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PubMedDate not supplied

Proliferative potential and DNA repair in lymphocytes from short-lived and long-lived strains of mice, relation to aging.

The replicative capacity and DNA repair ability of spleen lymphocytes of young and old mice from short-lived and long-lived strains were studied. DNA repair after both UV- and gamma-induced damage was investigated. Proliferation after Con A decreased as a function of age in both mouse strains and paralleled an age-associated decline in repair of DNA damage induced by either UV or gamma-irradiation. Compared to the long-lived, the short-lived strain displayed an earlier impairment of both proliferative and repair potentials. DNA repair after gamma-induced damage only occurred if lymphocytes were stimulated to proliferate. Resting lymphocytes appeared unable to repair strand breaks. By contrast, DNA repair of UV-induced damage showed two components: one was dependent on the cell proliferative state, the other was not. Both components were stimulated or induced by mitogen. Resting lymphocytes were able to perform an appreciable amount of repair after UV irradiation. Our results suggest that resting or post-mitotic cells possess a greater possibility to regulate repair of UV-induced than gamma-induced damage. We speculate that it may be the level of this proliferation-independent, but mitogen inducible form of repair which correlates with maximum life-spans between species, thereby explaining why repair of UV- but not gamma-induced damage reveals such a correlation.

Aging↗
PubMed2004

Real-time probing of membrane transport in living microbial cells using single nanoparticle optics and living cell imaging.

Membrane transport plays a leading role in a wide spectrum of cellular and subcellular pathways, including multidrug resistance (MDR), cellular signaling, and cell-cell communication. Pseudomonas aeruginosa is renowned for its intriguing membrane transport mechanisms, such as the interplay of membrane permeability and extrusion machinery, leading to selective accumulation of specific intracellular substances and MDR. Despite extensive studies, the mechanisms of membrane transport in living microbial cells remain incompletely understood. In this study, we directly measure real-time change of membrane permeability and pore sizes of P. aeruginosa at the nanometer scale using the intrinsic color index (surface plasmon resonance spectra) of silver (Ag) nanoparticles as the nanometer size index probes. The results show that Ag nanoparticles with sizes ranging up to 80 nm are accumulated in living microbial cells, demonstrating that these Ag nanoparticles transport through the inner and outer membrane of the cells. In addition, a greater number of larger intracellular Ag nanoparticles are observed in the cells as chloramphenicol concentration increases, suggesting that chloramphenicol increases membrane permeability and porosity. Furthermore, studies of mutants (nalB-1 and DeltaABM) show that the accumulation rate of intracellular Ag nanoparticles depends on the expression level of the extrusion pump (MexAB-OprM), suggesting that the extrusion pump plays an important role in controlling the accumulation of Ag nanoparticles in living cells. Moreover, the accumulation kinetics measured by Ag nanoparticles are similar to those measured using a small fluorescent molecule (EtBr), eliminating the possibility of steric and size effects of Ag nanoparticle probes. Susceptibility measurements also suggest that a low concentration of Ag nanoparticles (1.3 pM) does not create significant toxicity for the cells, further validating that single Ag nanoparticles (1.3 pM) can be used as biocompatible nanoprobes for the study of membrane transport kinetics in living microbial cells.

Anti-Bacterial Agents↗
PubMed2000

Protective long-term antibody memory by antigen-driven and T help-dependent differentiation of long-lived memory B cells to short-lived plasma cells independent of secondary lymphoid organs.

