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At least 505 records · Page 28Linked to original sources
PubMed2006

Disruption and overexpression of Arabidopsis phytosulfokine receptor gene affects cellular longevity and potential for growth.

Phytosulfokine (PSK), a 5-amino acid sulfated peptide that has been identified in conditioned medium of plant cell cultures, promotes cellular growth in vitro via binding to the membrane-localized PSK receptor. Here, we report that loss-of-function and gain-of-function mutations of the Arabidopsis (Arabidopsis thaliana) PSK receptor gene (AtPSKR1) alter cellular longevity and potential for growth without interfering with basic morphogenesis of plants. Although mutant pskr1-1 plants exhibit morphologically normal growth until 3 weeks after germination, individual pskr1-1 cells gradually lose their potential to form calluses as tissues mature. Shortly after a pskr1-1 callus forms, it loses potential for growth, resulting in formation of a smaller callus than the wild type. Leaves of pskr1-1 plants exhibit premature senescence after bolting. Leaves of AtPSKR1ox plants exhibit greater longevity and significantly greater potential for callus formation than leaves of wild-type plants, irrespective of their age. Calluses derived from AtPSKR1ox plants maintain their potential for growth longer than wild-type calluses. Combined with our finding that PSK precursor genes are more strongly expressed in mature plant parts than in immature plant parts, the available evidence indicates that PSK signaling affects cellular longevity and potential for growth and thereby exerts a pleiotropic effect on cultured tissue in response to environmental hormonal conditions.

Amino Acid Sequence↗
PubMed1978

The effect of tobacco smoke condensate on the growth and longevity of human diploid fibroblasts.

Human embryonic diploid lung fibroblasts were exposed to various fractions of cigarette smoke condensate over their in vitro life-time. Most fractions were toxic at a concentration of 50 microgram/ml, with the exception of the strong acid and one water soluble basic fraction, which stimulated growth and increased longevity significantly at this concentration. Most fractions produced no effect on cell growth at 10 microgram/ml, with the exception of another basic fraction which inhibited growth at 1 microgram/ml. Nicotine had no apparent effect on growth and longevity at 50 microgram/ml. The neutral fraction containing the polynuclear hydrocarbon carcinogens produced normal growth and longevity at 10 microgram/ml. No cell transformations were observed.

Cell Division↗
PubMed2005

Why females live longer than males: control of longevity by sex hormones.

Females live longer than males in many species, including humans. We have traced a possible explanation for this phenomenon to the beneficial action of estrogens, which bind to estrogen receptors and increase the expression of longevity-associated genes, including those encoding the antioxidant enzymes superoxide dismutase and glutathione peroxidase. As a result, mitochondria from females produce fewer reactive oxygen species than those from males. Administering estrogens has serious drawbacks, however--they are feminizing (and thus cannot be administered to males) and may increase the incidence of serious diseases such as uterine cancer in postmenopausal women. Phytoestrogens, which are present in soy or wine, may have some of the favorable effects of estrogens without their undesirable effects. Study of gender differences in longevity may help us to understand the basic processes of aging and to devise practical strategies to increase the longevity of both females and males.

Aged↗
PubMed1967

The ginkgo, the most ancient living tree. The resistance of Ginkgo biloba L. to pests accounts in part for the longevity of this species.

Fossil records clearly demonstrate that the group of trees known as Ginkgoales, of which today Ginkgo biloba is the sole living member, date back over 200 million years. Ginkgo bilboa itself is one of the oldest of living plants (4). It appears that the longevity of this tree and its long reproductive period are at least partially responsible for the persistence of the species. The resistance of these trees to pests such as insects, bacteria, viruses, and fungi has been studied. It is believed that their unusual resistance to pests accounts in part for the longevity of the trees and also, in turn, for the longevity of the species.

Air Pollution↗
PubMed1997

Mortality rate and longevity of food-restricted exercising male rats: a reevaluation.

