Dendrimer nanotherapy targeting of glial dysfunction improves inflammation and neurobehavioral phenotype in adult female Mecp2-heterozygous mouse model of Rett syndrome

Rett syndrome is an X-linked neurodevelopmental disorder caused by mutation of Mecp2 gene and primarily affects females. Glial cell dysfunction has been implicated in in Rett syndrome (RTT) both in patients and in mouse models of this disorder and can affect synaptogenesis, glial metabolism and inflammation. Here we assessed whether treatment of adult (5-6 months old) symptomatic Mecp2-heterozygous female mice with N-acetyl cysteine conjugated to dendrimer (D-NAC), which is known to target glia and modulate inflammation and oxidative injury, results in improved behavioral phenotype, sleep and glial inflammatory profile. We show that unbiased global metabolomic analysis of the hippocampus and striatum in adult Mecp2-heterozygous mice demonstrates significant differences in lipid metabolism associated with neuroinflammation, providing the rationale for targeting glial inflammation in this model. Our results demonstrate that treatment with D-NAC (10 mg/kg NAC) once weekly is more efficacious than equivalently dosed free NAC in improving the gross neurobehavioral phenotype in symptomatic Mecp2-heterozygous female mice. We also show that D-NAC therapy is significantly better than saline in ameliorating several aspects of the abnormal phenotype including paw clench, mobility, fear memory, REM sleep and epileptiform activity burden. Systemic D-NAC significantly improves microglial proinflammatory cytokine production and is associated with improvements in several aspects of the phenotype including paw clench, mobility, fear memory, and REM sleep, and epileptiform activity burden in comparison to saline-treated Mecp2-hetereozygous mice. Systemic glial-targeted delivery of D-NAC after symptom onset in an older clinically relevant Rett syndrome model shows promise in improving neurobehavioral impairments along with sleep pattern and epileptiform activity burden. These findings argue for the translational value of this approach for treatment of patients with Rett Syndrome.

Training Medical Students to Create and Collaboratively Review Multiple-Choice Questions: A Comprehensive Workshop

INTRODUCTION

Multiple-choice question (MCQ) creation is an infrequently used active-learning strategy. Previous studies demonstrated that medical students find value in the process, but have minimal training, which may limit potential learning benefits. We therefore developed a process for question-creation that required students to complete in-depth training, in addition to collaborative question-writing and editing.

METHODS

We created a question-writing workshop consisting of three components: (1) training in MCQ writing utilizing NBME online modules, a practice MCQ-writing session, and a training session, (2) writing MCQs independently after choosing topics from an institutionally generated blueprint, and (3) reviewing and editing MCQs via an in-person session. To understand students' perceptions, we held two four-student focus groups and recorded/transcribed the data. We iteratively reviewed the transcripts to generate a codebook and corresponding themes. We used the focus group data to generate a survey with Likert-scale questions, which we sent to the remaining 10 students and analyzed using Microsoft Excel.

RESULTS

Eighteen second-year medical students participated in this workshop. Students perceived that question-writing training (3.7/5.0±0.5) and question writing (3.9/5.0±0.3) benefitted their learning. Students perceived that MCQ writing required concept integration (4.1/5.0±0.6). Students described how question writing allowed them to recognize subtle distinctions between therapies and diagnoses. Each MCQ required about 1.5 hours to write and collaboratively edit.

DISCUSSION

Our results demonstrated that students perceived question writing to benefit their learning. More importantly, students felt that question writing actively engaged them to integrate content and compare concepts; students' engagement suggests that they learned from this question-writing activity.

'What I Wish My Surgeon Knew': A Novel Approach to Promote Empathic Curiosity in Surgery

OBJECTIVE

Physician empathy is associated with a variety of superior patient and physician outcomes. Teaching physicians to practice empathic curiosity is challenging however, and relatively few efficient and effective methods have been proposed toward this end. The goal of this study was to evaluate the impact and feasibility of a novel approach to foster empathic curiosity during surgical training.

DESIGN

We used an exploratory qualitative approach for our study. Postoperative patients at a single hospital were invited to participate in brief semistructured interviews to better understand their unmet needs. The interview began with the question, "What do you wish your surgeon knew about you?" We audio recorded and transcribed each patient interview. We then iteratively read the transcripts, applied an inductive approach to coding, and used qualitative content analysis to identify themes.

