"Teaching capital"- a sociological analysis of medical educator portfolios for promotion.

Medical educator portfolios (MEP) are increasingly recognized as a tool for developing and documenting teaching performance in Health Professions Education. However, there is a need to better understand the complex interplay between institutional guidelines and how teachers decode those guidelines and assign value to teaching merits. To gain a deeper understanding of this dynamic, this study employed a sociological analysis to understand how medical educators aspiring to professorships use MEPs to display their teaching merits and how cultural capital is reflected in these artefacts. We collected 36 medical educator portfolios for promotion from a large research-intensive university and conducted a deductive content analysis using institutional guidelines that distinguished between mandatory (accounting for the total body of teaching conducted) and optional content (arguing for pedagogical choices and evidencing the quality, respectively). Our analysis showed that the portfolios primarily included quantifiable data about teaching activities, e.g., numbers of students, topics and classes taught. Notably, they often lacked evidence of quality and scholarship of teaching. Looking at these findings through a Bourdieusian lens revealed that teachers in this social field exchange objectified evidence of hours spent on teaching into teaching capital recognized by their institution. Our findings highlight how institutional guidelines for MEPs construct a pedagogical battlefield, where educators try to decode and exchange the "right" and recognized teaching capital. This indicates that MEPs reflect the norms and practices of the academic field more than individual teaching quality.

Multicenter Evaluation of the Simplexa VZV Direct Assay for Detection of Varicella-Zoster Virus in Cerebrospinal Fluid and Lesion-Swab Specimens.

Varicella-zoster virus (VZV) is the etiologic agent of varicella (chickenpox) and herpes zoster (shingles) infections commonly involving skin, mucous membranes, and less frequently the central nervous system. Traditional methods for the laboratory diagnosis of these infections are time-consuming, labor-intensive, and often insensitive. As such, these tests are being replaced by more sensitive and rapid molecular methods. This study evaluated the performance of two different molecular assays, the Simplexa VZV Direct and Simplexa VZV Swab Direct, to detect VZV DNA in cerebrospinal fluid (CSF) and lesion-swab specimens, respectively. The Simplexa VZV Direct and Simplexa VZV Swab Direct assays were compared against individual composite reference methods that varied depending on the sample cohort examined. A total of 883 CSF and 452 cutaneous and mucocutaneous prospective, retrospective, and contrived specimens were evaluated in this multicenter study. The results of this study showed that the Simplexa assays demonstrated near perfect agreement (k = 0.98) compared to the composite reference methods for the detection of VZV in CSF and lesion swab specimens. A further comparison between the standard of care molecular assays employed at the site of specimen collection and the Simplexa assays demonstrated excellent agreement (k = 1.0). The Simplexa assays offer rapid and reliable alternatives for the detection of VZV in certain clinical specimens without the need for nucleic acid extraction.

Cytokine levels in children and adults with wheezing and asthma show specific patterns of variability over time.

Levels of cytokines are used for in-depth characterization of patients with asthma; however, the variability over time might be a critical confounder. To analyze the course of serum cytokines in children, adolescents and adults with asthma and in healthy controls and to propose statistical methods to control for seasonal effects. Of 532 screened subjects, 514 (91·5%) were included in the All Age Asthma Cohort (ALLIANCE). The cohort included 279 children with either recurrent wheezing bronchitis (more than two episodes) or doctor-diagnosed asthma, 75 healthy controls, 150 adult asthmatics and 31 adult healthy controls. Blood samples were collected and 25 µl serum was used for analysis with the Bio-Plex Pr human cytokine 27-Plex assay. Mean age, body mass index and gender in the three groups of wheezers, asthmatic children and adult asthmatics were comparable to healthy controls. Wheezers (34·5%), asthmatic children (78·7%) and adult asthmatics (62·8%) were significantly more often sensitized compared to controls (4·5, 22 and 22·6%, respectively). Considering the entire cohort, interleukin (IL)-1ra, IL-4, IL-9, IL-17, macrophage inflammatory protein (MIP)-1- α and tumor necrosis factor (TNF)- α showed seasonal variability, whereas IL-1ß, IL-7, IL-8, IL-13, eotaxin, granulocyte colony-stimulating factor (G-CSF), interferon gamma-induced protein (IP)-10, MIP-1 ß and platelet-derived growth factor (PDGF)-BB did not. Significant differences between wheezers/asthmatics and healthy controls were observed for IL-17 and PDGF-BB, which remained stable after adjustment for the seasonality of IL-17. Seasonality has a significant impact on serum cytokine levels in patients with asthma. Because endotyping has achieved clinical importance to guide individualized patient-tailored therapy, it is important to account for seasonal effects.