Memory is a hallmark of immunity. Memory carried by antibodies is largely responsible for protection against reinfection with most known acutely lethal infectious agents and is the basis for most clinically successful vaccines. However, the nature of long-term B cell and antibody memory is still unclear. B cell memory was studied here after infection of mice with the rabies-like cytopathic vesicular stomatitis virus, the noncytopathic lymphocytic choriomeningitis virus (Armstrong and WE), and after immunization with various inert viral antigens inducing naive B cells to differentiate either to plasma cells or memory B cells in germinal centers of secondary lymphoid organs. The results show that in contrast to very low background levels against internal viral antigens, no significant neutralizing antibody memory was observed in the absence of antigen and suggest that memory B cells (i) are long-lived in the absence of antigen, nondividing, and relatively resistant to irradiation, and (ii) must be stimulated by antigen to differentiate to short-lived antibody-secreting plasma cells, a process that is also efficient in the bone marrow and always depends on radiosensitive, specific T help. Therefore, for vaccines to induce long-term protective antibody titers, they need to repeatedly provide, or continuously maintain, antigen in minimal quantities over a prolonged time period in secondary lymphoid organs or the bone marrow for sufficient numbers of long-lived memory B cells to mature to short-lived plasma cells.

Animals↗
PubMed2002

Short-lived and long-lived bone marrow plasma cells are derived from a novel precursor population.

The contribution that long-lived bone marrow (BM) plasma cells (PCs) provide to enduring humoral immunity has been underscored by a number of recent studies. However, little is known about the immediate precursors that give rise to long-lived PCs in the BM of immune individuals. We have identified subsets of antigen-experienced B cells within the immune BM that are precursors to PCs. These PC precursors arise in the BM 14 days after immunization and persist for greater than 9 months. Phenotypically distinct subsets of PC precursors give rise to short-lived or long-lived PCs. The differentiation of PC precursors to PCs occurs in the absence of antigen and requires cell division. The functional significance of these newly identified PC precursors in the persistence and quality of the humoral immune response is discussed.

Animals↗
PubMed2005

Noninvasive imaging of protein-protein interactions from live cells and living subjects using bioluminescence resonance energy transfer.

This study demonstrates a significant advancement of imaging of a distance-dependent physical process, known as the bioluminescent resonance energy transfer (BRET2) signal in living subjects, by using a cooled charge-coupled device (CCD) camera. A CCD camera-based spectral imaging strategy enables simultaneous visualization and quantitation of BRET signal from live cells and cells implanted in living mice. We used the BRET2 system, which utilizes Renilla luciferase (hRluc) protein and its substrate DeepBlueC (DBC) as an energy donor and a mutant green fluorescent protein (GFP2) as the acceptor. To accomplish this objective in this proof-of-principle study, the donor and acceptor proteins were fused to FKBP12 and FRB, respectively, which are known to interact only in the presence of the small molecule mediator rapamycin. Mammalian cells expressing these fusion constructs were imaged using a cooled-CCD camera either directly from culture dishes or by implanting them into mice. By comparing the emission photon yields in the presence and absence of rapamycin, the specific BRET signal was determined. The CCD imaging approach of BRET signal is particularly appealing due to its capacity to seamlessly bridge the gap between in vitro and in vivo studies. This work validates BRET as a powerful tool for interrogating and observing protein-protein interactions directly at limited depths in living mice.

Animals↗
PubMed2006

Living in the shadow of fear: adolescents' lived experience of depression.

AIM: This paper reports a phenomenological study whose aim was to gain an understanding of what it was like to be an adolescent living with depression. BACKGROUND: Depression is a significant mental health problem among adolescents. Identifying the meanings that adolescents assign to their experiences with depression is needed in order to develop interventions that will improve their care and quality of life. METHOD: The study took place in a city in Western Canada. Fourteen adolescents (13.5 to 18 years) diagnosed with depression participated in individual open-ended interviews and focus group interviews between July 2001 and June 2002. Field notes were recorded. Thematic statements that were representative of the adolescents' lived experience were isolated from the interviews and field notes. Using all the phrases, sentence clusters and field notes, the data were then reduced until essential and incidental themes emerged. FINDINGS: "Living in the shadow of fear" emerged as the essence of the adolescents' experiences and ultimately defined what it was like to live with depression. The shadow of fear was associated not only with fear of a return of the "bad" feelings related to their depression, but also to fear of not getting help, not surviving the "bad" feelings, and fear of having to do all the "hard work" in overcoming the "bad" feelings. This essence was supported by four themes: "containing the shadow of fear", "keeping the self alive", "maintaining a sense of belonging in the world" and "feeling valued as a human being". CONCLUSIONS: Adolescents with depression need adequate resources and support throughout the illness trajectory, including those periods when their depression is under control.

