Beer spoilage and low pH tolerance is linked to manganese homeostasis in selected Lactobacillus brevis strains.

AIMS: Beer is a harsh medium for bacteria to survive, however, lactic acid bacteria including Lactobacillus brevis have evolved the ability to grow in beer. Here, the influence of environmental factors such as low pH, ethanol or hop content was assessed. METHODS AND RESULTS: A transcriptomic analysis of two Lact. brevis beer-spoiling strains was performed comparing growth in nutritive media with or without the imposition of a stressor related to the beer environment. This allowed the identification of a manganese transporter encoding gene that contributes to low pH tolerance. CONCLUSIONS: We report on the importance of a manganese transporter associated with pH tolerance and beer spoilage in Lact. brevis. The importance of manganese for Lact. brevis growth in a low pH environment was highlighted. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacterial spoilage of beer may result in product withdrawal with concomitant economic losses for the brewing industry. A limited number of genes involved in beer spoilage have been identified but none of them are universal. It is clear that other molecular players are involved in beer spoilage. The study highlights the complexity of the genetic requirements to facilitate beer spoilage and the role of multiple key players in this process.

Barriers and enablers in the implementation of a standardised process for nutrition care: findings from a multinational survey of dietetic professionals in 10 countries.

BACKGROUND: To explore the barriers and enablers experienced by nutrition and dietetic professionals in the implementation of the standardised Nutrition Care Process (NCP) across 10 different countries. NCP related beliefs, motivations and values were investigated and compared. METHODS: A validated online survey was disseminated to nutrition and dietetics professionals in 10 countries in the local language during 2017. Cross-sectional associations and differences between countries were explored for level of implementation, barriers/enablers and attitudes/motivation among the respondents. RESULTS: Higher NCP implementation was associated with greater occurrence of enabling aspects, as well as fewer occurrences of barriers. The most common enabler was 'recommendation by the national dietetic association' (69%) and the most common barrier was 'lack of time' (39%). A longer experience of NCP use was associated with a more positive attitude towards all NCP aspects. Differences between countries were identified, regarding both the occurrence of barriers/enablers and attitudes/motivations. CONCLUSIONS: Implementation efforts need to be tailored to country-specific contexts when implementing a new standard of care framework among nutrition and dietetic professionals. Additional research is needed to further assess the management and workplace strategies to support the development of nutrition and dietetics professionals in multidisciplinary healthcare organisations.

Development of an Insulin-Prescribing Chart for Paediatric Diabetes

Aim Our aim was to design a new insulin prescribing tool in compliance with the Irish Medicines Safety Network recommendations. Methods In 2015, we undertook a review of the existing paediatric subcutaneous insulin-prescribing sheet introduced to Cork University Hospital in 2013. This involved a retrospective analysis of 15 consecutive in-patient insulin prescribing charts and a questionnaire distributed to health professionals. Following this a new insulin prescribing chart was designed and implemented in 2016 and a re-audit was performed in 2017. Results The 2017 re-audit demonstrated that the new insulin chart was viewed as easier (95% of previous users n=18) and safer (n=16) to use. There was less confusion (2017: 28%, n=11/39 vs 2015: 50%, n=17/34 2015) and the ALERT system helped staff standardise hypo/hyperglycaemia management (71%, n=28). Conclusion The new paediatric insulin prescribing chart has improved safety and ease of prescribing insulin. The colour coded quasi graph and ALERT system has made it easier to appreciate capillary blood glucose trends and manage them safely.

Diffuse optical spectroscopic imaging of subcutaneous adipose tissue metabolic changes during weight loss.