Multiple breath washout in pediatric patients after lung transplantation.

Forced expiratory volume in 1 second (FEV1 ) from spirometry is the most commonly used parameter to detect early allograft dysfunction after lung transplantation (LTx). There are concerns regarding its sensitivity. Nitrogen-multiple breath washout (N2 -MBW) is sensitive at detecting early global (lung clearance index [LCI]) and acinar (Sacin ) airway inhomogeneity. We investigated whether N2 -MBW indices indicate small airways pathology after LTx in children with stable spirometry. Thirty-seven children without bronchiolitis obliterans syndrome [BOS] at a median of 1.6 (0.6-3.0) years after LTx underwent N2 -MBW and spirometry, 28 of those on 2 occasions (≤6 months apart) during clinically stable periods. Additional longitudinal data (11 and 8 measurements, respectively) are provided from 2 patients with BOS. In patients without BOS, LCI and Sacin were significantly elevated compared with healthy controls. LCI was abnormal at the 2 test occasions in 81% and 71% of patients, respectively, compared with 30% and 39% of patients with abnormal FEV1 /forced vital capacity (FVC). Correlations of LCI with FEV1 /FVC (r = 0.1, P = .4) and FEV1 (r = -0.1, P = .6) were poor. N2 -MBW represents a sensitive and reproducible tool for the early detection of airways pathology in stable transplant recipients. Moreover, indices were highly elevated in both patients with BOS. Spirometry and LCI showed poor correlation, indicating distinct and complementary physiologic measures.

Blastocyst-induced changes in the bovine endometrial transcriptome.

The objectives of this study were (i) to determine whether blastocyst-induced responses in endometrial explants were detectable after 6- or 24-h co-culture in vitro; (ii) to test if direct contact is required between embryos and the endometrial surface in order to stimulate endometrial gene expression; (iii) to establish the number of blastocysts required to elicit a detectable endometrial response; (iv) to investigate if upregulation of five interferon-stimulated genes (ISGs) in the endometrium was specific to the blastocyst stage and (v) to test if alterations in endometrial gene expression can be induced by blastocyst-conditioned medium. Exposure of endometrial explants to Day 8 blastocysts in vitro for 6 or 24 h induced the expression of ISGs (MX1, MX2, OAS1, ISG15, RSAD2); expression of IFNAR1, IFNAR2, NFKB1, IL1B, STAT1, LGALS3BP, LGALS9, HPGD, PTGES, ITGB1, AKR1C4, AMD1 and AQP4 was not affected. Culture of explants in the presence of more than five blastocysts was sufficient to induce the effect, with maximum expression of ISGs occurring in the presence of 20 blastocysts. This effect was exclusive to blastocyst stage embryos; oocytes, 2-cell embryos or Day 5 morulae did not alter the relative abundance of any of the transcripts examined. Direct contact between blastocysts and the endometrial surface was not required in order to alter the abundance of these transcripts and blastocyst-conditioned medium alone was sufficient to stimulate a response. Results support the notion that local embryo-maternal interaction may occur as early as Day 8 of pregnancy in cattle.

Pre- and post-puberty expression of genes and proteins in the uterus of Bos indicus heifers: the luteal phase effect post-puberty.

Progesterone signaling and uterine function are crucial in terms of pregnancy establishment. To investigate how the uterine tissue and its secretion changes in relation to puberty, we sampled tissue and uterine fluid from six pre- and six post-pubertal Brahman heifers. Post-pubertal heifers were sampled in the luteal phase. Gene expression of the uterine tissue was investigated with RNA-sequencing, whereas the uterine fluid was used for protein profiling with mass spectrometry. A total of 4034 genes were differentially expressed (DE) at a nominal P-value of 0.05, and 26 genes were significantly DE after Bonferroni correction (P < 3.1 × 10-6 ). We also identified 79 proteins (out of 230 proteins) that were DE (P < 1 × 10-5 ) in the uterine fluid. When we compared proteomics and transcriptome results, four DE proteins were identified as being encoded by DE genes: OVGP1, GRP, CAP1 and HBA. Except for CAP1, the other three had lower expression post-puberty. The function of these four genes hypothetically related to preparation of the uterus for a potential pregnancy is discussed in the context of puberty. All DE genes and proteins were also used in pathway and ontology enrichment analyses to investigate overall function. The DE genes were enriched for terms related to ribosomal activity. Transcription factors that were deemed key regulators of DE genes are also reported. Transcription factors ZNF567, ZNF775, RELA, PIAS2, LHX4, SOX2, MEF2C, ZNF354C, HMG20A, TCF7L2, ZNF420, HIC1, GTF3A and two novel genes had the highest regulatory impact factor scores. These data can help to understand how puberty influences uterine function.

