Intracranial calcification in Fam20c-deficient mice recapitulates human Raine syndrome

FAM20C (family with sequence similarity 20-member C) is a protein kinase that phosphorylates secretory proteins, including the proteins that are essential to the formation and mineralization of calcified tissues. FAM20C loss-of-function mutations cause Raine syndrome in humans, characterized by generalized osteosclerosis, distinctive craniofacial dysmorphism, along with extensive intracranial calcification. Our previous studies revealed that inactivation of Fam20c in mice led to hypophosphatemic rickets. In this study, we examined the expression of Fam20c in the mouse brain and investigated brain calcification in Fam20c-deficient mice. Reverse transcription polymerase chain reaction (RT-PCR), Western-blotting and in situ hybridization analyses demonstrated the broad expression of Fam20c in the mouse brain tissue. X-ray and histological analyses showed that the global deletion of Fam20c (mediated by Sox2-cre) resulted in brain calcification in mice after postnatal 3 months and that the calcifications were bilaterally distributed within the brain. There was mild perifocal microgliosis as well as astrogliosis around calcospherites. The calcifications were first observed in the thalamus, and later in the forebrain and hindbrain. Furthermore, brain-specific deletion (mediated by Nestin-cre) of Fam20c in mice also led to cerebral calcification at an older age (postnatal 6 months), but no obvious skeletal or dental defects. Our results suggest that the local loss of FAM20C function in the brain may directly account for intracranial calcification. We propose that FAM20C plays an essential role in maintaining normal brain homeostasis and preventing ectopic brain calcification.

Sex Differences in the Role of Neurexin 3α in Zoster Associated Pain

Varicella zoster virus (VZV) induces orofacial pain and female rats show greater pain than male rats. During the proestrus phase of the estrous cycle the VZV induce pain response is attenuated in female rats. A screen of gene expression changes in diestrus and proestrus female rats indicated neurexin 3α (Nrxn3α) was elevated in the central amygdala of proestrus rats vs. diestrus rats. GABAergic neurons descend from the central amygdala to the lateral parabrachial region and Nrxn3α is important for presynaptic γ-Aminobutyric acid (GABA) release. Thus, we hypothesized that the reduced orofacial pain in male rats and proestrus female rats is the result of increased Nrxn3α within the central amygdala that increases GABA release from axon terminals within the parabrachial and inhibits ascending pain signals. To test this hypothesis Nrxn3 α expression was knocked-down by infusing shRNA constructs in the central amygdala. Then GABA release in the parabrachial was quantitated concomitant with measuring the pain response. Results revealed that knockdown of Nrxn3α expression significantly increases the pain response in both male rats and proestrus female rats vs. diestrus rats. GABA release was significantly reduced in the parabrachial of male and proestrus female rats after Nrxn3α knockdown. Neuronal activity of excitatory neurons was significantly inhibited in the parabrachial after Nrxn3α knockdown. These results are consistent with the idea that Nrxn3 within the central amygdala controls VZV associated pain by regulating GABA release in the lateral parabrachial that then modulates ascending orofacial pain signals.

EphB3 as a Potential Mediator of Developmental and Reparative Osteogenesis

The ephrin-B family of membrane-bound ligands is involved in skeletal patterning, osteogenesis, and bone homeostasis. Yet, despite the increasing collection of data affirming their importance in bone, the Eph tyrosine kinases that serve as the receptors for these ephrins in osteoblast stem cell niches remain unidentified. Here we report the expression of EphB3 at sites of bone growth in the embryo, especially at the calvaria suture fronts, periosteum, chondrocytes, and trabeculae of developing long bones. Strong EphB3 expression persisted in the adult calvarial sutures and in the proliferative chondrocytes of long bones, both of which are documented niches for osteoblastic stem cells. We observed EphB3-positive cells in the tissue filling a created calvarial injury, further implying EphB3 involvement in bone healing. Genetic knockout of EphB3 caused an increase in the bone tissue volume as a fraction of total volume in 6-week-old calvaria and in femoral trabecular density, compared to wild type controls. This difference resolved by 12 weeks of age, when we instead observed an increase in the bone volume of femoral trabeculae and in trabecular thickness. Our data identify EphB3 as a candidate regulator of osteogenesis either alone or in combination with other bone-expressed Ephs, and indicate that it appears to function as a limiter of bone growth.

Long-term efficacy and safety of inotersen in patients with hereditary transthyretin amyloid polyneuropathy with or without cardiomyopathy: post hoc analysis of NEURO-TTR open-label extension

Background/Introduction

Cardiomyopathy (CM) with associated heart failure and polyneuropathy (PN) are common manifestations of hereditary transthyretin amyloidosis (ATTRv), a progressive, debilitating, and fatal disease that results from the deposition of misfolded transthyretin (TTR) protein throughout the body. NEURO-TTR (NCT01737398) showed that inotersen, an antisense oligonucleotide inhibitor of TTR protein production, slowed the progression of PN and maintained quality of life in patients with ATTRv.

Purpose

To report efficacy and safety from the open-label extension (OLE) of the NEURO-TTR study in patients with ATTRv PN overall and in CM subgroups.

Methods

Patients who completed NEURO-TTR, enrolled in the OLE (NCT02175004), and either switched from placebo in NEURO-TTR to inotersen in the OLE (placebo-inotersen) or received inotersen in NEURO-TTR and remained on inotersen in the OLE (inotersen-inotersen) were included. Assessments included the modified Neuropathy Impairment Score +7 composite score (mNIS+7 [range –22.3 to 346.3], a measure of neuropathy with higher scores indicative of poorer function), TTR levels, and safety monitoring. Utilizing patients from Europe and North America (EU+NA) as of 28 July 2020, this post hoc analysis examined two subgroups: CM ECHO and severe CM ECHO. CM was defined as a diagnosis of ATTRv CM at study entry or all of the following criteria: a left ventricular wall thickness of ≥1.3 cm on transthoracic echocardiography at baseline, no known history of persistent hypertension (systolic blood pressure ≥150 mm Hg) within 12 months before study screening, and evaluable baseline ECHO obtained by central assessment. Severe CM was defined as an interventricular septum thickness ≥1.5 cm at baseline. Descriptive statistics are reported.