BACKGROUND: Changes in subcutaneous adipose tissue (AT) structure and metabolism have been shown to correlate with the development of obesity and related metabolic disorders. Measurements of AT physiology could provide new insight into metabolic disease progression and response to therapy. An emerging functional imaging technology, diffuse optical spectroscopic imaging (DOSI), was used to obtain quantitative measures of near infrared (NIR) AT optical and physiological properties. METHODS: Ten overweight or obese adults were assessed during 3 months on calorie-restricted diets. DOSI-derived tissue concentrations of hemoglobin, water and lipid and the wavelength-dependent scattering amplitude (A) and slope (b) obtained from 30 abdominal locations and three time points (T0, T6, T12) were calculated and analyzed using linear mixed-effects models and were also used to form 3D surface images. RESULTS: Subjects lost a mean of 11.7±3.4% of starting weight, while significant changes in A (+0.23±0.04 mm(-1), adj. P<0.001),b (-0.17±0.04, adj. P<0.001), tissue water fraction (+7.2±1.1%, adj. P<0.001) and deoxyhemoglobin (1.1±0.3 µM, adj. P<0.001) were observed using mixed-effect model analysis. DISCUSSION: Optical scattering signals reveal alterations in tissue structure that possibly correlate with reductions in adipose cell volume, while water and hemoglobin dynamics suggest improved AT perfusion and oxygen extraction. These results suggest that DOSI measurements of NIR optical and physiological properties could be used to enhance understanding of the role of AT in metabolic disorders and provide new strategies for diagnostic monitoring of obesity and weight loss.

Evolutionary etiology of high-grade astrocytomas.

Glioblastoma (GBM), the most common brain malignancy, remains fatal with no effective treatment. Analyses of common aberrations in GBM suggest major regulatory pathways associated with disease etiology. However, 90% of GBMs are diagnosed at an advanced stage (primary GBMs), providing no access to early disease stages for assessing disease progression events. As such, both understanding of disease mechanisms and the development of biomarkers and therapeutics for effective disease management are limited. Here, we describe an adult-inducible astrocyte-specific system in genetically engineered mice that queries causation in disease evolution of regulatory networks perturbed in human GBM. Events yielding disease, both engineered and spontaneous, indicate ordered grade-specific perturbations that yield high-grade astrocytomas (anaplastic astrocytomas and GBMs). Impaired retinoblastoma protein RB tumor suppression yields grade II histopathology. Additional activation of v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) network drives progression to grade III disease, and further inactivation of phosphatase and tensin homolog (PTEN) yields GBM. Spontaneous missense mutation of tumor suppressor Trp53 arises subsequent to KRAS activation, but before grade III progression. The stochastic appearance of mutations identical to those observed in humans, particularly the same spectrum of p53 amino acid changes, supports the validity of engineered lesions and the ensuing interpretations of etiology. Absence of isocitrate dehydrogenase 1 (IDH1) mutation, asymptomatic low grade disease, and rapid emergence of GBM combined with a mesenchymal transcriptome signature reflect characteristics of primary GBM and provide insight into causal relationships.

Dairy product consumption, dietary nutrient and energy density and associations with obesity in Australian adolescents.

BACKGROUND: Dairy intake is likely to influence dietary energy density (ED) and nutrient density (ND), which are factors representing aspects of dietary quality. Although evidence suggests dairy intake is unlikely to contribute to obesity, intake tends to decrease over adolescence, potentially as a result of concerns around weight gain. We examined associations between dairy intake, ED and ND, and investigated relationships with obesity in adolescents. METHODS: The present study comprised a cross-sectional study of 1613 14-year-olds in the Western Australian Pregnancy Cohort (Raine) Study. Adolescents completed a 212-item food frequency questionnaire. Nutrient Rich Food index 9.3 (NRF9.3) was used to estimate ND. Age-specific body mass index (BMI) and waist-height cut-offs were used to categorise obesity risk. RESULTS: Mean (SD) dairy intake was: 2.62 (1.51) servings daily; ED was 4.53 (0.83) (food and beverage) and 6.28 (1.33) (food only); ND was 373 (109). Dairy intake was inversely associated with ED and positively associated with ND. The odds of being overweight (as assessed by BMI) increased by 1.24 (95% confidence interval = 1.09-1.42) with each 100-point increase in ND, after adjustment for potential confounders and energy intake. ED measures and dairy intake were inversely associated with obesity after adjustment for confounders; associations became nonsignificant after energy adjustment. CONCLUSIONS: The NRF9.3 was originally designed to assess foods, not diets. Further research in other cohorts to determine whether similar findings exist, or investigations into alternate measures of dietary ND, may prove useful. Our findings may be the result of factors such as an excess consumption of refined but fortified foods. Although higher dairy intakes were associated with higher ND, intakes were not associated with higher obesity risk.

