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D M Murasko

Publications and source records attributed to D M Murasko.

At least 19 recordsLinked to original sources
PubMed2000

Age-related changes in interferon-alpha/beta receptor expression, binding, and induction of apoptosis in natural killer cells from C57BL/6 mice.

Natural killer (NK) cells are a critical first line of defense against viral infections and tumors. We showed previously that basal NK cytotoxicity was comparable in adult (6 month) and aged (24 month) C57BL/6 (B6) mice. However, NK activity was significantly higher in adult compared with aged B6 mice after either in vitro or in vivo stimulation with IFN-alpha/beta. The present study explored whether age-related decreases in inducible NK activity after stimulation with IFN-alpha/beta were due to differences in (1) IFN-alpha/beta receptor expression or IFN-alpha/beta binding to NK cells or (2) apoptosis of NK cells. Flow cytometry revealed that, despite significantly higher IFN-alpha/beta receptor expression (P</=0.03) on NK cells of aged mice, IFN-alpha/beta binding to NK cells was comparable between adult and aged mice. In addition, IFN-alpha/beta treatment significantly increased Fas (CD95) expression (P</=0.05) on NK cells from both adult and aged mice. However, after IFN-alpha/beta stimulation, NK cells from aged mice demonstrated significantly higher CD95 expression (P</=0.03) and percent apoptosis (P</=0.05) relative to adult mice. These results suggest possible mechanisms for age-associated decreases in inducible NK cytotoxicity after IFN-alpha/beta stimulation may include altered IFN-alpha/beta receptors and/or increased percentages of NK cells undergoing apoptosis.

Aging↗
PubMed2000

Immune response to influenza vaccine in healthy elderly: lack of association with plasma beta-carotene, retinol, alpha-tocopherol, or zinc.

Immunity and nutritional status are compromised with age, yet the relationship between them is unclear. Immune responses and plasma micronutrient levels of 61 healthy elderly (mean 81 years) and 27 young (mean 27 years) were assessed before and after immunization with trivalent influenza vaccine (FLU). FLU-induced proliferation and IFN-gamma levels of elderly were lower than young before and after immunization. Proliferation and IFN-gamma levels increased after immunization of young, but not elderly. FLU-induced IL-6 and IL-10 levels did not change after immunization of either group. While antibody titers to all three FLU components increased after vaccination of young and elderly, post-vaccination titers of elderly were lower than young. Although plasma retinol and zinc levels of young and elderly were similar before and after vaccination, elderly had higher plasma beta-carotene and alpha-tocopherol levels at both assessments that increased after vaccination. Importantly, plasma micronutrient levels were comparable for elderly with or without intact (titers >/=40 and fourfold rise post-vaccination) antibody responses after vaccination. These results suggest that differences in these plasma micronutrients (1) are not required to observe decreased FLU responses of healthy elderly compared to young and (2) are not associated with differences in antibody responses among healthy elderly.

Adult↗
PubMed2000

Genetic differences in the age-associated decrease in inducibility of natural killer cells by interferon-alpha/beta.

Natural killer (NK) cells, which are important in viral infections and anti-tumor activity, show reduced cytotoxicity in aged mice. The mechanism(s) for this age-related decline in NK activity has not been clearly established. We assessed changes in NK cytotoxicity in splenocytes and peripheral blood mononuclear cells after interferon (IFN)-alpha/beta stimulation in adult (6 months) and aged (22-26 months) C57Bl/6, Balb/c, and (Balb/c x C57Bl/6)F1 mice. Aged C57Bl/6 and Balb/c mice had a significantly reduced IFN-alpha/beta-stimulated NK cytotoxicity compared to adult mice. In contrast, adult and aged F1 mice showed similar NK cytotoxicity after IFN-alpha/beta induction. The decreased ability of NK cells of aged mice to respond to induction by IFN-alpha/beta was not due to a requirement for an increased amount of IFN or for a longer period of treatment with IFN. Further, this decreased response did not appear to be the result of suppressive activity of adherent cells or T cells. While the percentage of NK cells (NK1.1+) was similar in adult and aged mice, the (CD8+ NK1.1+) subset of NK cells was significantly increased in aged mice. Importantly, the percentage of CD8+ NK1.1+ cells was inversely related to the cytotoxicity observed after IFN-alpha/beta treatment.