Adaptation, Psychological↗
PubMed1995

Peter Singer and 'lives not worth living'--comments on a flawed argument from analogy.

The Australian bioethicist Peter Singer has presented an intriguing argument for the opinion that it is quite proper (morally) to deem the lives of certain individuals not worth living and so to kill them. The argument is based on the alleged analogy between the ordinary clinical judgement that a life with a broken leg is worse than a life with an intact leg (other things being equal), and that the broken leg therefore ought to be mended, on the one hand, and the judgement that the lives of some individuals, for example, severely disabled infants, are not worth living and therefore ought to be terminated, on the other. In the present article it is argued that Singer's argument is flawed, intellectually and/or ethically.

Bioethics↗
PubMed1978

The replicative life spans of euploid hybrids derived from short-lived and long-lived human skin fibroblast cultures.

Two recent technical advances facilitate the derivation of proliferating hybrids from human diploid fibroblast strains without recourse to biochemical selection: (1) a new chemically-mediated method of somatic cell fusion (PEG-DMSO) yields hybrids at rates as high as 1 in 160 colonies after dilute plating of treated cell mixtures, and (2) a simple technology for assessment of DNA content (flow microfluorometry) permits rapid and highly sensitive monitoring of ploidy. Employing these techniques, we isolated 43 chromosomally stable hybrid clones from 12 crosses between seven different strains representing a wide range of longevities. Crosses between short-lived strains resulted in short-lived hybrid offspring, whereas hybrids derived from long-lived parents tended to be long-lived. Crosses between strains of contrasting longevities gave clones with intermediate growth potentials relative to the other types of hybrids. The failure to observe complementation (enhanced longevity) of hybrids argues against random recessive single-copy gene mutations as important determinants of clonal senescence.

Cell Fusion↗
PubMed2004

Characterization of coelenterazine analogs for measurements of Renilla luciferase activity in live cells and living animals.

In vivo imaging of bioluminescent reporters relies on expression of light-emitting enzymes, luciferases, and delivery of chemical substrates to expressing cells. Coelenterazine (CLZN) is the substrate for a group of bioluminescent enzymes obtained from marine organisms. At present, there are more than 10 commercially available CLZN analogs. To determine which analog is most suitable for activity measurements in live cells and living animals, we characterized 10 CLZN analogs using Renilla luciferase (Rluc) as the reporter enzyme. For each analog, we monitored enzyme activity, auto-oxidation, and efficiency of cellular uptake. All CLZN analogs tested showed higher auto-oxidation signals in serum than was observed in phosphate buffer or medium, mainly as a result of auto-oxidation by binding to albumin. CLZN-f, -h, and -e analogs showed 4- to 8-fold greater Rluc activity, relative to CLZN-native, in cells expressing the enzyme from a stable integrant. In studies using living mice expressing Rluc in hepatocytes, administration of CLZN-e and -native produced the highest signal. Furthermore, distinct temporal differences in signal for each analog were revealed following intravenous or intraperitoneal delivery. We conclude that the CLZN analogs that are presently available vary with respect to hRluc utilization in culture and in vivo, and that the effective use of CLZN-utilizing enzymes in living animals depends on the selection of an appropriate substrate.

Animals↗
PubMed2002

Live cell imaging: approaches for studying protein dynamics in living cells.

