Cancer cell-autonomous overactivation of PARP1 compromises immunosurveillance in non-small cell lung cancer

Background

High activity of poly(ADP-ribose) polymerase-1 (PARP1) in non-small cell lung cancer (NSCLC) cells leads to an increase in immunohistochemically detectable PAR, correlating with poor prognosis in patients with NSCLC, as well as reduced tumor infiltration by cytotoxic T lymphocytes (CTLs). Intrigued by this observation, we decided to determine whether PARP1 activity in NSCLC cells may cause an alteration of anticancer immunosurveillance.

Methods

Continuous culture of mouse NSCLC cells in the presence of cisplatin led to the generation of cisplatin-resistant PAR^high clones. As compared with their parental controls, such PAR^high cells formed tumors that were less infiltrated by CTLs when they were injected into immunocompetent mice, suggesting a causative link between high PARP1 activity and compromised immunosurveillance. To confirm this cause-and-effect relationship, we used CRISPR/Cas9 technology to knock out PARP1 in two PAR^high NSCLC mouse cell lines (Lewis lung cancer [LLC] and tissue culture number one [TC1]), showing that the removal of PARP1 indeed restored cisplatin-induced cell death responses.

Results

PARP1 knockout (PARP1^KO) cells became largely resistant to the PARP inhibitor niraparib, meaning that they exhibited less cell death induction, reduced DNA damage response, attenuated metabolic shifts and no induction of PD-L1 and MHC class-I molecules that may affect their immunogenicity. PAR^high tumors implanted in mice responded to niraparib irrespective of the presence or absence of T lymphocytes, suggesting that cancer cell-autonomous effects of niraparib dominate over its possible immunomodulatory action. While PAR^high NSCLC mouse cell lines proliferated similarly in immunocompetent and T cell-deficient mice, PARP1^KO cells were strongly affected by the presence of T cells. PARP1^KO LLC tumors grew more quickly in immunodeficient than in immunocompetent mice, and PARP1^KO TC1 cells could only form tumors in T cell-deficient mice, not in immunocompetent controls. Importantly, as compared with PAR^high controls, the PARP1^KO LLC tumors exhibited signs of T cell activation in the immune infiltrate such as higher inducible costimulator (ICOS) expression and lower PD-1 expression on CTLs.

Conclusions

These results prove at the genetic level that PARP1 activity within malignant cells modulates the tumor microenvironment.

Autoimmunity affecting the biliary tract fuels the immunosurveillance of cholangiocarcinoma

Cholangiocarcinoma (CCA) results from the malignant transformation of cholangiocytes. Primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC) are chronic diseases in which cholangiocytes are primarily damaged. Although PSC is an inflammatory condition predisposing to CCA, CCA is almost never found in the autoimmune context of PBC. Here, we hypothesized that PBC might favor CCA immunosurveillance. In preclinical murine models of cholangitis challenged with syngeneic CCA, PBC (but not PSC) reduced the frequency of CCA development and delayed tumor growth kinetics. This PBC-related effect appeared specific to CCA as it was not observed against other cancers, including hepatocellular carcinoma. The protective effect of PBC was relying on type 1 and type 2 T cell responses and, to a lesser extent, on B cells. Single-cell TCR/RNA sequencing revealed the existence of TCR clonotypes shared between the liver and CCA tumor of a PBC host. Altogether, these results evidence a mechanistic overlapping between autoimmunity and cancer immunosurveillance in the biliary tract.

Inhibition of transcription by dactinomycin reveals a new characteristic of immunogenic cell stress

Chemotherapy still constitutes the standard of care for the treatment of most neoplastic diseases. Certain chemotherapeutics from the oncological armamentarium are able to trigger pre‐mortem stress signals that lead to immunogenic cell death (ICD), thus inducing an antitumor immune response and mediating long‐term tumor growth reduction. Here, we used an established model, built on artificial intelligence to identify, among a library of 50,000 compounds, anticancer agents that, based on their molecular descriptors, were predicted to induce ICD. This algorithm led us to the identification of dactinomycin (DACT, best known as actinomycin D), a highly potent cytotoxicant and ICD inducer that mediates immune‐dependent anticancer effects in vivo. Since DACT is commonly used as an inhibitor of DNA to RNA transcription, we investigated whether other experimentally established or algorithm‐selected, clinically employed ICD inducers would share this characteristic. As a common leitmotif, a panel of pharmacological ICD stimulators inhibited transcription and secondarily translation. These results establish the inhibition of RNA synthesis as an initial event for ICD induction.