SETTING

Veterans Affairs Ann Arbor Healthcare System, an academic-affiliated tertiary care facility.

PARTICIPANTS

Patients who underwent general surgery procedures (n = 23) between July and August 2017.

RESULTS

Of those who provided demographic information (n = 21), all were male and 95% were white with a mean age of 63.9 (34-77) years. Of these, 33% (n = 7) of patients experienced a postoperative complication. Patients described 3 broad categories of unmet need in the perioperative setting including: (i) being treated holistically and with dignity; (ii) using clear communication and delineating provider roles; and (iii) setting specific and realistic expectations.

CONCLUSIONS

Promoting the use of empathically curious questions, such as "What do you wish your surgeon knew about you?" may help surgical trainees to identify unmet needs that are crucial for optimizing surgical care.

Amelioration of lesions associated with 24-hour suboptimal platelet storage at 16 °C by a p38MAPK inhibitor, VX-702

BACKGROUND AND OBJECTIVES

Previous studies with p38MAPK inhibitors at room temperature demonstrated that they improve a large number of platelet storage parameters, but cannot substantially inhibit p38MAPK activation nor protect against widespread decrements in platelet quality parameters during 4 °C storage. In this study, platelet quality parameters and inhibition of p38MAPK by VX-702 were studied after incubation of platelets at 16 °C without agitation, suboptimal storage conditions which produce moderate platelet decrements.

MATERIALS AND METHODS

Trima apheresis units were collected and aliquoted into three 60-ml CLX storage bags: (i) a control aliquot which was held at 20-24 °C with constant agitation; (ii) a test aliquot which was held at 20-24 °C with agitation until Day 2, when it was reincubated at 16 ± 1 °C for 24 ± 0·5 h without agitation and then returned 20-24 °C with agitation; (iii) a test aliquot containing 1 μm VX-702 stored in an identical fashion as aliquot 2. Aliquots were tested for an array of platelet storage parameters and p38MAPK activation on Days 1, 4 and 7.

RESULTS

Many platelet storage parameters and p38MAPK activation were adversely affected by 24-h incubation at 16 °C without agitation. With the exception of ESC, addition of VX-702 prevented p38MAPK activation and the decrements in most observed parameters.

CONCLUSION

Unlike 4 °C storage, VX-702 prevents activation of p38MAPK and decrements in many platelet storage parameters after exposure to 16 °C without agitation for 24 h.

Phase II trial of pegylated liposomal doxorubicin-cyclophosphamide combination as first-line chemotherapy in elderly metastatic breast cancer patients

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Background: Although the majority of metastatic breast cancer (MBC) patients (pts) responds to endocrine therapy, treatment failure is a concern, as well as front-line therapy for pts with ER/PR negative disease.The combination of anthracyclines (A) and cyclophosphamide (C) is active in younger pts, but cardiac toxicity of A in elderly MBC pts has to be considered. Pegylated liposomal doxorubicin (PLD) (Caelyx®) is active in MBC and has much less cardiotoxicity than A, and we present the preliminary data of the PLD/C in elderly MBC pts. Methods: This was a multicentric phase II trial. Inclusion criteria included: pts aged between 65 and 75, histologically proven measurable MBC, ECOG PS 0–1, LVEF = 50%, first-line chemotherapy for MBC. Prior adjuvant chemotherapy was allowed if stopped for = 6 or 12 months without and with anthracyclines, respectively. Endocrine therapy either in the adjuvant or metastatic setting had to be stopped for = 1 month. All pts gave a written informed consent. The treatment schedule was : PLD 40mg/m2 and C 500mg/m2 d1 every 4 weeks. Efficacy as well as response duration and tolerance were the primary and secondary end-points, respectively. Results: 35 patients were enrolled (Median age 71.3, range 65.6–75.9). A total of 166 cycles have been administered. The median number of cycles was 6 (range 1–9). No toxic death was reported, one patient died of diabetes mellitus decompensation. No congestive heart failure or decrease in LVEF was reported, although 1 pt experience grade 3 dyspnea and stopped treatment. Other (gr3–4) NCI-CTC toxicity included: neutropenia in 7 (gr3) and 3 (gr4) pts; gr3 mucositis (4). No febrile neutropenia was reported. Grade 3 hand-foot syndrome occurred in 1 pt, whereas treatment was stopped due to a generalized rash in 1 pt. An objective response (CR + PR) was achieved in 10 (28,6%) pts (1 CR and 8 PR), and a disease control in 24 (68.6%) with a progression free survival of 8.8 months and a median survival of 20.4 months Conclusions: The LPD-C combination is active in elderly MBC pts, with an acceptable toxicity profile.

