Efficacy of assisted reproductive technology after ovarian tissue transplantation in a cohort of 11 patients with or without associated infertility factors

PURPOSE

IVF treatment in women with grafted frozen-thawed ovarian tissue is associated with poor reproductive outcomes. The aim of this study was to evaluate the efficacy of ovarian tissue transplantation (OTT) followed by assisted reproductive technology (ART) in women with or without associated infertility factors.

METHODS

This is a prospective cohort study with retrospective data collection including eleven women, four of whom having an infertility factor (IF), who had undergone OTT in one university center between 2005 and 2017, followed by ART in six in vitro fertilization (IVF) centers.

RESULTS

In total, 25 of the 85 cycles initiated (29%) were canceled, resulting in 60 oocyte retrievals. Ninety-five oocytes were retrieved: 36 were abnormal or immature, 29/39 fertilized (74%) after ICSI and 13/20 (65%) after IVF. Thirty-five embryos were transferred in seven patients (5/7 patients without IF and 2/4 patients with IF). After ART, one patient with IF experienced two pregnancies, one resulting in a live birth. For all patients, pregnancy rates and live birth rates were 7.4% and 3.7% per embryo transfer, respectively. Nine pregnancies and four live births occurred after spontaneous conception in five patients without IF, none in the infertility group.

CONCLUSION

This study confirms that IVF treatment in women with grafted frozen-thawed ovarian tissue is associated with poor outcomes. However, the chances of natural conception are high in women without IF. Patients with IF, without the possibility of spontaneous pregnancy, should be informed of poor reproductive outcomes after OTT followed by ART.

TRIAL REGISTRATION NUMBER

NCT02184806.

A rapid assessment of the National Regulatory Systems for medical products in the Southern African Development Community

BACKGROUND

Access to quality-assured, safe and efficacious medical products is fundamental for Universal Health Coverage and attaining Sustainable Development Goal 3: Ensure Healthy Lives and Well-being for All. To guarantee this right, there is a need for robust and efficiently performing national regulatory systems for the regulation of medical products. Well-functioning regulatory systems apply globally accepted standards which ensure that the level of control is proportionate to the level of public health risk.

OBJECTIVE OF THE STUDY

The study aimed at analysing the regulatory systems for medical products in the 16 Member States of the Southern African Development Community (SADC). It provides an overview of the national regulatory systems for medical products in the region in 2017 and outlines the institutional frameworks, which enable the implementation of regulatory functions.

METHODOLOGY

A survey was conducted in March-December 2017 in English, French and Portuguese. National Regulatory Authorities for medical products (NMRAs) of the 16 Member States within SADC responded to the questions asked and sent in their answers. The survey was constructed around five themes instrumental for implementation of the Universal Health Coverage actions framework. Three of the themes are discussed in this article.

RESULTS

The outcome of the survey demonstrates that within SADC, NMRAs vary in terms of organisational set-up and modalities of medical product regulation. The majority are within the Ministries of Health, and a few are either semi-autonomous or autonomous. Legal frameworks for medical products are in place for some of the SADC NMRAs, although they vary in the scope of products subject to regulation. Traditional medicines, biologicals and medical devices are regulated, however not uniformly across the region.

CONCLUSION

Despite major progress over the years, the survey demonstrates variable levels of governance and regulatory framework among NMRAs in SADC. The survey supports the need for shifting from the broad strengthening of the regulatory systems which exist and are underpinned by the mandates, to more product-type focused approaches. This shift will ensure that medical products are quality-assured, safe and effective for a performant Health Systems attainment of the Universal Health Coverage and Sustainable Development Goals.

Impact of cancer chemotherapy before ovarian cortex cryopreservation on ovarian tissue transplantation

STUDY QUESTION

How efficacious is transplantation of ovarian cortex previously exposed to chemotherapy?

SUMMARY ANSWER

Prior exposure to chemotherapy did not disrupt the function of cryopreserved ovarian tissue after transplantation.

WHAT IS KNOWN ALREADY

Ovarian tissue cryopreservation (OTC) followed by ovarian tissue transplantation (OTT) is an efficacious technique for restoration of female fertility. At least 130 children have been born following this procedure. To date, little is known about the efficacy of OTT in patients exposed to cancer chemotherapy prior to OTC.

STUDY DESIGN, SIZE, DURATION

This study evaluates the recovery of ovarian function and fertility in 31 consecutive patients who had received OTT, between 2005 and 2015.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Thirty one patients, wanting children, were transplanted with autologous ovarian cortex, among which 22 patients (71%) had been exposed to chemotherapy before OTC. Recovery of ovarian function was considered total once menstruation occurred. Ovarian function recovery (OFR), ovarian graft survival, and incidence of pregnancy were related to previous chemotherapy exposure, type of chemotherapy and graft characteristics (number of grafted fragments and follicular density).

MAIN RESULTS AND ROLE OF CHANCE

The amount of ovarian tissue collected was the only parameter to show any significant change between patients with versus without previous chemotherapy. At 1 year after OTT, the cumulative incidence of OFR was 83% (93% in patients exposed to chemotherapy and 67% in others (P = 0.14)). A low follicular density (<0.3 foll/mm2) in the transplant and a low number of grafted fragments (<16) were significantly associated with a delayed OFR. Graft survival at 2 years after OTT was 77%. It was significantly lower in patients exposed to bifunctional alkylating agents before ovarian cryopreservation and in patients with a low follicular density. The proportion of women who succeeded in having at least one live birth was 23% in the total population, 0% (0/9) in the group 'no previous chemotherapy', and 32% (7/22) in the group 'previous chemotherapy'. The cumulative incidence of pregnancy (Kaplan-Meier) at 3 years after OTT was 36% overall and 49% in case of previous chemotherapy, with no difference related to previous chemotherapy exposure. In total there were 13 pregnancies and 8 births in 7 patients.

LIMITATIONS, REASONS FOR CAUTION

The pathology in the two groups of patients was not comparable. In the group of patients who had chemotherapy before OTC, there were 95% of hematological malignancies. In the group of patients who did not have chemotherapy before OTC only 1 out of 9 patients had a malignant hematological disease while 44% had some pathology affecting the ovaries. Few women are available for study and only large changes are likely to have statistical significance.

WIDER IMPLICATIONS OF THE FINDINGS

These results suggest that prior cancer chemotherapy should no longer be considered a limitation to cryopreservation of ovarian tissue and current recommendations in this regard should be revised.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Agence de la Biomédecine (France's biomedical office). There are no competing interests to report.

TRIAL REGISTRATION NUMBER

NCT02184806.