A synergistic triad of chemotherapy, immune checkpoint inhibitors, and caloric restriction mimetics eradicates tumors in mice

We have recently shown that chemotherapy with immunogenic cell death (ICD)-inducing agents can be advantageously combined with fasting regimens or caloric restriction mimetics (CRMs) to achieve superior tumor growth control via a T cell-dependent mechanism. Here, we show that the blockade of the CD11b-dependent extravasation of myeloid cells blocks such a combination effect as well. Based on the characterization of the myeloid and lymphoid immune infiltrates, including the expression pattern of immune checkpoint proteins (and noting a chemotherapy-induced overexpression of programmed death-ligand 1, PD-L1, on both cancer cells and leukocytes, as well as a reduced frequency of exhausted CD8+ T cells positive for programmed cell death 1 protein, PD-1), we then evaluated the possibility to combine ICD inducers, CRMs and targeting of the PD-1/PD-L1 interaction. While fasting or CRMs failed to improve tumor growth control by PD-1 blockade, ICD inducers alone achieved a partial sensitization to treatment with a PD-1-specific antibody. However, definitive cure of most of the tumor-bearing mice was only achieved by a tritherapy combining (i) ICD inducers exemplified by mitoxantrone and oxaliplatin, (ii) CRMs exemplified by hydroxycitrate and spermidine and substitutable for by fasting, and (iii) immune checkpoint inhibitors (ICIs) targeting the PD-1/PD-L1 interaction. Altogether, these results point to the possibility of synergistic interactions among distinct classes of anticancer agents.

Tumor lysis with LTX-401 creates anticancer immunity

Local immunotherapies such as the intratumoral injection of oncolytic compounds aim at reinstating and enhancing systemic anticancer immune responses. LTX-315 is a first-in-class, clinically evaluated oncolytic peptide-based local immunotherapy that meets these criteria. Here, we show that LTX-401, yet another oncolytic compound designed for local immunotherapy, depicts a similar safety profile and that sequential local inoculation of LTX-401 was able to cure immunocompetent host from subcutaneous MCA205 and TC-1 cancers. Cured animals exhibited long-term immune memory effects that rendered them resistant to rechallenge with syngeneic tumors. Nevertheless, the local treatment with LTX-401 alone had only limited abscopal effects on secondary contralateral lesions. Anticancer effects resulting from single as well as sequential injections of LTX-401 were boosted in combination with PD-1 and CTLA-4 immune checkpoint blockade (ICB), and sequential LTX-401 treatment combined with double ICB exhibited strong abscopal antineoplastic effects on contralateral tumors underlining the potency of this combination therapy.

Trial watch: dietary interventions for cancer therapy

Dietary interventions have a profound impact on whole body metabolism, including oncometabolism (the metabolic features allowing cancer cells to proliferate) and immunometabolism (the catabolic and anabolic reactions that regulate immune responses). Recent preclinical studies demonstrated that multiple dietary changes can improve anticancer immunosurveillance of chemo-, radio- and immunotherapy. These findings have fostered the design of clinical trials evaluating the capacity of dietary interventions to synergize with treatment and hence limit tumor progression. Here, we discuss the scientific rationale for harnessing dietary interventions to improve the efficacy of anticancer therapy and present up-to-date information on clinical trials currently investigating this possibility.