Spatiotemporal modulation of growth factors directs the generation of multilineage mouse embryonic stem cell-derived mammary organoids.

Ectodermal appendages, such as the mammary gland (MG), are thought to have evolved from hair-associated apocrine glands to serve the function of milk secretion. Through the directed differentiation of mouse embryonic stem cells (mESCs), here, we report the generation of multilineage ESC-derived mammary organoids (MEMOs). We adapted the skin organoid model, inducing the dermal mesenchyme to transform into mammary-specific mesenchyme via the sequential activation of Bone Morphogenetic Protein 4 (BMP4) and Parathyroid Hormone-related Protein (PTHrP) and inhibition of hedgehog (HH) signaling. Using single-cell RNA sequencing, we identified gene expression profiles that demonstrate the presence of mammary-specific epithelial cells, fibroblasts, and adipocytes. MEMOs undergo ductal morphogenesis in Matrigel and can reconstitute the MG in vivo. Further, we demonstrate that the loss of function in placode regulators LEF1 and TBX3 in mESCs results in impaired skin and MEMO generation. In summary, our MEMO model is a robust tool for studying the development of ectodermal appendages, and it provides a foundation for regenerative medicine and disease modeling.

The itchy locus encodes a novel ubiquitin protein ligase that is disrupted in a18H mice.

Non-agouti-lethal 18H (a18H) mice are dark agouti with black pinna hairs. What makes these mice unique is that they develop a spectrum of immunological diseases not seen in other agouti mutant mice. On the JU/Ct background, a18H mice develop an inflammatory disease of the large intestine. On the C57BL/6J background, they develop a fatal disease characterized by pulmonary chronic interstitial inflammation and alveolar proteinosis, inflammation of the glandular stomach and skin resulting in scarring due to constant itching, and hyperplasia of lymphoid cells, haematopoietic cells and the forestomach epithelium. Previous studies suggested that the a18H mutation results from a paracentric inversion that affects two loci: agouti and another, as yet unidentified locus designated itchy (the provisional gene symbol is Itch), that is responsible for the immunological phenotype of a18H mice. Here we confirm that a18H results from an inversion and show that Itch encodes a novel E3 ubiquitin protein ligase, a protein involved in ubiquitin-mediated protein degradation. Our results indicate that ubiquitin-dependent proteolysis is an important mediator of the immune response in vivo and provide evidence for Itch's role in inflammation and the regulation of epithelial and haematopoietic cell growth.

Ru2 and Ru encode mouse orthologs of the genes mutated in human Hermansky-Pudlak syndrome types 5 and 6.

Hermansky-Pudlak syndrome (HPS) is a genetically heterogeneous disease involving abnormalities of melanosomes, platelet dense granules and lysosomes. Here we have used positional candidate and transgenic rescue approaches to identify the genes mutated in ruby-eye 2 and ruby-eye mice (ru2 and ru, respectively), two 'mimic' mouse models of HPS. We also show that these genes are orthologs of the genes mutated in individuals with HPS types 5 and 6, respectively, and that their protein products directly interact. Both genes are previously unknown and are found only in higher eukaryotes, and together represent a new class of genes that have evolved in higher organisms to govern the synthesis of highly specialized lysosome-related organelles.

A descriptive study of weaned piglet transport practices in Alberta, Ontario, and Saskatchewan, Canada between 2014 and 2018.

