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PubMed2026

A lipid-sensitive food choice behavior influences aging outcomes from a longevity-promoting diet.

Organisms utilize sophisticated neurocircuitry to select optimal food sources. Methylobacterium is a lifespan-promoting diet for C. elegans that drives faster development and longevity; however, after ingestion, C. elegans consistently choose any other food option available. A screen for genetic regulators of this avoidance behavior toward Methylobacterium identified the AWB/AWC sensory neurons and the odr-1 guanylate cyclase expressed in those four ciliated neurons as mediators of the aversive response. Metabolic profiling of the Methylobacterium diet reveals enrichment for saturated fats, and here, we show that C. elegans sense and integrate signals related to these ingested lipids that subsequently cue food-related behaviors. Moreover, disruption of endogenous lipid metabolism modifies the intensity of the avoidance from Methylobacterium, suggesting the current state of lipid homeostasis influences food preference. Taken together, our work reveals that C. elegans modify food choice contemporaneously based in part on the chemosensory capacity to detect and utilize dietary lipids, which has longevity-promoting consequences.

AWB↗
PubMed1988

Pacemaker longevity modelling.

A generalized mathematical technique is presented for computing the elapsed time necessary for a lithium iodine powered pacemaker to reach any specified battery voltage or degree of battery discharge within its life span. In particular, the method yields a direct mathematical expression for the longevity of pacemakers the circuits of which possess linear load lines. Because the current-voltage relationship, which defines the load line, is affected by programmed output settings, electrode/tissue interface impedance and degree of inhibition, the method enables the direct determination of the effect of these parameters on pacemaker longevity.

Electric Power Supplies↗
PubMed1995

Determinants of dual chamber pulse generators longevity.

The aim of this study was to investigate the effect of battery capacity, internal current drain, and stimulation energy on pulse generators longevity, and if battery impedance measurements can reliably predict pulse generators end-of-life. For this purpose, the records of 577 patients with a mean age of 65 +/- 14 years who had undergone implantation of two different dual chamber pulse generators (PG1: 409; PG2: 168) were retrospectively reviewed. Battery capacity were 2.3 Ah (PG1) and 3.0 Ah (PG2) while current drain at comparable nominal settings was 20 microA (PG1) and 30 microA (PG2) indicating a higher internal current drain of PG2. After a mean follow-up of 46 +/- 23 months, stimulation energy at reprogrammed output settings was significantly higher in PG1 as compared to PG2 (17.1 +/- 0.14) vs 15.5 +/- 0.24 J). Three PG1 (0.7%) and 12 PG2 (7.1%) (P < 0.01) had to be exchanged after a mean of 77.3 +/- 5.3 months (PG1) and 75 +/- 13.5 months (PG2) (P = NS) due to end-of-life being reached. The difference in battery impedances of PG1 and PG2 gained statistical significance 5 years after implantation (1.0 k omega vs 2.4 +/- 6.7 k omega) preceding the significant difference in PG survival after 6 years (98.7 +/- 1.3% vs 90.7 +/- 4.8%). These results indicate that internal current drain is the most important determinant of the pulse generators longevity and that battery impedance can reliably predict end-of-life. Therefore, the essential information about internal current drain should be available for each pacemaker, since it is required for adequate pulse generator selection. Diagnostic functions of dual chamber pulse generators should include measurements of battery impedance.

Adult↗
PubMed1998

Telemetry guided pacemaker programming: impact of output amplitude and the use of low threshold leads on projected pacemaker longevity.