Results

In the overall population and both CM subgroups, the placebo-inotersen group demonstrated slowing of neurological disease progression compared with natural history based on NEURO-TTR placebo projection (estimated natural history will be presented). Furthermore, in the overall population and both CM subgroups, the inotersen-inotersen group demonstrated sustained benefit compared with the placebo-inotersen group (Table). Change in serum TTR levels will be presented. There have been no reports of grade 4 thrombocytopenia or acute glomerulonephritis under enhanced monitoring in patients in the EU+NA despite the increased duration of exposure. No new safety concerns were identified.

Conclusions

Inotersen treatment for >3 years slowed the progression of PN associated with ATTRv in patients with CM, including severe CM. In both subgroups, greater neurological preservation was observed in those who initiated inotersen earlier (inotersen-inotersen group), underscoring the benefits of early treatment. No new safety signals were detected in this OLE analysis; enhanced monitoring is successful in managing the risk for thrombocytopenia and acute glomerulonephritis.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): This study was sponsored by Akcea Therapeutics, an affiliate of Ionis Pharmaceuticals, Inc.

Diagnosis and Screening of Patients with Hereditary Transthyretin Amyloidosis (hATTR): Current Strategies and Guidelines

The outlook for transthyretin amyloidosis (ATTR) is changing with the availability of new and emerging treatments. ATTR now appears to be more common than previously thought and is no longer viewed as an obscure diagnosis with a grim prognosis. Now more than ever, there is growing emphasis on the need for early diagnosis because the treatments appear to be most effective if started in earlier stages of the disease. Diagnosing ATTR is a challenge as it may initially present with nonspecific symptoms and it is often thought of as a diagnosis of exclusion. Increased awareness is imperative as new treatments offer hope and have the potential to change the disease trajectory. ATTR commonly presents with neurological and cardiac features. Transthyretin (TTR) is a protein produced in the liver which misfolds either due to genetic mutations or due to aging and results in deposition of amyloid fibrils in organs and tissues. Apart from the traditional imaging modalities, newer techniques including echocardiographic strain imaging, magnetic resonance imaging (MRI), and nuclear scintigraphy, as well as the increased availability of genetic testing are aiding in making a timely diagnosis. In this review, we present the current understanding of the ATTR disease process, diagnostic and surveillance approaches, newer treatment modalities, and the future directions.

Early data on long-term efficacy and safety of inotersen in patients with hereditary transthyretin amyloidosis: a 2-year update from the open-label extension of the NEURO-TTR trial

BACKGROUND AND PURPOSE

Hereditary transthyretin (hATTR) amyloidosis causes progressive polyneuropathy resulting from transthyretin (TTR) amyloid deposition throughout the body, including the peripheral nerves. The efficacy and safety of inotersen, an antisense oligonucleotide inhibitor of TTR protein production, were demonstrated in the pivotal NEURO-TTR study in patients with hATTR polyneuropathy. Here, the long-term efficacy and safety of inotersen are assessed in an ongoing open-label extension (OLE) study.

METHODS

Patients who completed NEURO-TTR were eligible to enroll in the OLE (NCT02175004). Efficacy assessments included the modified Neuropathy Impairment Score plus seven neurophysiological tests composite score (mNIS + 7), the Norfolk Quality of Life - Diabetic Neuropathy (Norfolk QOL-DN) questionnaire total score and the Short-Form 36 Health Survey (SF-36) Physical Component Summary (PCS) score. Safety and tolerability were also assessed.

RESULTS

Overall, 97% (135/139) of patients who completed NEURO-TTR enrolled in the OLE. Patients who received inotersen for 39 cumulative months in NEURO-TTR and the OLE continued to show benefit; patients who switched from placebo to inotersen in the OLE demonstrated improvement or stabilization of neurological disease progression by mNIS + 7, Norfolk QOL-DN and SF-36 PCS. No new safety concerns were identified. There was no evidence of increased risk for grade 4 thrombocytopenia or severe renal events with increased duration of inotersen exposure.

CONCLUSION

Inotersen slowed disease progression and reduced deterioration of quality of life in patients with hATTR polyneuropathy. Early treatment with inotersen resulted in greater long-term disease stabilization than delayed initiation. Routine platelet and renal safety monitoring were effective; no new safety signals were observed.

Noggin inhibition of mouse dentinogenesis

OBJECTIVES

The Bone Morphogenetic Proteins (BMPs) direct tooth development and still express in the adult tooth. We hypothesized that inhibition of BMP function would therefore disrupt dentinogenesis by differentiated odontoblasts.

METHODS

We generated mice overexpressing the BMP-inhibitory protein Noggin in differentiated odontoblasts and osteocytes under control of a Dmp1 promoter-driven cre transgene. We compared the dentin phenotype in these mice with that in WT littermates and in mice with a Smad4 odontoblast/osteocyte knockout mediated by the same cre and therefore lacking all BMP and Tgfβ signaling in the same tissues.