In the last decade, the long-standing biologist's dream of seeing the molecular events within the living cell came true. This technological achievement is largely due to the development of fluorescence microscopy technologies and the advent of green fluorescent protein as a fluorescent probe. Such imaging technologies allowed us to determine the subcellular localization, mobility and transport pathways of specific proteins and even visualize protein-protein interactions of single molecules in living cells. Direct observation of such molecular dynamics can provide important information about cellular events that cannot be obtained by other methods. Thus, imaging of protein dynamics in living cells becomes an important tool for cell biology to study molecular and cellular functions. In this special issue of review articles, we review various imaging technologies of microscope hardware and fluorescent probes useful for cell biologists, with a focus on recent development of live cell imaging.

Animals↗
PubMed1993

The effect of live weight gain and live weight loss on body composition of merino wethers: noncarcass organs.

The weight of the noncarcass external tissues, thoracic organs, and visceral organs was measured during live weight gain (LWG) and live weight loss (LWL) to evaluate the effect of different periods of normal and retarded growth on noncarcass organs. Thirty-five Merino wethers were allowed ad libitum access to an experimental diet of 80% alfalfa chaff and 20% cereal grain (17.23% CP and 12.09 MJ/kg of DE) to grow from 23.0 to 33.0 kg live weight and then fed to lose 10 kg at 133 g/d. Groups of five animals were slaughtered at live weights of 23.0, 26.3, 29.6, and 33.0 kg during LWG and 29.6, 26.3, and 23.0 kg during LWL. Although total weight of noncarcass organs was significantly lower in LWL animals than in LWG animals at 23.0- and 26.3-kg (P < .05) common slaughter weights, the weight of some noncarcass organs was significantly greater in LWL animals. For example, the weight of the head at 23.0 and 26.3 kg (P < .05), of the feet and esophagus at 23.0 (P < .01) and 26.3 kg (P < .05), and of the total alimentary tract fat at 23.0 kg (P < .01) was greater in LWL wethers. Weights of other organs, however, were lower in LWL animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1997

Effect of live weight and differing economic values on responses to selection for milk fat, protein, volume, and live weight.

Five traits of major economic importance in the New Zealand dairy industry are milk volume, milk fat, milk protein, live weight, and survival. This study evaluated the impact of live weight as a trait in the selection objectives for the New Zealand dairy industry. Live weight of the lactating cow is an important measure because it reflects feeding costs via maintenance feed and salvage values of cows to be culled. In addition, selection responses were evaluated for differing relative economic values for milk protein and milk fat, and selection indexes that included or excluded phenotypic and genotypic correlations between traits were compared. Inclusion of live weight, with a negative economic value in a four-trait selection index with milk, milk fat, and protein resulted in higher economic response. Protein response to selection was not more than 2% when the relative economic value for the ratio of protein to milk fat exceeded 5:1 in a two-trait model; however, milk fat response decreased by over 10%. When a negative relative economic value was assigned to milk fat, economic returns were lower because of lower milk fat responses and the lack of higher protein responses compared with the same ratio for relative economic value but a positive weight for milk fat. Accounting for phenotypic and genetic correlations in deriving selection index weight improved economic response 5%.

Animals↗
PubMed1990

Living arrangements of young adults living independently: evidence from the Luxembourg Income Study.

A cross-country comparison of the impact of socioeconomic factors on household formation by young adults in the 15-24 age group is presented. "Of those young people living independently (not in their parental homes), how do incomes from various sources affect their decision whether to live alone or with others? The sample did not include all persons in the 15-24 age group, only those living independently. A logit analysis of the living alone question was conducted using data from five countries (Canada, the Federal Republic of Germany, the United Kingdom, Australia, and the United States) included in the LIS [Luxembourg Income Study] data base to determine whether differences across countries exist."

Americas↗
PubMed2000

Living kidney donation: recovery and return to activities of daily living.