In a prospective study, a low threshold screw-in electrode (Medtronic 5078, group I, n = 9) was compared to a conventional active fixation lead (Biotronik Y60BP, group II, n = 9) to investigate whether lower pacing thresholds really translate into longer projected service life of the pacemaker. The leads were implanted in the atrium and were connected to a dual chamber pacing system which included the same ventricular lead (Medtronic 5024) and the same pulse generator model (Intermedics 294-03) in both groups. Eighteen months after implantation, atrial and ventricular pacing thresholds were measured as the charge delivered per pulse [microC] at 0.5, 1.0, 1.5, 2.0, and 3.5 V, respectively. For chronic output programming in both channels, patients capturing at 0.5 V were set to 1.0 V, those capturing at 1.5 V were permanently programmed to 2.0 V with the double of the charge threshold as the safety margin for pacing ("safety charge"). A combination of atrial and ventricular output settings was optimal, if it resulted in minimum battery current drain (microA] as measured by pacemaker telemetry. In both groups, current consumption [microA] decreased significantly as output amplitude was decreased, exhibiting its lowest value at 1.0 V in either channel. All ventricular leads could be programmed to the optimum output amplitude of 1.0 V in groups 1 and 2. As the 2:1 "safety charge" values were almost identical, the ventricular channel essential contributes the same amount to the battery drain of the pacing system in both groups. In the atrium, all patients of group 1 could be programmed to the optimum output amplitude of 1.0 V with an average pulse duration of 0.42 +/- 0.15 ms. In group 2, however, all patients had to be programmed to 2.0 V with a mean pulse width of 0.52 +/- 0.15 ms. With the atrial and ventricular output being optimized, the average battery drain of the whole pacing system was 12.19 +/- 0.63 microA in group 1 versus 14.42 +/- 0.32 microA in group 2 (P < 0.001). As patients were chronically programmed to these output settings, this difference translates into a clinically relevant gain in projected pacemaker longevity of 17 months or 18.3% (121 +/- 4 vs. 104 +/- 2 months; P < 0.001). Thus, programming a 2:1 safety margin in terms of charge and optimizing the output parameters by real-time telemetry of the battery current is a useful approach to reduce battery current drain. Making the most of modern lead technology with a different performance in only one channel of an otherwise identical DDD pacing system translates into a significant prolongation of projected pacemaker service life which is of great importance with the increasing awareness of health care expenditures. The gain in projected longevity is mainly due to the option of reducing the output amplitude which is still significantly beneficial well below the nominal voltage of the power source.

Aged↗
PubMed1987

Dental restoration longevity: a critique of the life table method of analysis.

The use of the life table method for assessing the longevity of dental restorations is growing. One reason for this is the availability of statistical computer packages which can be used by the non-expert, and this is tending to lead to an uncritical approach to the methodology. Although much can be learnt regarding the durability of restorations by using life table analysis, there are many inherent problems related to its use in dental studies. The survival pattern of many restorations is such that long-term studies are required to obtain valid assessments of durability. Results reported after only a few years of study contain many restorations not followed to failure. The ways in which data on these restorations are handled can greatly affect the estimates of longevity. These considerations have not, to date, received sufficient attention.

Actuarial Analysis↗
PubMed2003

Increased longevities of post-Paleozoic marine genera after mass extinctions.

Cohorts of marine taxa that originated during recoveries from mass extinctions were commonly more widespread spatially than those originating at other times. Coupled with the recognition of a correlation between the geographic ranges and temporal longevities of marine taxa, this observation predicts that recovery taxa were unusually long-lived geologically. We analyzed this possibility by assessing the longevities of marine genus cohorts that originated in successive substages throughout the Phanerozoic. Results confirm that several mass extinction recovery cohorts were significantly longer lived than other cohorts, but this effect was limited to the post-Paleozoic, suggesting differences in the dynamics of Paleozoic versus post-Paleozoic diversification.

Animals↗
PubMed2004

Nicotinamide clearance by Pnc1 directly regulates Sir2-mediated silencing and longevity.

The Saccharomyces cerevisiae Sir2 protein is an NAD(+)-dependent histone deacetylase (HDAC) that functions in transcriptional silencing and longevity. The NAD(+) salvage pathway protein, Npt1, regulates Sir2-mediated processes by maintaining a sufficiently high intracellular NAD(+) concentration. However, another NAD(+) salvage pathway component, Pnc1, modulates silencing independently of the NAD(+) concentration. Nicotinamide (NAM) is a by-product of the Sir2 deacetylase reaction and is a natural Sir2 inhibitor. Pnc1 is a nicotinamidase that converts NAM to nicotinic acid. Here we show that recombinant Pnc1 stimulates Sir2 HDAC activity in vitro by preventing the accumulation of NAM produced by Sir2. In vivo, telomeric, rDNA, and HM silencing are differentially sensitive to inhibition by NAM. Furthermore, PNC1 overexpression suppresses the inhibitory effect of exogenously added NAM on silencing, life span, and Hst1-mediated transcriptional repression. Finally, we show that stress suppresses the inhibitory effect of NAM through the induction of PNC1 expression. Pnc1, therefore, positively regulates Sir2-mediated silencing and longevity by preventing the accumulation of intracellular NAM during times of stress.