Aging↗
PubMed1999

Immune response to influenza vaccination in a large healthy elderly population.

Elderly individuals not only demonstrate a greater risk of morbidity and mortality from influenza than the young, but also have greater difficulty mounting a protective response to influenza vaccine. The mechanism of the decreased efficacy of influenza vaccination in the elderly is not well understood. The present study was designed to assess the interaction between cell-mediated and humoral immune responses to influenza vaccine in a large population (n = 233) of healthy elderly individuals (mean age = 80.7) living in six continuing care retirement communities (CCRCs). While influenza vaccination resulted in significant increases in the mean anti-influenza antibody titres and mean proliferative responses of peripheral blood mononuclear cells to purified subvirion trivalent influenza vaccine one month after vaccination, only 48.9% and 30.0% of subjects had intact humoral and cell-mediated immune responses, respectively. No association was observed between intact cell-mediated and humoral responses: 14.7% of subjects had an intact cell-mediated, but not humoral response, and 32.6% of subjects had an intact humoral, but not cell-mediated response. However, IFNgamma production was significantly correlated with both antibody and cell-mediated responses to influenza vaccination, a finding not previously reported in the elderly. These results indicate that there is considerable heterogeneity among immune responses of the elderly to influenza vaccination. This heterogeneity needs to be a major consideration in evaluation of new vaccine preparations.

Aged↗
PubMed1998

T-kininogen is a biomarker of senescence in rats.

We have previously reported on the identification of T-kininogen (T-KG) as a gene whose expression is increased during senescence in male Sprague-Dawley (S-D) rats. Serum T-KG levels increase 2.5-4 months before the time of death for any given animal, irrespective of the actual age of the animal at the time of this event. Furthermore, dietary restriction (DR) delays, but does not prevent, the increase in serum T-KG levels. In the present study, we have assessed whether or not the age-related increase in T-KG is a common feature of senescence in other strains of rat. We have analyzed hepatic T-KG mRNA levels in male Fischer 344 rats (F344), as well as in male and female (Fischer 344 x Brown Norway)F1 rats (F1). In both of these strains, we observed a dramatic increase in hepatic T-KG mRNA levels when male rats approach senescence. The mRNA levels behave similarly in F1 and S-D rats, in that the increase occurs late in life, and it is either repressed or delayed by DR. In contrast, the increase in T-KG mRNA levels in F344 rats occurs earlier in life, and is not significantly affected by DR. Young female F1 rats fed ad libitum (AL) show a statistically significant (P = 0.0009) 2.6-fold higher level of T-KG mRNA, as compared to their male counterparts. Thus, while we still observe an age-related increase in this parameter in both AL and DR female F1 rats, the difference is statistically significant (P = 0.0001) only in DR animals. We conclude that the increase in T-KG gene expression is a common feature of senescence and that, at least in males of these commonly used rat strains, T-KG can be used as a reliable biomarker of aging. Since the increase in T-KG gene expression does not appear to correlate with inflammatory processes, and since different strains of animals succumb to different pathologies, these results further suggest that the increase in T-KG expression might be related to the process of aging per se, rather than to any given age-related pathology.

Aging↗
PubMed1998

Cytokine production after influenza vaccination in a healthy elderly population.