Production of recycled manure solids for bedding in Canadian dairy farms: I. Solid-liquid separation

Canadian dairy producers have an increasing interest in recycled manure solids (RMS) as bedding material because of reduced availability of traditional bedding resources. Information regarding methods to obtain RMS and composition of RMS is very limited. Hence, a 2-part investigation was developed to compare the performances of 3 mechanical solid-liquid manure separators (part I) and 4 composting methods (part II; companion paper in this issue) for the production of high quality RMS. In this first study, a roller press, a screw press, and a decanter centrifuge were tested for the separation of slurry manure from a commercial dairy farm. During the experiment, the quantity of slurry manure processed and the volume and mass of the liquid and solid fractions were measured. The energy consumption of each separator was recorded, and samples of the slurry, liquid, and solid effluents were collected for analysis. The type of separator did not significantly influence the chemical and bacteriological composition of RMS produced. The choice of a separator for Canadian dairy producers should thus be based on the equipment cost and its capacity, targeted solids dry matter (DM) content and structure, and fertilizing quality of the separated liquid. The decanter centrifuge produced the solid phase with the highest DM and best separation efficiencies for DM, N, and P. However, its low production capacity (1.5 m³/h vs. 9.1-20.3 m³/h) combined with its high acquisition cost (Can$145,000 vs. Can$75,000) and energy consumption (4.99 kWh/m³ vs. 0.10-0.35 kWh/m³) reduce its technical and profitability values. Besides, the centrifuge produced fine structured RMS and a low-quality liquid fraction, not suitable as dairy cow bedding and fertilizer, respectively. Both presses reached acceptable production capacity at a minimal operation cost. However, the poor performance in terms of DM (25%) of the model of screw press used in this study produced RMS unsuitable for immediate use without further processing. The model of roller press used in this study had the advantages of almost reaching the recommended DM content in RMS (>34%), being flexible in terms of inputs, and producing fluffy RMS. Nevertheless, its compression process seemed to allow greater passage of solids into the liquid fraction compared with the screw press. Part II of this work explores different composting methods to reduce the health risks associated with screw-pressed RMS before their use as bedding.

Production of recycled manure solids for use as bedding in Canadian dairy farms: II. Composting methods

Recent technological advances in the dairy industry have enabled Canadian farms with liquid manure systems to use mechanical solid-liquid separation paired with composting of the separated solids for on-farm production of low-cost bedding material. However, because several approaches are available, it is difficult for farmers to select the appropriate one to achieve high quality recycled manure solids (RMS). Whereas 3 solid-liquid manure separators were compared in part I of the series (companion paper in this issue), the present study (part II) aims to assess the performance of 4 composting methods (static or turned windrow and drum composter for 24 or 72 h) under laboratory conditions. Parameters evaluated included temperature, physico-chemical characteristics, and bacterial composition of RMS, as well as airborne microorganisms, dust, and gases associated with composting RMS. Because each treatment attained the desired composting temperature range of 40 to 65°C (either in heaps or in the drum composter), reductions in bacteria were a better indicator of the sanitation efficiency. The treatment of fresh RMS in a drum composter for 24 h showed decreased bacterial counts, especially for Escherichia coli (from 1.0 × 10⁵ to 2.0 × 10¹ cfu/g of dry matter) and Klebsiella spp. (from 3.2 × 10⁴ to 4.0 × 10² cfu/g of dry matter). Increasing the time spent in the rotating vessel to 72 h did not result in further decreases of these pathogens. Composting in a static or turned windrow achieved similar E. coli and Klebsiella spp. reductions as the 24-h drum composting but in 5 or 10 d, and generally showed the lowest occupational exposure risk for dairy farmers regarding concentrations of airborne mesophilic bacteria, mesophilic and thermotolerant fungi, and total dust. Drum-composted RMS stored in piles exhibited intermediate to high risk. Composting approaches did not have a major influence on the physico-chemical characteristics of RMS and gas emissions. Drum composting for 24 h was the best compromise in terms of product quality, temperature reached, decreased bacterial numbers, and emitted airborne contaminants. However, because levels of pathogenic agents rapidly increase once composted RMS are spread in stalls, bacteriological characteristics of RMS along with milk quality and animal health and welfare features should be monitored in Canadian dairy barns applying recommended separation (part I) and composting (part II) systems to evaluate health risk and optimize management practices.

Comparison of a Mediterranean to a low-fat diet intervention in adults with type 1 diabetes and metabolic syndrome: A 6-month randomized trial

BACKGROUND AND AIMS

The metabolic syndrome (MS) is an emerging complication in patients with type 1 diabetes (T1D), with no preventive or therapeutic treatment reported yet. We wanted to compare the impact of two 6-month nutritional interventions, based on a Mediterranean (MED) or a low-fat diet, on waist circumference, anthropometric and metabolic outcomes in patients with both T1D and the MS.

METHODS AND RESULTS

Participants were randomized into 2 intervention groups: 1) MED-diet or 2) low-fat diet. The 6-month study included 9 teaching sessions with a registered dietitian. Anthropometric (primary outcome: waist circumference), metabolic and nutritional assessments were performed at inclusion, 3 and 6-month. We used mixed effects models to assess the effects of both interventions. 28 participants were included (50.9 ± 10.3 years old) with a mean BMI of 30.7 ± 3.3 kg/m² and a waist circumference of 105.5 ± 8.9 cm at inclusion. A trend towards a greater reduction of dietary fat intakes in the low-fat diet group was observed (P-interaction = 0.09). Waist circumference was reduced at 6-month in both groups (-3.5 cm low-fat; -1.5 cm MED-diet) with no significant difference between groups (P-interaction = 0.43). Body mass index also significantly decreased in both groups (-0.7 kg/m² low-fat; -1.1 kg/m² MED-diet; P-interaction = 0.56). No significant differences between groups were observed for other metabolic parameters.

CONCLUSIONS

This study suggests that a 6-month non-restrictive dietary intervention in patients with T1D and MS could contribute to weight management, without significant differences between interventions for anthropometric and metabolic parameters. Further studies should investigate the long-term benefits of these diets.

CLINICAL TRIAL REGISTRY

NCT02821585 (https://clinicaltrials.gov/).

Predictors of cardiovascular risk among patients with type 1 diabetes: A critical analysis of the metabolic syndrome and its components

Patients with type 1 diabetes (T1D) are at increased risk for cardiovascular diseases. The metabolic syndrome (MetS), a complex disorder defined by a cluster of interconnected factors including abdominal obesity, hypertension, dyslipidaemia and insulin resistance, has been proposed to identify patients with T1D at high cardiovascular risk. The MetS has been identified in 8-45% of patients with T1D, depending on the definition and cohort studied. However, clinicians and researchers face several issues with the criteria for MetS in patients with T1D, therefore questioning its value in routine care. For example, three criteria can lead to overestimation of MetS prevalence; the impaired fasting glucose criterion is irrelevant as it is automatically fulfilled; and the widespread use of antihypertensive and lipid-lowering medications for cardiac and renal preventative purposes can contribute to overestimations of the prevalence of raised blood pressure and elevated triglycerides. In cross-sectional studies, the MetS has been associated mostly with an increased risk of microvascular complications whereas, in prospective cohorts, the predictive value of MetS for micro- and macrovascular outcomes has been inconsistent. While identifying diabetes patients at increased risk for cardiovascular complications and early mortality is crucial from a prevention standpoint, for patients with T1D, the current definition of MetS may not be the most suitable tool. The aims of the present report are to review the applicability and limitations of the MetS in patients with T1D, and to discuss alternative avenues to identify high-risk patients.