DNA, Ribosomal↗
PubMedDate not supplied

Longevity of screenwriters who win an academy award: longitudinal study.

OBJECTIVE: To determine whether the link between high success and longevity extends to academy award winning screenwriters. DESIGN: Retrospective cohort analysis. PARTICIPANTS: All screenwriters ever nominated for an academy award. MAIN OUTCOME MEASURES: Life expectancy and all cause mortality. RESULTS: A total of 850 writers were nominated; the median duration of follow up from birth was 68 years; and 428 writers died. On average, winners were more successful than nominees, as indicated by a 14% longer career (27.7 v 24.2, P=0.004), 34% more total films (23.2 v 17.3, P<0.001), 58% more four star films (4.8 v 3.1, P<0.001), and 62% more nominations (2.1 v 1.3, P<0.001). However, life expectancy was 3.6 years shorter for winners than for nominees (74.1 v 77.7 years, P=0.004), equivalent to a 37% relative increase in death rates (95% confidence interval 10 to 70). After adjustment for year of birth, sex, and other factors, a 35% relative increase in death rates was found (7% to 70%). Additional wins were associated with a 22% relative increase in death rates (3% to 44%). Additional nominations and additional other films in a career otherwise caused no significant increase in death rates. CONCLUSION: The link between occupational achievement and longevity is reversed in screenwriters who win academy awards. Doubt is cast on simple biological theories for the survival gradients found for other members of society.

Achievement↗
PubMed1988

Albumin improves stability and longevity of perfluorochemical-perfused hearts.

We determined the effect of protein and nonprotein oncotic agents on physiological function and substructural integrity of perfluorochemical emulsion-perfused isolated working rabbit hearts. We used four media that contained Fluosol-43 (FL) emulsion and either 3.4% hydroxyethylstarch (HES), 2.9% albumin, 0.8% HES, or neither HES nor albumin (n = 5 hearts/group). All four groups of hearts had stable function for the first 5.5 h of perfusion; the FL plus albumin hearts continued to exhibit stability in most indexes of function until 9.5 h. The FL plus albumin hearts had a longer total period of ejecting function (12.5 +/- 0.5 h) compared with the other groups (mean longevities = 7.4-8.4 h). Functional stability and longevity correlated with maintenance of coronary flow and coronary vascular resistance. The rates of excess fluid accumulation and creatine kinase leakage were lower in the FL plus albumin hearts than in the other groups. We conclude that: 1) albumin maintained function, coronary flow, and myocardial cell integrity of FL-perfused hearts better than did HES; 2) albumin may exert its effect by preserving capillary permeability, thereby reducing the rate of interstitial fluid accumulation and preventing edema-induced vascular compression; and 3) HES had no effect on cardiac function or integrity and was ineffective in preventing interstitial fluid accumulation when it was used in FL-perfused isolated hearts in the absence of protein.

Animals↗
PubMed1980

The effect of coronary artery bypass on longevity. A surgeon's viewpoint.

Enthusiasm for new therapeutic modalities frequently results in a ground swell of overuse, which recedes to leave a trough of negativism before a definitive level is established. In the case of CABG, the ground swell has become a 10-year flood tide, without an ebb, although ripples have marred the surface. It is generally agreed that suitable control populations are needed to determine the role of a therapy and that the best controls would arise from randomized prospective trials. At present, the best randomized trial is the VA study which has shown that operation does not enhance longevity for single vessel disease, but clearly does for left main coronary disease. In those individuals with two- and three-vessel disease, the VA study has not shown that surgical therapy is better than medical treatment. However, three other studies containing patients selected by the VA criteria indicate that operation provides significantly greater longevity for patients in these two categories. Acceptance of this position requires acknowlegement of the validity of the VA study and the comparison of extramural concurrent surgical series.

Coronary Artery Bypass↗
PubMed1997

Longevity and cariostatic effects of everyday conventional glass-ionomer and amalgam restorations in primary teeth: three-year results.