Influenza vaccination is less efficacious in the elderly than in the young. To characterize this age-related decrease in immune response to influenza vaccination, antibody and cell-mediated responses to influenza vaccine were assessed before immunization and 4 weeks after vaccination of a population of 270 healthy elderly individuals (mean age: 80.2 years) living in eight local continuing care retirement communities (CCRCs) and 30 young individuals (mean age: 27.8 years). The antibody titres produced against all three influenza strains increased significantly after vaccination in both the young and elderly (p < 0.0005); however, the young demonstrated significantly higher titres to all three strains than did the elderly (p < 0.03). Peripheral blood mononuclear cells (PBMC) cultured with influenza vaccine demonstrated significantly increased proliferation (elderly: p < 0.00005; young: p < 0.001) after vaccination, with proliferative responses in the young significantly higher than the elderly both before (p < 0.04) and after (p < 0.0005) vaccination. Similarly, IFN gamma production in these PBMC cultures increased significantly pre- to postvaccination in both young and elderly (young: p < 0.006; elderly: p < 0.00005), but the young produced more than the elderly both pre- and postvaccination (p < 0.0001). Following vaccination, PBMC production of IL-10 was higher in the young than in the elderly (p < 0.0015), while IL-6 production was comparable in both young and elderly individuals. Greater than 13% of the elderly population did not produce detectable IL-6, IL-10, or IFN gamma either before or after vaccination. The data show that the decreased cell-mediated and humoral responses to influenza vaccination of this healthy elderly population are accompanied by the production of lower levels of cytokines. A unique finding in this population of 270 healthy elderly was the association between a TH0 cytokine profile and intact immune responses to influenza vaccine. A similar relationship was not seen in the young.

Adult↗
PubMed1997

The age-associated decline in immune function of healthy individuals is not related to changes in plasma concentrations of beta-carotene, retinol, alpha-tocopherol or zinc.

The decline in the lymphoproliferative response to mitogenic stimuli shows marked heterogeneity in elderly individuals. Adequate nutriture is required for optimal immune function, yet nutritional status may be compromised in the elderly. To address whether this variation in the proliferative response of elderly individuals is related to their nutritional status, we studied 61 elderly (80.5 +/- 5.7 year-old) and 27 young (27.3 +/- 3.8 year-old) individuals participating in an ongoing assessment of their immune response to influenza vaccine. Ambulatory elderly individuals were recruited from five different retirement communities and were in good health upon enrollment in the study. Thirty-three percent of young and 54% of elderly subjects reported consuming micronutrient supplements daily during the study. Plasma and peripheral blood mononuclear cells (PBMC) were isolated from fasting individuals twice, 4-6 weeks apart. At both times, proliferative responses to the mitogens phytohemagglutinin (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM) were significantly lower (P < 0.004) in the elderly compared to the young. However, at both times, elderly participants had plasma concentrations of beta-carotene, retinol, alpha-tocopherol and zinc that were either significantly greater than, or equal to, those of young subjects. No significant correlations between plasma concentrations of beta-carotene, retinol, alpha-tocopherol and zinc and level of proliferative responses to each stimuli were observed in elderly individuals at either time. Thus, the heterogeneity in the proliferative response to mitogenic stimuli exhibited by a healthy elderly population cannot be attributed to differences in these nutritional parameters.

Adult↗
PubMed1997

The effects of general anesthesia and surgery on basal and interferon stimulated natural killer cell activity of humans.