Gold Standard Assessment of Immunogenic Cell Death in Oncological Mouse Models

The efficacy of cancer therapies strongly relies on their ability to reinstate cancer immunosurveillance. Numerous biomedical approaches with immunotherapeutic activity have been developed to reeducate the host immune system to detect and clear tumor cells. Cytotoxicants have been primarily designed to slow down malignant cell proliferation and to induce programmed cell death. Some cytotoxic stimuli are able to activate a particular type of apoptosis, which is referred to as immunogenic cell death (ICD), that de facto convert cancer cells into their own vaccine. This effect ultimately facilitates the establishment of an antitumor immune response that potentially annihilates spared malignant cells, as well as an immune memory that prevents cancer recurrence. Based on the characteristic hallmarks of ICD, protocols have been developed to validate ICD induction in vitro, ex vivo, and in vivo. These methods may contribute to identify novel ICD inducers and to design multimodal regimens with superior therapeutic efficacy. Moreover, their translation into clinical research could have prognostic or predictive value. This chapter will introduce the "gold standard" protocol for the in vivo assessment of ICD in mice. The procedure relies on vaccination with treated cancer cells, followed by rechallenge with living entities of the same type, in syngeneic immunocompetent animals.

Anticancer effects of anti-CD47 immunotherapy in vivo

The treatment of breast cancer largely depends on the utilization of immunogenic chemotherapeutics, which, as a common leitmotif, stimulate the exposure of calreticulin (CALR) on the surface of cancer cells, thereby facilitating their recognition by dendritic cells for the uptake of tumor-associated antigens and subsequent antigen cross-presentation to cytotoxic T cells. Breast cancer cells also express the calreticulin antagonist CD47, which inhibits tumor cell phagocytosis and consequently subverts anticancer immune responses. Here, we treated carcinogen-induced or transplantable mouse models of cancer by a CD47 blocking antibody that was at least as efficient as chemotherapy and that could be favorably combined with the anthracycline mitoxantrone in the context of carcinogen-induced orthotopic breast cancers. Monotherapy by CD47 blockade led to a reduction in tumor growth and an increase in overall survival. Of note, this treatment lead to a moderate depletion of M2 macrophages as well as close-to-complete elimination of regulatory T cells from the tumor bed, suggesting a strong favorable impact of CD47 blockade on the tumor microenvironment.

Trial Watch: Oncolytic viro-immunotherapy of hematologic and solid tumors

Oncolytic viruses selectively target and kill cancer cells in an immunogenic fashion, thus supporting the establishment of therapeutically relevant tumor-specific immune responses. In 2015, the US Food and Drug Administration (FDA) approved the oncolytic herpes simplex virus T-VEC for use in advanced melanoma patients. Since then, a plethora of trials has been initiated to assess the safety and efficacy of multiple oncolytic viruses in patients affected with various malignancies. Here, we summarize recent preclinical and clinical progress in the field of oncolytic virotherapy.

Trends in the use of laboratory tests for the diagnosis of Clostridium difficile infection and association with incidence rates in Quebec, Canada, 2010-2014

BACKGROUND

Several Clostridium difficile infection (CDI) surveillance programs do not specify laboratory strategies to use. We investigated the evolution in testing strategies used across Quebec, Canada, and its association with incidence rates.

METHODS

Cross-sectional study of 95 hospitals by surveys conducted in 2010 and in 2013-2014. The association between testing strategies and institutional CDI incidence rates was analyzed via multivariate Poisson regressions.

RESULTS

The most common assays in 2014 were toxin A/B enzyme immunoassays (EIAs) (61 institutions, 64%), glutamate dehydrogenase (GDH) EIAs (51 institutions, 53.7%), and nucleic acid amplification tests (NAATs) (34 institutions, 35.8%). The most frequent algorithm was a single-step NAAT (20 institutions, 21%). Between 2010 and 2014, 35 institutions (37%) modified their algorithm. Institutions detecting toxigenic C difficile instead of C difficile toxin increased from 14 to 37 (P < .001). Institutions detecting toxigenic C difficile had higher CDI rates (7.9 vs 6.6 per 10,000 patient days; P = .01). Institutions using single-step NAATs, GDH plus toxigenic cultures, and GDH plus cytotoxicity assays had higher CDI rates than those using an EIA-based algorithm (P < .05).

CONCLUSIONS

Laboratory detection of CDI has changed since 2010. There is an association between diagnostic algorithms and CDI incidence. Mitigation strategies are warranted.