Investigation of in vitro measurable sperm attributes and their influence on electroejaculated bull semen with a fixed-time artificial insemination protocol in Australian Bos indicus cattle.

Increasing use of fixed-time artificial insemination (FTAI) in beef cattle production has presented an opportunity for the use of fresh or chilled semen as an alternative to standard cryopreserved semen. The objective of this study was to examine in vitro sperm function and pregnancy rate of electroejaculated semen, chilled and stored for 48 hr, compared to conventionally cryopreserved semen with an optimized FTAI protocol in Brahman cattle. Semen from three Brahman bulls was collected, and aliquots were extended in either chilled (at 5°C) or frozen (LN2 ) in a Tris-egg yolk extender base with 2.4% or 7.0% glycerol, respectively. Semen samples were assessed 48 hr after collection or post-thaw and warming, for sperm motility, in vitro sperm function and fertilizing ability, and used in a FTAI programme. The overall pregnancy rates was significantly different (p < .01) after FTAI with frozen (n = 173; 53.2%) and chilled semen (n = 174; 31.6%). In contrast, the in vitro sperm assessment showed that the chilled semen had significantly faster motility (p < .05), a higher proportion of progressively motile spermatozoa (p < .05), with significantly higher proportions of acrosome intact, viable spermatozoa (p < .01). This study showed that reasonable pregnancy rates in Brahman cattle can be achieved using FTAI with chilled semen collected using electroejaculation and stored for up to 48 hr. However, improvements in semen extenders are required in consideration of semen collection method to improve the longevity of sperm fertilizing ability to significantly increase FTAI output using chilled storage of bull semen.

Robust anti-obesity and metabolic effects of a dual GLP-1/glucagon receptor peptide agonist in rodents and non-human primates.

AIMS: To characterize the pharmacology of MEDI0382, a peptide dual agonist of glucagon-like peptide-1 (GLP-1) and glucagon receptors. MATERIALS AND METHODS: MEDI0382 was evaluated in vitro for its ability to stimulate cAMP accumulation in cell lines expressing transfected recombinant or endogenous GLP-1 or glucagon receptors, to potentiate glucose-stimulated insulin secretion (GSIS) in pancreatic ß-cell lines and stimulate hepatic glucose output (HGO) by primary hepatocytes. The ability of MEDI0382 to reduce body weight and improve energy balance (i.e. food intake and energy expenditure), as well as control blood glucose, was evaluated in mouse models of obesity and healthy cynomolgus monkeys following single and repeated daily subcutaneous administration for up to 2 months. RESULTS: MEDI0382 potently activated rodent, cynomolgus and human GLP-1 and glucagon receptors and exhibited a fivefold bias for activation of GLP-1 receptor versus the glucagon receptor. MEDI0382 produced superior weight loss and comparable glucose lowering to the GLP-1 peptide analogue liraglutide when administered daily at comparable doses in DIO mice. The additional fat mass reduction elicited by MEDI0382 probably results from a glucagon receptor-mediated increase in energy expenditure, whereas food intake suppression results from activation of the GLP-1 receptor. Notably, the significant weight loss elicited by MEDI0382 in DIO mice was recapitulated in cynomolgus monkeys. CONCLUSIONS: Repeated administration of MEDI0382 elicits profound weight loss in DIO mice and non-human primates, produces robust glucose control and reduces hepatic fat content and fasting insulin and glucose levels. The balance of activities at the GLP-1 and glucagon receptors is considered to be optimal for achieving weight and glucose control in overweight or obese Type 2 diabetic patients.

Dentin Dysplasia in Notum Knockout Mice.