UNLABELLED: Natural killer (NK) cells can lyse certain tumor cells as well as virally infected cells without prior sensitization. Animal studies have shown that general anesthesia (GA) alone or GA followed by surgery decreases both basal NK cytotoxicity and enhancement of NK activity by interferon (IFN). The purpose of this study was to determine whether similar inhibition of NK activity by anesthesia and surgery occurs in humans. Venous blood was drawn 1 h before and 20-24 h after surgery under isoflurane/N2O anesthesia. Peripheral blood mononuclear cells (PBMC) were assayed for basal and IFN-alpha-stimulated NK cytotoxicity using a chromium release assay with K562 cells as targets. Flow cytometry was used to enumerate NK, T-helper, and T-cytotoxic/suppressor cell populations in each sample. Basal NK activity was significantly depressed after GA and GA and surgery. Although the postoperative IFN treatment increased NK activity to the preoperative basal level, the level achieved was significantly lower than the level observed after IFN stimulation of PBMC as evaluated preoperatively. This decreased activity does not seem to be the result of a decrease in the percentage of circulating NK cells. The decrease in NK activity after anesthesia and surgery may lead to increased susceptibility to infection and/or tumor dissemination and thus needs to be explored. IMPLICATIONS: Natural killer cells can kill cancer cells and virally infected cells. This study shows that surgery with general anesthesia leads to decreased natural killer cell activity as assessed int he laboratory. This decreased natural killer cell activity may lead to infection or tumor dissemination. NK activity can be restored to presurgery levels by treating isolated NK cells with interferon-alpha.

Adolescent↗
PubMed1996

Age-associated decline in IL-2 and IL-12 induction of LAK cell activity of human PBMC samples.

Previously we reported that young and elderly natural killer (NK) cell activity against the standard NK sensitive K562 cell line can be augmented to the same degree by IL-2 and IFN-alpha. We have extended these studies to include IL-12. Similar to IL-2 and IFN-alpha, IL-12 can enhance NK cytotoxicity to the same degree in both young and elderly samples over a wide range of doses and incubation times when K562 cells are used as targets. However, in contrast to our findings with the NK system, we have observed that induction of lymphokine activated killer (LAK) cell activity, as defined by the ability of peripheral blood mononuclear cells (PBMC) samples to lyse the normally NK resistant Daudi cell line, was significantly decreased in the elderly samples compared to young samples. Comparable age-associated differences were observed in LAK activity after induction with IL-2, IL-12, and IFN-alpha at varying doses and incubation times. We hypothesize an age-associated deficiency either in the mechanism of LAK induction or in target cell recognition.

Adult↗
PubMed1996

Natural killer cell cytotoxicity in elderly humans after influenza immunization.

Previous studies have reported that human natural killer (NK) cytotoxicity can be augmented by either in vitro stimulation with influenza virus antigens or in vivo administration of killed influenza vaccine. The study demonstrating the latter conclusion reported an increase in NK cytotoxicity lasting for 4 weeks postvaccination in young subjects. We initiated our study to determine if a similar increase in NK activity was observed in an elderly population after immunization with the 1992-1993 influenza vaccine. NK activity of 34 elderly (mean age, 77.3 years) was determined at 3 time points: prevaccination, 4 to 6 weeks postvaccination, and 5 to 6 months after vaccination. In contrast to the results of the previous study, the NK cytotoxicity of our elderly subjects was not augmented by the influenza vaccine at any time tested. We also determined the number of CD56+ cells in whole-blood samples at each of the time points and found that there is no change in NK cell number after influenza vaccination.

Aged↗
PubMed1995

Age-associated changes in mitogen-induced lymphoproliferation and lymphokine production in the long-lived brown-Norway rat: effect of caloric restriction.

We have previously demonstrated that age-related declines in Concanavalin A (ConA), induced proliferation and lymphokine production, occur in ad-libitum fed Brown Norway (AL BN) rats. Since caloric restriction (CR) extends lifespan, we expected that the age related changes in immune parameters would be delayed by CR. CR does act to delay age-related changes in proliferation in response to ConA. In addition, CR postpones the plateau in ConA induced interferon (IFN) production seen after 23 months of age in AL rats. However, CR does not postpone the age-related decline in ConA induced interleukin-2 (IL-2) production. Therefore, ConA induced IFN production maybe a good candidate as an early marker of physiologic aging, while ConA induced proliferative response is a possible candidate for a marker of late stages of aging.

Aging↗
PubMed1995

A replication-competent, endogenous retrovirus from an aged DBA/2 mouse contains the complete env from Emv-3 and a novel gag partially related to AKT-8.