No significant financial relationships to disclose.

Resistance against heterogeneous sequential infections: experimental studies with a tapeworm and its copepod host

Parasite heterogeneity is thought to be an important factor influencing the likelihood and the dynamics of infection. Previous studies have demonstrated that simultaneous exposure of hosts to a heterogeneous mixture of parasites might increase infection success. Here this view is extended towards the effect of parasite heterogeneity on subsequent infections. Using a system of the tapeworm Schistocephalus solidus and its copepod intermediate host, heterogeneity of the tapeworm surface carbohydrates is investigated, i.e. structures that are potentially recognized by the invertebrate host's immune system. With lectin labelling, a significant proportion of variation in surface carbohydrates is related to differences in worm sibships (i.e. families). Tapeworm sibships were used for experimental exposure of copepods to either homogeneous combinations of tapeworm larvae, i.e. worms derived from the same sibship or heterogeneous mixtures of larvae, and copepods were subsequently challenged with an unrelated larva to study re-infection. Contrary to expectation, neither an effect of parasite heterogeneity on the current infection, nor on re-infection were found. The effect of parasitic heterogeneity on host immunity is therefore complex, potentially involving increased cross-protection on the one hand, with higher costs of raising a more heterogeneous immune response on the other.

Infectivity of two nematode parasites, Camallanus lacustris and Anguillicola crassus, in a paratenic host, the three-spined stickleback Gasterosteus aculeatus

Three-spined sticklebacks Gasterosteus aculeatus are frequent paratenic hosts of the nematode parasites Anguillicola crassus and Camallanus lacustris. As paratenic hosts, sticklebacks could spread infection by carrying high numbers of infective stages. In contrast, low infective ability of either parasite for the paratenic host could hinder the spread of infection. In the present study, G. aculeatus was, for the first time, infected under controlled laboratory conditions with defined doses of the parasites. Sticklebacks were exposed to 6, 12, 18 and 24 parasite larvae to determine the infective ability of the 2 nematode species. There were significantly higher infection rates for C. lacustris (18 to 49%) than for A. crassus (4 to 14%) at each exposure dose. In C. lacustris-infected sticklebacks, infection rates tended to be highest after exposure to 12 C. lacustris larvae and lowest after exposure to 24 parasites. In A. crassus-infected sticklebacks, no effect of parasite exposure dose on infection rates was observed. Immunity parameters such as respiratory burst activity and lymphocyte proliferation of head kidney leukocytes recorded 18 wk post exposure were not significantly affected by either parasite or exposure dose. Granulocyte:lymphocyte ratios were elevated only within the stickleback group showing the highest infection intensity of C. lacustris, i.e. to those exposed 18 parasites.

Increased risk of acute myeloid leukaemia after treatment for breast cancer

This study evaluates the risk of acute myeloid leukaemia (AML) in patients treated for breast cancer. We included all 6360 breast cancer patients that were recorded at the Geneva Cancer Registry between 1970 and 1999. Patients were followed for AML occurrence until December 2000. We calculated standardized incidence ratios of AML and identified factors modifying the risk of AML by multivariate Cox analysis. Twelve (0.2%) patients developed AML. In general, patients treated for breast cancer had a 3.5-fold (95% confidence interval (CI): 1.8-6.0) increased risk of developing AML compared with the general population. In particular, patients who were older than 70 years at breast cancer diagnosis and those treated with radiotherapy (with or without chemotherapy) had a significantly increased risk of developing AML. This population-based study confirms that radiotherapy increases the risk of AML. Due to the relatively low number of women treated with chemotherapy without radiotherapy and due to the infrequency of the disease, the question of whether chemotherapy alone increases this risk of AML cannot yet be answered.