RESULTS

Three-month-old first molars from both Noggin-expressing and Smad4-deleted mice showed decreased dentin volume with enlarged pulp cavities, and both displayed less organized and mineralized dentinal tubules compared to WT. The Smad4-ablated phenotype was more severe. While dentin sialophosphoprotein (DSPP) and bone sialoprotein (BSP) were decreased in the dentin of both lines, dentin matrix protein 1 (DMP1) was sharply increased in Noggin-expressing teeth.

CONCLUSIONS

The phenotypes we observed in Noggin-overexpressing and Smad4-conditional knockout teeth resemble the phenotype of Dentinogenesis Imperfecta (DGI) type III. Our results show that BMPs regulate post-natal dentinogenesis and that BMP-inhibitory proteins like Noggin play a role in that regulation. The increased severity of the Smad4 phenotype indicates that Tgfβ ligands, in addition to BMPs, play a crucial role in post-developmental dentinogenesis.

Extracellular Matrix in Secondary Palate Development

The secondary palate arises from outgrowths of epithelia-covered embryonic mesenchyme that grow from the maxillary prominence, remodel to meet over the tongue, and fuse at the midline. These events require the coordination of cell proliferation, migration, and gene expression, all of which take place in the context of the extracellular matrix (ECM). Palatal cells generate their ECM, and then stiffen, degrade, or otherwise modify its properties to achieve the required cell movement and organization during palatogenesis. The ECM, in turn, acts on the cells through their matrix receptors to change their gene expression and thus their phenotype. The number of ECM-related gene mutations that cause cleft palate in mice and humans is a testament to the crucial role the matrix plays in palate development and a reminder that understanding that role is vital to our progress in treating palate deformities. This article will review the known ECM constituents at each stage of palatogenesis, the mechanisms of tissue reorganization and cell migration through the palatal ECM, the reciprocal relationship between the ECM and gene expression, and human syndromes with cleft palate that arise from mutations of ECM proteins and their regulators. Anat Rec, 2019. © 2019 American Association for Anatomy.

Medial epithelial seam cell migration during palatal fusion

The mammalian secondary palate forms from two shelves of mesenchyme sheathed in a single-layered epithelium. These shelves meet during embryogenesis to form the midline epithelial seam (MES). Failure of MES degradation prevents mesenchymal confluence and results in a cleft palate. Previous studies indicated that MES cells undergo features of epithelial-to-mesenchymal transition (EMT) and may become migratory as part of the fusion mechanism. To detect MES cell movement over the course of fusion, we imaged the midline of fusing embryonic ephrin-B2/GFP mouse palates in real time using two-photon microscopy. These mice express an ephrin-B2-driven green fluorescent protein (GFP) that labels the palatal epithelium nuclei and persists in those cells through the time window necessary for fusion. We observed collective migration of MES cells toward the oral surface of the palatal shelf over 48 hr of imaging, and we confirmed histologically that the imaged palates had fused by the end of the imaged period. We previously reported that ephrin reverse signaling in the MES is required for palatal fusion. We therefore added recombinant EphA4/Fc protein to block this signaling in imaged palates. The blockage inhibited fusion, as expected, but did not change the observed migration of GFP-labeled cells. Thus, we uncoupled migration and fusion. Our data reveal that palatal MES cells undergo a collective, unidirectional movement during palatal fusion and that ephrin reverse signaling, though required for fusion, controls aspects of the fusion mechanism independent of migration.

The role of bone morphogenetic proteins 2 and 4 in mouse dentinogenesis

OBJECTIVE

The bone morphogenetic proteins (BMPs) play crucial roles in tooth development. However, several BMPs retain expression in the dentin of the fully patterned and differentiated tooth. We hypothesized that BMP signaling therefore plays a role in the function of the differentiated odontoblast, the job of which is to lay down and mineralize the dentin matrix.

DESIGN

We generated mice deficient in Bmp2 and 4 using a dentin matrix protein 1 (Dmp1) promoter-driven cre recombinase that was expressed in differentiated odontoblasts.

RESULTS

The first and second molars of these Bmp2 and Bmp4 double conditional knockout (DcKO) mice displayed reduced dentin and enlarged pulp chambers compared to cre-negative littermate controls. DcKO mouse dentin in first molars was characterized by small, disorganized dentinal fibers, a wider predentin layer, and reduced expression of dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1), and bone sialoprotein (BSP). DcKO mouse odontoblasts demonstrated increased type I collagen mRNA production, indicating that the loss of BMP signaling altered the rate of collagen gene expression in these cells. Bmp2 and Bmp4 single Dmp1-cre knockout mice displayed no discernable dentin phenotype.

CONCLUSIONS

These data demonstrate that BMP signaling in differentiated odontoblasts is necessary for proper dentin production in mature teeth.

Maternal collapse: Challenging the four-minute rule

Introduction

The current approach to, cardiopulmonary resuscitation of pregnant women in the third trimester has been to adhere to the “four-minute rule”: If pulses have not returned within 4 min of the start of resuscitation, perform a cesarean birth so that birth occurs in the next minute. This investigation sought to re-examine the evidence for the four-minute rule.

Methods

A literature review focused on perimortem cesarean birth was performed using the same key words that were used in formulating the “four-minute rule.” Maternal and neonatal injury free survival rates as a function of arrest to birth intervals were determined, as well as actual incision to birth intervals.

Results

Both maternal and neonatal injury free survival rates diminished steadily as the time interval from maternal arrest to birth increased. There was no evidence for any specific survival threshold at 4 min. Skin incision to birth intervals of 1 min occurred in only 10% of women.

Conclusion

Once a decision to deliver is made, care providers should proceed directly to Cesarean birth during maternal cardiac arrest in the third trimester rather than waiting for 4 min for restoration of the maternal pulse. Birth within 1 min from the start of the incision is uncommon in these circumstances.

