The MoxFo initiative-Mechanisms of action: Biomarkers in multiple sclerosis exercise studies.

BACKGROUND: As exercise exerts neurobiological and immunomodulatory effects, it might also act as a disease-modifying intervention in MS. However, a clear mechanistic link between exercise and disease-modifying effects in MS has yet to be established. OBJECTIVE: Establish recommendations for future mechanistic exercise studies in MS. METHODS: In regular meetings, members of the mechanisms of action group within the MoXFo (Moving eXercise research Forward in MS) initiative evaluated gaps of knowledge and discussed unmet needs in mechanistic MS research. RESULTS: We concluded that biomarkers assessed in translational studies in humans and animals are essential to decipher the underlying mechanisms of exercise in MS. Consequently, we defined clear definitions of different types of biomarkers examined in MS exercise studies and operationalized their use to align with the research question and optimal testing time points. Furthermore, we provide key considerations to improve the rigor of translational studies and defined minimal reporting criteria for animal studies. CONCLUSION: The resulting recommendations are intended to improve the quality of future mechanistic exercise studies in MS and consequently lead to a better understanding of therapeutic approaches.

Real-world effectiveness of elbasvir/grazoprevir In HCV-infected patients in the US veterans affairs healthcare system.

Elbasvir/grazoprevir (EBR/GZR) is an all-oral direct-acting antiviral agent (DAA) with high sustained virologic response (SVR) in clinical trials. This study's primary objective was to evaluate effectiveness of EBR/GZR among HCV-infected patients in a real-world clinical setting. We conducted a nationwide retrospective observational cohort study of HCV-infected patients in the US Department of Veterans Affairs (VA) using the VA Corporate Data Warehouse. The study population included patients with positive HCV RNA who initiated EBR/GZR from February 1 to August 1, 2016. We calculated the 95% confidence interval for binomial proportions for SVR overall and by demographic subgroups. Clinical and demographic characteristics were also evaluated. We included 2436 patients in the study cohort. Most were male (96.5%), African American (57.5%), with mean age of 63.5 (SD = 5.9) and 95.4% infected with genotype (GT) 1 [GT1a (34.7%), GT1b (58.6%)]. Other comorbidities included diabetes (53.2%), depression (57.2%) and HIV (3.0%). More than 50% had history of drug or alcohol abuse (53.9% and 60.5%, respectively). 33.2% of the cohort had cirrhosis. A total of 95.6% (2,328/2,436; 95% CI: 94.7%-96.4%) achieved SVR. The SVR rates by subgroups were: male, 95.5% (2245/2350); female, 96.5% (83/86); GT1a, 93.4%, GT1b, 96.6%, GT4, 96.9%, African American, 95.9% (1,342/1,400); treatment-experienced, 96.3% (310/322); cirrhosis, 95.6% (732/766); stage 4-5 CKD, 96.3% (392/407); and HIV, 98.6% (73/74). SVR rates were high overall and across patient subgroups regardless of gender, race/ethnicity, cirrhosis, renal impairment or HIV. This study provided important data regarding the effectiveness of EBR/GZR in a large clinical setting.

Naturally occurring tolerance acquisition to foods in previously allergic children is characterized by antigen specificity and associated with increased subsets of regulatory T cells.