Local differences in immunocompetence reflect resistance of sticklebacks against the eye fluke Diplostomum pseudospathaceum

We investigated population differences in immunological adaptation of three-spined sticklebacks (Gasterosteus aculeatus) to one of their most abundant macroparasites, the eye fluke Diplostomum pseudospathaceum. We compared infection success in lab-bred fish of 2 populations in northern Germany, from a lake, where eye flukes are prevalent, and a river, where these parasites do not occur. In order to discriminate between protection through innate and acquired immunity, we exposed fish either only once or repeatedly. Lake fish were significantly less susceptible than river sticklebacks already after a single exposure, indicating that in sympatric hosts innate immunity plays the major role in the defence against this helminth infection. In both habitat types, previous exposures only marginally decreased infection rates within 12 weeks. Lake fish showed higher immunocompentence by means of respiratory burst activity and spleen size, regardless of the infection status. Furthermore, they were in a better energy status than river fish, as indicated by a higher hepatosomatic index and haematocrit value. Interestingly, F1 hybrid fish of both populations ranged between the pure habitat types in parasite susceptibility as well as in immunological and condition parameters. Our results suggest that sticklebacks from lakes are better adapted to cope with higher parasite abundance in this habitat.

Genetic variation in MHC class II expression and interactions with MHC sequence polymorphism in three-spined sticklebacks

Genes of the major histocompatibility complex (MHC) have been studied for several decades because of their pronounced allelic polymorphism. Structural allelic polymorphism is, however, not the only source of variability subjected to natural selection. Genetic variation may also exist in gene expression patterns. Here, we show that in a natural population of three-spined sticklebacks (Gasterosteus aculeatus) the expression of MHC class IIB genes was positively correlated with parasite load, which indicates increased immune activation of the MHC when infections are frequent. To experimentally study MHC expression, we used laboratory-bred sticklebacks that were exposed to three naturally occurring species of parasite. We found strong differences in MHC class IIB expression patterns among fish families, which were consistent over two generations, thus demonstrating a genetic component. The average number of MHC class IIB sequence variants within families was negatively correlated to the MHC expression level suggesting compensatory up-regulation in fish with a low (i.e. suboptimal) MHC sequence variability. The observed differences among families and the negative correlation with individual sequence diversity imply that MHC expression is evolutionary relevant for the onset and control of the immune response in natural populations.

Juvenile immune status affects the expression of a sexually selected trait in field crickets

Parasite-mediated sexual selection theory presumes that variation in sexual traits reliably reflects variation in parasite resistance among available mates. One mechanism that may warrant signal honesty involves costs of immune system activation in the case of a parasitic infection. We investigated this hypothesis in male field crickets Gryllus campestris, whose attractiveness to females depends on characteristics of the sound-producing harp that are essentially fixed following adult eclosion. During the nymphal stage, males subjected to one of two feeding regimes were challenged with bacterial lipopolysaccharides (LPS) to investigate condition-dependent effects on harp development as compared to other adult traits. Nymphal nutritional status positively affected adult body size, condition, and harp size. However, nymphal immune status affected harp size only, with LPS-males having smaller harps than control-injected males. In addition, the harps of LPS-males showed a lesser degree of melanization, indicating an enhanced substrate use by the melanin-producing enzyme cascade of the immune system. Thus, past immune status is specifically mirrored in sexual traits, suggesting a key role for deployment costs of immunity in parasite-mediated sexual selection.