To determine donor nephrectomy outcomes, a one page 20-item survey of 42 cases was reviewed, including demographics, intervals to normal activities (e.g., driving a car, returning to work), and an open inquiry about the donation process. Hospital records were also reviewed. Nephrectomy under general anesthesia was through an anterior flank, extra-retroperitoneal approach with postoperative epidural pain control. Early self-care, progressive ambulation, and prescriptive pulmonary care were undertaken to facilitate recovery. Length of stay averaged 3.4 (range 2-8) d, and mean hospitalization charge was $15 169 (range $10 733-S29 579). Thirty-four donors were employed outside the home; 18 (53%) returned to work within 4 wk, and the average duration away from work was 4.6 wk (range 6 d 10 wk). Within 2 wk, 25 (59%) were driving an automobile. Usual activities of daily living were fully performed by all donors at a mean of 4.8 wk (minimum 5 d). Forty respondents would donate again, and one might; one did not respond to this question. None reported intermediate or long-term disabilities and all reported return to their pre-donation level of activity. With the anterior extra-retroperitoneal nephrectomy, most donors were out of the hospital within 4 d, were driving within 2 wk, and returned to gainful employment within 4 wk. Living kidney donation, as viewed by the donors, was a positive experience, which appeared to disrupt their lives minimally.

Activities of Daily Living↗
PubMed2003

Assessing the effectiveness of a walking program on physical function of residents living in an assisted living facility.

The purpose of this study was to assess the effectiveness of a resident-led walking program at an assisted living facility (ALF). Seventeen women (mean age 80, range 62-99) agreed to participate in a "walking club." Pre and post measurements included the Tinetti Performance-Oriented Assessment of Mobility Problems in Elderly Patients, the Functional Reach Test, and the Barthel Index to measure independence in activities of daily living (ADLs). Participants set their own goals for walking distance and frequency, with the assistance of the lead researcher if requested. Distances ranged from 75 ft to over 1 mile. At the end of the 9-week intervention, there was a significant increase in all of the pre-test measurements. In addition, post-test assessment included individual interviews with participants about their experiences with the physical activity program. Four positive themes about the walking program emerged: (a) as a pleasurable activity, (b) as a way to manage current health problems, (c) as a way to continue life-long activity, and (d) because of perceived physical and psychological benefits from the activity. The participants planned to continue the walking program. The results of this pilot study suggest that a walking program can be instituted in an assisted living facility with minimal staff effort and significant benefit to residents.

Activities of Daily Living↗
PubMed2004

The effects of Ginkgo biloba extract (LI 1370) supplementation and discontinuation on activities of daily living and mood in free living older volunteers.

The aim of the study was to investigate the effects of continuing treatment with Ginkgo biloba extract (GBE) 120 mg/day on the activities of daily living (ADLs) and mood in healthy older volunteers who had immediately previously participated in a survey of the effects of a 4 month treatment with the drug. Following a prior postal survey investigating the effects of 4 months supplementation with GBE on ADLs and various aspects of mood and sleep, 1570 volunteers continued onto a 6 month follow-up postal survey. Subjects selected their own treatment option for the follow-up survey, which effectively created four groups: a continuation group who received GBE in the initial 4 month study and during the 6 month follow-up (GBE-GBE), a discontinuation group who received GBE in the initial study but not during the follow-up (GBE-NT), a new treatment group who did not receive GBE in the initial 4 month study but who did receive GBE during the 6 month follow-up (NT-GBE), and a no treatment group who received no treatment in either survey (NT-NT). At the end of the 6 month follow-up period each subject completed a line analogue rating scale (LARS) and a self-rating activities of daily living scale (SR-ADL). There were signi fi cant differences in the mean overall LARS and SR-ADL scores between the four treatment combination groups at the end of the follow-up period. A factor analysis of the LARS revealed two factors, 'mood' and 'alertness'. When scores from each of the treatment groups were examined over the whole 10 month period it was evident that the ratings of overall competence in the SR-ADL and both factors of the LARS were diminished on cessation of treatment with GBE, and improved when GBE treatment was initiated. The magnitude of the improvements on all scales was related to the overall duration of GBE supplementation.Signi fi cant differences between the groups of subjects treated with GBE for different periods of time (4-10 months) suggests that the extract has a demonstrable effect in improving mood and the self-assessed performance of the tasks of everyday living.