BACKGROUND: Food allergy affects approximately 6-8% of children, and increasing in prevalence. Some children naturally outgrow their food allergy without intervention, but the mechanisms by which this occurs remain poorly understood. We sought to investigate the role of regulatory T cells in the development of naturally acquired tolerance. METHODS: Fifty-eight children (1-18 years) with either egg or peanut allergy, recent acquisition of natural tolerance to egg or peanut, or no food allergy were studied. Peripheral blood mononuclear cells (PBMC) from these groups were stimulated with relevant antigen for 48 h and flow cytometry performed to characterize both surface (CD3, CD4, CD25, CD14, CD19, and CD127) and intracellular markers (IL-10, Foxp3, and IL-5). RESULTS: Resting PBMC from naturally tolerant patients had significantly increased CD3+CD4+CD25+CD127loFoxp3+ cells, when compared to allergic or control patients (mean 6.36 vs. 2.37 vs. 2.62%, respectively, P < 0.05). Upon stimulation with relevant antigen, naturally tolerant patients also had increased IL-10-expressing CD25+CD127lo cells (6.33 vs. 1.65 vs. 0.7, P < 0.01), Foxp3+ cells (mean 12.6 vs. 5.42 vs. 3%, P < 0.01), and CD4+ cells (mean 4.48 vs. 1.59 vs. 0.87%, P < 0.01); the increase was not observed in PBMCs from allergic or control patients. Additionally, this upregulation was only seen with relevant antigen stimulation and not upon stimulation with unrelated antigen. CONCLUSION: The increased CD3+CD4+CD25+CD127lo cells at baseline and upon stimulation and increased induction of IL-10-producing cells of several types, including Tr1 cells, from naturally tolerant patients suggests an important role for regulatory T cell subsets in the acquisition of natural tolerance.

Functional transplant of megabase human immunoglobulin loci recapitulates human antibody response in mice.

We constructed two megabase-sized YACs containing large contiguous fragments of the human heavy and kappa (kappa) light chain immunoglobulin (Ig) loci in nearly germline configuration, including approximately 66 VH and 32 V kappa genes. We introduced these YACs into Ig-inactivated mice and observed human antibody production which closely resembled that seen in humans in all respects, including gene rearrangement, assembly, and repertoire. Diverse Ig gene usage together with somatic hypermutation enables the mice to generate high affinity fully human antibodies to multiple antigens, including human proteins. Our results underscore the importance of the large Ig fragments with multiple V genes for restoration of a normal humoral immune response. These mice are likely to be a valuable tool for the generation of therapeutic antibodies.

Reintroducing a keystone bioturbator can facilitate microbial bioremediation in urban polluted sediments.

Anthropogenic environmental stressors have significantly reduced biodiversity and the capacity of remnant natural habitats to deliver ecosystem functions and services in urban areas. To mitigate these impacts and recover biodiversity and function, ecological restoration strategies are needed. While habitat restoration is proliferating in rural and peri-urban areas, strategies purposely designed to succeed under the environmental, social and political pressures of urban areas are lacking. Here, we propose that ecosystem health in marine urban areas can be improved by restoring biodiversity to the most dominant habitat, unvegetated sediments. We reintroduced a native ecosystem engineer, the sediment bioturbating worm Diopatra aciculata, and assessed their effects on microbial biodiversity and function. Results showed that worms can affect the diversity of microbes, but effects varied between locations. Worms caused shifts in microbial community composition and function at all locations. Specifically, the abundance of microbes capable of chlorophyll production (i.e. benthic microalgae) increased and the abundance of microbes capable of methane production decreased. Moreover, worms increased the abundances of microbes capable of denitrification in the site with lowest sediment oxygenation. Worms also affected microbes capable of degrading the polycyclic aromatic hydrocarbon toluene, although the direction of that effect was site-specific. This study provides evidence that a simple intervention such as the reintroduction of a single species can enhance sediment functions important for the amelioration of contamination and eutrophication, although further studies are needed to understand the variation in outcomes between sites. Nevertheless, restoration strategies targeting unvegetated sediments provide an opportunity to combat anthropogenic stressors in urban ecosystems and may be used for precondition before more traditional forms of habitat restoration such as seagrass, mangrove and shellfish restoration.

Resistance Exercise Program in Cognitively Normal Older Adults: CERT-Based Exercise Protocol of the AGUEDA Randomized Controlled Trial.