Canadian transport practices for shipments of newly weaned piglets are not well-described despite documentation requirements for those conducting the movement of these animals. The objective of this study was to describe the characteristics of weaned piglet transport events that occurred between 2014 and 2018 using records provided by five Canadian swine companies. Following cleaning and validation, the dataset included records from 6203 transport events involving the transport of approximately 6.9 million piglets (5.7 kg, 4.1-7.9 kg) from 62 origin sites in Alberta, Ontario, or Saskatchewan, Canada. This represents approximately 4.7% of the piglets estimated to have been weaned in Canada between 2014 and 2018, and 1.7% of sow farms in Canada according to 2016 National census data. Most transport events ended at farms in Canada (71.3%), while the remaining delivered piglets to one of eight American states. The predominant trailer types used were Straightdeck (51.4%) and Potbelly (36.6%), but this did not reflect the number of piglets transported as Potbelly trailers have greater load capacity. Transport events most frequently involved loading piglets from one origin barn and delivering them to a single destination barn (78.1%). Only transport events involving export to the United States picked up piglets from, or delivered them to, more than one farm site. Most transport events had very short trip distances (median distance: 48.0 km; IQR: 497.0), but a marked range was observed (1.8-2931.2 km). Average daily temperature data matched to the transport records by origin and destination location demonstrated ambient environmental conditions during these transport events ranged from - 30.3-28.7 °C. Overall, less than 10% of transport events had mortality occur. Comparable with other observational studies documenting weaned piglet mortality, the average in-transit mortality rate observed over the multiple seasons, companies, trip distances, and other characteristics in this dataset was 0.027%. However, instances of mortality over 1% did sporadically occur and could translate to considerable losses given the large load sizes common for piglets of this age and size (median load size: 1105 piglets; IQR: 1036 piglets). These data provide a better understanding of the interconnectedness of the Canadian swine industry as well as common transport practices which may inform future research on disease transmission in swine transport networks, or piglet welfare during transport. Additionally, variables that were not present in this dataset that would further strengthen these types of investigations are highlighted (e.g., space allowance).

Effect of season on weaned piglet mortality during transport greater than 8 h under Canadian conditions.

North American swine producers commonly transport piglets away from sow farms at weaning. However, limited information on factors associated with piglet mortality during these transports is available. The objectives of this study were to identify transport characteristics that were associated with the occurrence of in-transit mortality (≥1 piglet found dead on arrival) and/or associated with increased rates of in-transit mortality using records of weaned piglet transport voluntarily provided by Canadian swine companies. Following cleaning and validation, records of 810 long duration (>8 h to <28 h) weaned piglet (min.: 4.2, max.: 7.7 kg) transports conducted between 2016 and 2017 by four companies were available to investigate risk factors for the occurrence of in-transit mortality. Transports originated in Ontario, Saskatchewan, or Alberta and 30% of transports had one or more mortality events recorded. Season of transport was significant in the final logistic regression model; the odds of a transport having mortality occur was greater during the winter (December, January, February) compared to the spring (March, April, May) (OR=1.8; 95% CI: 1.13-2.96; P = 0.013), summer (June, July, August) (OR= 2.1; 95% CI: 1.28-3.34; P = 0.003) and fall (September, October, November) (OR=2.2; 95% CI: 1.36-3.62; P = 0.001), with no differences observed between the other seasons. Additionally, records from 755 long duration weaned piglet (min.: 4.2, max.: 7.9 kg) transports conducted between 2014 and 2017 by a single company was used to identify risk factors for increased rates of in-transit mortality. Transports originated in Saskatchewan or Alberta and 44.9% of transports had one or more mortality events recorded with in-transit mortality rates ranging from 0.00% to 6.16%. Season of transport was again significant in the final negative binomial regression model. The rate of piglet death in-transit was increased in all seasons compared to the summer with winter transport having the highest predicted rate of in-transit mortality. Transports conducted during the winter had a rate of in-transit mortality nearly five times greater compared to transports conducted during the summer (IRR= 4.94; 95% CI: 3.11-7.87; P = 0.000) and approximately three times greater compared to transports conducted during the fall (IRR=2.7; 95% CI: 1.73-4.30; P = 0.000) and spring (IRR=3.1; 95% CI: 1.96-4.99; P = 0.000). These results suggest that winter transport in Western Canada is an area of opportunity to reduce in-transit mortality during long duration weaned piglet transport. Research investigating transport practices that may mitigate the effects of extreme cold (e.g., space allowance, bedding provision) would be useful for informing specific recommendations for this age group.