Efficacy of domestic cooking inactivation of human hepatitis A virus in experimentally infected manila clams (Ruditapes philippinarum)

AIM

The aim of this work was to evaluate the efficacy of domestic cooking in inactivating Manila clams experimentally infected with human hepatitis A virus (HAV).

METHODS AND RESULTS

Electronic temperature probes were positioned to measure the internal temperature of Manila clams during domestic cooking. Two batches were infected with 10(7) and 10(5) TCID50  ml(-1) of HAV. The infected whole-in-shell clams were divided into three replicates and cooked on a conventional stove both singularly and in group and removed from the pan at fixed intervals. Pools of three digestive glands were examined by virus isolation for three blind passages and cell culture supernatant tested with real-time PCR.

CONCLUSION

Results showed that 2-min cooking by a traditional domestic method at a temperature close to 100°C, after the opening up of the valves of all the clams, can completely devitalize the HAV in high viral load-infected clams.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first study on inactivation of HAV in experimentally infected Manila clams subjected to domestic cooking. At present, labelling all lagoon products as 'requiring cooking before consumption' is highly recommended, but no specifications are given on how long and at what temperature they should be cooked. Considering the high commercial value of Manila clams, our results can provide both the producers and the consumer with useful indications on how to cook clams to prevent the risk of HAV foodborne illness.

Cysteamine broadly improves the anti-plasmodial activity of artemisinins against murine blood stage and cerebral malaria

BACKGROUND

The potential emergence and spread of resistance to artemisinins in the Plasmodium falciparum malaria parasite constitutes a major global health threat. Hence, improving the efficacy of artemisinins and of artemisinin-based combination therapy (ACT) represents a major short-term goal in the global fight against malaria. Mice defective in the enzyme pantetheinase (Vnn3) show increased susceptibility to blood-stage malaria (increased parasitaemia, reduced survival), and supplementation of Vnn3 mutants with the reaction product of pantetheinase, cysteamine, corrects in part the malaria-susceptibility phenotype of the mutants. Cysteamine (Cys) is a small, naturally occurring amino-thiol that has very low toxicity in vivo and is approved for clinical use in the life-long treatment of the kidney disorder nephropathic cystinosis.

METHODS

The ability of Cys to improve the anti-plasmodial activity of different clinically used artemisinins was tested. The effect of different CYS/ART combinations on malarial phenotypes (parasite blood-stage replication, overall and survival from lethal infection) was assessed in a series of in vivo experiments using Plasmodium strains that induce either blood-stage (Plasmodium chabaudi AS) or cerebral disease (Plasmodium berghei ANKA). This was also evaluated in an ex vivo experimental protocol that directly assesses the effect of such drug combinations on the viability of Plasmodium parasites, as measured by the ability of tested parasites to induce a productive infection in vivo in otherwise naïve animals.

RESULTS

Cys is found to potentiate the anti-plasmodial activity of artesunate, artemether, and arteether, towards the blood-stage malaria parasite P. chabaudi AS. Ex vivo experiments, indicate that potentiation of the anti-plasmodial activity of artemisinins by Cys is direct and does not require the presence of host factors. In addition, potentiation occurs at sub-optimal concentrations of artemisinins and Cys that on their own have little or no effect on parasite growth. Cys also dramatically enhances the efficacy and protective effect of artemisinins against cerebral malaria induced by infection with the P. berghei ANKA parasite.

CONCLUSION

These findings indicate that inclusion of Cys in current formulations of ACT, or its use as adjunct therapy could improve the anti-plasmodial activity of artemisinin, decrease mortality in cerebral malaria patients, and prevent or delay the development and spread of artemisinin resistance.

Oleylphosphocholine (OlPC) arrests Cryptosporidium parvum growth in vitro and prevents lethal infection in interferon gamma receptor knock-out mice

Cryptosporidium parvum is a species of protozoa that causes cryptosporidiosis, an intestinal disease affecting many mammals including humans. Typically, in healthy individuals, cryptosporidiosis is a self-limiting disease. However, C. parvum can cause a severe and persistent infection that can be life-threatening for immunocompromised individuals, such as AIDS patients. As there are no available treatments for these patients that can cure the disease, there is an urgent need to identify treatment options. We tested the anti-parasitic activity of the alkylphosphocholine oleylphosphocholine (OlPC), an analog of miltefosine, against C. parvum in in vitro and in vivo studies. In vitro experiments using C. parvum infected human ileocecal adenocarcinoma cells (HCT-8 cells) showed that OlPC has an EC₅₀ of 18.84 nM. Moreover, no cell toxicity has been seen at concentrations ≤50 μM. C57BL/6 interferon gamma receptor knock-out mice, were infected by gavage with 4000 C. parvum oocysts on Day 0. Oral treatments, with OlPC, miltefosine, paromomycin or PBS, began on Day 3 post-infection for 10 days. Treatment with OlPC, at 40 mg/kg/day resulted in 100% survival, complete clearance of parasite in stools and a 99.9% parasite burden reduction in the intestines at Day 30. Doses of 30 and 20 mg/kg/day also demonstrated an increased survival rate and a dose-dependent parasite burden reduction. Mice treated with 10 mg/kg/day of miltefosine resulted in 50% survival at Day 30. In contrast, control mice, treated with PBS or 100 mg/kg/day of paromomycin, died or had to be euthanized between Days 6 and 13 due to severe illness. Results of parasite burden were obtained by qPCR and cross-validated by both flow cytometry of stool oocysts and histological sections of the ileum. Together, our results strongly support that OlPC represents a potential candidate for the treatment of C. parvum infections in immunocompromised patients.

Direct comparison of the efficacy and safety of oral treatments with oleylphosphocholine (OlPC) and miltefosine in a mouse model of L. major cutaneous leishmaniasis

Background

Cutaneous leishmaniasis (CL) represents a range of skin diseases caused by infection with Leishmania parasites and associated with tissue inflammation and skin ulceration. CL is clinically widespread in both the Old and New World but lacks treatments that are well tolerated, effective and inexpensive. Oleylphosphocholine (OlPC) is a new orally bioavailable drug of the alkylphosphocholine family with potent antileishmanial activity against a broad range of Leishmania species/strains.