OBJECTIVES: To provide a comprehensive CERT (Consensus on Exercise Reporting Template)-based description of the resistance exercise program implemented in the AGUEDA (Active Gains in brain Using Exercise During Aging) study, a randomized controlled trial investigating the effects of a 24-week supervised resistance exercise program on executive function and related brain structure and function in cognitively normal older adults. DESIGN AND PARTICIPANTS: 90 cognitively normal older adults aged 65 to 80 were randomized (1:1) to a: 1) resistance exercise group; or a 2) wait-list control group. Participants in the exercise group (n = 46) performed 180 min/week of resistance exercise (3 supervised sessions per week, 60 min/session) for 24 weeks. INTERVENTION: The exercise program consisted of a combination of upper and lower limb exercises using elastic bands and the participant's own body weight as the main resistance. The load and intensity were based on the resistance of the elastic bands (7 resistances), number of repetitions (individualized), motor complexity of exercises (3 levels), sets and rest (3 sets/60 sec rest), execution time (40-60 sec) and velocity (as fast as possible). SETTINGS: The maximum prescribed-target intensity was 70-80% of the participants' maximum rate of perceived exertion (7-8 RPE). Heart rate, sleep quality and feeling scale were recorded during all exercise sessions. Those in the wait-list control group (n = 44) were asked to maintain their usual lifestyle. The feasibility of AGUEDA project was evaluated by retention, adherence, adverse events and cost estimation on the exercise program. RESULTS AND CONCLUSIONS: This study details the exercise program of the AGUEDA trial, including well-described multi-language manuals and videos, which can be used by public health professionals, or general public who wish to implement a feasible and low-cost resistance exercise program. The AGUEDA exercise program seems to be feasible by the high retention (95.6%) and attendance rate (85.7%), very low serious adverse event (1%) and low economic cost (144.23 € /participant/24 weeks). We predict that a 24-week resistance exercise program will have positive effects on brain health in cognitively normal older adults.

Functional anatomy of autobiographical memory recall deficits in depression.

BACKGROUND: Major depressive disorder (MDD) is associated with deficits in recalling specific autobiographical memories (AMs). Extensive research has examined the functional anatomical correlates of AM in healthy humans, but no studies have examined the neurophysiological underpinnings of AM deficits in MDD. The goal of the present study was to examine the differences in the hemodynamic response between patients with MDD and controls while they engage in AM recall. METHOD: Participants (12 unmedicated MDD patients; 14 controls) underwent functional magnetic resonance imaging (fMRI) scanning while recalling AMs in response to positive, negative and neutral cue words. The hemodynamic response during memory recall versus performing subtraction problems was compared between MDD patients and controls. Additionally, a parametric linear analysis examined which regions correlated with increasing arousal ratings. RESULTS: Behavioral results showed that relative to controls, the patients with MDD had fewer specific (p=0.013), positive (p=0.030), highly arousing (p=0.036) and recent (p=0.020) AMs, and more categorical (p<0.001) AMs. The blood oxygen level-dependent (BOLD) response in the parahippocampus and hippocampus was higher for memory recall versus subtraction in controls and lower in those with MDD. Activity in the anterior insula was lower for specific AM recall versus subtraction, with the magnitude of the decrement greater in MDD patients. Activity in the anterior cingulate cortex was positively correlated with arousal ratings in controls but not in patients with MDD. CONCLUSIONS: We replicated previous findings of fewer specific and more categorical AMs in patients with MDD versus controls. We found differential activity in medial temporal and prefrontal lobe structures involved in AM retrieval between MDD patients and controls as they engaged in AM recall. These neurophysiological deficits may underlie AM recall impairments seen in MDD.

Genetic variation in cholinergic muscarinic-2 receptor gene modulates M2 receptor binding in vivo and accounts for reduced binding in bipolar disorder.

Genetic variation in the cholinergic muscarinic-2 (M(2)) receptor gene (CHRM2) has been associated with the risk for developing depression. We previously reported that M(2)-receptor distribution volume (V(T)) was reduced in depressed subjects with bipolar disorder (BD) relative to depressed subjects with major depressive disorder (MDD) and healthy controls (HCs). In this study, we investigated the effects of six single-nucleotide polymorphisms (SNPs) for CHRM2 on M(2)-receptor binding to test the hypotheses that genetic variation in CHRM2 influences M(2)-receptor binding and that a CHRM2 polymorphism underlies the deficits in M(2)-receptor V(T) observed in BD. The M(2)-receptor V(T) was measured using positron emission tomography and [(18)F]FP-TZTP in unmedicated, depressed subjects with BD (n=16) or MDD (n=24) and HCs (n=25), and the effect of genotype on V(T) was assessed. In the controls, one SNP (with identifier rs324650, in which the ancestral allele adenine (A) is replaced with one or two copies of thymine (T), showed a significant allelic effect on V(T) in the pregenual and subgenual anterior cingulate cortices in the direction AA

Developing a Patient-Centered Model of Prostate Cancer Care: Patient Satisfaction With a Survivorship Program Embedded in Urologic-Oncologic Care.

