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R Weindruch

Publications and source records attributed to R Weindruch.

At least 19 recordsLinked to original sources
PubMed2000

Caloric restriction improves thermotolerance and reduces hyperthermia-induced cellular damage in old rats.

Adult-onset, long-term caloric restriction (CR) prolongs maximum life span in laboratory rodents. However, the effect of this intervention on an organism's ability to cope with a physical challenge has not been explored. We investigated the influence of CR and aging on stress tolerance in old rats exposed to an environmental heating protocol on two consecutive days. We hypothesized that CR would increase heat tolerance by reducing cellular stress and subsequent accrual of oxidative injury. All calorically restricted rats survived both heat exposures compared with only 50% of their control-fed counterparts. CR also decreased heat-induced radical generation, stress protein accumulation, and cellular injury in the liver. In addition, heat stress stimulated marked induction of the antioxidant enzymes manganese-containing superoxide dismutase and catalase, along with strong nuclear catalase expression in liver samples from rats subjected to CR. In contrast, stress-related induction of antioxidant enzymes was blunted, and nuclear catalase expression was unchanged from euthermic conditions in the control-fed group. These data suggest that CR reduces cellular injury and improves heat tolerance of old animals by lowering radical production and preserving cellular ability to adapt to stress through antioxidant enzyme induction and translocation of these proteins to the nucleus.

Adaptation, Physiological↗
PubMed2000

Androgen and taxol cause cell type-specific alterations of centrosome and DNA organization in androgen-responsive LNCaP and androgen-independent DU145 prostate cancer cells.

We investigated the effects of androgen and taxol on the androgen-responsive LNCaP and androgen-independent DU145 prostate cancer cell lines. Cells were treated for 48 and 72 h with 0.05-1 nM of the synthetic androgen R1881 and with 100 nM taxol. Treatment of LNCaP cells with 0.05 nM R1881 led to increased cell proliferation, whereas treatment with 1 nM R1881 resulted in inhibited cell division, DNA cycle arrest, and altered centrosome organization. After treatment with 1 nM R1881, chromatin became clustered, nuclear envelopes convoluted, and mitochondria accumulated around the nucleus. Immunofluorescence microscopy with antibodies to centrosomes showed altered centrosome structure. Although centrosomes were closely associated with the nucleus in untreated cells, they dispersed into the cytoplasm after treatment with 1 nM R1881. Microtubules were only faintly detected in 1 nM R1881-treated LNCaP cells. The effects of taxol included microtubule bundling and altered mitochondria morphology, but not DNA organization. As expected, the androgen-independent prostate cancer cell line DU145 was not affected by R1881. Treatment with taxol resulted in bundling of microtubules in both cell lines. Additional taxol effects were seen in DU145 cells with micronucleation of DNA, an indication of apoptosis. Simultaneous treatment with R1881 and taxol had no additional effects on LNCaP or DU145 cells. These results suggest that LNCaP and DU145 prostate cancer cells show differences not only in androgen responsiveness but in sensitivity to taxol as well.

Androgens↗
PubMed1999

Gene expression profile of aging and its retardation by caloric restriction.

The gene expression profile of the aging process was analyzed in skeletal muscle of mice. Use of high-density oligonucleotide arrays representing 6347 genes revealed that aging resulted in a differential gene expression pattern indicative of a marked stress response and lower expression of metabolic and biosynthetic genes. Most alterations were either completely or partially prevented by caloric restriction, the only intervention known to retard aging in mammals. Transcriptional patterns of calorie-restricted animals suggest that caloric restriction retards the aging process by causing a metabolic shift toward increased protein turnover and decreased macromolecular damage.

Aging↗
PubMed1999

Effect of antioxidants on androgen-induced AP-1 and NF-kappaB DNA-binding activity in prostate carcinoma cells.

BACKGROUND: Previous studies have suggested that male hormones (androgens) and certain forms of oxygen (reactive oxygen species) are linked to the development of prostate cancer. We hypothesized that androgens contribute to prostate carcinogenesis by increasing oxidative stress. We further hypothesized that antioxidants reduce prostate cancer risk by modulating androgen effects on cellular processes. METHODS: To test these hypotheses, we looked for 1) a change in the level of reactive oxygen species in the presence of androgens, 2) androgen-induced binding activity of transcriptional activators AP-1 and NF-kappaB, whose activities are known to be altered during cell proliferation, and 3) the effect of antioxidants on androgen-induced transcription factor binding. RESULTS: Physiologic concentrations (1 nM) of 5alpha-dihydrotestosterone or 1-10 nM R1881, a synthetic androgen, produced sustained elevation of AP-1 and NF-kappaB DNA-binding activity in LNCaP cells, an androgen-responsive human prostate carcinoma cell line. Androgen-independent DU145 cells (another human prostate carcinoma cell line) were unaffected by R1881 treatment. AP-1-binding activity increased 5 hours after 1 nM R1881 treatment; NF-kappaB DNA-binding activity increased after 36 hours. Both activities remained elevated for at least 120 hours. Nuclear AP-1 and NF-kappaB protein levels were not elevated. Antioxidant vitamins C plus E blocked both androgen-induced DNA-binding activity and production of reactive oxygen species. CONCLUSION: Physiologic concentrations of androgens induce production of reactive oxygen species and cause prolonged AP-1 and NF-kappaB DNA-binding activities, which are diminished by vitamins C and E.