Food restriction increases the maximal longevity of rats. Male rats do not increase their food intake to compensate for the increase in energy expenditure in response to exercise. However, a decrease in the availability of energy for growth and cell proliferation that induces an increase in maximal longevity in sedentary rats only results in an improvement in average survival, with no extension of maximal life span, when caused by exercise. In a previous study (J.O. Holloszy and K.B. Schechtman. J. Appl. Physiol. 70:1529-1535, 1991), to test the possibility that exercise prevents the extension of life span by food restriction, wheel running and food restriction were combined. The food-restricted runners showed the same increase in maximal life span as food-restricted sedentary rats but had an increased mortality rate during the first one-half of their mortality curve. The purpose of the present study was to determine the pathological cause of this increased early mortality. However, in contrast to our previous results, the food-restricted wheel-running rats in this study showed no increase in early mortality, and their survival curves were virtually identical to those of sedentary animals that were food restricted so as to keep their body weights the same as those of the runners. Thus it is possible that the rats in the previous study had a health problem that had no effect on longevity except when both food restriction and exercise were superimposed on it. Possibly of interest in this regard, the rats in this study did considerably more voluntary running than those in the previous study. It is concluded that 1) moderate caloric restriction combined with exercise does not normally increase the early mortality rate in male rats, 2) exercise does not interfere with the extension of maximal life span by food restriction, and 3) the beneficial effects of food restriction and exercise on survival are not additive or synergistic.

Animals↗
PubMed2003

Longevity of batteries in internal pulse generators used for deep brain stimulation.

The longevity of batteries in internal pulse generators (IPGs) used clinically for deep brain stimulation is not known. We conducted a study to assess the life span of these batteries. From 1993 to 2000, 163 single-channel batteries were surgically implanted in our institution. The electrical settings utilized in patients who had battery failures were assessed and the total electrical energy delivered (TEED) was calculated and correlated with battery longevity. Fourteen IPGs had battery failure requiring replacement. The median life span of the batteries was 45 months. Batteries with high energy consumption as assessed by TEED had a reduced life span (r = -0.82, p < or = 0.001). Patients with essential tremor who required battery replacement needed higher settings to control their symptoms and therefore presented a shorter battery life when compared to patients with Parkinson's disease. In our series of patients who needed battery replacement, battery longevity varied with stimulation parameters but was longer than expected from the manufacturer's specifications.

Electric Power Supplies↗
PubMed1983

Genetic effects on the longevity of cultured human fibroblasts. I. Werner's syndrome.

Fibroblast cultures were established from skin biopsies from 4 male Werner's syndrome patients, aged 45-50. Several subcultures were obtained from each primary outgrowth and these were passaged to the end of their in vitro lifespan. Their average longevity was significantly less than control skin fibroblasts, but there was extreme variability amongst parallel cultures. In the most thoroughly studied case, the longevity of 19 subcultures derived from a single biopsy varied from 5 to 26 passages, showing that there was considerable heterogeneity in the growth potential of the cells in the primary culture. Moreover, the growth rate from any one culture was not uniform, since long periods of slow growth were sometimes succeeded by much more rapid proliferation. These features of Werner's syndrome fibroblast populations are not seen in cultures from normal individuals. The longevity of fibroblasts from one progeria patient was also shown to be much shorter than controls. Metaphases from 3 Werner's patients demonstrated a much higher frequency of chromosome abnormalities than in normal fibroblasts and also provided evidence of subclones containing a characteristic 'marker' chromosome.

Adolescent↗
PubMed1983

Genetic effects on the longevity of cultured human fibroblasts. IV. Enhanced growth potential of cystic fibrosis cells.

The in vitro longevity of skin fibroblasts in several parallel cultures from each of 4 cystic fibrosis (CF) patients and 3 control patients was measured by serial passages. The control cultures reached 51-56 passages before growth ceased. 1 CF strain achieved an average of 69 passages and another 64 passages. Both of these longevities are significantly greater than the controls. 2 CF strains had significantly shorter longevities than the controls. The results indicate that the CF gene is expressed in cultured fibroblasts and provide further evidence that there may be more than one form of the disease.

Adolescent↗
PubMed2004

Aging, longevity, inflammation, and cancer.