OBJECTIVE: To evaluate patients' and partners' satisfaction with a prostate cancer survivorship program embedded in urologic-oncologic care. As a part of quality improvement activity, we developed a patient and partner-centered, biopsychosocial support program for men and partners coping with the urinary and sexual side-effects of surgical treatment for prostate cancer. The program became a part of usual care for all prostate cancer patients. METHODS: Patients who saw both an advanced practice provider and a sex therapist between August 1, 2018 and July 31, 2019 were eligible. Surveys packets were sent to 146 patients with surveys included for partners (N = 292). We used descriptive statistics to characterize participant responses. RESULTS: Responses were received from 88 patients and 70 partners (56% response rate for the group). Patients and partners reported very high or fairly high satisfaction with the rehabilitation activities of the program (86-97% and 90%-100%, respectively); 91% of patients and 84% of partners thought having pre-operative education and post-operative rehabilitation was a good or fairly good idea; 83% of patients and 79% of partners would very much or somewhat recommend the program to a friend who was considering surgical treatment for prostate cancer. CONCLUSION: Embedding a patient and partner-centered prostate cancer survivorship support program in oncologic care can positively impact patients' and partners' engagement in and satisfaction with post-operative rehabilitation.

Carotid artery disease: stenting vs endarterectomy.

Several multicentre, randomized trials have validated the efficacy of carotid endarterectomy (CEA). Comparative randomized trials are also currently developing insight into the role of carotid angioplasty and stenting (CAS), and identifying factors for optimal patient selection. Although these interventions are aimed at embolic stroke prevention, anaesthetic management might prevent the subset of strokes that are haemodynamic in nature by maintaining tight physiological control. The perioperative risk of myocardial events is increased in this population. Hence, preoperative attention to cardiovascular disease, hypertension, renal insufficiency, and diabetes mellitus might reduce neurological and cardiovascular complications. During carotid artery cross-clamping, the risk of cerebral ischaemia can be decreased by maintaining normal to high perfusion pressure. Although there is no demonstrable advantage of a specific anaesthetic technique for patients undergoing CEA, it is imperative that cerebral blood flow is optimized, that there is minimal cardiac stress, and that anaesthetic recovery is rapid. Carotid angioplasty and stenting is performed under light sedation with antithrombotic therapy and vigilance for bradycardia and hypotension. Tight haemodynamic control remains a priority in the immediate postoperative period for both interventions.

Revisiting the bis(dimethylamido) metallocene complexes of thorium and uranium: improved syntheses, structure, spectroscopy, and redox energetics of (C5Me5)2An(NMe2)2 (An = Th, U).

The reaction of (C5Me5)2AnCl2 (An = Th, U) with 2.8 or 4 equivalents of LiNMe2, respectively, affords (C5Me5)2An(NMe2)2 in high yields. In addition to improved syntheses, the solid-state structures, voltammetric data, and UV-visible-NIR spectra for these classic actinide bis(dimethylamido) complexes are presented for the first time.

In Vivo Imaging of Venous Side Cerebral Small-Vessel Disease in Older Adults: An MRI Method at 7T.