Abrogation of Rb Tumor Suppression Initiates GBM in Differentiated Astrocytes by Driving a Progenitor Cell Program.

Glioblastoma (GBM) remains lethal with no effective treatments. Despite the comprehensive identification of commonly perturbed molecular pathways, little is known about the disease's etiology, particularly in early stages. Several studies indicate that GBM is initiated in neural progenitor and/or stem cells. Here, we report that differentiated astrocytes are susceptible to GBM development when initiated by perturbation of the RB pathway, which induces a progenitor phenotype. In vitro and in vivo inactivation of Rb tumor suppression (TS) induces cortical astrocytes to proliferate rapidly, express progenitor markers, repress differentiation markers, and form self-renewing neurospheres that are susceptible to multi-lineage differentiation. This phenotype is sufficient to cause grade II astrocytomas which stochastically progress to GBM. Together with previous findings, these results demonstrate that cell susceptibility to GBM depends on the initiating driver.

Recent advances in the transesterification of ß-keto esters.

The ability to selectively transesterify ß-keto esters is a useful transformation in organic synthesis. The increasing interest in transesterification for the synthesis of compounds of pharmaceutical importance, as well as for biodiesel production, has led to the development of a variety of different approaches. This article aims to summarise recent advances in the transesterifications of ß-keto esters. Particular interest has been paid to methodologies with minimal environmental impact.

Novel Humanized Mesothelin-Expressing Genetically Engineered Mouse Models Underscore Challenges in Delivery of Complex Therapeutics to Pancreatic Cancers.

Antibody-based therapies designed for human use frequently fail to cross-react with the murine isoform of their target. Because of this problem, preclinical studies of antibody-based mesothelin (Msl)-targeted therapeutics in immunocompetent systems have been limited by the lack of suitable mouse models. Here, we describe two immunocompetent humanized mesothelin transgenic mouse lines that can act as tolerant hosts for C57Bl/6-syngeneic cell lines expressing the human isoform of mesothelin. Thyroid peroxidase (TPO) mice have thyroid-restricted human mesothelin expression. Mesothelin (Msl) mice express human mesothelin in the typical serosal membrane distribution and can additionally be utilized to assess on-target, off-tumor toxicity of human mesothelin-targeted therapeutics. Both transgenic strains shed human mesothelin into the serum like human mesothelioma and patients with ovarian cancer, and serum human mesothelin can be used as a blood-based surrogate of tumor burden. Using these models, we examined the on-target toxicity and antitumor activity of human mesothelin-targeted recombinant immunotoxins. We found that immunotoxin treatment causes acute and chronic histologic changes to serosal membranes in Msl mice, while human mesothelin-expressing thyroid follicular cells in TPO mice are resistant to immunotoxin despite excellent drug delivery. Furthermore, poor delivery of immunotoxin to syngeneic orthotopic human mesothelin-expressing pancreatic adenocarcinoma limits antitumor activity both alone and in combination with immune checkpoint inhibition. In summary, we have developed two high-fidelity, immunocompetent murine models for human cancer that allow for rigorous preclinical evaluation of human mesothelin-targeted therapeutics.

Dietary glycaemic carbohydrate in relation to the metabolic syndrome in adolescents: comparison of different metabolic syndrome definitions.