Secreted WNT proteins control cell differentiation and proliferation in many tissues, and NOTUM is a secreted enzyme that modulates WNT morphogens by removing a palmitoleoylate moiety that is essential for their activity. To better understand the role this enzyme in development, the authors produced NOTUM-deficient mice by targeted insertional disruption of the Notum gene. The authors discovered a critical role for NOTUM in dentin morphogenesis suggesting that increased WNT activity can disrupt odontoblast differentiation and orientation in both incisor and molar teeth. Although molars in Notum(-/-) mice had normal-shaped crowns and normal mantle dentin, the defective crown dentin resulted in enamel prone to fracture during mastication and made teeth more susceptible to endodontal inflammation and necrosis. The dentin dysplasia and short roots contributed to tooth hypermobility and to the spread of periodontal inflammation, which often progressed to periapical abscess formation. The additional incidental finding of renal agenesis in some Notum (-/-) mice indicated that NOTUM also has a role in kidney development, with undiagnosed bilateral renal agenesis most likely responsible for the observed decreased perinatal viability of Notum(-/-) mice. The findings support a significant role for NOTUM in modulating WNT signaling pathways that have pleiotropic effects on tooth and kidney development.

Nephronophthisis and retinal degeneration in tmem218-/- mice: a novel mouse model for Senior-Løken syndrome?

Mice deficient in TMEM218 (Tmem218(-/-) ) were generated as part of an effort to identify and validate pharmaceutically tractable targets for drug development through large-scale phenotypic screening of knockout mice. Routine diagnostics, expression analysis, histopathology, and electroretinogram analyses completed on Tmem218(-/-) mice identified a previously unknown role for TMEM218 in the development and function of the kidney and eye. The major observed phenotypes in Tmem218(-/-) mice were progressive cystic kidney disease and retinal degeneration. The renal lesions were characterized by diffuse renal cyst development with tubulointerstitial nephropathy and disruption of tubular basement membranes in essentially normal-sized kidneys. The retinal lesions were characterized by slow-onset loss of photoreceptors, which resulted in reduced electroretinogram responses. These renal and retinal lesions are most similar to those associated with nephronophthisis (NPHP) and retinitis pigmentosa in humans. At least 10% of NPHP cases present with extrarenal conditions, which most often include retinal degeneration. Senior-Løken syndrome is characterized by the concurrent development of autosomal recessive NPHP and retinitis pigmentosa. Since mutations in the known NPHP genes collectively account for only about 30% of NPHP cases, it is possible that TMEM218 could be involved in the development of similar ciliopathies in humans. In reviewing all other reported mouse models of NPHP, we suggest that Tmem218(-/-) mice could provide a useful model for elucidating the pathogenesis of cilia-associated disease in both the kidney and the retina, as well as in developing and testing novel therapeutic strategies for Senior-Løken syndrome.

Neonatal murine macrophages show enhanced chemotactic capacity upon toll-like receptor stimulation.

BACKGROUND: The neonatal surgical patient is threatened by exuberant inflammatory reactions. Neonatal macrophages are key players in this process. We investigated the ability of neonatal macrophages to initiate a local inflammatory reaction upon exposure to different bacterial or viral ligands to toll-like receptors (TLRs). METHODS: Peritoneal wash outs from neonatal (<24 h) and adult (42 days) C57BL/6J mice were gained by peritoneal lavages. In a first set of experiments, macrophages were purified and stimulated for 6 h by four different TLR ligands. mRNA was extracted for transcriptome analysis. In a second set of experiments, lipopolysaccharide was applied into peritoneal cavities. After 6 h of incubation, the cellular composition of the inflamed cavities was evaluated by cytological staining as well as chipcytometry. RESULTS: Neonatal murine peritoneal macrophages differed significantly in the expression of pro- and anti-chemotactic genes. Functional assignment of these genes revealed enhanced chemotactic potential of neonatal macrophages and was confirmed by a higher influx of pro-inflammatory cells into neonatal peritoneal cavities. CONCLUSION: Neonatal peritoneal macrophages demonstrated an enhanced chemotactic potential upon stimulation with four TLR ligands. This was associated with an increased influx of inflammatory cells to the peritoneal cavity. This might contribute to the strong inflammatory responses of neonates and preterms.

Cryptogenic organizing pneumonia in Tomm5(-/-) mice.