BACKGROUND AND PURPOSE: Traditional neuroimaging markers of small-vessel disease focus on late-stage changes. We aimed to adapt a method of venular assessment at 7T for use in older adults. We hypothesized that poorer venular morphologic characteristics would be related to other small-vessel disease neuroimaging markers and a higher prevalence of small-vessel disease-Alzheimer disease risk factors. MATERIALS AND METHODS: Venules were identified in periventricular ROIs on SWI and defined as tortuous or straight. The tortuosity ratio was defined as total tortuous venular length divided by total straight venular length. White matter hyperintensity burden (visually rated from 0 to 3) and the number of microbleeds (0, 1, >1) were determined. Differences in tortuous and straight venular lengths were evaluated. Relationships with demographic variables, allele producing the e4 type of apolipoprotein E (APOE4), growth factors, pulse pressure, physical activity, and Modified Mini-Mental State Examination were assessed via Spearman correlations. RESULTS: Participants had 42% more tortuous venular tissue than straight (median, 1.42; 95% CI, 1.13-1.62). APOE4 presence was associated with a greater tortuosity ratio (ρ = 0.454, P = .001), and these results were robust to adjustment for confounders and multiple comparisons. Associations of the tortuosity ratio with sex and vascular endothelial growth factor did not survive adjustment. Associations of the tortuosity ratio with other variables of interest were not significant. CONCLUSIONS: Morphologic measures of venules at 7T could be useful biomarkers of the early stages of small-vessel disease and Alzheimer disease. Longitudinal studies should examine the impact of apolipoprotein E and vascular endothelial growth factor on the risk of venular damage.

Dietary fat influences on murine melanoma growth and lymphocyte-mediated cytotoxicity.

The effects of fat concentration and saturation on the growth of a B16 melanoma and lymphocyte-mediated cytotoxicity against the cells were studied with the use of inbred C57BL/6J and C3H/HeJ mice subjected to dietary manipulation before and after tumor transplantation. The tumor latency for mice initially given injections of 5 X 10(6) syngeneic B16 melanoma cells was significantly less for those mice fed at 20% fat concentration than those fed only the essential fatty acid (EFA) diet. When mice were given injections of 10(6) melanoma cells, the initiation time required for visible tumor growth in mice receiving the polyunsaturated fat (PUF) diet was significantly less than that in mice receiving the saturated fat (SF) diet. Cytolysis mediated by lymphocytes from diet-manipulated mice toward allogeneic B16 melanoma cells was greater for those mice receiving the EFA diet only and 8% SF diets than for those mice fed a diet without fat. The cytolytic response decreased immediately with the additional PUF in the diet, whereas additional SF decreased cytolytic responses only when dietary SF concentration was greater than 8%. Thus dietary fat, particularly PUF, has a significant influence on the growth and lymphocyte-mediated cytotoxicity of a murine melanoma. This effect cannot be attributed to differences in the energy content between high-fat and low-fat diets.

Lipid modulation of mammary tumor cell cytolysis: direct influence of dietary fats on the effector component of cell-mediated cytotoxicity.

For understanding the mechanism by which fatty acids promote mammary tumor growth, experiments were designed to determine the influence of dietary fat concentration and saturation on both effector (Ef) and target (Ta) cells in an allogeneic antitumor cell-mediated immune response. Exposure of cytotoxic T-lymphocytes (CTL) to different fatty acids led to significant changes in the subsequent cytolytic capacity of these cells after both primary and secondary immunization. An increase in both saturated (SF) and polyunsaturated (PUF) fats led to decreased cytotoxic function after primary immunization. After a secondary challenge, the suppressive influence of SF was significantly greater than that of PUF, compared to that of the control diet containing essential fatty acids as the only fat source. This response was mediated by a direct effect on the CTL and not through an increase in suppressor or a decrease in Ef or helper cell frequency. In contrast, manipulation of the fatty acid environment of the Ta mammary tumor cells in vivo or in vitro had no significant effect on their susceptibility to lymphocyte-mediated cytotoxicity. Therefore, dietary fats may mediate their effect by a direct influence on the immunocompetent lymphocyte and not on the Ta mammary tumor cell.

Susceptibility of mammary tumor cells to complement-mediated cytolysis after in vitro or in vivo fatty acid manipulation.