Modulation of granulocyte responses in three-spined sticklebacks Gasterosteus aculeatus infected with the tapeworm Schistocephalus solidus

Leukocytes isolated from the head kidney and peripheral blood of 3-spined sticklebacks Gasterosteus aculeatus L. were analysed by means of flow cytometry during infection with the tapeworm Schistocephalus solidus (Müller, 1776). Although parasites increased their body weight continuously throughout the observation period (98 d), proportions of granulocytes increased in blood and head kidney only up to Day 63 post-infection (p.i.). Thereafter, declining proportions of granulocytes were observed in both organs. Thus the relative decrease in granulocyte number was not correlated to a decline in the parasitic load of the fish. To investigate a possible modulatory impact of S. solidus on granulocyte function, head kidney leukocytes were isolated at times before Day 63 p.i. and tested in vitro for their capacity to produce reactive oxygen species (ROS). Head kidney leukocytes from S. solidus-infected fish, analysed immediately after isolation (ex vivo, Day 40 p.i.), exhibited a higher ROS production when stimulated with phorbol myristate acetate (PMA), than leukocytes from naive, sham-treated control fish and fish that had resisted or cleared the infection (exposed but not infected). The latter showed an increased spontaneous ROS production that was not correlated to the numbers of granulocytes present in the head kidney isolates. In infected sticklebacks, spontaneous and PMA-induced ROS production was significantly correlated with numbers of granulocytes present in the head kidney isolates, suggesting that elevated ROS production was due to higher numbers of responding cells rather than an increased capacity of single cells. In vitro, after cultivation for 4 d in the presence of pokeweed mitogen (PWM) or extracts from S. solidus, head kidney leukocytes from control fish showed an increased ROS production and phagocytic activity compared with non-stimulated control cultures. In contrast, head kidney leukocytes from infected fish isolated on Days 48 and 44 p.i., failed to respond to S. solidus antigens in vitro. During S. solidus infection, granulocyte mobilisation resulted in elevated numbers of these cells in head kidneys, but the lack of an in vitro response to S. solidus antigens indicates an in vivo priming of granulocytes by the parasite. These observations may reflect the ability of S. solidus to impair the host's immune response once the parasite is developing in the body cavity of G. aculeatus.

Infantile herpes simplex encephalitis: diagnostic features and differentiation from non-accidental injury

OBJECTIVES

Neonatal herpes simplex virus (HSV) encephalitis is rare, but associated with considerable morbidity and mortality. After a baby, subsequently proven to have HSE, had initially been diagnosed as non-accidental injury (NAI), we reviewed the clinical features and radiology of infants with HSE recently diagnosed by our laboratory.

METHODS

Screening of cerebrospinal fluid (CSF) samples sent to Oxford for HSV polymerase chain reaction (PCR) analysis, from wide range of British hospitals, identified HSV infected infants. After a diagnosis was made, the case notes and neuroradiology (where available) were reviewed and a limited follow-up was undertaken.

RESULTS

Thirteen infants had HSV encephalitis (HSE), which in four followed a relapsing course. On subsequent assessment six infants had neurological sequelae, six appeared to be normal, and one was lost to follow-up. Neither a history of primary HSV infection in pregnancy, nor skin lesions in the baby, were helpful diagnostically. Magnetic resonance imaging indicated haemorrhage in the cortex, but no subdural haematomata, a hallmark of NAI, in 5/6 infants.

CONCLUSIONS

The early clinical features of HSE and NAI may be indistinguishable. As early diagnosis is important, infants with an unidentified encephalopathic illness should be examined by neuroradiology and their CSF tested for HSV DNA. Together these examinations can confirm and differentiate between those two conditions. Relapsing HSE may mimic recurrent encephalopathy caused by multiple NAIs.

Altered host behaviour: manipulation or energy depletion in tapeworm-infected copepods?

Parasites are able to influence intermediate hosts in a way that optimizes their growth and transmission to the next host. Macrocyclops albidus (Copepoda) suffer from a reduced escaping ability and an increased level of general activity, when infected with Schistocephalus solidus (Cestoda). This facilitates predation by the subsequent host, the three-spined stickleback. However, instead of adaptive host manipulation by the tapeworm, the altered copepod behaviour might be explained more simply as a constraint of the infection. Energy depletion could lead to decreased muscle performance and increased food searching activity. Furthermore, resource allocation among host tissues might change after infection. We therefore analysed the amount of storage lipids and muscle tissue before and after experimental infection. To determine the amount of muscles, we developed a new polarization-microscopic technique. Irrespective of infection, lipids and muscles were predictors of copepod survival. However, we found no effect of the parasite infection on muscles or lipids, and no indication of a change in resource allocation between these tissues. Our study suggests that behavioural changes in infected copepods are mediated by a mechanism different from energy depletion or a re-allocation of resources between muscles and lipids. We rather propose that the tapeworms directly manipulate copepod behaviour.