Almost all mitochondrial proteins are encoded in the nuclear DNA and synthesized in the cytosol as pre-proteins. There is a protein translocase located in the mitochondrial outer membrane that transports mitochondrial pre-proteins into mitochondria. The central component of this translocase of the outer mitochondrial membrane (TOMM) complex is TOMM40, and TOMM5 is one of three small subunits associated with TOMM40. Translocase of outer mitochondrial membrane 5 homolog (Tomm5(-/-)) knockout mice demonstrated an unexpected lung-specific phenotype characterized by widespread intra-alveolar fibrosis. Although TOMM5-deficient mice tested normal in a very broad range of phenotyping assays, they displayed histopathological lesions in the lung that were consistent with those reported in humans with cryptogenic organizing pneumonia (COP), which is also known as bronchiolitis obliterans organizing pneumonia (BOOP). The lesions had a patchy distribution in the lung and were characterized by the presence of intraluminal fibrogenic buds consisting of fibroblasts and myofibroblasts embedded in a loose connective tissue matrix that occupied the lumina of alveoli and alveolar ducts, with preservation of underlying alveolar architecture. In addition to macrophages, which were numerous in affected and surrounding alveoli, eosinophils comprised the most common and widespread inflammatory cell. Taken together, the findings in Tomm5(-/-) mice provide yet another example of the value of histopathology as a baseline assay in high-throughput phenotyping systems.

Increased breath naphthalene in children with asthma and wheeze of the All Age Asthma Cohort (ALLIANCE).

Exhaled breath contains numerous volatile organic compounds (VOCs) known to be related to lung disease like asthma. Its collection is non-invasive, simple to perform and therefore an attractive method for the use even in young children. We analysed breath in children of the multicenter All Age Asthma Cohort (ALLIANCE) to evaluate if 'breathomics' have the potential to phenotype patients with asthma and wheeze, and to identify extrinsic risk factors for underlying disease mechanisms. A breath sample was collected from 142 children (asthma: 51, pre-school wheezers: 55, healthy controls: 36) and analysed using gas chromatography-mass spectrometry (GC/MS). Children were diagnosed according to Global Initiative for Asthma guidelines and comprehensively examined each year over up to seven years. Forty children repeated the breath collection after 24 or 48 months. Most breath VOCs differing between groups reflect the exposome of the children. We observed lower levels of lifestyle-related VOCs and higher levels of the environmental pollutants, especially naphthalene, in children with asthma or wheeze. Naphthalene was also higher in symptomatic patients and in wheezers with recent inhaled corticosteroid use. No relationships with lung function or TH2 inflammation were detected. Increased levels of naphthalene in asthmatics and wheezers and the relationship to disease severity could indicate a role of environmental or indoor air pollution for the development or progress of asthma. Breath VOCs might help to elucidate the role of the exposome for the development of asthma. The study was registered at ClinicalTrials.gov (NCT02496468).

CD137 deficiency does not affect development of airway inflammation or respiratory tolerance induction in murine models.

The co-stimulatory molecule CD137 (4-1BB) plays a crucial role in the development and persistence of asthma, characterized by eosinophilic airway inflammation, mucus hypersecretion, airway hyperreactivity, increased T helper type 2 (Th2) cytokine production and serum immunoglobulin (Ig)E levels. We have shown previously that application of an agonistic CD137 monoclonal antibody (mAb) prevented and even reversed an already established asthma phenotype. In the current study we investigated whether deficiency of the CD137/CD137L pathway affects the development of allergic airway inflammation or the opposite immune reaction of respiratory tolerance. CD137⁻/⁻ and wild-type (WT) mice were sensitized and challenged with the model allergen ovalbumin (OVA) and analysed for the presence of allergic disease parameters (allergy protocol). Some animals were tolerized by mucosal application of OVA prior to transferring the animals to the allergy protocol to analyse the effect of CD137 loss on tolerance induction (tolerance protocol). Eosinophilic airway inflammation, mucus hypersecretion, Th2 cytokine production and elevated allergen-specific serum IgE levels were increased equally in CD137⁻/⁻ and WT mice. Induction of tolerance resulted in comparable protection from the development of an allergic phenotype in both mouse strains. In addition, no significant differences could be identified in CD4⁺, CD8⁺ and forkhead box protein 3 (FoxP3⁺) regulatory T cells, supporting the conclusion that CD137⁻/⁻ mice show equal Th2-mediated immune responses compared to WT mice. Taken together, CD137⁻/⁻ mice and WT mice develop the same phenotype in a murine model of Th2-mediated allergic airway inflammation and respiratory tolerance.