Methodology/principal findings

The potential of OlPC against Old World CL was evaluated in a mouse model of Leishmania (L.) major infection in BALB/c mice. Initial dose-response experiments showed that an oral daily dose of 40 mg/kg of OlPC was needed to impact time to cure and lesion sizes. This dose was then used to directly compare the efficacy of OlPC to the efficacy of the antileishmanial drugs miltefosine (40 mg/kg/day), fluconazole (160 mg/kg/day) and amphotericin B (25 mg/kg/day). OlPC, miltefosine and fluconazole were given orally for 21 days while amphotericin B was administered intraperitoneally for 10 days. Ulcer sizes and animal weights were followed up on a weekly basis and parasitemia was determined by means of a real-time in vivo imaging system which detects luminescence emitted from luciferase-expressing infecting L. major parasites. Amphotericin B and OlPC showed excellent efficacy against L. major lesions in terms of reduction of parasitic loads and by inducing complete healing of established lesions. In contrast, treatment with miltefosine did not significantly affect parasitemia and lesion sizes, while fluconazole was completely ineffective at the dose regimen tested.

Conclusions/Significance

Given the data showing the outstanding efficacy and tolerability of OlPC, our results suggest that OlPC is a promising new drug candidate to improve and simplify current clinical management of L. major CL.

Cutaneous leishmaniasis (CL) is a vector-borne parasitic disease transmitted to humans by sandflies and characterized by local ulcerative skin lesions. The disease is linked to poverty in the Middle-East, North and East Africa, South-Central Asia and South America, with 0.7 to 1.2 million new annual cases estimated. In most endemic regions CL treatment relies on injections with pentavalent antimonials, old generation drugs with considerable side effects and long treatment regimens. CL is therefore a highly undertreated disease in need of easy-to-administer, orally bioavailable and well-tolerated agents with broad clinical activity. To date, the only oral drug with acceptable efficacy against leishmaniasis is miltefosine, an alkylphosphocholine with a narrow therapeutic window that limits its use. Given the existing clinical need for CL, we tested the efficacy of oleylphosphocholine (OlPC) in a validated mouse model of Old World (Leishmania major) CL. OlPC is a new orally bioavailable drug of the same family as miltefosine with potent and broad leishmanicidal activity. In direct comparison with miltefosine, our results indicate that OlPC induces higher parasite clearance and lesion healing with measurable improved tolerance. These promising observations warrant further research on OlPC as a new drug to improve clinical management of CL.

Challenges faced by multidisplinary new investigators on addressing grand challenges in global health

Background

The grand challenges approach aims to spark innovative and transformative strategies to overcome barriers to significant global health issues. Grand Challenges Canada endorses an ‘Integrated Innovation™’ approach that focuses on the intersection of scientific/technological, social and business innovation. In this article we explore themes emerging from a dialogue between the authors, who are multidisciplinary recipients of the ‘Rising Stars in Global Health’ award from Grand Challenges Canada, regarding benefits of engaging in integrated innovation research, and recommendations for how this approach may develop in the future.

Discussion

Our dialogue followed a semi-structured interview format that addressed three topics: 1) reflections on applying an Integrated Innovation™ approach for global health; 2) thoughts on participation in the Grand Challenges 2012 meeting; and 3) authors’ visions of Grand Challenges Canada and the Grand Challenge movement towards 2020. The dialogue was transcribed verbatim and we used thematic analysis techniques to identify, analyze and report themes in the data. Benefits of working using the Grand Challenges approach centered on two themes: a) the potential for scientific breakthrough and b) building interdisciplinary collaborations and a community of scholars. Challenges and opportunities for Grand Challenges in moving forward included: a) capacity building, particularly regarding Integrated Innovation™ and scale-up planning; b) interdisciplinary and international mentorship for new investigators; and c) potential for future commercialization.

Conclusions

Our discussion highlighted that Integrated Innovation™ offers the opportunity to develop new theories, methods and approaches to global health while simultaneously fostering a collaborative spirit grounded in international, interdisciplinary collaborations. However, the arguable over-emphasis on corporatization poses a major challenge for new investigators. We propose a more balanced way forward that can harness technology to foster mentorship across time and space to support the development of such skills and ideas among new investigators.

Convective Instabilities in the Coextrusion Process

This paper is devoted to the numerical study of the stability of the plane flow for two immiscible fluids obeying Maxwell constitutive equation in a channel of aspect ratio 8. For fixed viscosity and flow rate ratios, the shape and non-linear behavior of interfacial waves induced by small perturbations of the input flow rate are studied using finite element simulations for various elasticity stratifications. The stationary flow, close to a Poiseuille flow and presenting a flat interface is first computed. Then the interfacial wave generated by a pulse-like disturbance on entry flow rates is computed by using time dependent computations. It takes the shape of a wave packet which is amplified or damped while moving towards the die exit. In unstable cases, the maximum deviation increases with elasticity (the Weissenberg number). Interestingly, the elastic stratification between the two layers can counteract unstable waves due to viscous stratification.

Development of backfat and individual fat layers in the pig and its relationship with carcass lean

The development of backfat (total and individual layers) was monitored in 140 Yorkshire pigs (71 castrates and 69 gilts) during a growing period extending from 14·5 kg to 137·0 kg live weight using a serial slaughter procedure. The allometric coefficient (b) for fat thickness was calculated at several locations extending from the shoulder to the M. gluteus medius at the mid-line and lateral to the mid-line. The relationships between backfat (total and individual layers) and the yield of trimmed boneless meat were also obtained from 80 carcasses. Total backfat was the thickest at the shoulder, decreased gradually to the last rib, increased at the maximum loin, decreased to the middle of the M. gluteus medius and then increased posterior to the M. gluteus medius. The development of total backfat relative to weight at slaughter was generally slowest at the shoulder (b = 0·555-0·767), most rapid in the region extending from the 5/6 last rib to the last rib b = 0·729-0·810) and intermediate at the loin and in the region of the M. gluteus medius (b = 0·609-0·834). The development of the middle fat layer (b = 0·609-1·107) was more rapid than that of the outer layer (b = 0·500-0·817), the inner layer being intermediate (b = 0·515-0·966). Consistent with the rate of development observed for the individual fat layers, at light weights, the outer layer was usually more predominant, particularly at positions above the M. longissimus, whereas, at heavier weights, the middle layer became predominant. It was observed that backfat (total or individual layers) measurements, which were the most precise predictors of yield of trimmed boneless meat, that is, measurements from the 5/6 last rib to the last rib (RSE = 4·6-3·1), also had the most rapid rate of development. Furthermore, the middle layer of backfat which exhibited the fastest rate of development of all three individual layers (b = 0·609-1·107), also contributed the most to the observed precision (RSE = 4·6-3·1).