AIMS: High dietary glycaemic carbohydrate, as measured by the dietary glycaemic index and glycaemic load has been associated with increased risk of the metabolic syndrome in adults, but limited research exists for younger populations. We aimed to evaluate associations between dietary glycaemic carbohydrate and insulin resistance or the prevalence of the metabolic syndrome defined by three different criteria in a population-based adolescent cohort. METHODS: Diet was assessed using 3 day food records in 769 adolescents aged 13-15 years participating in the Western Australian Pregnancy Cohort (Raine) Study. The metabolic syndrome was identified using age-specific adolescent definitions from the International Diabetes Federation, the National Cholesterol Education Program Adult Treatment Panel III and a population-derived 'high-risk' metabolic cluster algorithm. Presence of a high waist circumference was mandatory only in the International Diabetes Federation definition. Insulin resistance was measured using homeostasis model assessment (HOMA-IR). RESULTS: The prevalence of the metabolic syndrome as defined by the International Diabetes Federation and the Adult Treatment Panel III was 3.6 and 4.0%, respectively; 25.9% of subjects were classified into the high-risk cluster. Significantly increased odds of International Diabetes Federation-defined metabolic syndrome were independently associated with a 20 unit glycaemic load increase (odds ratio 2.18; 95% confidence interval 1.26-3.78) and a 30 g carbohydrate increase (odds ratio 3.86; 95% confidence interval 1.80-8.28). No significant associations were observed when using the Adult Treatment Panel III, or the cluster-defined metabolic syndrome, or with HOMA-IR. CONCLUSIONS: This study supports the concept that high dietary glycaemic carbohydrate is associated with a higher prevalence of the metabolic syndrome in adolescents. However, relationships vary according to the definition of the metabolic syndrome used, with waist circumference a potentially relevant factor.

Dietary patterns and markers for the metabolic syndrome in Australian adolescents.

BACKGROUND AND AIMS: Overweight and other risk factors for cardiovascular disease (CVD) as well as their clustering, are increasingly prevalent among adolescents. We examined dietary patterns, CVD risk factors, and the clustering of these risk factors in 1139 14-year-olds living in Western Australia. METHODS AND RESULTS: Usual dietary intake was assessed using a food frequency questionnaire. Two dietary patterns, 'Western' and 'Healthy', were identified using factor analysis. Associations between these dietary patterns and BMI, waist circumference, systolic blood pressure, fasting levels of serum glucose, insulin, total cholesterol, HDL-C, LDL-C, triglycerides and insulin resistance were assessed using ANOVA. Cluster analysis identified a high risk group (the 'high risk metabolic cluster') with features akin to adult metabolic syndrome. Belonging to the 'high risk metabolic cluster' was examined in relation to dietary patterns using logistic regression, adjusting for aerobic fitness and socio-demographic factors. Higher 'Western' dietary pattern scores were associated with greater odds for the 'high risk metabolic cluster' (p for trend=0.02) and greater mean values for total cholesterol (p for trend=0.03), waist circumference (p for trend=0.03) and BMI (p for trend=0.02) in girls, but not boys. Scores for the 'Healthy' dietary pattern were not related to the 'high risk metabolic cluster' but were inversely associated with serum glucose in boys and girls (p for trend=0.01 and 0.04, respectively) and were positively associated with HDL-C in boys (p for trend=0.02). CONCLUSIONS: Dietary patterns are associated with CVD risk factors and the clustering of these risk factors in adolescence.

Risk factors for duration of equine rhinitis A virus respiratory disease.

BACKGROUND: Infectious respiratory disease is common in young horses and can impact athletic performance and long-term health. Significant variation in the duration of clinical disease has been observed, even in the absence of secondary complications. The determination of factors associated with disease chronicity may facilitate clinical decision-making and the development of improved biosecurity protocols. OBJECTIVE: To investigate contact network characteristics, and demographic variables associated with time to clinical recovery from Equine Rhinitis A virus respiratory disease. STUDY DESIGN: Prospective cohort study. METHODS: Yearling Standardbred racehorses (n = 58) housed in a multi-barn training facility in Southern Ontario were included. Horses were monitored daily for clinical signs of acute respiratory disease over a 41-day period in Autumn 2017. Contact patterns between horses, including older racehorses, were determined through use of proximity loggers attached to halters during the initial 7-day of the study. Associations between duration of disease, demographic factors (birth month, gait, sex and yearling sale), serologic titres and network metrics (degree, betweenness and Eigenvector centrality) were investigated using a Cox proportional hazard model. RESULTS: Yearling attack rate for infectious respiratory disease was 87.9% (n = 51). Median time to recovery was 6 days (IQR = 1-32) and 17 horses were censored due to early withdrawal or failure to recover during the study period. In those yearlings born February-May, birth month was significant in the Cox proportional hazard model (Hazard Ratio 0.7, 95% CI 0.49-1, P = 0.05). MAIN LIMITATION: Probability of censoring was not independent of outcome which necessitated use of sensitivity analysis. CONCLUSIONS: These findings suggest late born foals are less likely to recover quickly from infectious respiratory disease.