Cancer rates increase sharply with age in both sexes, and the majority of cases of cancer occur in patients over the age of 65 years. However, the incidence and mortality for cancer level off around 85-90 years of age, followed by a plateau, or even a decline in the last decades of life. Therefore, it seems reasonable to conclude that centenarians are endowed with a peculiar resistance to cancer. Tumor progression is a complex process that depends on interactions between tumor and host cells. One aspect of the host response, the inflammatory response, is of particular interest because it includes the release of proinflammatory cytokines, some of which may promote tumor growth and hence influence survival. Data in the literature reviewed in this paper suggest that some kind of solid tumors are affected by regulatory cytokine genotypes. In particular proinflammatory genotypes characterized by a low IL-10 producer or a high IL-6 producer seem to be associated with a worse clinical outcome. On the other hand, recent evidence has linked IL-10 and IL-6 cytokine polymorphisms to longevity. In fact, those individuals who are genetically predisposed to produce high levels of IL-6 have a reduced capacity to reach the extreme limits of human life, whereas the high IL-10-producer genotype is increased among centenarians. This opposite effect of IL-6 and IL-10 common gene polymorphisms in cancer and longevity is intriguing. These data prompt considerations of the role that antagonistic pleiotropy plays in disease and in longevity. Inflammatory genotypes may be both friends and enemies. In fact, they are an important and necessary part of the normal host responses to pathogens, but the overproduction of inflammatory cytokines might cause immune-inflammatory diseases and eventually death. In fact, our immune system has evolved to control pathogens, so proinflammatory responses are likely to be evolutionarily programmed to resist fatal infections, and a high IL-6 or a low IL-10 production is associated with increased resistance to pathogens. However, decreased level of IL-6 or increased level of IL-10 might better control inflammatory responses and cancer development. These conditions might result in an increased chance of long-life survival in an environment with a reduced antigen (i.e., pathogen) load.

Adult↗
PubMed2000

Ultrasonographic study of carotid artery structural changes with natural longevity.

The changes in carotid artery structure during the natural longevity of the Uighurs people were compared with other ethnic groups. The 419 subjects were divided into (1) longevity and (2) older groups as follows: Uighurs longevity group in Hotan (ULH); and Uighurs, Hans and Kazaks older groups in Hotan or Balikun (UOH, HOH, HOB and KOB). The wall thickness of the common carotid artery (CCA) was measured by ultrasonography. Risk factors were evaluated by measuring total cholesterol (T-C), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglyceride (TG) and fasting glucose, and by 24-h ambulatory blood pressure monitoring. Wall thickness and blood pressure were greater in the Balikun groups than in the Hotan groups. The CCA wall was thicker in Uighurs and Kazaks than in Hans, in the ULH than in the UOH. There was no significant difference in blood pressure among the Hotan groups. LDL-C and glucose were higher and HDL-C was lower in the Hotan groups than in the Balikun groups. T-C, LDL-C, TG and glucose were higher in the HOH than in the ULH and UOH. Systolic blood pressure and LDL-C were higher and TG was lower in the KOB than in the HOB. These results suggest that an increased CCA wall thickness can be attributed to age in Hotan, and to a higher blood pressure level in Balikun, and that the higher blood pressure affected the Balikun groups more than the Hotan groups.

Aged↗
PubMed2001

Enhancing longevity of pacemakers through reprogramming. Underutilization and cost-effectiveness.

OBJECTIVE: This study was performed to observe the number of pacemakers that had never been reprogrammed after implantation, and the effect of optimised output programming on estimated longevity of pulse generators in patients with pacemaker METHODS: Sixty patients with Teletronics Reflex pacemakers were evaluated in a pacemaker clinic, from the time of the beginning of its activities, in June 1998, until March 1999. Telemetry was performed during the first clinic visit, and we observed how many pulse generators retained nominal output settings of the manufactures indicating the absence of reprogramming until that date. After evaluation of the capture threshold, reprogramming of pacemakers was performed with a safety margin of 2 to 2.5:1, and we compared the estimated longevity based on battery current at the manufacturer's settings with that based on settings achieved after reprogramming. RESULTS: In 95% of the cases, the original programmed setting was never reprogrammed before the patients attended the pacemaker clinic. Reprogramming the pacemaker prolonged estimated pulse generator life by 19.7+/-15.6 months (35.5%). CONCLUSION: The majority of the pacemakers evaluated had never been reprogrammed. Estimated pulse generator longevity can be prolonged significantly, using this simple, safe, efficacious, and cost-effective procedure.