Evaluation of three ultrasound instruments, CVT-2, UltraFom 300 and AutoFom for predicting salable meat yield and weight of lean in the primals of pork carcasses

Three commercially available ultrasound instruments were evaluated using pigs representative of the Canadian pig population: CVT-2, UltraFom 300 and AutoFom. The reflectance probe HGP2 was utilized as the baseline instrument. Sampling was stratified by fat thickness. The original data set (n=236) was divided randomly into a calibration set (n=194 [85 barrows and 109 gilts]) to calibrate the instruments and a validation set (n=72[32 barrows and 40 gilts]) for validating the calibration models. For salable meat yield, RMSE values for the calibration models were: HGP2, 1.56; CVT-2, 1.57; UltraFom, 1.70; and AutoFom, 1.68. For lean (kg) in butt, picnic, loin and ham, and weight (kg) of the skinless, trimmed belly, RMSE for the calibration models was similar for all four instruments: respectively, 0.19-0.21, 0.21-0.23, 0.31-0.37, 0.35-0.40 and 0.35-0.36 kg. Validation results for predicting salable meat yield show that the improvement in precision and/or accuracy associated with the UltraFom 300 or AutoFom, over the baseline reflectance probe HGP2, was negligible whereas a definite advantage was observed for the CVT-2. However, validation results for predicting kg of lean in the primals did not show any clear advantage for the three commerciallly available ultrasound instruments over the baseline reflectance probe HGP2. Calibration and validation procedures showed that, if one was to base the assessment of these three ultrsound instruments uniquely on the precision and accuracy for predicting salable meat yield and/or kg of lean in the primals, any amelioration over the baseline reflectance probe HGP2 would have to be viewed as rather negligible; particularly for the UltraFom 300 or AutoFom.

The influence of pre-slaughter oral loading of acid or base on post-mortem changes in Longissimus Dorsi muscle of pork

Twenty-four pigs were assigned to one of four ad libitum water treatments: control, sodium bicarbonate (12·6 g/litre), low ammonium chloride (4 g/litre) or high ammonium chloride (8 g/litre) for 5 days, to study the influence of an oral acid or base load on post-mortem changes in longissimus dorsi muscle and ultimate pork quality. Physiological changes before slaughter were monitored by measuring blood pH, pCO(2) and HCO(3)(-). The influence of dietary treatments on post-mortem changes and ultimate meat quality was determined by measuring glycolytic enzymes and intermediates, and muscle pH, color and water-holding capacity (WHC). As expected, sodium bicarbonate generated a metabolic alkalosis, whereas ammonium chloride resulted in a metabolic acidosis. Pre-slaughter acid-base status was positively correlated with muscle WHC (P < 0·05). However, no significant dietary treatment effect was observed in muscle quality traits such as color (a, b, L) and WHC. Muscle pH(45) was significantly (P < 0·05) higher in bicarbonate than control and high ammonium chloride treatments. The activity of Ca(2+)-dependent protein kinase was significantly (P < 0·05) higher at 45 min post-mortem but that of pyruvate kinase was significantly lower at 2 and 4 h post mortem in bicarbonate-treated pigs. At 45 min post mortem, the activity of fructose-1,6-diphosphatase in the control pigs was significantly higher (P < 0·05) than on other treatments. The concentration of glycogen was significantly (P < 0·05) higher in bicarbonate and high ammonium chloride pigs; bicarbonate-treated pigs also has significantly higher adenosine-5'-triphosphate (ATP) and pH values than other treatment groups (P < 0·05) at early post-mortem. It was concluded that pre-slaughter oral loading of acid or base could induce changes in muscle metabolism and post-mortem muscle pH. Further research is required to confirm that altering diet acidogenicity or alkalinogenicity may be a means of enhancing ultimate pork quality.

Genetic control of high density lipoprotein-cholesterol in AcB/BcA recombinant congenic strains of mice

Epidemiological studies show that high HDL-cholesterol (HDLc) decreases the risk of cardiovascular disease. To map genes controlling lipid metabolism, particularly HDLc levels, we screened the plasma lipids of 36 AcB/BcA RC mouse strains subjected to either a normal or a high-fat/cholesterol diet. Strains BcA68 and AcB65 showed deviant HDLc plasma levels compared with the parental A/J and C57BL/6J strains; they were thus selected to generate informative F2 crosses. Linkage analyses in the AcB65 strain identified a locus on chromosome 4 (Hdlq78) responsible for high post-high fat diet HDLc levels. This locus has been previously associated at genome-wide significance to two regions in the human genome. A second linkage analysis in strain BcA68 identified linkage in the vicinity of a gene cluster known to control HDLc levels. Sequence analysis of these candidates identified a de novo, loss-of-function mutation in the ApoA1 gene of BcA68 that prematurely truncates the ApoA1 protein. The possibility of dissecting the specific effects of this new ApoA1 deficiency in the context of isogenic controls makes the BcA68 mouse a valuable new tool.

Identification of loci controlling restriction of parasite growth in experimental Taenia crassiceps cysticercosis

Human neurocysticercosis (NC) caused by Taenia solium is a parasitic disease of the central nervous system that is endemic in many developing countries. In this study, a genetic approach using the murine intraperitoneal cysticercosis caused by the related cestode Taenia crassiceps was employed to identify host factors that regulate the establishment and proliferation of the parasite. A/J mice are permissive to T. crassiceps infection while C57BL/6J mice (B6) are comparatively restrictive, with a 10-fold difference in numbers of peritoneal cysticerci recovered 30 days after infection. The genetic basis of this inter-strain difference was explored using 34 AcB/BcA recombinant congenic strains derived from A/J and B6 progenitors, that were phenotyped for T. crassiceps replication. In agreement with their genetic background, most AcB strains (A/J-derived) were found to be permissive to infection while most BcA strains (B6-derived) were restrictive with the exception of a few discordant strains, together suggesting a possible simple genetic control. Initial haplotype association mapping using >1200 informative SNPs pointed to linkages on chromosomes 2 (proximal) and 6 as controlling parasite replication in the AcB/BcA panel. Additional linkage analysis by genome scan in informative [AcB55xDBA/2]F1 and F2 mice (derived from the discordant AcB55 strain), confirmed the effect of chromosome 2 on parasite replication, and further delineated a major locus (LOD = 4.76, p<0.01; peak marker D2Mit295, 29.7 Mb) that we designate Tccr1 (T. crassiceps cysticercosis restrictive locus 1). Resistance alleles at Tccr1 are derived from AcB55 and are inherited in a dominant fashion. Scrutiny of the minimal genetic interval reveals overlap of Tccr1 with other host resistance loci mapped to this region, most notably the defective Hc/C5 allele which segregates both in the AcB/BcA set and in the AcB55xDBA/2 cross. These results strongly suggest that the complement component 5 (C5) plays a critical role in early protective inflammatory response to infection with T. crassiceps.

Infection with the cestode Taenia solium causes cysticercosis in humans and pigs. Neurocysticercosis is a severe manifestation of T. solium infection that constitutes an important health concern in developing countries. Studies in humans living in areas of endemic disease and in pigs experimentally infected have suggested a large spectrum of permissiveness to T. solium multiplication, with the possible contribution of genetic factors. In the present report, we have used an experimental mouse model of intraperitoneal infection with Taenia crassiceps to study the potential role of genetic factors in regulating replication of this parasite. Our study focused on two inbred mouse strains A/J and C57BL/6J that are respectively permissive and non-permissive to intraperitoneal multiplication of T. crassiceps. We have used a set of AcB/BcA recombinant congenic strains of mice along with standard F2 crosses to decipher the complexity and nature of the genetic component of the A/J vs. C57BL/6J interstrain difference in permissiveness. Our results point to a major role of the complement component 5 (C5) in early response and protection against T. crassiceps infection.