Treatment of a mixed wood preservative leachate by a hybrid constructed wetland and a willow planted filter

The performance and removal mechanisms of a hybrid constructed wetland (HCW) followed by a willow planted filter (WPF) were evaluated for the treatment of a leachate contaminated by wood pole preservatives (pentachlorophenol (PCP) and chromated copper arsenate) to reach the storm sewer discharge limits. The HCW aimed to dechlorinate the PCP and polychlorodibenzo-p-dioxins/polychlorodibenzofuran (PCDD/F) and to remove metals by adsorption and precipitation. The HCW was efficient in removing PCP (>98.6%), oil, arsenic (99.4%), chromium (>99.2%), copper (>99.6%%) and iron (29%) to under their discharge limits, but it was unable to reach those of Mn and PCDD/F, with residual concentrations of 0.11 mg Mn/L and 0.32 pg TEQ/L. Iron and manganese could be removed but were subsequently released by the HCW due to low redox conditions. No dechlorination of PCDD/F was observed since its chlorination profile remained the same in the different sections of the HCW. Adsorption was the most probable removal mechanism of PCDD/F. The WPF was able to remove some residual contamination, but it released Mn at a gradually decreasing rate. Total evapotranspiration of the leachate by a larger fertilized WPF and the construction of an underground retention basin are proposed to prevent any discharge of PCDD/F traces in the environment.

Management of a hospital outbreak of extensively drug-resistant Acinetobacter baumannii using a multimodal intervention including daily chlorhexidine baths

BACKGROUND

Extensively drug-resistant Acinetobacter baumannii (XDR-Ab) is an increasingly important cause of healthcare-associated infection. Uncertainties remain concerning optimal control measures for healthcare-associated outbreaks.

AIM

To describe the epidemiology and control of an XDR-Ab outbreak that involved multiple units of a large hospital from March 2012 to January 2014.

METHODS

Case-finding included screening of rectum, groin, throat, nose, wounds, iatrogenic portals of entry, and catheterized sites. Antimicrobial susceptibility was evaluated by disc diffusion and E-test. Resistance genes were detected by polymerase chain reaction. Clonality was assessed by pulsed-field gel electrophoresis. Charts of cases were reviewed to identify risk factors for invasive infection. Control measures included isolation and cohorting of cases, hand hygiene reinforcement, environmental decontamination, and source control with daily baths using wipes pre-impregnated with chlorhexidine gluconate.

FINDINGS

A single clonal strain of XDR-Ab colonized or infected 29 patients. Five patients died of XDR-Ab bacteraemia. Transmission occurred primarily on two wards. Colonization was detected at all anatomical screening sites; only 57% (16/28) of cases were rectal carriers. Advanced malignancy was a risk factor for bacteraemia (relative risk: 5.8; 95% confidence interval: 1.2-27.0). Transmission ended following implementation of the multimodal control strategy. No additional nosocomial cases occurred during the following 20 months.

CONCLUSION

Our study highlights the need to screen multiple anatomic sites to diagnose carriage and identifies risk factors for XDR-Ab bacteraemia. A multimodal intervention that included daily chlorhexidine baths for cases was rapidly followed by the termination of the outbreak. Hospitals should consider similar interventions when managing future XDR-Ab outbreaks.

Molecular confirmation of nine cases of Cornelia de Lange syndrome diagnosed prenatally

OBJECTIVES

Cornelia de Lange syndrome (CdLS) is characterized by distinct facial features, growth retardation, upper limb reduction defects, hirsutism, and intellectual disability. NIPBL mutations have been identified in approximately 60% of patients with CdLS diagnosed postnatally. Prenatal ultrasound findings include upper limb reduction defects, intrauterine growth restriction, and micrognathia. CdLS has also been associated with decreased PAPP-A and increased nuchal translucency (NT). We reviewed NIPBL sequence analysis results for 12 prenatal samples in our laboratory to determine the frequency of mutations in our cohort.

METHODS

This retrospective study analyzed data from all 12 prenatal cases with suspected CdLS, which were received by The University of Chicago Genetic Services Laboratories. Diagnostic NIPBL sequencing was performed for all samples. Clinical information was collected from referring physicians.