•

Half of maternal/fetal pairs who are delivered by Cesarean birth within 25 min survive without injury.

•

The injury free survival rate for both has a roughly linear decrease as the time interval from arrest to birth increases.

•

Very few babies could be delivered within 1 min of the Cesarean section incision.

This information suggests that the current cardio-pulmonary resuscitation guideline in pregnancy, known as the four-minute rule, needs to be changed. Injury free survival for both mother and baby decreases steadily from the moment of cardiac arrest until cesarean birth. Furthermore, in actual practice, the baby usually cannot be delivered within 1 min of the start of surgery. Once a decision for delivery has been made, Cesarean birth should be initiated promptly without waiting for 4 min. In practice, the recommendation to proceed to cesarean birth without delay is also likely to result in less confusion than the current “Four-Minute rule.”

Ephrin reverse signaling mediates palatal fusion and epithelial-to-mesenchymal transition independently of Tgfß3

The mammalian secondary palate forms from shelves of epithelia-covered mesenchyme that meet at midline and fuse. The midline epithelial seam (MES) is thought to degrade by apoptosis, epithelial-to-mesenchymal transition (EMT), or both. Failure to degrade the MES blocks fusion and causes cleft palate. It was previously thought that transforming growth factor ß3 (Tgfß3) is required to initiate fusion. Members of the Eph tyrosine kinase receptor family and their membrane-bound ephrin ligands are expressed on the MES. We demonstrated that treatment of mouse palates with recombinant EphB2/Fc to activate ephrin reverse signaling (where the ephrin acts as a receptor and transduces signals from its cytodomain) was sufficient to cause mouse palatal fusion when Tgfß3 signaling was blocked by an antibody against Tgfß3 or by an inhibitor of the TgfßrI serine/threonine receptor kinase. Cultured palatal epithelial cells traded their expression of epithelial cell markers for that of mesenchymal cells and became motile after treatment with EphB2/Fc. They concurrently increased their expression of the EMT-associated transcription factors Snail, Sip1, and Twist1. EphB2/Fc did not cause apoptosis in these cells. These data reveal that ephrin reverse signaling directs palatal fusion in mammals through a mechanism that involves EMT but not apoptosis and activates a gene expression program not previously associated with ephrin reverse signaling.

Decreasing NF-κB expression enhances odontoblastic differentiation and collagen expression in dental pulp stem cells exposed to inflammatory cytokines

Inflammatory response in the dental pulp can alter the collagen matrix formation by dental pulp stem cells and lead to a delay or poor healing of the pulp. This inflammatory response is mediated by cytokines, including interleukin-1β and tumor necrosis factor-α. In this study, it is hypothesized that suppressing the actions of these inflammatory cytokines by knocking down the activity of transcription factor Nuclear Factor-κB will lead to dental pulp stem cell differentiation into odontoblasts and the production of collagen. Here, the role of Nuclear Factor-κB signaling and its reduction was examined during odontogenic behavior in the presence of these cytokines. The results showed a significant increase in Nuclear Factor-κB gene expression and p65 protein expression by interleukin-1β and tumor necrosis factor-α. Nuclear Factor-κB activation in the presence of these cytokines decreased significantly in a dose-dependent manner by a Nuclear Factor-κB inhibitor (MG132) and p65 siRNA. Down-regulation of Nuclear Factor-κB activity also enhanced the gene expression of the odontoblastic markers (dentin sialophosphoprotein, Nestin, and alkaline phosphatase) and displayed an odontoblastic cell morphology indicating the promotion of odontogenic differentiation of dental pulp stem cells. Finally, dental pulp stem cells exposed to reduced Nuclear Factor-κB activity resulted in a significant increase in collagen (I)-α1 expression in the presence of these cytokines. In conclusion, a decrease in Nuclear Factor-κB in dental pulp stem cells in the presence of inflammatory cytokines enhanced odontoblastic differentiation and collagen matrix formation.

Amniotic fluid embolism: Then and now

BACKGROUND

The first case report to describe amniotic fluid embolism that appeared in 1926 in Basil-Medico is translated from Portuguese to English.

CASE

A patient with a dead fetus for several weeks, presented in labor and died suddenly with fetal squames evident in the maternal pulmonary vasculature at autopsy.

CONCLUSION

As can be seen from the translation, this case report is remarkably similar in many of its features to some of the eight patients described 15 years later in the first English language discussion of the disease by Steiner and Luschbaugh in JAMA. An enigma presented by this first case remains today: fetal material in the maternal pulmonary vasculature appears specific for amniotic fluid embolism at autopsy but not in living patients.

Ephrin-B2 expression in the proprioceptive sensory system

Recent studies have shown that ephrin-B2 on sensory afferent fibers from the dorsal root ganglia (DRG) controls transmission of pain sensation to the spinal cord. We examined ephrin-B2 expression in mouse DRG and spinal cord using an ephrin-B2/ß-galactosidase chimeric allele. We found that ephrin-B2 is expressed exclusively in proprioceptive neurons and fibers in neonates, while expression in lamina III and IV of the adult spinal cord was observed in addition to that in the deeper laminae. We confirmed that ephrin-B2 protein causes co-clustering of EphB2 and glutamate receptors in spinal cord neurons. Our data are consistent with a role for ephrin-B2 in transmission of positional information to the CNS, and thus suggest a role in synaptic plasticity of spinal cord locomotor circuits that are known to be sensitive to proprioceptive sensory input after spinal cord injury.

Ephrin-B stimulation of calvarial bone formation

INTRODUCTION

Ephrin-B2 on osteoclasts was reported to promote bone formation as part of homeostasis by activating the EphB4 tyrosine kinase receptor on osteoblasts. Little is known about the role of ephrin-B signaling to EphBs in developmental bone formation.