The susceptibility of line 168 murine mammary tumor cells to complement (C)-mediated lysis was tested after in vitro treatment with several saturated or unsaturated fatty acids dissolved in different solvents or presented in the form of micelles to the cells. The lytic susceptibility of these cultured cells was compared with similar tumor cells obtained either from mice maintained on diets containing different concentrations and saturations of fatty acids or from cultures supplemented with serum from tumor-free control mice fed pair-matched diets. Although changes in dietary fat concentration and saturation resulted in alterations of the tumor cell fatty acid composition, those alterations did not influence the susceptibility of tumor cells to C-mediated lysis. However, single, or combinations of, unsaturated fatty acids dissolved in ethanol, unlike saturated fatty acids, reduced the lytic susceptibility of tumor cells in vitro. Hexane added to culture medium significantly suppressed the lytic susceptibility; however, when used as a carrier no significant differences were observed among treatments with the individual fatty acids at several concentrations. This result may be due to the effect of hexane on the cell membrane because this treatment also affected the osmotic fragility of the cells. Fatty acids as micelles did not influence the susceptibility of tumor cells to lysis. We concluded that only in vitro manipulation of fatty acids in some vehicles influenced the susceptibility of target tumor cells to C-mediated lysis; this finding did not parallel the situation that occurred in vivo. Moreover, the use of different vehicles to present fatty acids to tumor cells may further alter the susceptibility to C-mediated lysis.

Enhancement of heterotransplanted human tumor graft survival in nude mice treated with antilymphocyte serum and in congenitally athymic-asplenic (Lasat) mice.

The latency period, success rate, and minimal cell inoculum size required for transplantation of continuously passaged human tumor lines into congenitally athymic (nude) mice, antilymphocyte serum (ALS)-treated congenitally athymic (nude) mice, and congenitally athymic-asplenic (lasat) mice were compared. The 11 tumor lines studied included examples of breast adenocarcinoma, transitional cell carcinoma, osteosarcoma, fibrosarcoma, Hodgkin's disease, malignant melanoma, and rhabdomyosarcoma. Of these 11 tumor lines, 3 were successfully transplanted into nude mice, compared to 5 of 10 tumor lines in ALS-treated nude mice and 9 of 11 lines in lasat mice. Moreover, the latency period was shorter and the minimal cell inoculum size was lower for lasat mice than for either nude or ALS-treated nude mice. Despite this enhancement of heterotransplantation into lasat mice and despite the growth of large local masses, no evidence of distant metastases was found.

Enhancement of metastasis from a transplantable mouse mammary tumor by dietary linoleic acid.

The influence of quantitative differences in dietary linoleic acid (18:2) on the metastasis as well as the development of line 4526 mouse mammary tumors was investigated. High fat diets (20%, w/w) that contained either 1, 2, 4, 8, or 12% 18:2 by weight, were prepared by using mixtures of coconut and safflower oil and fed to female BALB/c mice that were subsequently inoculated with 10(4) 4526 tumor cells s.c., either at the lateral abdominal wall (LAW) or in the mammary fat pad (MFP). Latency of LAW tumors was influenced by the level of dietary 18:2, whereas the latency of MFP tumors was not. When metastasis was assessed, mice with MFP tumors fed 1, 2, 4, or 8% 18:2 diets had 62-73% fewer lung surface tumor nodules than similar mice fed 12% 18:2. Mice in all dietary groups with LAW tumors had fewer metastatic lung nodules than mice with MFP tumors; mice with LAW tumors fed diets containing 1, 2, or 4% 18:2 had 52-69% fewer nodules than similar mice fed diets containing 8 or 12% 18:2. There were no significant differences in the rate of increase of body weight or the daily mean tumor volumes when compared with dietary 18:2 level. Fatty acid composition of the tumor, particularly the level of 18:2, was significantly altered by diet. This study demonstrates that while the level of dietary 18:2 does not enhance the growth rate of primary 4526 tumors and does or does not affect the latency depending on the primary site, it does significantly alter the metastasis. These results stress the importance of metastasis assessment in future studies involving dietary fat effects on tumorigenesis.

Dietary fat modulation of murine mammary tumor metabolism studied by in vivo 31P-nuclear magnetic resonance spectroscopy.