RESULTS

NIPBL mutations were identified in 9 out of the 12 cases prenatally (75%). Amongst the NIPBL mutation-positive cases with clinical information available, the most common findings were upper limb malformations and micrognathia. Five patients had NT measurements in the first trimester, of which four were noted to be increased.

CONCLUSION

We demonstrate that prenatally-detected phenotypes of CdLS, particularly severe micrognathia and bilateral upper limb defects, are associated with an increased frequency of NIPBL mutations.

Improvement of Adjuvant Systems to Obtain a Cost-Effective Production of High Levels of Specific IgY

Incomplete Freund's adjuvant (IFA) is used as standard adjuvant for the production of specific antibodies. In this study, we evaluated the ability of supplementation of IFA with 1alpha,25-dihydroxyvitamin D(3) [1alpha,25(OH)(2)D(3)] or C-phosphate-guanosine-oligodeoxynucleotide (CpG-ODN) to enhance the quantity of specific IgY found in the eggs of hyperimmunized laying hens. In this comparative study, the fimbrial adhesin F4 of porcine enterotoxigenic Escherichia coli was used as prototype immunogen. Hens of 3 groups received by i.m. injection 20 microg of purified F4 adhesin emulsified with 1 of the following adjuvants: 0.5 mL of IFA alone (F4-IFA group), 0.5 mL of IFA supplemented with 285.6 ng of 1alpha,25(OH)(2)D(3) (F4-IFA-D(3) group), or 0.5 mL of IFA supplemented with 10 microg of CpG-ODN (F4-IFA-CpG group). Hens of 2 control groups received PBS or purified F4 alone. Immunization was repeated after 2 and 5 or 7 wk. Eggs were collected at 3- to 4-d intervals from preimmunization to d 79, and whole eggs were tested to measure the quantity of anti-F4 IgY by a standardized indirect ELISA. The quantity of specific anti-F4 IgY present in eggs from immunized hens of the F4-IFA group increased from d 13 to 79, corresponding to the end of the experiment. The values for this group at each time were considered as 100%. Results obtained for the other adjuvants were expressed in relation to this reference method. Supplementation of IFA with 1alpha,25(OH)(2)D(3) did not result in any enhancement of the quantity of anti-F4 IgY present in the eggs. On the other hand, supplementation of IFA with CpG-ODN resulted in an enhancement of yield up to 942% of the F4-specific antibody response. Moreover, the use of CpG-ODN is a cost-effective and ethical refinement for the production of specific antibodies, permitting a reduction in the number of immunizations needed. In conclusion, this study provides strong evidence for the use of IFA supplemented with CpG-ODN rather than IFA alone for the production of high levels of specific antibody in laying hens.

Premutation and intermediate-size FMR1 alleles in 10572 males from the general population: loss of an AGG interruption is a late event in the generation of fragile X syndrome alleles

We previously reported a 1:259 prevalence of female carriers of FMR1 premutation-size alleles (greater than 54 triplet repeats) in the general population. We now have screened 10 572 independent males from the same population for similar alleles using high-throughput Southern blotting. We identified 13 male carriers of an allele with more than 54 repeats. This corresponds to a prevalence of 1:813 males (95% confidence interval 1:527 to 1:1781). Haplotype analysis of four markers flanking the triplet array revealed that the prevalence of the major fragile X mutation-associated haplotype was increased among FMR1 alleles of 40-54 repeats. Although sequencing of highly unstable premutation alleles from fragile X families revealed only pure CGG tracts, this was not the case for alleles of similar size that were identified in males from the general population. Forty-eight out of forty-nine alleles of 40 or more triplets had one or two AGG interruptions. This observation, combined with the observation of the enrichment of major fragile X syndrome haplotypes in all alleles of this size, is evidence that the loss of an AGG interruption in the triplet repeat array is not necessary for expansion of normal alleles of 29-30 triplets to intermediate size. The loss of AGG interruptions thus appears to be a late event that leads to greatly increased instability and may be related to the haplotype background of specific FMR1 alleles.