Rapid Communication: Postmortem lesions and heart weights of in-transit-loss market pigs in Ontario.

In-transit losses (ITL) of market-weight pigs are defined as pigs that die or pigs that become nonambulatory during loading and shipping from the farm to the abattoir. The low proportion of ITL in market pigs implies that individual pig factors may influence ITL, in addition to commonly considered environmental or transport factors. Postmortem examinations of in-transit-loss pigs ( = 85) from 1 Ontario, Canada, abattoir indicated the cause of death to be acute heart failure as a result of cardiac lesions that developed prior to transport. The presence of preexisting cardiac lesions may explain why no or only a few pigs die in a trailer even when the entire load is exposed to extreme temperatures and other common transport risk factors.

RB inactivation in keratin 18 positive thymic epithelial cells promotes non-cell autonomous T cell hyperproliferation in genetically engineered mice.

Thymic epithelial cells (TEC), as part of thymic stroma, provide essential growth factors/cytokines and self-antigens to support T cell development and selection. Deletion of Rb family proteins in adult thymic stroma leads to T cell hyperplasia in vivo. To determine whether deletion of Rb specifically in keratin (K) 18 positive TEC was sufficient for thymocyte hyperplasia, we conditionally inactivated Rb and its family members p107 and p130 in K18+ TEC in genetically engineered mice (TgK18GT121; K18 mice). We found that thymocyte hyperproliferation was induced in mice with Rb inactivation in K18+ TEC, while normal T cell development was maintained; suggesting that inactivation of Rb specifically in K18+ TEC was sufficient and responsible for the phenotype. Transplantation of wild type bone marrow cells into mice with Rb inactivation in K18+ TEC resulted in donor T lymphocyte hyperplasia confirming the non-cell autonomous requirement for Rb proteins in K18+ TEC in regulating T cell proliferation. Our data suggests that thymic epithelial cells play an important role in regulating lymphoid proliferation and thymus size.

Development rationale for an articular surface replacement: a science-based evolution.

Hip resurfacing has an enduring appeal because of the advantages of bone conservation and maximal joint stability. However, a far from satisfactory experience with earlier resurfacing designs led to its virtual disappearance in the 1980s. The concept was reintroduced in the late 1990s. The current generation of resurfacing devices generally consisted of a large-diameter metal-on-metal articulation, the femoral components being cemented and the acetabular components utilizing various forms of cementless fixation. The encouraging medium-term results, with a follow-up of up to 8 years using the current generation of surface replacement joints, combined with favourable reports related to long-term performance of some metal bearings have led to a rapid increase in the use of such components with these devices. This trend is most marked in younger, more active patients who have expectations of restoration of lifestyle in addition to improved mobility and pain relief and in whom failure with conventional total hip replacement is much higher than previously reported with more sedentary patients. The aim of this paper is, firstly, to highlight a number of areas of improvement and, secondly, to explain how these may be addressed by making modifications to the design of both implants and instrumentation and to the surgical technique. The areas identified for improvement were tissue preservation (thinner components, and reduced steps between sizes), acetabular cup issues (fixation, insertion, and positioning), femoral component issues (design, loading, and cementation), improved bearing surface characteristics, and simplified precise instrumentation with a low-trauma surgical technique.