Contribution of regulatory T cells to alleviation of experimental allergic asthma after specific immunotherapy.

BACKGROUND: Allergen-specific immunotherapy (SIT) has been used since 1911, yet its mechanism of action remains to be elucidated. There is evidence indicating that CD4(+)FOXP3(+) regulatory T cells (Treg cells) are induced during SIT in allergic patients. However, the contribution of these cells to SIT has not been evaluated in vivo. OBJECTIVE: To evaluate the in vivo contribution of (i) CD4(+) CD25(+) T cells during SIT and of (ii) SIT-generated inducible FOXP3(+) Treg cells during allergen exposure to SIT-mediated suppression of asthmatic manifestations. METHODS: We used a mouse model of SIT based on the classical OVA-driven experimental asthma. Treg cells were quantified by flow cytometry 24 and 96 h post SIT treatment. We depleted CD4(+) CD25(+) T cells prior to SIT, and CD4(+)FOXP3(+) T cells prior to allergen challenges to study their contribution to the suppression of allergic manifestations by SIT treatment. RESULTS: Our data show that depletion of CD4(+)CD25(+) T cells at the time of SIT treatment reverses the suppression of airway hyperresponsiveness (AHR), but not of airway eosinophilia and specific IgE levels in serum. Interestingly, the number of CD4(+)CD25(+)FOXP3(+) T cells is transiently increased after SIT in the spleen and blood, suggesting the generation of inducible and presumably allergen-specific Treg cells during treatment. Depletion of CD4(+)FOXP3(+) Treg cells after SIT treatment partially reverses the SIT-induced suppression of airway eosinophilia, but not of AHR and serum levels of specific IgE. CONCLUSION AND CLINICAL RELEVANCE: We conclude that SIT-mediated tolerance induction towards AHR requires CD4(+)CD25(+) T cells at the time of allergen injections. In addition, SIT generates CD4(+)CD25(+)FOXP3(+) T cells that contribute to the suppression of airway eosinophilia upon allergen challenges. Therefore, enhancing Treg cell number or their activity during and after SIT could be of clinical relevance to improve the therapeutic effects of SIT.

Liraglutide: short-lived effect on gastric emptying -- long lasting effects on body weight.

AIM: Previous studies with the novel once daily glucagon-like peptide-1 (GLP-1) analogue liraglutide and the GLP-1 receptor agonist exenatide have revealed profound insulinotrophic and antidiabetic effects, but also potent effects on gastric emptying (GE) and long-term and lasting reductions in body weight. In this study, we examined the acute and chronic effects of two different GLP-1 analogues with different pharmacokinetic profiles on GE, food intake and body weight. METHODS: On the basis of a series of dose-finding studies, the doses of exenatide and liraglutide with similar acute anorectic effects were identified. GE was assessed using a standard acetaminophen release assay. After the acute test, rats were dosed bi-daily for 14 days in which period food intake and body weight was monitored. On day 14, the GE rate was reassessed. RESULTS: While both compounds exerted robust acute reductions in GE, the effect was markedly diminished following 14 days of dosing with liraglutide. In contrast, exenatide-treated rats still displayed a profound reduction in GE at the 14-day time-point. Both compounds exerted similar effects on body weight. CONCLUSION: The data suggest that the 'gastric inhibitory' GLP-1 receptors in rats are subject to desensitization/tachyphylaxis but that this effect is dependent on full 24-h exposure as obtained by liraglutide. The body weight-lowering effects of GLP-1 receptor stimulation are not subject to desensitization. These data indicate that regulation of appetite signals in the brain, and not GE, is the main mechanism for liraglutide-induced weight loss.

Cardiomyopathy in α-kinase 3 (ALPK3)-deficient mice.