RESULTS

We observed expression of an ephrin-B2 LacZ chimeric allele in the periosteum, sutural bone fronts, and dura mater of embryonic and neonatal mice. Expression in the adult skull was confined to sutures, but was heavily upregulated at sites of bone injury. Culture of embryonic calvariae with soluble recombinant ephrin-B2/Fc doubled their bone content without altering suture width or overall skull morphology. Ephrin-B2/Fc also stimulated osteoblast marker gene expression in cultured MC3T3 preosteoblastic cells without the need for type 1 collagen-induced differentiation. EphB4 was absent in embryonic and adult skulls. However, EphB1 and EphB2, both physiological receptors for ephrin-Bs, were expressed at sites of osteogenesis, and EphB1 knockout mice displayed a reduction in calvarial bone content compared to controls.

CONCLUSIONS

These data support a role for ephrin-B2 in the development and healing of bone through activation of osteoblast-specific gene expression. EphB1 and EphB2 are likely candidates receptors for the ephrin-B2 in bone.

Pulmonary embolism in pregnancy. Consensus and controversies

Venous thrombotic events (VTE) occur 1-2 per 10,000 pregnancies and remain one of the leading causes of maternal mortality in the developed world. The two largest risk factors are a personal history of VTE and heritable thrombophilias. D-dimer tests for VTE in pregnancy have a high false positive rate and at least some false negatives have been reported. Compression ultrasound should be used to evaluate pregnant women for deep venous thrombosis followed by magnetic resonance imaging of the pelvis for a negative test and strong remaining clinical suspicion. For pulmonary embolism, a chest x-ray should be used to triage the patient to either a ventilation/perfusion study after a normal X-ray or a CT pulmonary angiogram after an abnormal one. Treatment generally consists of low molecular weight heparin through a minimum of six weeks post-partum. Thombolysis might have merit in life-threatening, massive pulmonary embolism. VTE prophylaxis in at-risk populations remains a major area of uncertainty. Mechanical prophylaxis for all women undergoing cesarean, in particular, has a paucity of supportive evidence.

Ephrin regulation of palate development

Studies of palate development are motivated by the all too common incidence of cleft palate, a birth defect that imposes a tremendous health burden and can leave lasting disfigurement. Although, mechanistic studies of palate growth and fusion have focused on growth factors such as Transforming Growth Factor ß-3 (Tgfß3), recent studies have revealed that the ephrin family of membrane bound ligands and their receptors, the Ephs, play central roles in palatal morphogenesis, growth, and fusion. In this mini-review, we will discuss the recent findings by our group and others on the functions of ephrins in palatal development.

Osteoblasts responses to three-dimensional nanofibrous gelatin scaffolds

The development of suitable scaffolds for bone tissue engineering requires an in-depth understanding of the interactions between osteoblasts and scaffolding biomaterials. Although there have been a large amount of knowledge accumulated on the cell-material interactions on two-dimensional (2D) planar substrates, our understanding of how osteoblasts respond to a biomimetic nanostructured three-dimensional (3D) scaffold is very limited. In this work, we developed an approach to use confocal microscopy as an effective tool for visualizing, analyzing, and quantifying osteoblast-matrix interactions and bone tissue formation on 3D nanofibrous gelatin scaffolds (3D-NF-GS). Integrin β1, phosphor-paxillin, and vinculin were used to detect osteoblasts responses to the nanofibrous architecture of 3D-NF-GS. Unlike osteoblasts cultured on 2D substrates, osteoblasts seeded on 3D-NF-GS showed less focal adhesions for phospho-paxillin and vinculin, and the integrin β1 was difficult to detect after the first 5 days. Bone sialoprotein (BSP) expression on the 3D-NF-GS was present mainly in the cell cytoplasm at 5 days and inside secretory vesicles at 2 weeks, whereas most of the BSP on the 2D gelatin substrates was concentrated either in cell interface toward the periphery or at focal adhesion sites. Confocal images showed that osteoblasts were able to migrate throughout the 3D matrix within 5 days. By 14 days, osteoblasts were organized as nodular aggregations inside the scaffold pores and a large amount of collagen and other cell secretions covered and remodeled the surfaces of the 3D-NF-GS. These nodules were mineralized and were uniformly distributed inside the entire 3D-NF-GS after being cultured for 2 weeks. Taken together, these results give insight into osteoblast-matrix interactions in biomimetic nanofibrous 3D scaffolds and will guide the development of optimal scaffolds for bone tissue engineering.

Ephrin reverse signaling controls palate fusion via a PI3 kinase-dependent mechanism

Secondary palate fusion requires adhesion and epithelial-to-mesenchymal transition (EMT) of the epithelial layers on opposing palatal shelves. This EMT requires transforming growth factor β3 (TGFβ3), and its failure results in cleft palate. Ephrins, and their receptors, the Ephs, are responsible for migration, adhesion, and midline closure events throughout development. Ephrins can also act as signal-transducing receptors in these processes, with the Ephs serving as ligands (termed "reverse" signaling). We found that activation of ephrin reverse signaling in chicken palates induced fusion in the absence of TGFβ3, and that PI3K inhibition abrogated this effect. Further, blockage of reverse signaling inhibited TGFβ3-induced fusion in the chicken and natural fusion in the mouse. Thus, ephrin reverse signaling is necessary and sufficient to induce palate fusion independent of TGFβ3. These data describe both a novel role for ephrins in palate morphogenesis, and a previously unknown mechanism of ephrin signaling.