Novel bicyclic lactam inhibitors of thrombin: potency and selectivity optimization through P1 residues

Peptidomimetic inhibitors of thrombin lacking the important Ser195-carbonyl interaction have been prepared. The binding energy lost after the removal of the activated carbonyl was recaptured through a series of modifications of the P1 residues of the bicyclic lactam inhibitors. Selected substituted compounds displayed useful pharmacological profiles both in vitro and in vivo.

Sequencing of peach latent mosaic viroid variants from nine North American peach cultivars shows that this RNA folds into a complex secondary structure

We sequenced 34 new peach latent mosaic viroid (PLMVd) variants isolated from nine different peach cultivars. This study provides the widest view of PLMVd diversity reported to date and includes the original characterization of North American variants, which cannot be differentiated from European sequences. PLMVd appears as a species in which each isolate is a complex mixture of RNAs. Analysis of base-pair covariations supports the hypothesis that PLMVd folds into a complex branched structure with the potential of including three new pseudoknots. The resulting "globular-like" structure is in contrast to the rod-like one adopted by most other viroids.

Lipid uptake across the wall of an expanded polytetrafluoroethylene vascular graft

Previous studies have shown that vascular grafts were prone to inducing an atherosclerosis-like phenomenon, thus possibly jeopardizing their performance. Furthermore, lipid retention, observed in most synthetic arterial prostheses explanted from humans, appears to have an important role in the progression of this atherosclerotic process, therefore hindering the healing process and neo-intima formation of these synthetic conduits. The current study examined lipid concentration profiles across prosthesis membranes exposed to lipid dispersion under various transmural pressures, flow rates, and durations of exposure. It was demonstrated that the lipids rapidly permeated the prosthesis membrane, as lipid advection increased to a maximum, then steadily decreased until the membrane became completely impermeable to the fluid. The concentration of lipids within the grafts was monitored using FT-IR microspectroscopy, then correlated as a function of time in order to evaluate the mass transfer coefficients and lipid saturation concentration. Lipid sorption, as a function of time, was described by a mechanism taking into account two first-order kinetic models. The lipids were first rapidly adsorbed onto the Teflon(R), potentially influenced by the strong affinity of these lipids for the highly hydrophobic polytetrafluoroethylene polymer. This affinity then enhanced the germination of the lipid deposits that filled in the prosthesis wall. For lipid retention as a function of the transmural pressure and flow rate, no clear tendency was established.

Potent bicyclic lactam inhibitors of thrombin: Part I: P3 modifications

Peptidomimetic inhibitors of general structure 1 have been prepared. Optimization of the binding affinities of these compounds through variation of the P3 hydrophobic residue is described. Selected substituted bicylic lactams displayed interesting pharmacological profiles both in vitro and in vivo.

Effects of dietary gamma-linolenic acid and prenatal ethanol on mouse brain and behavior

Pregnant B6D2F mice were treated with ethanol (25% Kcal) from days 5-17 of gestation. The diet was supplemented with either 18 : 2n-6 [linoleic acid (LA)] or 18 : 3n-6 [gamma-linolenic acid (GLA)] throughout the study. Ethanol reduced 20 and 22 carbon n-6 and n-3 fatty acids in the brains of adult offspring. Feeding of GLA, compared with LA, increased levels of 20 : 3n-6 and 22 : 4n-6, but reduced 22 : 6n-3, particularly in the offspring of dams administered ethanol during gestation; adult brain weight was also lower in this group. Ethanol reduced the number of viable litters and adult body weight, and GLA reduced birth weight. Neither prenatal ethanol nor GLA affected open-field activity in adult males, nor did either treatment have an effect on the duration of immobility in the forced swimming test. However, GLA did affect circadian activity by increasing running wheel activity during the dark cycle, and decreasing it slightly during the light cycle. These results do not support a beneficial effect of GLA in preventing the developmental effects of ethanol; we suggest caution in the administration of high doses of GLA with ethanol during pregnancy.