We previously described an endogenous murine retrovirus, rv-DBA/2aged, isolated from an aged DBA/2 mouse. The previous report showed that a recombination which resulted in the replacement of Emv-3 gag sequences with gag sequences homologous to those found in the AKT-8 virus had taken place. This recombination allowed production of a competent virus from the defective Emv-3 locus. However, the extent of replacement of Emv-3 gag was not known. We report here the entire sequence for the gag gene of rv-DBA/2aged as well as the previously unsequenced 3' end of the Emv-3 gag gene. These data demonstrate that while sequences homologous to the entire gag gene fragment found in AKT-8 are represented in rv-DBA/2aged, the remainder of rv-DBA/2aged gag is not derived from Emv-3 but is a unique gag sequence. Furthermore, a complete comparison of env sequences shows that the env of rv-DBA/2aged is derived entirely from Emv-3. Additional data suggest that the recombination which led to production of the rv-DBA/2aged virus may be a common event in aging DBA/2 mice. Finally, comparison of the new sequences of Emv-3 with those of the Akv virus (also designated AKR-623 and Emv-11) and Emv-1 shows that this endogenous virus locus is very closely related to the other Emv loci at the nucleotide sequence level.

Aging↗
PubMed1994

A murine leukemia virus expressed in aged DBA/2 mice is derived by recombination of the Emv-3 locus and another endogenous gag sequence.

Although most inbred strains of mice contain endogenous retroviral sequences, these sequences are usually not capable of producing infectious retroviruses. In some cases, the retroviral sequences are small fragments of viral genomes. In a few cases the sequences for complete retroviruses exist, but contain small defects which prevent the production of infectious virus. While the ability of reversions of these defects to produce retroviruses has been studied by site-directed mutagenesis and chemical-mediated mutagenesis, the presence of spontaneously occurring reversions has not been completely evaluated. We characterized an infectious ecotropic retrovirus spontaneously expressed in aged DBA/2 mice, which carries the complete but defective Emv-3. Although this endogenously produced retrovirus was related to the endogenous Emv-3 sequence, it had undergone recombination with another retroviral sequence to correct the defect which resided in the gag of Emv-3. Thus, recombination of endogenous ecotropic retroviral sequences may be a mechanism to produce infectious retroviruses in adult animals that contributes to pathologic disease.

3T3 Cells↗
PubMed1994

Effects of aging on natural killer cell activity and activation by interleukin-2 and IFN-alpha.

To address the conflicting reports concerning both innate and lymphokine-inducible NK activity of elderly individuals, NK activity of peripheral blood mononuclear cells (PBMC) of 21 young (23 to 35 years old) and 43 elderly (65 to 100 years old) subjects was assessed using a 4-hr chromium release assay with K562 or Daudi cells as targets. Significantly higher innate NK cell activity was observed in elderly compared to young individuals (P < 0.001, Student t test). NK activity of both groups was enhanced to the same degree by IL-2. Although intermediate amounts of IFN-alpha (100-500 mu/10(6) cells) induced comparable maximal NK activity of both young and elderly subjects, young subjects responded better than elderly to low amounts of IFN-alpha (10 mu/10(6) cells), while higher amounts (10(3) mu/10(6) cells) reduced the NK activity of the elderly, but not young, to basal levels. IFN-alpha also expanded the range of target cells susceptible to NK activity. Untreated cells of neither young nor elderly showed activity against Daudi targets. Two-hour treatment with IFN-alpha resulted in significant activity against Daudi cells; however, this activity was significantly lower in the elderly compared to the young subjects.

Adult↗
PubMed1994

Monocyte culture and adherence modifies LPS-induced IL-6 production and inhibition by hydrocortisone.