Androgens↗
PubMed1999

Dietary intervention at middle age: caloric restriction but not dehydroepiandrosterone sulfate increases lifespan and lifetime cancer incidence in mice.

Dietary manipulations to prevent cancer and other diseases of aging have drawn broad public and scientific attention. One indicator of this interest is that dehydroepiandrosterone (DHEA) supplements are widely consumed by those who hope that this hormone may keep them "younger longer." However, key data to support this belief are lacking. For example, the influence of DHEA treatment on spontaneous cancer and life span in healthy, long-lived strains of mice or rats is unknown. This is in contrast to the situation for caloric restriction (CR), which is known to oppose cancer development and increase maximum life span in rodents. To address this issue, we assigned 300 middle age (12-month-old) male C57BL/6 mice to one of four groups (n = 75 for each group) and evaluated them for longevity and spontaneous disease patterns. Two groups were fed a normal diet (ND), and two others were fed a calorie-restricted diet (RD). One ND group and one RD group were also given 25 microg/ml DHEA sulfate (DHEAS) in their drinking water. Although urine samples from DHEAS-treated mice contained 10-fold more DHEA and DHEAS than did samples from unsupplemented mice, DHEAS administration did not affect body weight, life span, or cancer patterns. The RD lowered body weight by 26% and increased maximum life span by approximately 15%. The incidence of the most prevalent cancer, plasma cell neoplasm, was higher in RD mice (66%) than in ND mice (41%). Thus, DHEAS, as administered here, influenced neither cancer nor longevity at two caloric intakes. In contrast, CR from middle age increased longevity, the age at which tumor-bearing mice died, and the percentage of mice dying with cancers, suggesting that CR may retard promotion and/or progression of existing lymphoid cancers.

Age Factors↗
PubMed1999

Localization of 4-hydroxy-2-nonenal-modified proteins in kidney following iron overload.

Intraperitoneal (IP) injection of ferric nitrilotriacetate (Fe-NTA) to rats and mice results in iron-induced free radical injury and cancer in kidneys. We sought to clarify the exact localization of acute oxidative damage in Fe-NTA-induced nephrotoxicity by performing immunogold light and electron microscopic (EM) techniques using an antibody against 4-hydroxy-2-nonenal (HNE)-modified proteins. Biochemical assays were done to provide complementary quantitative data. Renal accumulation of lipid peroxidation-derived aldehydes, such as malondialdehyde (MDA) and 4-hydroxy-2-alkenals (4-HDA), increased in parallel with protein carbonyl content, an indicator of protein oxidation, 30 min after administration of Fe-NTA. Immunogold light microscopy showed that HNE-modified proteins increased at 30 min with positivity localized to proximal tubular cells. Immunogold EM demonstrated that HNE-modified proteins were mainly in the mitochondria and nuclei of the proximal tubular epithelium. The intensity of labeling at both the light and EM levels increased together with levels of biochemically measured lipid peroxidation products and protein carbonyl content. Our data suggest that the mechanism of acute nephrotoxicity of Fe-NTA involves mitochondrial and nuclear oxidative damage, findings that may help to define the mechanisms of iron-induced cell injury.

Aldehydes↗
PubMed1999

Caloric intake and aging: mechanisms in rodents and a study in nonhuman primates.