The effect of dietary fat concentration and saturation on high energy phosphate metabolites and phospholipid turnover in transplanted line 168 murine mammary tumors was studied using surface coil 31P-nuclear magnetic resonance spectroscopy. Female BALB/c mice were fed one of five diets each containing at least the minimum of essential fatty acids (EFA). Four diets contained additional safflower or palm oil for a total fat concentration of 5 or 20% by weight. The growth rate of tumors from mice fed the high safflower oil diet was significantly greater than the growth rate of tumors for mice fed all other diets including the one which contained the minimal EFA. 31P-nuclear magnetic resonance-observable phosphate metabolite ratios. ATP/Pi, ATP/phosphomonoester (ATP/PME), and PME/Pi, and tumor pH of line 168 tumors decreased with increasing tumor volume, indicating a shift from active to inactive tumor metabolism. The rates of those decreases with progressive tumor growth differed significantly among tumors of mice fed the different diets. Decreases in ATP/Pi, ATP/PME, and pH were the most rapid in the tumors of mice fed the high safflower oil diet and significantly faster than tumors of mice fed the diet containing minimum EFA. In addition, the decrease in the PME/Pi ratio of tumors was significantly greater in mice fed the high fat (high palm oil and high safflower oil) diets than mice fed the diet containing the minimum of EFA. The rate of decline of ATP/Pi and ATP/PME with progressive tumor growth was directly correlated with levels of linoleic acid as well as total unsaturated fat. High levels of a polyunsaturated fat had a significant effect on mammary tumor metabolism particularly during early stages of tumor growth. Differences in high energy phosphate metabolite dynamics relative to dietary fat were present in tumors of equal volume. Thus, dietary fat influences on mammary tumorigenesis may be related to high energy phosphate metabolites.

Linoleic acid metabolism in metastatic and nonmetastatic murine mammary tumor cells.

The mechanism(s) by which dietary linoleic acid (18:2n-6) enhances mammary tumor growth and metastasis is not known. Since arachidonic acid (20:4n-6)-derived prostaglandins (PG) may play a role in the metastatic dissemination of tumor cells, the ability of two murine mammary tumor cell lines, 4526 (metastasis positive) and line 168 (spontaneous metastasis negative), to convert 18:2n-6 into prostaglandins was examined. Cells were initially incubated with [14C]18:2n-6 and after 8-24 h the [14C]fatty acids were quantitated by high-performance liquid chromatography following transesterification. [14C]18:2n-6 was metabolized primarily to [14C]dihomogammalinolenic acid (20:3n-6) in line 4526 cells and [14C]20:4n-6 in line 168 cells. Examination of cellular fatty acid levels revealed a 20:3n-6/20:4n-6 ratio of 1.79 +/- 0.36 and 0.20 +/- 0.02 in line 4526 and 168 cells, respectively. These data are consistent with an inherently lower delta 5 desaturase activity in line 4526 relative to 168. To assess the metabolism of 18:2n-6 into eicosanoid products, the cell lines were prelabeled with [14C]18:2n-6 or 0-40 microM nonradiolabeled 18:2n-6 overnight and subsequently stimulated with calcium ionophore A23187 for 1 h. Total PGE production, as determined by radioimmunoassay, was greater in 168 relative to 4526 cells at all 18:2n-6 concentrations. 14C-prostaglandins detected by high-performance liquid chromatography and argentation thin-layer chromatography were: PGF1 alpha and PGE1 (derived from 20:3n-6) and PGF2 alpha and PGE 2 (derived from 20:4n-6) from line 4526; PGE1 and PGE2 from line 168. PGE1/PGE2 ratios were 1.43 +/- 0.07 and 0.23 +/- 0.03 for 4526 and 168 lines, respectively. Neither cell line synthesized lipoxygenase products following [14C]18:2n-6 or [3H]-20:4n-6 incubations under the conditions employed. Additional studies are warranted in order to define the biological properties of 1- and 2-series cyclooxygenase products as they relate to tumor cell metastasis.