IRF8 mutations and human dendritic-cell immunodeficiency

BACKGROUND

The genetic analysis of human primary immunodeficiencies has defined the contribution of specific cell populations and molecular pathways in the host defense against infection. Disseminated infection caused by bacille Calmette-Guérin (BCG) vaccines is an early manifestation of primary immunodeficiencies, such as severe combined immunodeficiency. In many affected persons, the cause of disseminated BCG disease is unexplained.

METHODS

We evaluated an infant presenting with features of severe immunodeficiency, including early-onset disseminated BCG disease, who required hematopoietic stem-cell transplantation. We also studied two otherwise healthy subjects with a history of disseminated but curable BCG disease in childhood. We characterized the monocyte and dendritic-cell compartments in these three subjects and sequenced candidate genes in which mutations could plausibly confer susceptibility to BCG disease.

RESULTS

We detected two distinct disease-causing mutations affecting interferon regulatory factor 8 (IRF8). Both K108E and T80A mutations impair IRF8 transcriptional activity by disrupting the interaction between IRF8 and DNA. The K108E variant was associated with an autosomal recessive severe immunodeficiency with a complete lack of circulating monocytes and dendritic cells. The T80A variant was associated with an autosomal dominant, milder immunodeficiency and a selective depletion of CD11c+CD1c+ circulating dendritic cells.

CONCLUSIONS

These findings define a class of human primary immunodeficiencies that affect the differentiation of mononuclear phagocytes. They also show that human IRF8 is critical for the development of monocytes and dendritic cells and for antimycobacterial immunity. (Funded by the Medical Research Council and others.).

NCIC-CTG MA.20: An intergroup trial of regional nodal irradiation in early breast cancer

LBA1003

Background: Randomized trials have demonstrated that locoregional radiation after mastectomy reduces locoregional recurrence and improves overall survival (OS) in women with node positive breast cancer treated with adjuvant systemic therapy. MA.20 evaluated the addition of regional nodal irradiation (RNI) to whole breast irradiation (WBI) following breast conserving surgery (BCS). Methods: Women with high risk node-negative or node-positive breast cancer treated with BCS and adjuvant chemotherapy and/or endocrine therapy were stratified by positive nodes, axillary nodes removed, chemo- and endocrine therapy and randomized to WBI (50Gy in 25 fractions +/- boost irradiation) or WBI plus RNI (45Gy in 25 fractions) to the internal mammary, supraclavicular, and high axillary lymph nodes. The primary outcome was OS. The Data Safety Monitoring Committee approved the analysis plan for the protocol specified interim analysis of relapse patterns, survival and toxicity at 5 years. Upon review of the data, they recommended release of the results. Results: Between March 2000 to March 2007, 1,832 women were randomly assigned to WBI+RNI (916) or WBI (916). Median follow-up was 62 months. Characteristics of the study population were: mean age, 53.3 years; node negative, 10%; 1-3 positive nodes, 85%; > 4 positive nodes, 5%; adjuvant chemotherapy, 91%; and adjuvant endocrine therapy, 71%. WBI+RNI in comparison to WBI alone was associated with an improvement in isolated locoregional disease free survival (DFS; HR=.59, p=.02, 5 year risk: 96.8% and 94.5% respectively), distant DFS (HR=.64, p=.002, 5 year risk: 92.4% and 87.0% respectively), DFS (HR=.68, p=.003, 5 year risk: 89.7% and 84.0% respectively) and OS (HR=.76, p=.07, 5 year risk: 92.3% and 90.7% respectively). WBI+RNI in comparison to WBI was associated with an increase in grade 2 or greater pneumonitis (1.3% and 0.2% respectively, p=.01), and lymphedema (7.3% and 4.1% respectively, p=.004). Conclusions: The majority of women with node positive breast cancer are now managed by BCS followed by WBI and adjuvant systemic therapy. Results from MA.20 demonstrate that additional RNI reduces the risk of locoregional and distant recurrence, and improves DFS with a trend in improved OS.

Positional cloning of a quantitative trait locus contributing to pain sensitivity: possible mediation by Tyrp1

To identify novel pain-relevant genes, a set of 35 recombinant congenic strains derived from the sensitive C57BL/6 and resistant A/J strains were tested for their sensitivity to noxious heat on the radiant heat paw-withdrawal test. Nine strains were found to display differential sensitivity, and the two most extreme responders were used to generate independent secondary crosses for quantitative trait locus (QTL) mapping. From these genetic analyses, a QTL, which we call Tpnr5, was mapped to a 14-Mb interval of mouse chromosome 4 containing 39 genes. In addition to the paw-withdrawal test phenotype, Tpnr5 may be relevant to mechanical and inflammatory nociception. A series of strategies - including in silico analyses, reverse transcriptase polymerase chain reaction (RT-PCR) in multiple tissues and exonic DNA sequencing - were used to generate a list of six prioritized candidate genes. One of these, tyrosinase-related protein 1 (Tyrp1), displayed enriched expression in the dorsal root ganglia, an inactivating (C110Y) mutation in the resistant A/J strain, and a null mutant found to be more resistant to thermal nociception compared to its wild-type counterpart. Although other genes cannot be definitively ruled out, existing data are supportive of the candidacy of Tyrp1 as representing the Tpnr5 QTL. Tyrosinase-related protein 1 is the rate-limiting enzyme in the production of eumelanin, and possible relationships between eumelanin-expressing cells and thermal nociception are discussed. The positional cloning of Tpnr5 is also considered in light of the heuristic value but continuing challenges of QTL mapping in the mouse.

Cysteamine, the natural metabolite of pantetheinase, shows specific activity against Plasmodium

In mice, loss of pantetheinase activity causes susceptibility to infection with Plasmodium chabaudi AS. Treatment of mice with the pantetheinase metabolite cysteamine reduces blood-stage replication of P. chabaudi and significantly increases survival. Similarly, a short exposure of Plasmodium to cysteamine ex vivo is sufficient to suppress parasite infectivity in vivo. This effect of cysteamine is specific and not observed with a related thiol (dimercaptosuccinic acid) or with the pantethine precursor of cysteamine. Also, cysteamine does not protect against infection with the parasite Trypanosoma cruzi or the fungal pathogen Candida albicans, suggesting cysteamine acts directly against the parasite and does not modulate host inflammatory response. Cysteamine exposure also blocks replication of P. falciparum in vitro; moreover, these treated parasites show higher levels of intact hemoglobin. This study highlights the in vivo action of cysteamine against Plasmodium and provides further evidence for the involvement of pantetheinase in host response to this infection.