Management of women with ductal carcinoma in situ of the breast: a population-based study

BACKGROUND

Increasing incidence of ductal carcinoma in situ (DCIS) confronts patients and clinicians with optimal treatment decisions. This multidisciplinary study investigates therapeutic modalities of DCIS in daily practice and provides recommendations on how to increase quality of care.

PATIENTS AND METHODS

All women (n = 116) with unilateral DCIS recorded in the Geneva Cancer Registry from 1995 to 1999 were considered. Information concerned patient and tumor characteristics, treatment and outcome. Factors linked to therapy were determined using a case-control approach. Cases were women with treatment of interest and controls other women on the study.

RESULTS

Most DCIS cases (62%) were discovered by mammography screening. Ninety (78%) women had breast-conserving surgery (BCS), 18 (16%) mastectomy and seven (6%) bilateral mastectomy. Eight (7%) patients had tumor-positive margins, 18 (16%) lymph node dissection and two (1.7%) chemotherapy. Twenty-five per cent of women with BCS had no radiotherapy, three had radiotherapy after mastectomy. Less than 50% underwent breast reconstruction after mastectomy. Method of discovery, multifocality, tumor localization, size and differentiation were linked to the use of BCS or lymph node dissection.

CONCLUSIONS

Because of important disparities in DCIS management, recommendations are made to increase quality of care, in particular to prevent axillary dissection or bilateral mastectomy and to increase the use of radiotherapy after BCS.

To avoid or eliminate: cestode infections in copepods

The outcome of a parasite infection is the result of the interaction between the host and the parasite. In the system we studied, there are 3 critical stages for the outcome of infection of the (intermediate) host, the copepod Macrocyclops albidus, with the cestode Schistocephalus solidus. During the establishment phase of the parasite, the host may firstly avoid ingesting the parasite and, secondly, may prevent the parasite from entering the body cavity and, thirdly, during the growth phase of the parasite, the host's immune system may eliminate the parasite from the body cavity. We were able to study the growth phase separately from the establishment phase. The establishment phase was influenced by characteristics of the host as well as characteristics of the parasites. Small copepods and males performed poorly; they were more often infected and had a lower survival. Parasites from different sib-groups differed in infectivity. During the growth phase some disappearance of parasites was observed. However, this could not be related to any of the studied characteristics of the host, and the sib-groups of parasites did not seem to differ in their likelihood to disappear. Instead, we suggest that disappearance of parasites, once they have entered the body cavity, may be due to intrinsic mortality of the parasites, independent of the host or the sib-group that the parasites belong to. This indicates that the crucial interactions between host and parasite determining the outcome of infection takes place in the short time-period between ingestion and penetration of the gut-wall.

Mechanisms involved in the establishment of tolerance through costimulatory blockade and BMT: lack of requirement for CD40L-mediated signaling for tolerance or deletion of donor-reactive CD4+ cells

We have previously shown that high levels of multiline-age mixed hematopoietic chimerism and systemic T-cell tolerance can be achieved in mice without myeloablation through the use of anti-CD40L and costimulatory blockade alone (plus CTLA4Ig) or with recipient CD8 depletion and allogeneic bone marrow transplantation. Chimeric mice permanently accept donor skin grafts (> 100 days), and rapidly reject third-party grafts. The mechanisms by which costimulatory blockade facilitates the engraftment of allogeneic hematopoietic cells have not been defined. To further understand the in vivo mechanisms by which the administration of anti-CD40L mAb facilitates the engraftment of donor bone marrow and rapidly tolerizes CD4+ T cells, we analyzed the establishment of chimerism and tolerance in CD40L -/- mice. We demonstrate here that anti-CD40L mAb treatment is required only to prevent CD40L/CD40 interactions, and that no signal to the T cell through CD40L is necessary for the induction of CD4+ tolerance. Peripheral deletion of donor-reactive CD4+ T cells occurs rapidly in CD40L -/- mice receiving bone marrow transplantation (BMT), indicating that this deletion in the presence of anti-CD40L is not due to targeting of activated CD4+ cells by the antibody. Complete CD4+ cell tolerance is observed by both skin graft acceptance and in vitro assays before deletion is complete, indicating that additional mechanisms play a role in inducing CD4+ T-cell tolerance as the result of BMT in the presence of CD40/CD40L blockade.