Calibration↗
PubMedDate not supplied

Effects of gamma irradiation on the reproductive capacity and the longevity of Panstrongylus megistus (Hemiptera: Reduviidae).

The effects of radiation on the reproductive capacity and the longevity of Panstrongylus megistus were studied. An indirect correlation between longevity and radiation doses was observed. Males were more affected than females. Longevity of females submitted to 10 Gy was not different when compared to controls. Some of the irradiated males copulated and in these cases semen was transferred to females, but only few eggs were laid. Fertility was seriously affected in all irradiated groups, decreasing with increasing intensity of dose. The dose of 80 Gy induced sterility in males and females. Gelatinous spermatophores that were expelled by females irradiated with 20 and 40 Gy, may be a consequence of irradiation that induced modification in the bursa copulatrix pH.

Animals↗
PubMed2000

The longevity of actinosporean spores from oligochaetes of Lake Sasajewun, Algonquin Park, Ontario, and their reaction to fish mucus.

The longevity of 7 forms of actinosporean spores and the reaction of 6 forms of actinosporeans to fish mucus were investigated. The maximum longevity of actinosporean spores kept at ambient laboratory temperatures was 14 days. Spore longevity ranged from 11 to 14 days among actinosporeans. The reaction of spores to fish mucus varied among the actinosporeans. Triactinomyxon F of Xiao and Desser, 1998 reacted only to the mucus of the common shiner Luxilus cornutus, and golden shiner Notemigonus crysoleucas, whereas the aurantiactinomyxon form of Xiao and Desser, 1998, and raabeia B of Xiao and Desser, 1998 reacted readily to mucus of all fish species tested. The differences in reaction to fish mucus among actinosporeans may indicate their different host range. These results indicate that actinosporean spores are short-lived and that actinosporeans respond to their hosts by chemodetection.

Animals↗
PubMed1985

Pursuing longevity: delay vs elimination of degenerative diseases.

Using a new model which allows for projection of mortality change resulting from preventive health care measures, prospective changes in longevity for the resident United States population in 1978 were compared with projections of longevity gains occurring under a standard single cause-elimination model. Results indicate that equal or greater gains accrue from the prevention or delay of several major degenerative diseases, than from the complete elimination of some single major degenerative diseases. Observed declines in mortality from 1960 to 1978 have resulted in gains in longevity equivalent to the successful elimination of some major degenerative diseases.

Adolescent↗
PubMed2004

Remarkable longevity of dilute sperm in a free-spawning colonial ascidian.

Many benthic marine invertebrates reproduce by releasing sperm into the sea (free-spawning), but the amount of time that sperm are viable after spawning may have different consequences for fertilization, depending on the type of free-spawner. In egg-broadcasting marine organisms, gamete age is usually assumed to be irrelevant because of the low probability of contact between dilute sperm and egg. However, direct dilution effects might be reduced in egg-brooding free-spawners that filter dilute sperm out of the water column, and sperm longevity may play a role in facilitating fertilization in these taxa. We investigated the effects of time, temperature, and mixing on the viability of naturally released sperm of the colonial ascidian Botryllus schlosseri. Our data indicate that B. schlosseri sperm have a functional life span that is considerably longer than those of the sperm of many other marine invertebrate taxa (half-life of approximately 16 to 26 h), are able to fertilize eggs at extremely low external sperm concentrations (ca. 10(1) sperm ml(-1)), and have a longevity that varies with temperature. It is possible that such prolonged sperm longevity may be achieved by reductions in motility, reactivation of quiescent sperm by chemical cues, or intermittent swimming.