Metabolism of amyloid proteins

Metabolic processing of amyloid precursor proteins is an important factor in the genesis of practically all forms of amyloidosis. Of the three major forms of systemic amyloidosis, reactive amyloid (amyloid A protein; AA) formation shows the most consistent role of partial proteolysis of serum amyloid A (SAA) to AA proteins which form fibrils. Immunoglobulin amyloidosis is also usually associated with C-terminal degradation of the fibril precursor light chain protein. Although it is commonly thought that transthyretin amyloidosis is associated with fibril formation from the tetrameric circulating plasma transthyretin, chemical analyses of transthyretin fibril deposits show significant fragmentation of the fibril protein constituents. In addition, it has been documented that proteolytic fragments are the fibril subunit proteins in gelsolin, cystatin C. Alzheimer's beta-amyloid precursor protein and apolipoprotein AI (apoAI) amyloidoses. Notable exceptions to the role of proteolysis in amyloid fibril formation would appear to be the lysozyme and beta 2-microglobulin amyloidoses. Few studies have examined the metabolism of amyloid-forming proteins. Perhaps the best data are on apoAI, which show decreased plasma residence time for the amyloidogenic Gly26Arg apoAI (1.8 d vs. normal 4.5 d). Similarly, preliminary data show increased clearance of Val30Met transthyretin when compared with the wild-type protein (18 h vs. 26 h). Also, biosynthetically 35S-labelled SAA proteins reconstituted with HDL show increased plasma clearance of murine SAA2, the amyloid fibril subunit protein, when compared with murine SAA1. Few data are available on metabolism of amyloid immunoglobulin light chain proteins, but it has been shown that radiolabelled Bence-Jones proteins are cleared very rapidly from the circulation. A better understanding of the metabolism of precursor proteins in each of the amyloid deposition diseases will give insight into the mechanisms of fibril formation and pathogenesis of amyloidosis.

ATF4 mediation of NF1 functions in osteoblast reveals a nutritional basis for congenital skeletal dysplasiae

The transcription factor ATF4 enhances bone formation by favoring amino acid import and collagen synthesis in osteoblasts, a function requiring its phosphorylation by RSK2, the kinase inactivated in Coffin-Lowry Syndrome. Here, we show that in contrast, RSK2 activity, ATF4-dependent collagen synthesis, and bone formation are increased in mice lacking neurofibromin in osteoblasts (Nf1(ob)(-/-) mice). Independently of RSK2, ATF4 phosphorylation by PKA is enhanced in Nf1(ob)(-/-) mice, thereby increasing Rankl expression, osteoclast differentiation, and bone resorption. In agreement with ATF4 function in amino acid transport, a low-protein diet decreased bone protein synthesis and normalized bone formation and bone mass in Nf1(ob)(-/-) mice without affecting other organ weight, while a high-protein diet overcame Atf4(-/-) and Rsk2(-/-) mice developmental defects, perinatal lethality, and low bone mass. By showing that ATF4-dependent skeletal dysplasiae are treatable by dietary manipulations, this study reveals a molecular connection between nutrition and skeletal development.

Cardiopulmonary distress during obstetrical anaesthesia: attempts to diagnose amniotic fluid embolism in a case series of suspected allergic anaphylaxis

BACKGROUND

Cardiopulmonary distress during obstetrical anaesthesia may result from a drug-induced allergic reaction, but, in the obstetrical setting, allergic anaphylaxis may be inseparable from amniotic fluid embolism in terms of the clinical presentation. Further investigations, using allergy tests and other laboratory analyses, are then needed to pursue a diagnostic clarification.

METHODS

Twelve women suspected of having developed anaphylaxis during obstetrical anaesthesia underwent allergy follow-up investigations and further serological tests with the amniotic fluid embolism marker sialyl Tn and complement factors (C3 and C4) in an attempt to differentiate amniotic fluid embolism from drug-induced allergic anaphylaxis.

RESULTS

The diagnostic programme revealed one case of probable amniotic fluid embolism and four cases of probable drug-induced allergic anaphylaxis. Of the remaining seven cases, there were two cases that, by diagnostic exclusion, could be classified as possible cases of amniotic fluid embolism. The cause of the reactions remained unresolved in five cases.

CONCLUSIONS

It can be difficult to differentiate between anaphylaxis and amniotic fluid embolism, especially amongst survivors. Diagnostic markers that can be applied on peripheral blood samples are promising, but larger studies are needed to validate their use in the diagnosis of causes of cardiopulmonary distress during obstetrical anaesthesia.

Diaphragmatic paralysis: the use of M mode ultrasound for diagnosis in adults

STUDY DESIGN

Retrospective, case series.

OBJECTIVES

To evaluate the use of M mode ultrasonography in the evaluation of diaphragmatic paralysis in adults.

SETTING

Radiology department, Princess Alexandra Hospital, Brisbane, Australia.

METHODS

Ten patients who were referred for evaluation of suspected diaphragmatic paralysis were evaluated using M mode ultrasound.

RESULTS

Three of the patients who were scanned demonstrated normal diaphragmatic movement. The M mode trace demonstrated normal movement of the diaphragm bilaterally with quiet respiration and a sharp upstroke on the sniff test (indicating normal caudal movement of the diaphragm). Six patients were found to have a unilateral diaphragmatic paralysis. Four of these patients were noted to have a raised hemi-diaphragm on chest radiography. Of the two who did not have a raised hemi-diaphragm on chest radiography, one was permanently ventilated. The M mode trace of the paralyzed side showed no active caudal movement of the diaphragm with inspiration and abnormal paradoxical movement (ie cranial movement on inspiration) particularly with the sniff test.

CONCLUSION

M mode ultrasonography is a relatively simple and accurate test for diagnosing paralysis of the diaphragm, in the adult population. It can be performed, if necessary, at the bedside and can be easily repeated if paralysis is not thought to be permanent.

