectionally using Wechsler Adult Intelligence Scale-Revised (WAIS-R) and diffusion-tensor imaging. Structural brain networks were reconstructed individually using deterministic tractography, global network properties (global efficiency, mean shortest path length, and clustering coefficient) were determined by graph theory and correlated to intelligence scores within both age groups. Network properties were significantly correlated to age, whereas no significant correlation to WAIS-R was observed. However, in a subgroup of 15 individuals aged 75 and above, the network properties were significantly correlated to WAIS-R. Our findings suggest that general intelligence and global properties of structural brain networks may not be generally associated in cognitively healthy elderly. However, we provide first evidence of an association between global structural brain network properties and general intelligence in advanced elderly. Intelligence might be affected by age-associated network deterioration only if a certain threshold of structural degeneration is exceeded. Thus, age-associated brain structural changes seem to be partially compensated by the network and the range of this compensation might be a surrogate of cognitive reserve or brain resilience.