A novel form of cell type-specific partial IFN-gammaR1 deficiency caused by a germ line mutation of the IFNGR1 initiation codon

IFN-gammaR1 deficiency is a genetic etiology of Mendelian susceptibility to mycobacterial diseases, and includes two forms of complete recessive deficiency, with or without cell surface expression, and two forms of partial deficiency, dominant or recessive. We report here a novel form of partial and recessive Interferon gamma receptor 1 (IFN-gammaR1) deficiency, which is almost as severe as complete deficiency. The patient is homozygous for a mutation of the initiation codon (M1K). No detectable expression and function of IFN-gammaR1 were found in the patient's fibroblasts. However, IFN-gammaR1 expression was found to be impaired, but not abolished, on the EBV-transformed B cells, which could respond weakly to IFN-gamma. The mechanism underlying this weak expression involves leaky translation initiation at both non-AUG codons and the third AUG codon at position 19. It results in the residual expression of IFN-gammaR1 protein of normal molecular weight and function. The residual IFN-gamma signaling documented in this novel form of partial IFN-gammaR1 deficiency was not ubiquitous and was milder than that seen in other forms of partial IFN-gammaR1 deficiency, accounting for the more severe clinical phenotype of the patient, which was almost as severe as that of patients with complete deficiency.

Identification of novel chromosomal regions associated with airway hyperresponsiveness in recombinant congenic strains of mice

Airway responsiveness is the ability of the airways to respond to bronchoconstricting stimuli by reducing their diameter. Airway hyperresponsiveness has been associated with asthma susceptibility in both humans and murine models, and it has been shown to be a complex and heritable trait. In particular, the A/J mouse strain is known to have hyperresponsive airways, while the C57BL/6 strain is known to be relatively refractory to bronchoconstricting stimuli. We analyzed recombinant congenic strains (RCS) of mice generated from these hyper- and hyporesponsive parental strains to identify genetic loci underlying the trait of airway responsiveness in response to methacholine as assessed by whole-body plethysmography. Our screen identified 16 chromosomal regions significantly associated with airway hyperresponsiveness (genome-wide P <or= 0.05): 8 are supported by independent and previously published reports while 8 are entirely novel. Regions that overlap with previous reports include two regions on chromosome 2, three on chromosome 6, one on chromosome 15, and two on chromosome 17. The 8 novel regions are located on chromosome 1 (92-100 cM), chromosome 5 (>73 cM), chromosome 7 (>63 cM), chromosome 8 (52-67 cM), chromosome 10 (3-7 cM and >68 cM), and chromosome 12 (25-38 cM and >52 cM). Our data identify several likely candidate genes from the 16 regions, including Ddr2, Hc, Fbn1, Flt3, Utrn, Enpp2, and Tsc.

Characterization of a major colon cancer susceptibility locus (Ccs3) on mouse chromosome 3

Treatment of mice with the carcinogen azoxymethane (AOM) induces a number of lesions in the colon, including hyperplastic lesions, as well adenomas and carcinomas in situ. Inbred strains of mice show different responses to AOM-induced carcinogenesis. A/J mice are highly susceptible and develop a greater number of hyperplastic lesions and tumors (15-70 tumors per mouse) than resistant C57BL/6J mice (0-6 tumors per mouse). Susceptibility to AOM-induced tumors segregates as a co-dominant trait in (A x B6)F1 hybrids. Using a set of 23 AcB and BcA recombinant congenic mouse strains derived from A/J (susceptible) and B6 (resistant) parents, we observed that the number of hyperplastic lesions and tumors induced by AOM was under different genetic controls in AcB/BcA strains. The multiplicity of AOM-induced tumors is controlled by a major locus that we have mapped on the distal portion of chromosome 3, to which we have given the temporary designation colon cancer susceptibility locus 3 (Ccs3). B6 and A/J alleles at Ccs3 are associated with resistance and susceptibility, respectively. Haplotype analysis in key informative AcB/BcA strains restricts the size of the Ccs3 locus to a 14 Mb segment that contains 94 annotated genes. The expression level of all these genes in normal colon has been established by transcript profiling with microarrays, and has led to the identification of a subset of positional candidates that are expressed at high levels in this tissue. The 4q and 1p human chromosomal segments sharing syntenic homology with the mouse Ccs3 segment are known to be associated with inflammatory bowel diseases and colorectal tumors in humans, suggesting that the study of the mouse Ccs3 locus may help further the pathogenesis of these human conditions.

Gnao1 (G alphaO protein) is a likely genetic contributor to variation in physical dependence on opioids in mice

Chronic exposure to opioids leads to physical dependence, which manifests as the symptoms of drug withdrawal. Interindividual differences in withdrawal symptom severity are well known, and at least partially due to genetic variation. To identify genes contributing to variation in withdrawal severity, we chronically treated 30 strains of the AcB/BcA recombinant congenic mouse strain set, including their A/J and C57BL/6J (B6) progenitors, with morphine for seven days and compared jumping frequencies--a sensitive and widely used index of withdrawal magnitude--during naloxone-precipitated withdrawal (NPW). Jumping frequencies of B6 mice were more than threefold greater than values obtained in A/J mice. Visual inspection of the genomic distribution of parental haplotypes in the AcB/BcA strains identified a putative quantitative trait locus (QTL) localized to chromosome 8 (90-117 Mb), and this QTL was confirmed in a B6AF2 intercross. The most salient candidate gene within this QTL, Gnao1 (guanine nucleotide binding protein, alpha(o); G alpha(o); 96.3 Mb), was tested for functional relevance using quantitative PCR and an antisense oligodeoxynucleotide strategy. The expression of Gnao1 in the locus coeruleus was found to be upregulated in morphine-dependent B6 but not A/J mice. Antisense knockdown of Gnao1 reduced NPW jumping in B6, but not A/J, mice rendered dependent on either morphine or heroin, largely rescuing the original strain difference. These data strongly implicate the G alpha(o) protein in the locus coeruleus as contributing to interindividual variability in physical dependence on opioids in mice.

[Surgical and functional results of rectosigmoidal resection for severe endometriosis]

OBJECTIVES

Indications of colorectal resection for endometriosis are controversial because of the risk of major complications. This study aims to evaluate the value of different diagnostic tests in decision-making, and to evaluate the surgical results and complications, as well as long-term functional results after surgery.

PATIENTS AND METHODS

In the set of a retrospective case series, 50 patients who have been admitted for a colorectal resection because of deep endometriosis were included. Most of them have had an MRI and an endorectal ultrasonography. Specific questionnaires have been proposed in order to evaluate symptoms, sexuality (BISF-W) and quality of life (EHP-30).