EQUIPMENT

Philips ATL Sono CT 5000 using a 2-5 MHz curved linear transducer.

Ephrin-B3 is a myelin-based inhibitor of neurite outgrowth

The inability of CNS axons to regenerate after traumatic spinal cord injury is due, in part, to the inhibitory effects of myelin. The three major previously identified constituents of this activity (Nogo, myelin-associated glycoprotein, and oligodendrocyte myelin glycoprotein) were isolated based on their potent inhibition of axon outgrowth in vitro. All three myelin components transduce their inhibitory signals through the same Nogo receptor/p75 neurotrophin receptor/LINGO-1 (NgR1/p75/LINGO-1) complex. In this study, we considered that molecules known to act as repellants in vertebrate embryonic axonal pathfinding may also inhibit regeneration. In mice, ephrin-B3 functions during development as a midline repellant for axons of the corticospinal tract. We therefore investigated whether this repellant was expressed in the adult spinal cord and retained inhibitory activity. We demonstrate that ephrin-B3 is expressed in postnatal myelinating oligodendrocytes and, by using primary CNS neurons, show that ephrin-B3 accounts for an inhibitory activity equivalent to that of the other three myelin-based inhibitors, acting through p75, combined. Our data describe a known vertebrate axon guidance molecule as a myelin-based inhibitor of neurite outgrowth.

NF1 tumor suppressor protein and mRNA in skeletal tissues of developing and adult normal mouse and NF1-deficient embryos

NF1 is a heritable disease with multiple osseous lesions. The expression of the NF1 gene was studied in embryonic and adult rodent skeleton and in NF1-deficient embryos. The NF1 gene was expressed intensely in the cartilage and the periosteum. Impaired NF1 expression may lead to inappropriate development and dynamics of bones and ultimately to the osseous manifestations of the disease.

INTRODUCTION

Neurofibromatosis type 1 is caused by mutations in the NF1 gene encoding the Ras GTPase activating protein (Ras-GAP) neurofibromin. Skeletal ailments such as short stature, kyphoscoliosis, and tibial bowing and pseudarthrosis are common osseous manifestations of NF1. These symptoms are congenital, implying a role for neurofibromin in proper bone growth. However, little is known about its expression in skeletal tissues during their development.

MATERIALS AND METHODS

The expression of the NF1 gene was studied in normal and NF1+/- mouse fetuses at embryonic days 12.5-15.5 and in skeletal tissues of adult mice and rats. In situ hybridization, immunohistochemistry, and Western blot analysis were used to identify the NF1 gene expression profile.

RESULTS

NF1 mRNA and protein were elevated in resting, maturation, and hypertrophic chondrocytes at the growth plate. Parallel studies on NF1+/- embryos showed expression patterns identical to wildtype. The periosteum, including osteoblasts and osteoclasts, and osteocytes of the cortical bone of adult mice were also intensely labeled for NF1 protein and mRNA. Western transfer analysis detected NF1 protein in the respective rat tissues. Phosphorylation of p42 and p44 MAP kinases, the downstream consequence of Ras activation, was elevated in hypertrophic chondrocytes of NF1+/- embryos.

CONCLUSIONS

The results suggest that neurofibromin may act as a Ras-GAP in skeletal cells to attenuate Ras transduced growth signals and thus play a role during ossification and dynamics of bone. Loss of NF1 function may therefore lead to dysplastic bone growth, thereby causing the debilitating osseous symptoms of NF1.

Intracellular ferritin accumulation in neural and extraneural tissue characterizes a neurodegenerative disease associated with a mutation in the ferritin light polypeptide gene

Abnormal accumulation of ferritin was found to be associated with an autosomal dominant slowly progressing neurodegenerative disease clinically characterized by tremor, cerebellar ataxia, parkinsonism and pyramidal signs, behavioral disturbances, and cognitive decline. These symptoms may appear sequentially over a period of 4 decades. Pathologically, intranuclear and intracytoplasmic bodies were found in glia and subsets of neurons in the central nervous system as well as in extraneural tissue. Biochemical analyses of these bodies isolated from the striatum and cerebellar cortex revealed that ferritin light polypeptide (FTL) and ferritin heavy polypeptide (FTH1) were the main constituents. Molecular genetic studies revealed a 2-bp insertion mutation in exon 4 of the FTL gene. The resulting mutant polypeptide is predicted to have a carboxy terminus that is altered in amino-acid sequence and length. In tissue sections, the bodies were immunolabeled by anti-ferritin and anti-ubiquitin antibodies and were stained by Perls' method for ferric iron. Synthetic peptides homologous to the altered and wild-type carboxy termini were used to raise polyclonal antibodies. These novel antibodies as well as an antibody recognizing FTH1 immunolabeled the bodies. This study of this disorder has provided additional knowledge and insights in the growing area of ferritin-related neurodegeneration.

A homeodomain protein binding element in the bone sialoprotein promoter is critical for tissue-specific expression in bone

Bone sialoprotein (BSP) expression is restricted to cells associated with the mineralization of bones and teeth. We previously identified a homeodomain binding element in a 2.5 kb fragment of the murine Bsp promoter that is required for osteoblast-selective expression in cell culture. To examine the role of this element (called OSHE1; osteoblast-specific homeodomain element 1) in the tissue-specific expression of Bsp in vivo, we generated transgenic mice using the wild-type 2472 bp promoter or the same promoter containing a 2 bp mutation in OSHE1. Promoter constructs driving both luciferase and lacZ reporter genes were microinjected into fertilized eggs from (C57BL/6 X SJL)F1 mice. Four lines containing the wild-type promoter and 5 lines containing the mutated promoter were established, and the tissue specificity of beta-galactosidase staining and luciferase expression was examined. Beta-gal staining was observed in osteoblasts of calvaria and trabecular regions of tibia and femur in 12-day-old mice while chondrocytes, kidney, heart, muscle, spleen, liver, skin, stomach, and lung were negative. Whole tissue luciferase activity was also much higher in mineralized tissues although some soft tissue expression was detected. In contrast, analysis of OSHE1 mutant lines revealed expression of luciferase and beta-gal in kidney, skin, liver, and lung. Beta-gal expression in these tissues was restricted to specific cell populations. Trabecular regions were devoid of beta-gal staining in the tibia and femur of the mutant mice, while staining was seen in the chondrocytes. We therefore hypothesize that the OSHE1 site is involved in both the expression of Bsp in mineralizing tissues and the suppression of transcription in nonmineralizing tissues.