Analysis of Variance↗
PubMed2000

Improved longevity and functionality of a canine model providing portal vein and multi-site intestinal access.

BACKGROUND AND PURPOSE: The canine intestinal and venous access port (IVAP) model is valuable for investigating hepatic elimination and region-specific intestinal absorption of pharmaceuticals. Previously, long-term functionality of this preparation has been variable. METHODS: Catheters of different construction were placed in the proximal and distal portions of the small intestine, colon, and portal vein of subject animals and were attached to separate subcutaneous access ports. Intraoperative, postoperative, and long-term maintenance techniques were developed, modified, and analyzed. RESULTS: Intestinal catheter infections and access site failures were associated with breakdown at the intestinal insertion site. The ileal catheter was prone to obstruction with ingesta. A modified Witzel technique, specialized port-catheter systems, scheduled port-flushing methods, and venous port infection treatment protocols improved the model's longevity. CONCLUSIONS: The canine IVAP model is a powerful tool for investigation of regional differences in intestinal absorption and hepatic elimination of drugs. Other researchers can derive increased longevity with the IVAP model by using the technical modifications detailed here: strict sterile technique, closed-end slit-valve catheters, GPV ports, the Witzel tunnel technique, routine portal vein infection surveillance, 50% dextrose intestinal catheter infusion, rapid removal of infected intestinal catheters, and critical appraisal of their results. Longevity of the model continues to be improved.

Animals↗
PubMed2001

Longevity of restorations in posterior teeth and reasons for failure.

PURPOSE: This article compiles a survey on the longevity of restorations in stress-bearing posterior cavities and assesses possible reasons for failure. MATERIALS AND METHODS: The dental literature predominantly of the last decade was reviewed for longitudinal, controlled clinical studies and retrospective cross-sectional studies of posterior restorations. Only studies investigating the clinical performance of restorations in permanent teeth were included. Longevity and annual failure rates of amalgam, direct composite restorations, glass ionomers and derivative products, composite and ceramic inlays, and cast gold restorations were determined for Class I and II cavities. RESULTS: Annual failure rates in posterior stress-bearing restorations are: 0% to 7% for amalgam restorations, 0% to 9% for direct composites, 1.4% to 14.4% for glass ionomers and derivatives, 0% to 11.8% for composite inlays, 0% to 7.5% for ceramic restorations, 0% to 4.4% for CAD/CAM ceramic restorations, and 0% to 5.9% for cast gold inlays and onlays. CONCLUSION: Longevity of dental restorations is dependent upon many different factors that are related to materials, the patient, and the dentist. The principal reasons for failure were secondary caries, fracture, marginal deficiencies, wear, and postoperative sensitivity. A distinction must be made between factors causing early failures and those that are responsible for restoration loss after several years of service.

Bicuspid↗
PubMedDate not supplied

Seed cryopreservation and longevity of two Salix hybrids.

The effects of desiccation and storage temperature on the viability and longevity of willow seeds was investigated using two hybrids, Salix rehderiana x (Salix x capreola) [cross 458] and Salix x sericans x Salix viminalis [cross 512]. Freshly harvested seed of both crosses survived silica gel drying down to c. 3 to 5% moisture content. Hybrid 458 seed stored in liquid nitrogen (-196C) for 3 d retained viability when equilibrated to < or = 45% RH (pre-storage), showed slightly reduced survival at 65% RH and exhibited no survival at > or =82% RH. The level of survival after 68 d for seeds pre-equilibrated to either c. 10 or 65% (5 or 10% moisture) and stored at four temperatures was -196C > -20C > 2C > 16C. At all temperatures, drier seed stored better than wetter seed. For hybrid 512, seed longevity at 20C > 40C > 60C, and a 10% fall in pre-storage seed RH resulted in a c. 2-fold increase in longevity at each storage temperature. The response of hybrid willow seeds to desiccation and cooling raises possibilities for the long-term seed conservation of Salix species by cryopreservation.

Cryopreservation↗