Caloric restriction (CR) increases maximum life span in rodents while attenuating the development of age-associated pathological and biological changes. Although nearly all of the rodent studies have initiated CR early in life (1-3 months of age), CR, when started at 12 months of age, also extends maximum life span in mice. Two main questions face investigators of CR. One concerns the mechanisms by which CR retards aging and diseases in rodents. There is evidence that CR may act, at least in part, by reducing oxidative stress. A CR-induced decrease in oxidative stress appears to be most profound in post-mitotic tissues and may derive from lower mitochondrial production of free radicals. The second issue is whether CR will exert similar effects in primates. Studies on CR in rhesus monkeys (maximum life span approximately 40 years) support the notion of human translatability. We describe the University of Wisconsin Study of rhesus monkeys subjected to a 30% reduction of caloric intake starting at either 1989 or 1994 when they were approximately 10 years old. The data from our study and from other trials suggest that CR can be safely carried out in monkeys and that certain physiological effects of CR that occur in rodents (e.g., decreased blood glucose and insulin levels, improved insulin sensitivity, and lowering of body temperature) also occur in monkeys. Whether oxidative stress in monkeys is reduced by CR will be known by the year 2000, while effects on longevity and diseases should be clearly seen by, appropriately, 2020.

Aging↗
PubMed1999

Influence of caloric restriction on the development of atherosclerosis in nonhuman primates: progress to date.

Caloric restriction (CR) has been observed to retard aging processes and extend the maximum life span in rodents. In an effort to evaluate the effect of this nutritional intervention on physiologic variables in higher species, several nonhuman primate trials are ongoing. In particular, a study evaluating the independent effect of CR on the extent of atherosclerosis was initiated in 1993 in 32 adult cynomolgus monkeys. Therefore, the trial was designed to achieve identical cholesterol intake after animals were randomized to a control group or a calorie-restricted group (30% reduction from baseline caloric intake). The animals were routinely evaluated for glycated proteins, plasma insulin and glucose levels, insulin sensitivity, and specific measures for abdominal fat distribution by CT scans over a 4-year interval. The results from 4 years of intervention demonstrate that CR improves cardiovascular risk factors (such as visceral fat accumulation) and improves insulin sensitivity. In contrast to other primate studies with normolipidemic animals, CR had no independent effects on plasma lipid levels and composition in the presence of equivalent amounts of dietary cholesterol intake. Preliminary analysis of atherosclerotic lesion extent in the abdominal aorta has failed to demonstrate differences between control animals and CR animals. Follow-up studies are being conducted to determine the effect of CR on atherosclerosis extent in coronary and carotid arteries.

Aging↗
PubMed1998

Influences of caloric restriction on age-associated skeletal muscle fiber characteristics and mitochondrial changes in rats and mice.

The effect of caloric restriction (CR) initiated in adult rats (17 months of age) on the abundance of deleted mitochondrial genomes, mitochondrial enzymatic abnormalities, and fiber number was examined in rat skeletal muscle. Vastus lateralis muscle from young (3-4 months) ad libitum-fed, old (30-32 months) restricted (35% and 50% CR, designated CR35 and CR50, respectively), and old ad libitum-fed rats (29 months) was studied. CR preserved fiber number and fiber-type composition in the CR50 rats. In the old rats from all groups, individual fibers were found with either no detectable cytochrome-c oxidase activity (COX-), hyperactive for succinate dehydrogenase activity (SDH++), or both COX- and SDH++. Muscle from the CR50 rats contained significantly fewer COX- and SDH++ fibers than did the muscle from the CR35 rats. CR50 rats also had significantly lower numbers of mtDNA deletion products in two (adductor longus and soleus) of the four muscles examined compared to CR35 rats. These data indicate that CR begun in late middle age can retard age-associated fiber loss and fiber-type changes as well as lower the number of skeletal muscle fibers exhibiting mitochondrial enzyme abnormalities. CR can also decrease the accumulation of deleted mitochondrial genomes.

Aging↗
PubMed1998

Association of age-related mitochondrial abnormalities with skeletal muscle fiber atrophy.

The hypothesis that mitochondrial dysfunction contributes to the senescent loss of skeletal muscle was investigated in quadriceps from 2- to 39-year old rhesus monkeys. Histological approaches, both cross-sectional (a single cross-section of the muscle) and longitudinal (multiple cross-sections of individual fibers spanning a 350-1600 microm region), were used to identify muscle fibers with abnormal mitochondrial electron transport system (ETS) enzyme activities and mitochondrial DNA deletions. Fibers were examined for two ETS activities, succinate dehydrogenase (SDH, ETS complex II) and cytochrome c oxidase (COX, ETS complex IV). The number of individual fibers containing ETS abnormalities (predominately negative for cytochrome c oxidase activity and/or hyperreactive for succinate dehydrogenase) increased with age. Deletions of the mitochondrial genome were observed in 89% of these ETS abnormal fibers. Longitudinal analysis allowed characterization of the ETS abnormal phenotype along their length. A decrease in cross-sectional area in 14% of the ETS abnormal fibers supports the hypothesis that deleted mitochondrial genomes may contribute to age-related fiber atrophy.