CD4 T cell-mediated alloresistance to fully MHC-mismatched allogeneic bone marrow engraftment is dependent on CD40-CD40 ligand interactions, and lasting T cell tolerance is induced by bone marrow transplantation with initial blockade of this pathway

Costimulatory blockade can be used to promote allogeneic marrow engraftment and tolerance induction, but on its own is not 100% reliable. We sought to determine whether one or the other of the CD4 or CD8 T cell subsets of the recipient was primarily responsible for resistance to allogeneic marrow engraftment in mice receiving costimulatory blockade, and to use this information to develop a more reliable, minimal conditioning regimen for induction of mixed chimerism and transplantation tolerance. We demonstrate that a single anti-CD40 ligand mAb treatment is sufficient to completely overcome CD4 cell-mediated resistance to allogeneic marrow engraftment and rapidly induce CD4 cell tolerance, but does not reliably overcome CD8 CTL-mediated alloresistance. The data suggest that costimulation, which activates alloreactive CTL, is insufficient to activate alloreactive CD4 cells when the CD40 pathway is blocked. The addition of host CD8 T cell depletion to anti-CD40 ligand treatment reliably allows the induction of mixed chimerism and donor-specific skin graft tolerance in 3 Gy-irradiated mice receiving fully MHC-mismatched bone marrow grafts. Thus, despite the existence of multiple costimulatory pathways and pathways of APC activation, our studies demonstrate an absolute dependence on CD40-mediated events for CD4 cell-mediated rejection of allogeneic marrow. Exposure to donor bone marrow allows rapid tolerization of alloreactive CD4 cells when the CD40 pathway is blocked, leading to permanent marrow engraftment and intrathymic tolerization of T cells that develop subsequently.

Peripheral deletion after bone marrow transplantation with costimulatory blockade has features of both activation-induced cell death and passive cell death

Two major pathways of death of previously activated T cells have been described: activation-induced cell death can be triggered by restimulating activated T cells with high concentrations of Ag, is Fas-dependent, is not influenced by proteins of the Bcl family, and is blocked by cyclosporin A; in contrast, passive cell death is induced by the withdrawal of growth factors and activation stimuli, is Fas-independent, and is blocked by Bcl family proteins. We examined the role of these two forms of cell death in the peripheral deletion of donor-reactive host T cells after allogeneic bone marrow transplantation and costimulatory blockade with anti-CD154 plus CTLA4Ig in two murine models. The substantial decline in donor-reactive CD4 cells seen in wild-type recipients 1 wk after bone marrow transplantation with costimulatory blockade was largely inhibited in Fas-deficient recipients and in Bcl-x(L)-transgenic recipients. We observed these effects both in a model involving low-dose total body irradiation and a conventional dose of bone marrow, and in a radiation-free regimen using high-dose bone marrow transplantation. Furthermore, cyclosporin A did not completely block the deletion of donor-reactive CD4(+) T cells in recipients of bone marrow transplantation with costimulatory blockade. Thus, the deletion of donor-reactive T cells occurring early after bone marrow transplantation with costimulatory blockade has features of both activation-induced cell death and passive cell death. Furthermore, these in vivo data demonstrate for the first time the significance of in vitro results indicating that proteins of the Bcl family can prevent Fas-mediated apoptosis under certain circumstances.

Breast cancer and active and passive smoking: the role of the N-acetyltransferase 2 genotype