RESULTS

For the diagnosis of rectal involvement, the sensitivity of MRI and endorectal ultrasonography were 55 and 100%, respectively. Forty-one colorectal amputations and nine partial colorectal resections have been done by 24 laparotomies, two laparoscopies and 24 laparoconversions. Major complications included six (12.5%) digestive fistulas, three (6%) anastomotic strictures, one ureterovaginal fistula and one ureteral stricture. Risk factors associated with digestive fistulas were the association of a vaginal opening (p=0.002) and an additional ileocaecal resection (p=0.007). The mean follow-up period was of 42 months. A significant improvement of dysmenorrhea (p<10(-4)), dyschesia (p<10(-4)), chronic pelvic pain (p<10(-4)), and of some digestive symptoms such as catamenial epreintes (p=0.002) and catamenial diarrheas (p=0.006), was noted. We noted postoperative 14 dysurias, six constipations and 12 rectal polykynesias. Four patients have had deep recurrent lesions. Twenty patients had a desire of pregnancy after the operation, 17 pregnancies were obtained (eight spontaneous and nine by ART) giving birth to 14 living children. Sexuality evaluation was below normal range. The quality of life was improved for most of the items. The global satisfaction was good (91%).

DISCUSSION AND CONCLUSION

Colorectal resection for deep endometriosis improve significantly most of the pain symptoms, but the women should have detailed counselling about the risks of major complications and recurrence.

Genetic determinants of emotionality and stress response in AcB/BcA recombinant congenic mice and in silico evidence of convergence with cardiovascular candidate genes

Genomic loci bearing stress-related phenotypes were dissected in recombinant congenic strains (RCS) of mice with C57BL/6J (B6) and A/J progenitors. Adult male mice from 14 A/J and 22 B6 background lines were evaluated for emotional reactivity in open-field (OF) and elevated plus-maze tests. Core temperature was monitored by radio telemetry during immobilization and on standard as well as salt-enriched diets. In addition, urinary electrolytes were measured. Genome-wide linkage analysis of the parameters revealed over 20 significant quantitative trait loci (QTL). The highest logarithm of odds (LOD) scores were within the previously-reported OF emotionality locus on Chr 1 (LOD = 4.6), in the dopa decarboxylase region on Chr 11 for the plus-maze (LOD = 4.7), and within a novel region of calmodulin 1 on Chr 12 for Ca++ excretion after a 24-h salt load (LOD = 4.6). RCS stress QTL overlapped with several candidate loci for cardiovascular (CV) disease. In silico evidence of functional polymorphisms by comparative sequence analysis of progenitor strains assisted to ascertain this convergence. The anxious BcA70 strain showed down regulation of Atp1a2 gene expression in the heart (P < 0.001) and brain (P < 0.05) compared with its parental B6 strain, compatible with the enhanced emotionality described in knock out animals for this gene, also involved in the salt-sensitive component of hypertension. Functional polymorphisms in regulatory elements of candidate genes of the CV/inflammatory/immune systems support the hypothesis of genetically-altered environmental susceptibility in CV disease development.

Genetic Control of Host-Pathogen Interactions in Mice

The onset, progression and outcome of infections are determined by performance of host defence mechanisms and expression of pathogen virulence determinants. Genetic analysis in mouse can identify host genes that play critical roles at the interface of host-pathogen interactions. Genetic effects detected as variations in susceptibility in inbred, recombinant and mutant strains of mice can be mapped as simple traits or quantitative trait loci followed by identification by positional cloning. We have used mouse models of infection with bacterial (Mycobacterium, Legionella) and parasitic pathogens (Plasmodium) to discover genes and proteins that are important for macrophage function against such infectious agents. These studies have identified Nrampl-mediated exclusion of divalent metals from the phagosomal space as a key regulator of intracellular replication of Mycobacteria. Also, intracellular sensing of Legionella by functional Birc1e/Naip5 protein is essential to prevent replication of this bacterium in macrophages. Finally, we have identified two new loci that affect blood-stage replication of Plasmodium chabaudi AS in mice, and have cloned the corresponding genes.

The AcB/BcA recombinant congenic strains of mice: strategies for phenotype dissection, mapping and cloning of quantitative trait genes

The AcB/BcA gene discovery platform consists of a series of 36 recombinant congenic strains (RCS) produced from the second backcross generation of the progenitor mouse strains A/J and C57BL/6J. Each individual inbred RCS carries 12.5% of the donor genome in 87.5% of the background genome. As the two parental strains are known to vary in the expression of resistance and susceptibility to a considerable number of mouse models of human diseases, the AcB/BcA RCS platform represents a valuable and versatile genetic tool to study many different phenotypes. RCS can be used to follow the segregation of single gene effects in individual strains, or to look at association/dissociation of mechanistic aspects of complex phenotypes. In addition, one can select strains with fixed alleles at known loci to look for novel gene effects, or use strains with overlapping congenic segments to delineate minimal QTL, intervals. The AcB/BcA RCS platform was used by our group and others to study a series of complex phenotypes including nociception, malaria susceptibility and lipid metabolism. Linkage mapping in secondary crosses and gene expression analysis in targeted organs allowed the identification of chromosomal regions, genes, and biological pathways which might unravel novel targets for preventive and therapeutic interventions.

Complex genetic control of susceptibility to malaria: positional cloning of the Char9 locus

Mouse strains AcB55 and AcB61 are resistant to malaria by virtue of a mutation in erythrocyte pyruvate kinase (Pklr^I90N). Linkage analysis in [AcB55 × A/J] F2 mice detected a second locus (Char9; logarithm of odds = 4.74) that regulates the blood-stage replication of Plasmodium chabaudi AS independently of Pklr. We characterized the 77 genes of the Char9 locus for tissue-specific expression, strain-specific alterations in gene expression, and polymorphic variants that are possibly associated with differential susceptibility. We identified Vnn1/Vnn3 as the likely candidates responsible for Char9. Vnn3/Vnn1 map within a conserved haplotype block and show expression levels that are strictly cis-regulated by this haplotype. The absence of Vnn messenger RNA expression and lack of pantetheinase protein activity in tissues are associated with susceptibility to malaria and are linked to a complex rearrangement in the Vnn3 promoter region. The A/J strain also carries a unique nonsense mutation that leads to a truncated protein. Vanin genes code for a pantetheinase involved in the production of cysteamine, a key regulator of host responses to inflammatory stimuli. Administration of cystamine in vivo partially corrects susceptibility to malaria in A/J mice, as measured by reduced blood parasitemia and decreased mortality. These studies suggest that pantetheinase is critical for the host response to malaria.

Host genetics of mycobacterial diseases in mice and men: forward genetic studies of BCG-osis and tuberculosis

In humans, genetic factors have long been suspected to contribute to the onset and outcome of tuberculosis. Such effects are difficult to identify owing to their complex inheritance, and to the confounding impact of environmental factors, notably pathogen-associated virulence determinants. Recently, forward genetic approaches in mouse models and in human populations have been used to elucidate a molecular basis for predisposition to mycobacterial diseases. The genetic dissection of host predisposition to infection with Mycobacterium bovis BCG and M. tuberculosis will help to define the key molecules involved in host antituberculous immunity and should provide new insights into this important infectious disease.