The aim of this study was to compare the longevity and cariostatic effects of everyday conventional glass-ionomer and amalgam restorations in primary teeth. The materials consisted of 515 Ketac-Fil glass-ionomer restorations and 543 Dispersalloy amalgam restorations prepared in 666 children, from 3 to 13 years of age, by 14 dentists within the Danish Public Dental Health Service in the municipalities of Vaerløse and Hillerød. The restorations, of which 79% were of the Class II type, were in contact with 593 unrestored surfaces in adjacent primary and permanent teeth. After 3 years, 6% of the patients had dropped out of the study, and 33% of the teeth were exfoliated with the restoration in situ. A further 37% of the glass-ionomer and 18% of th amalgam restorations were recorded as failed (p < 0.001). The frequency of failures was highest for Class II glass-ionomer restorations, which showed a 50% median survival time of only 34 1/2 months, because of many fractures, while the 75% survival time for Class II amalgam restorations just exceeded the actual 36 months (p < 0.001). Caries progression was most often recorded in surfaces adjacent to amalgam restorations, and 21% of these surfaces needed restorative treatment vs. 12% of the surfaces adjacent to glass-ionomer restorations (p < 0.001). The three-year results indicated that conventional glass ionomer is not an appropriate alternative to amalgam for all types of restorations in primary teeth. In particular, the short longevity of Class II glass-ionomer restorations could not be compensated for by the reduced caries progression and need for restorative therapy of adjacent surfaces.

Adolescent↗
PubMedDate not supplied

Islet cell mass and the longevity of islet grafts in diabetic rats.

In an attempt to demonstrate that a limited beta-cell mass is able to maintain normoglycemia in streptozocin-diabetic rats, two groups of inbred rats received transplants of 500 or 1000 neonatal islets (corresponding to 10 and 20% of total islet cell mass, respectively) into the spleen. A close correlation was found between the functional longevity of the islet graft, and the total beta-cell mass transplanted into the diabetic animals. Although euglycemia was maintained for 4-12 mo, the islet transplants were insufficient to produce glucose tolerance tests equal to those observed in normal rats. Relapse of diabetes correlated with histological findings of distorted islet architecture containing vacuolated beta-cells in the grafts. This condition was not reversed after a month of normoglycemia. Spontaneous recovery of beta-cell function in native islets was documented in 50% of the diabetic rats with prolonged normoglycemia following islet transplantation. This report shows that transplantation of as few as 500 neonatal islets, the equivalent of 10% of total islet cell mass, is sufficient to maintain normoglycemia in diabetic rats, albeit temporarily. A close correlation was found between the transplanted islet cell mass and the functional longevity of the islet graft.

Animals↗
PubMed2004

A small observational study of the longevity of syringe driver sites in palliative care.

Although the use of portable syringe drivers is common in palliative care, problems do occur. A small observational study of local practice was undertaken to establish the rate of syringe driver reactions and duration of sites; to determine whether a predictable relationship existed between the number of days on a syringe driver and the number of sites used consecutively; and to discover whether the location of a syringe driver site influenced the site longevity. Eighty-six syringe driver sites were established in 27 patients during the 3-month study period. Site duration ranged between 1 hour and 9 days (mean 2 days). An association was found between the number of days on a syringe driver and the number of sites used. However, this relationship is not close enough to predict when a site may be discontinued. Thirty-eight syringe drivers (44%) were discontinued because of site reactions. The location of a syringe driver site appeared to be an important factor influencing the site longevity, with cannula dislodgment three times more prevalent from the chest wall than the upper arm (P=0.05). However, the findings suggest that if it is possible to prevent dislodgement from the chest wall, then this site can be used for significantly longer before a site reaction develops (P=0.02). In view of the unpredictability of site reactions, it is concluded that sites must be assessed regularly and changed as soon as problems develop. As this was a small study in one unit without standardization of site reaction assessment, the results should be interpreted with caution. However, given the lack of published work in this area, this study contributes to the evidence base and raises important questions for both clinical practice and future research.

Adult↗
PubMed2001

Increasing longevity and Medicare expenditures.