Aging↗
PubMed1998

Caloric restriction prevents age-associated accrual of oxidative damage to mouse skeletal muscle mitochondria.

The purpose of this study was to understand the nature of the causes underlying the senescence-related decline in skeletal muscle mass and performance. Protein and lipid oxidative damage to upper hindlimb skeletal muscle mitochondria was compared between mice fed ad libitum and those restricted to 40% fewer calories--a regimen that increases life span by approximately 30-40% and attenuates the senescence-associated decrement in skeletal muscle mass and function. Oxidative damage to mitochondrial proteins, measured as amounts of protein carbonyls and loss of protein sulfhydryl content, and to mitochondrial lipids, determined as concentration of thiobarbituric acid reactive substances, significantly increased with age in the ad libitum-fed (AL) C57BL/6 mice. The rate of superoxide anion radical generation by submitochondrial particles increased whereas the activities of antioxidative enzymes superoxide dismutase, catalase, and glutathione peroxidase in muscle homogenates remained unaltered with age in the AL group. In calorically-restricted (CR) mice there was no age-associated increase in mitochondrial protein or lipid oxidative damage, or in superoxide anion radical generation. Crossover studies, involving the transfer of 18- to 22-month-old mice fed on the AL regimen to the CR regimen, and vice versa, indicated that the mitochondrial oxidative damage could not be reversed by CR or induced by AL feeding within a time frame of 6 weeks. Results of this study indicate that mitochondria in skeletal muscles accumulate significant amounts of oxidative damage during aging. Although such damage is largely irreversible, it can be prevented by restriction of caloric intake.

Age Factors↗
PubMed1998

Oxidative stress and aging reduce COX I RNA and cytochrome oxidase activity in Drosophila.

Drosophila melanogaster displays an age-associated increase in oxidative damage and a decrease in mitochondrial transcripts. To determine if these changes result in energy production deficiencies, we measured the electron transport system (ETS) enzyme activity, and ATP levels with age. No statistically significant influences of age on activities of complexes I and II or citrate synthase were observed. In contrast, from 2 to 45 days post-eclosion, declines were found in complex IV cytochrome c oxidase activity (COX, 40% decline) and ATP abundance (15%), while lipid peroxidation increased 71%. We next examined flies that were either genetically or chemically oxidatively stressed to determine the effect on levels of mitochondrial-encoded cytochrome oxidase I RNA (coxI) and COX activity. A catalase null mutant line had 48% of coxI RNA compared to the wild type. In Cu/Zn superoxide dismutase (cSOD) null flies, the rate of coxI RNA decline was greater than in controls. CoxI RNA also declined with increasing hydrogen peroxide (H2O2) treatment, which was reflected in reduced cytochrome c oxidase (COX) activity. These results show that oxidative stress is closely associated with reductions in mitochondrial transcript levels and support the hypothesis that oxidative stress may contribute to mitochondrial dysfunction and aging in D. melanogaster.

Adenosine Triphosphate↗
PubMed1998

Decreased mitochondrial RNA levels without accumulation of mitochondrial DNA deletions in aging Drosophila melanogaster.

Declines in electron transport system (ETS) activity have been reported to occur with advancing age in Drosophila melanogaster and many other animals. It has been proposed that these changes are importantly involved in the aging process. ETS decline has been attributed to mitochondrial nucleic acid damage. We analyzed various ages of D. melanogaster (embryos to 60-day-old adults) for the presence of mutated mitochondrial DNA (mtDNA) genomes. Although mtDNA genomes with large DNA deletions (up to 5 kb) were identified, abundance was low and remained constant throughout adult life. Therefore, these mtDNA deletions do not appear to be sufficiently abundant to cause large declines in ETS activity. Next, we analyzed various ages of D. melanogaster for the abundance of four mitochondrial-encoded and two nuclear-encoded ETS transcripts. The abundance of the mitochondrial transcripts declined 5-10-fold, while the nuclear-encoded transcripts declined 2-5-fold with advancing age. Separation of flies on the basis of flight loss was used to distinguish physiologic age from chronological age. Insects capable of flight at 30 days of age were found to have a 4-fold higher abundance of cox I mitochondrial-encoded RNA compared to flightless insects. No difference, however, was apparent in the nuclear-encoded beta-ATPase RNA level, suggesting only mitochondrial RNA (mtRNA) declines are associated with life expectancy.

Aging↗
PubMed1998

Caloric restriction in rhesus monkeys reduces low density lipoprotein interaction with arterial proteoglycans.