The association of breast cancer with passive and active smoking was investigated in slow and fast acetylators of aromatic amines in a Geneva, Switzerland, study in 1996-1997. A slow acetylator was homozygous for one, or heterozygous for two, of three N-acetyltransferase 2 (NAT2) polymorphisms determined on buccal cell DNA from 177 breast cancer cases and 170 age-matched, population controls. The reference group consisted of women never regularly exposed to active or passive smoke. Among premenopausal women, the odds ratios were homogeneous in slow and fast acetylators: 3.2 (95% confidence interval (CI): 1.2, 8.7) for passive smoking and 2.9 (95% CI: 1.1, 7.5) for active smoking. Among postmenopausal women, the odds ratios for fast acetylators were 11.6 (95% CI: 2.2, 62.2) for passive and 8.2 (95% CI: 1.4, 46.0) for active smoking; the corresponding effects were also apparent but less strong in slow acetylators. After the nonexposed and the passive smokers were grouped in a single reference category, active smoking was associated with postmenopausal breast cancer in slow acetylators (odds ratio (OR) = 2.5, 95% CI: 1.0, 6.2) but not in fast acetylators (OR = 1.3, 95% CI: 0.5, 3.3). Thus, the associations of both passive and active smoking with breast cancer appear stronger in fast than in slow NAT2 genotypes. Separating passive smokers from the nonexposed impacts on the inference about a possible NAT2-smoking interaction.

Allogeneic bone marrow transplantation with co-stimulatory blockade induces macrochimerism and tolerance without cytoreductive host treatment

Allogeneic bone marrow transplantation (in immunocompetent adults) has always required cytoreductive treatment of recipients with irradiation or cytotoxic drugs to achieve lasting engraftment at levels detectable by non-PCR-based techniques ('macrochimerism' or 'mixed chimerism'). Only syngeneic marrow engraftment at such levels has been achieved in unconditioned hosts. This requirement for potentially toxic myelosuppressive host pre-conditioning has precluded the clinical use of allogeneic bone marrow transplantation for many indications other than malignancies, including tolerance induction. We demonstrate here that treatment of naive mice with a high dose of fully major histocompatibility complex-mismatched allogeneic bone marrow, followed by one injection each of monoclonal antibody against CD154 and cytotoxic T-lymphocyte antigen 4 immunoglobulin, resulted in multi-lineage hematopoietic macrochimerism (of about 15%) that persisted for up to 34 weeks. Long-term chimeras developed donor-specific tolerance (donor skin graft survival of more than 145 days) and demonstrated ongoing intrathymic deletion of donor-reactive T cells. A protocol of high-dose bone marrow transplantation and co-stimulatory blockade can thus achieve allogeneic bone marrow engraftment without cytoreduction or T-cell depletion of the host, and eliminates a principal barrier to the more widespread use of allogeneic bone marrow transplantation. Although efforts have been made to minimize host pre-treatment for allogeneic bone marrow transplantation for tolerance induction, so far none have succeeded in eliminating pre-treatment completely. Our demonstration that this can be achieved provides the rationale for a safe approach for inducing robust transplantation tolerance in large animals and humans.

Genetic variability in the diapause response of the burnet moth Zygaena trifolii (Lepidoptera: Zygaenidae)

A high degree of phenotypic variability was observed in the diapause response of the burnet moth Zygaena trifolii. In this study, we show that the observed variability is partly based on genetic differences between individuals. In a selection experiment, the larval instar at which diapause occurs was changed within six generations. Diapause instars were dependent on the time of pre-diapause development of larvae, which varied considerably between larvae. A heritability analysis indicates that a part of the variability in development time is based on additive genetic variance. The maintenance of genetic variability in the development time and the diapause response of Z. trifolii is discussed in the context of spatially and temporally changing selection pressures.

Gender differences and individual variation in the immune system of the scorpionfly Panorpa vulgaris (Insecta: Mecoptera)

From investigations of the vertebrate immune system gender specific differences in individual immunocompetence are well known. In general, females seem to possess more powerful immune systems than males. In invertebrates, the situation is much less clear. Therefore, we investigated the immune system of an invertebrate species, the scorpionfly Panorpa vulgaris. We found a high degree of individual variation in both traits studied, the lysozyme-like antibacterial activity of hemolymph and the capacity for in vitro phagocytosis of artificial particles. These two immune traits were positively correlated. As expected, hemolymph derived from females had higher lysozyme-like activity and hemocytes from females phagocytosed more particles. The difference in phagocytosis was mainly based on higher total hemocyte counts and higher proportions of phagocytically active cells in females, while the average number of ingested particles per active phagocyte was not significantly different. The observed gender differences are discussed in the context of reproductive strategies and parasite-mediated sexual selection.