Amyloidoma of a spinal root

A unique case of amyloidoma presenting as a dumbbell-shaped tumor of a spinal root without bony erosion is described. Amyloid was also present in the facial nerve. DNA analysis for transthyretin was negative. Isolated amyloid fibers contained lambda light chains, and although plasma and urine immunoelectrophoresis performed by immunofixation was normal, it is possible the tumor may have been derived from an isolated plasmacytoma.

Oculoleptomeningeal amyloidosis in a large kindred with a new transthyretin variant Tyr69His

OBJECTIVE

To describe the clinical, radiologic, and pathologic findings of a kindred with oculoleptomeningeal amyloidosis and a newly associated transthyretin mutation.

BACKGROUND

Transthyretin (TTR) amyloidosis can present in the form of oculoleptomeningeal amyloidosis. Clinical features include dementia, seizures, stroke-like episodes, subarachnoid hemorrhage, ataxia, myelopathy, deafness, radiculopathy, and ocular amyloidosis. Eight TTR mutations associated with oculoleptomeningeal amyloidosis have been described.

METHODS

Fourteen individuals from a kindred with oculoleptomeningeal amyloidosis were examined clinically and radiologically. Analysis of the TTR gene was performed. Neuropathologic examination was obtained on the index patient.

RESULTS

Affected individuals had vitreous amyloid, radiculopathy, seizures, stroke-like episodes, encephalopathy, and dementia. Severely affected individuals died by the end of the fifth decade. Leptomeningeal enhancement on contrast MRI and elevated CSF protein were the defining features on investigations. Sequencing of exon 3 in the TTR gene found a base pair substitution at codon 69. This resulted in heterozygosity for normal tyrosine and variant histidine (ATTR Tyr69His) in affected family members. Domino liver transplantation was attempted as treatment for one family member.

CONCLUSIONS

The ATTR Tyr69His mutation is associated with oculoleptomeningeal amyloidosis. Expression of the genotype is variable. This has implications for treatment of affected individuals and counseling of family members. Efficacy of liver transplantation in patients with oculoleptomeningeal amyloidosis remains unknown. The authors advocate the investigation of liver transplantation in patients with severe symptoms due to oculoleptomeningeal amyloidosis.

Bone morphogenetic proteins, extracellular matrix, and mitogen-activated protein kinase signaling pathways are required for osteoblast-specific gene expression and differentiation in MC3T3-E1 cells

Osteoblasts secrete a complex extracellular matrix (ECM) containing collagenous and noncollagenous proteins, bone morphogenetic proteins (BMPs), and growth factors. Osteoblast-specific gene expression requires ascorbic acid (AA)-dependent assembly of a collagenous ECM. Matrix responsiveness requires an alpha2beta1 integrin-collagen interaction and mitogen-activated protein kinase (MAPK) activity, which phosphorylates and activates the osteoblast-specific transcription factor Cbfa1. This study examines interactions between this integrin/MAPK-mediated pathway and signals initiated by BMPs contained in the osteoblast matrix. MC3T3-E1 cells were shown to constitutively express BMP-2, BMP-4, and BMP-7. Noggin, a specific BMP inhibitor, reversibly blocked AA-induced gene expression, indicating that BMP production by MC3T3-E1 cells was necessary for differentiation. The ability of exogenously added BMP-2, BMP-4, or BMP-7 to stimulate osteocalcin (OCN) and bone sialoprotein (BSP) mRNAs or OCN promoter activity was synergistically increased in cells that were actively synthesizing an ECM (i.e., were grown in the presence of AA). A minimum of 4 days of ECM accumulation was required for this synergistic response to be observed. Neither BMP-7, AA, nor a combination of these two treatments had major effects on Cbfa1 messenger RNA (mRNA) or protein levels, as would be expected if regulation was mainly at the posttranscriptional level. U0126, a specific inhibitor of MAPK/extracellular signal-regulated kinase (MEK), blocked AA- or BMP-7/AA-dependent gene expression in a time- and dose-dependent manner that was closely correlated with inhibition of extracellular signal-regulated kinase (ERK) phosphorylation. This work establishes that autocrine BMP production as well as integrin-mediated cell-collagen interactions are both required for osteoblast differentiation, and both these pathways require MAP kinase activity.

Cardiac amyloidosis associated with the transthyretin Ile122 mutation in a Caucasian family

The Ile122 transthyretin variant associated with restrictive cardiomyopathy has been described in African-Americans and estimated to be present in approximately 4% of the Black population. We report the first American-Caucasian family with cardiomyopathy due to the TTR Ile122 mutation. The high prevalence of this mutation in the Black population and the discovery that it may cause disease in other ethnic populations highlights the importance of considering this autosomal dominant systemic amyloidosis in all individuals with restrictive cardiomyopathy. Inadequate diagnosis combined with inappropriate treatment may have a significant impact on morbidity and mortality.