Cardiomyopathy developed in mice deficient for α-kinase 3 (ALPK3), a nuclear kinase previously implicated in the differentiation of cardiomyocytes. Alpk3 (-/-) mice were produced according to normal Mendelian ratios and appeared normal except for a nonprogressive cardiomyopathy that had features of both hypertrophic and dilated forms of cardiomyopathy. Cardiac hypertrophy in Alpk3 (-/-) mice was characterized by increased thickness of both left and right ventricular (LV and RV) walls and by markedly increased heart weight and increased heart weight/body weight and heart weight/tibia length ratios. Magnetic resonance imaging studies confirmed the increased thickness in both septal and LV free walls at end-diastole, although there was no significant change in LV wall thickness at end-systole. Myocardial hypertrophy was the predominant feature in Alpk3 (-/-) mice, but several changes more typically associated with dilated cardiomyopathy included a marked increase in end-diastolic and end-systolic LV volume, as well as reduced cardiac output, stroke volume, and ejection fractions, suggesting LV chamber dilation. Magnetic resonance imaging showed a 50% reduction in both septal and free wall LV contractility in Alpk3 (-/-) mice. Interstitial fibrosis and inflammation were notably absent in Alpk3 (-/-) mice; however, light and electron microscopy revealed altered cardiomyocyte architecture, characterized by reduced numbers of abnormal intercalated discs being associated with mild disarray of myofibrils. These lesions could account for the impaired contractility of the myofibrillar apparatus and contribute to the pathogenesis of cardiomyopathy in Alpk3 (-/-) mice.

Congenital hydrocephalus in genetically engineered mice.

There is evidence that genetic factors play a role in the complex multifactorial pathogenesis of hydrocephalus. Identification of the genes involved in the development of this neurologic disorder in animal models may elucidate factors responsible for the excessive accumulation of cerebrospinal fluid in hydrocephalic humans. The authors report here a brief summary of findings from 12 lines of genetically engineered mice that presented with autosomal recessive congenital hydrocephalus. This study illustrates the value of knockout mice in identifying genetic factors involved in the development of congenital hydrocephalus. Findings suggest that dysfunctional motile cilia represent the underlying pathogenetic mechanism in 8 of the 12 lines (Ulk4, Nme5, Nme7, Kif27, Stk36, Dpcd, Ak7, and Ak8). The likely underlying cause in the remaining 4 lines (RIKEN 4930444A02, Celsr2, Mboat7, and transgenic FZD3) was not determined, but it is possible that some of these could also have ciliary defects. For example, the cerebellar malformations observed in RIKEN 4930444A02 knockout mice show similarities to a number of developmental disorders, such as Joubert, Meckel-Gruber, and Bardet-Biedl syndromes, which involve mutations in cilia-related genes. Even though the direct relevance of mouse models to hydrocephalus in humans remains uncertain, the high prevalence of familial patterns of inheritance for congenital hydrocephalus in humans suggests that identification of genes responsible for development of hydrocephalus in mice may lead to the identification of homologous modifier genes and susceptibility alleles in humans. Also, characterization of mouse models can enhance understanding of important cell signaling and developmental pathways involved in the pathogenesis of hydrocephalus.

Amelogenesis imperfecta and other biomineralization defects in Fam20a and Fam20c null mice.

The FAM20 family of secreted proteins consists of three members (FAM20A, FAM20B, and FAM20C) recently linked to developmental disorders suggesting roles for FAM20 proteins in modulating biomineralization processes. The authors report here findings in knockout mice having null mutations affecting each of the three FAM20 proteins. Both Fam20a and Fam20c null mice survived to adulthood and showed biomineralization defects. Fam20b (-/-) embryos showed severe stunting and increased mortality at E13.5, although early lethality precluded detailed investigations. Physiologic calcification or biomineralization of extracellular matrices is a normal process in the development and functioning of various tissues (eg, bones and teeth). The lesions that developed in teeth, bones, or blood vessels after functional deletion of either Fam20a or Fam20c support a significant role for their encoded proteins in modulating biomineralization processes. Severe amelogenesis imperfecta (AI) was present in both Fam20a and Fam20c null mice. In addition, Fam20a (-/-) mice developed disseminated calcifications of muscular arteries and intrapulmonary calcifications, similar to those of fetuin-A deficient mice, although they were normocalcemic and normophosphatemic, with normal dentin and bone. Fam20a gene expression was detected in ameloblasts, odontoblasts, and the parathyroid gland, with local and systemic effects suggesting both local and/or systemic effects for FAM20A. In contrast, Fam20c (-/-) mice lacked ectopic calcifications but were severely hypophosphatemic and developed notable lesions in both dentin and bone to accompany the AI. The bone and dentin lesions, plus the marked hypophosphatemia and elevated serum alkaline phosphatase and FGF23 levels, are indicative of autosomal recessive hypophosphatemic rickets/osteomalacia in Fam20c (-/-) mice.