Brain and behavioral effects of dietary n-3 deficiency in mice: a three generational study

Feeding mice a diet deficient in n-3 fatty acids for three generations resulted in a 53% decrease in docosahexaenoic acid (DHA, 22:6n-3) in the brain. Maternal pup retrieval and social learning of a food preference are both tasks based on olfactory function. All dams made contact more readily with pups of their own dietary group, and animals of both dietary groups demonstrated the ability to learn a food preference through exposure to a conspecific that had previously eaten the food. Both groups showed similar ability to learn the location of the hidden platform in the Morris water maze, while the n-3 deficient animals were marginally faster in locating the platform on the cued trial. They were also more active when tested in the open field. While they did not differ in their duration of immobility in a forced swimming test, the deficient animals did have longer paw-lick latencies on a hot plate. Thus, in this study a significant reduction in brain n-3 fatty acid composition, while associated with some indications of change in emotional reactivity, did not impair olfactory function or learning of either a latent or spatial nature.

Effects of different weight loss treatments on weight cycling and metabolic measures in male mice

The effects of different weight loss treatments on subsequent weight regain, food efficiency, body composition, metabolic rate, and corticosterone concentrations were investigated in obese male B6D2F1 mice. Treatment groups were: restricted (RES, food restricted); exercised (EX, treadmill exercised); sham control (SHAM, treadmill exposure, not exercised); lab chow control (LC). Weight loss, regardless of treatment, resulted in increased rate of weight regain and food efficiency. There were significant alterations in body composition after a cycle of weight gain/loss. These results demonstrate that a cycle of weight gain/loss causes increased food efficiency and concomitant alterations in body composition in male mice.

The effects of dietary fatty acid composition combined with environmental enrichment on brain and behavior in mice

In this study we investigated the effects of dietary fatty acid (FA) composition combined with postweaning environmental enrichment on brain fatty acid composition and behavior in mice. There were three dietary conditions: a saturated fat group deficient in essential fatty acids, a group deficient in n-3 fatty acids only, and a control group containing both n-3 and n-6 fatty acids in a ratio of 0.27. Animals were fed these diets during pregnancy and lactation and after weaning. Brain fatty acid composition was determined on days 1, 9, 17 and 25 after birth and in adult animals at 3 months. At weaning two females from each litter were assigned randomly to either an enriched or standard environmental condition. After six weeks in these environments they were tested in the Morris water maze and open field. Adult percentages of 22:6n-3 were present in the brain within the first week after birth. These values were reduced by 50% in the n-3 deficient diet and by 80% in the saturated fat diet; adult animals on the saturated fat diet were also severely retarded in growth. Animals fed the saturated fat diet were initially slightly slower in locating the hidden platform in the Morris maze relative to the control group, but this was not apparent in the reversal learning phase; a cued learning task using a visible platform indicated that these effects did not appear to be related to differences in motor or motivational capacities. The n-3 deficient group did not differ from either the saturated fat group or the controls. All dietary groups showed beneficial effects of environmental enrichment in decreasing their latency to locate the hidden platform, and these effects appeared to be partially independent of the increased swimming speed of the enriched animals. Enriched animals in all groups showed less rearing activity in the open field and spent more time stationary; the animals fed saturated fat reared less and travelled shorter distances more slowly. In all cases the effects of diet and environment were additive, thereby providing little support for the hypothesis that dietary fatty acid composition would affect the animals' capacity to benefit from the functional effects of environmental enrichment.

Effects of environmental enrichment on cortical depth and Morris-maze performance in B6D2F2 mice exposed prenatally to ethanol

Pregnant mice were fed a liquid diet with 25% of the calories as ethanol from day 5 to 17 of gestation; controls received equivalent amounts of diet with maltose-dextrin substituted isocalorically for the ethanol. Two male weanlings from each litter were assigned randomly to an enriched or isolated environmental condition. After 6 weeks in these environments measures of brain growth were obtained, including thickness of frontal, parietal, and occipital cortex (study 1), or their behavioral capabilities were assessed in a Morris water maze (study 2). Ethanol decreased birth weight (both studies), postweaning body weight (study 2), and brain weight (study 1), while the enriched animals in both studies were heavier. Ethanol decreased the thickness of the occipital cortex only. All groups demonstrated learning by showing a decrease in latency to locate the hidden platform over the 5 days of testing; this was supported by their spending most time in the target quadrant during the probe trial. The latencies of the enriched animals were shorter than the isolated; covariance analysis indicated that this was not due solely to their faster swimming speed.