Activities of Daily Living↗
PubMed2002

Hypovitaminosis D and hyperparathyroidism in physically inactive elderly Japanese living in nursing homes: relationship with age, sunlight exposure and activities of daily living.

BACKGROUND AND AIMS: The purposes of this study were to investigate the prevalences of hypovitaminosis D and hyperparathyroidism in physically inactive elderly people living in Japanese nursing homes and determine any correlations with demographic, environmental and/or life-style factors. METHODS: We targeted 220 elderly people living in nursing homes for the physically disabled in Japan. Of these, 133 (women, 113; men, 20) subjects who agreed and met our inclusion criteria were studied. The average age of the subjects was 84.6 years (SD 8.2). Serum 25-hydroxyvitamin D3 (25[OH]D3), intact parathyroid hormone (intact PTH), creatinine, and albumin concentrations were measured in each subject. Total hours of sunshine during the previous 5 weeks, activities of daily living (ADL) levels, and dietary vitamin D intake were also measured. ADL levels were evaluated using the Physical Self-Maintenance Scale (5-point scale). The examinations were performed between October and December, 1999. RESULTS: The average concentrations of serum 25(OH)D3 and intact PTH were 29.9 nmol/L (SD 13.1) and 5.04 pmol/L (SD 2.27), respectively. The prevalences of hypovitaminosis D (25[OH]D3<30 nmol/L) and hyperparathyroidism (intact PTH>6.90 pmol/L) were 77/133 (57.9%) and 21/133 (15.8%), respectively. Serum 25(OH)D3 concentrations were positively associated with hours of sunshine (R2=0.371, p<0.001) and serum albumin concentrations (R2=0.086, p<0.001), but not with age (p=0.075) or total ADL score (p=0.527). A negative association between serum intact PTH and 25(OH)D3 levels was found in subjects who were 80 years or older (p<0.001) but not in subjects under the age of 80 years. CONCLUSIONS: Hypovitaminosis D and hyperparathyroidism are commonly seen in elderly Japanese with low ADL levels. Hypovitaminosis D seems to adversely affect PTH levels, especially in the very elderly.

Activities of Daily Living↗
PubMed2000

Hepatic grafts from live donors: donor morbidity for 470 cases of live donation.

Living donor-morbidity was evaluated in 470 consecutive cases of living donor liver transplantation carried out from June 1990 to May 1999 at Kyoto University. Grafting was categorized into 4 groups according to the resection lines; left lateral segmentectomy (S2 + 3, n = 282, R1), extended left lateral segmentectomy without middle hepatic vein (MHV) (S2 + 3 + part4, n = 45, R2), left lobectomy with MHV (S2 + 3 + 4, n = 99, R3) and right lobectomy without MHV (S5 + 6 + 7 + 8, n = 43, R4). Intraoperative blood loss and operation duration were less for left lateral segmentectomy, but no significant difference was observed between left lobectomy and right lobectomy. The length of postoperative hospital stays was comparable among all groups except for the group with right lobe grafting. The AST values at the peak and at POD 7 were significantly elevated for right lobectomy, but the AST value normalized within one month in the majority of the cases. The close follow-up of donors with more than 1,000 ml intraoperative bleeding, and of those donors who stayed in hospital for more than 30 days, the close follow-up, furthermore, of those donors with AST values higher than 100 IU/ L AST after one month, revealed complete recovery. Biliary leakage was the most common and annoying complication after donor operations, especially in for right lobe grafting, but all donors recovered completely with conservative or minimal invasive therapy. The two cases of re-operation due to adhesive mechanical ileus we encountered were resolved completely. Finally, no donor-operation related death was noted. In conclusion, the morbidity of living donors is low or minimal even for right lobectomy, the most extended procedure, and complete recovery can be expected in all cases.

Adult↗