The effect of hydrocortisone (HC) on IL-6 production by monocytes (Mo) that were cultured under either adherent or limited-adherent culture conditions was determined. Although freshly isolated Mo produced more IL-6 in response to LPS than Mo cultured 24 hr, culture had little effect on inhibition of IL-6 by HC. In contrast, the conditions of Mo culture had a significant impact on the kinetics of IL-6 production and inhibition by HC. Adherent Mo produced significantly higher levels of IL-6 4 hr after LPS compared to limited-adherent Mo. By 12 hr of LPS stimulation, comparable quantities of IL-6 were produced by both cultures. HC inhibition was complete 4 hr after LPS stimulation of adherent Mo, while 12 hr was required for maximum inhibition of limited-adherent Mo. Production of an IL-6 inhibitor was not responsible for the increased inhibition by HC with adherence, because both IL-6 protein and bioactivity were comparably decreased. The kinetics of inhibition of TNF alpha and IL-1 beta production by HC were similarly affected by adherence. Phenotypic analysis of cultured vs freshly isolated Mo showed a decrease in Mo expressing CD14, but not CD11b, which paralleled a decrease in IL-6 production by the cultured Mo. However, there were no phenotypic differences between adherent and limited-adherent Mo. The results demonstrate that the time of Mo culture, as well as adherence, may serve to alter LPS-induced IL-6 production and its inhibition by HC.

Animals↗
PubMed1994

Differences between young and aged mice in susceptibility to Friend virus.

Friend virus (FV) is a murine leukemia virus that infects progenitor red blood cells and causes an erythroleukemia in susceptible mouse strains, resulting in splenomegaly. Several genetic loci of the host have been identified that affect erythroleukemia development, differentiation status of target cells and virus replication. Since age may change expression of these loci, age may affect FV disease. To explore this possibility, FV expression in four genetically diverse strains of mice of different ages was examined. Extent of viral replication and of disease were evaluated by measuring spleen focus forming units (SFFU), spleen weight and reverse transcriptase (RT) activity in target organs. Young DBA/2 and (C57BL/6 x DBA/2)F1 mice exhibited a greater level of virus expression than their aged counterparts in all parameters investigated. Young CBA/Ca mice had slightly higher spleen weights and SFFU values than aged CBA/Ca mice, but a definitive age-related change was not observed in the RT activity of the target organs. C57BL/6 mice, which are genetically resistant to the development of FV-induced erythroleukemia, exhibited a limited degree of virus replication that was not effected by the age of the animal. Our results indicate that the age of the mouse, as well as the genetic background, can contribute to the level of susceptibility to FV.

Aging↗
PubMed1994

Inhibition of macrophage-induced, antigen-specific T-cell proliferation by poly I:C role of suppressor macrophages.

Poly I:C treatment can inhibit the ability of macrophages (M phi) to induce antigen-specific T-cell proliferation. This study investigated whether this inhibition is the result of suppressor or cytotoxic activity. Pretreatment of M phi with indomethacin in vivo, in vitro or both failed to reverse the inhibition of T-cell proliferation induced by poly I:C-treated, keyhole limpet haemocyanin (KLH)-pulsed M phi, suggesting that prostaglandin production does not mediate the inhibition of T-cell proliferation. The transfer of supernatants from cultures containing poly I:C-treated, KLH-pulsed M phi to cultures containing saline-treated, KLH-pulsed M phi and T cells did not inhibit T-cell proliferation, suggesting that the inhibition of T-cell proliferation by poly I:C is not mediated by the production of soluble suppressor factors. As addition of poly I:C-treated, KLH-pulsed M phi to cultures containing saline-treated, KLH-pulsed M phi did not significantly inhibit KLH-specific T-cell proliferation, the inhibition of T-cell proliferation is also not mediated by direct cell contact or short-range soluble suppressor factors. In addition, poly I:C-treated, KLH-pulsed M phi did not induce cytolysis of syngeneic T cells. These results indicate that cytotoxic or suppressor effector functions of M phi are not involved in the mechanism by which poly I:C inhibits M phi-induced, antigen-specific T-cell proliferation.

Animals↗