Caloric restriction (CR) has been shown to retard aging processes in many species. We investigated effects of CR on plasma low density lipoproteins (LDL), a major risk factor for the age-associated process of atherosclerosis. Studies emphasized effects of CR on LDL composition and their interaction with arterial proteoglycans (PG). Rhesus monkeys were fed a control diet (n=13) or subjected to CR (n=12 fed 30% less calories) for > 5 years. Plasma LDL cholesterol concentrations were similar for control and CR groups (82+/-8 vs 72+/-6 mg/dL, mean+/-SEM). LDL was isolated by ultracentrifugation and HPLC. LDL particles from CR animals had a lower molecular weight (2.9+/-0.1 vs 3.2+/-0.1 g/micromol, p < .05) and were depleted in triglyceride (249+/-16 vs 433+/-49 mol/particle, p < .005) and phospholipid (686+/-20 vs 837+/-33 mol/particle, p <.001). Lower PG binding was measured for LDL from CR animals (10.1+/-0.8 vs 15.6+/-1.1 microg LDL cholesterol/microg PG, p <.005). This was associated with the lower triglycerides (r=.76, p < .0005) and phospholipids (r=.48, p < .01). Thus, a dietary intervention which may retard aging inhibits a proposed mechanism of atherogenesis.

Animals↗
PubMed1998

Age-related increase in mitochondrial proton leak and decrease in ATP turnover reactions in mouse hepatocytes.

Age-related changes in mitochondria, including decreased respiratory control ratios and altered mitochondrial inner membrane lipid composition, led us to study oxidative phosphorylation in hepatocytes from old (30 mo) and young (3 mo) male C57BL/J mice. Top-down metabolic control analysis and its extension, elasticity analysis, were used to identify changes in the control and regulation of the three blocks of reactions constituting the oxidative phosphorylation system: substrate oxidation, mitochondrial proton leak, and the ATP turnover reactions. Resting oxygen consumption of cells from old mice was 15% lower (P < 0.05) than in young cells. This is explained entirely by a decrease in oxygen consumption supporting ATP turnover reactions. At all values of mitochondrial membrane potential assessed, the proportion of total oxygen consumption used to balance the leak was greater in the old cells than in the young cells. Metabolic control coefficients indicate a shift in control over respiration and phosphorylation away from substrate oxidation toward increased control by leak and by ATP turnover reactions. Control of the actual number of ATP molecules synthesized by mitochondria for each oxygen atom consumed by the ATP turnover and leak reactions was greater in old than in young cells, showing that efficiency in older cells is more sensitive to changes in these two blocks of reactions than in young cells.

Adenosine Triphosphate↗
PubMed1997

Caloric restriction diminishes the age-associated loss of immunoreactive catalase in rat prostate.

BACKGROUND: Caloric restriction (CR) retards aging and diseases in mice, rats, and other animals by unknown mechanisms. A popular hypothesis is that CR acts by opposing age-associated increases in oxidative stress. METHODS: Because influences of CR on antioxidant enzymes in the prostate have not been previously investigated, immunohistologic methods (light and electron microscopy) were used to determine the prostatic localization of catalase (CAT) in rats of diverse ages (3-32 months) fed either normally or subjected to CR from age 16 months. RESULTS: In 20-month-old rats fed either diet, CAT appeared as dense deposits at the apical poles of the epithelium in the lateral lobes, and within the ductular lumens, suggesting that CAT is secreted. Confirmation of both liver peroxisomal and prostatic apical cytoplasmic localization of CAT was provided by electron microscopic immunogold staining. The amount of CAT was reduced at 30 months in normally fed rats but not in those on CR. CONCLUSIONS: CAT appears to be a secretory product of the epithelial cells in the lateral lobes of the rat prostate. Further, CR from late-middle age opposed the age-associated loss of this intracellular enzyme activity.

Aging↗
PubMed1997

Dietary restriction in rhesus monkeys: lymphopenia and reduced mitogen-induced proliferation in peripheral blood mononuclear cells.

Dietary restriction (DR) markedly extends mean and maximal life span, and retards the rate of biological aging in rodent models; however, it is unknown if these results occur in primate species. The purpose of the current study was to investigate selected immunologic outcomes in Rhesus monkeys subjected to DR for a period of seven years. Similar to observations in mice on DR, lymphopenia occurred in the restricted monkeys. Compared to normally fed controls, the mitogen-induced proliferative responses of peripheral blood mononuclear cells (PBMC) were reduced in monkeys subjected to DR very early in life (up to 1 year), but not in others restricted in young adulthood (3-5 years). These data indicate that lymphopenia is a shared occurrence in rodents and primates on DR. However, the mitogen-induced proliferative data accumulated in rodents and primates cannot now be compared because PBMC have not been studied long enough or in comparable detail in primates fed restricted diets.

Aging↗