Official Medicare projections forecast that the elderly population will be less healthy and more costly over the next century. This prediction stems from the use of age as an indicator of health status: increases in longevity are assumed to increase demand for health care as individuals survive to older and higher-use ages. In this paper I suggest an alternative approach, in which time until death replaces age as the demographic indicator of health status. Increases in longevity are assumed to postpone the higher Medicare use and costs associated with the final decade of life. I contrast the two approaches, using mortality forecasts consistent with recent projections from the U.S. Census Bureau and the Social Security Administration. The time-until-death method yields significantly lower-cost forecasts. The hypothetical cost savings from improved health care small, however, relative to the size of the Medicare solvency problem caused by population aging.

Accounting↗
PubMed2006

How does cross-reactive stimulation affect the longevity of CD8+ T cell memory?

Immunological memory--the ability to "remember" previously encountered pathogens and respond faster upon re-exposure is a central feature of the immune response in vertebrates. The cross-reactive stimulation hypothesis for the maintenance of memory proposes that memory cells specific for a given pathogen are maintained by cross-reactive stimulation following infections with other (unrelated) pathogens. We use mathematical models to examine the cross-reactive stimulation hypothesis. We find that: (i) the direct boosting of cross-reactive lineages only provides a very small increase in the average longevity of immunological memory; (ii) the expansion of cross-reactive lineages can indirectly increase the longevity of memory by reducing the magnitude of expansion of new naive lineages which occupy space in the memory compartment and are responsible for the decline in memory; (iii) cross-reactive stimulation results in variation in the rates of decline of different lineages of memory cells and enrichment of memory cell population for cells that are cross-reactive for the pathogens to which the individual has been exposed.

Animals↗
PubMed1986

Longevity of restorations: survey results of dentists' estimates and attitudes.

A cross-sectional survey of 571 clinicians was conducted to obtain information about expected and observed restoration longevity. Clinicians believed that average large amalgam, small amalgam, and cast restorations lasted 6, 11, and 13 years, respectively. Patients were thought to be responsible for 47%, dentists for 30%, and materials used for 23% of restoration failures. The clinicians perceived the restorations that they placed to be more long-lasting than those placed by other clinicians. Clinical measurements of restoration longevity were shown to be influenced by the judgment criteria used by clinicians.

Adult↗
PubMed2005

Dental sealant longevity in a cohort of young U.S. naval personnel.

BACKGROUND: The U.S. Navy emphasizes caries prevention and encourages the placement of dental sealants on the caries-susceptible teeth of patients at risk of developing caries. The authors analyzed dental records to assess the longevity of dental sealants placed in naval personnel. METHODS: A cluster sample of dental records from 1,123 personnel who entered naval service in 1997 was drawn from eight Navy dental treatment facilities. The authors determined the number of sealants provided, the number of sealants that failed over the observation period (1997-2001), the dates of sealant failure and the longevity of sealants placed during and after recruit training. RESULTS: A total of 319 personnel received sealants during their first two years of service. The authors evaluated 1,467 sealed teeth. They followed the sealants for an average of 35 months. They noted 179 sealant failures in 102 subjects; 69 previously sealed teeth required sealant replacement, and 110 sealed teeth required restoration of the occlusal surface. Among those sealants that failed, the mean length of time from placement to failure was 26 months. Sealant failure rates were significantly higher among subjects at moderate risk or high risk of developing caries than among subjects at low risk. CONCLUSIONS: After an average of 35 months, 87.8 percent of the sealants placed in this population were retained and functional. Subjects who were at moderate or high risk of developing caries demonstrated significantly higher sealant failure rates than those at low risk of developing caries. CLINICAL IMPLICATIONS: Dental sealants can be retained successfully in adults. They should be considered a viable treatment alternative for adult patients who are susceptible to caries; however, patients at elevated risk of developing caries may require more frequent re-evaluation and maintenance to achieve maximum benefit.

Adolescent↗
PubMed2005

Longevity of posterior tooth dental restorations.

Several forms of restorative techniques are used for posterior teeth. They vary significantly in cost and longevity. The following restorative concepts are the most commonly used: amalgam, resin-based composite, PFM, cast gold alloy restorations and all-ceramic restorations. I suggest that patients be informed about the potential longevity of restorative treatment for posterior teeth as they make decisions about treatment for their oral restorative needs.

Bicuspid↗