Common and divergent gene regulatory networks control injury-induced and developmental neurogenesis in zebrafish retina

Following acute retinal damage, zebrafish possess the ability to regenerate all neuronal subtypes through Müller glia (MG) reprogramming and asymmetric cell division that produces a multipotent Müller glia-derived neuronal progenitor cell (MGPC). This raises three key questions. First, do MG reprogram to a developmental retinal progenitor cell (RPC) state? Second, to what extent does regeneration recapitulate retinal development? And finally, does loss of different retinal cell subtypes induce unique MG regeneration responses? We examined these questions by performing single-nuclear and single-cell RNA-Seq and ATAC-Seq in both developing and regenerating retinas. Here we show that injury induces MG to reprogram to a state similar to late-stage RPCs. However, there are major transcriptional differences between MGPCs and RPCs, as well as major transcriptional differences between activated MG and MGPCs when different retinal cell subtypes are damaged. Validation of candidate genes confirmed that loss of different subtypes induces differences in transcription factor gene expression and regeneration outcomes.

Common and divergent gene regulatory networks control injury-induced and developmental neurogenesis in zebrafish retina

Following acute retinal damage, zebrafish possess the ability to regenerate all neuronal subtypes. This regeneration requires Müller glia (MG) to reprogram and divide asymmetrically to produce a multipotent Müller glia-derived neuronal progenitor cell (MGPC). This raises three key questions. First, does loss of different retinal cell subtypes induce unique MG regeneration responses? Second, do MG reprogram to a developmental retinal progenitor cell state? And finally, to what extent does regeneration recapitulate retinal development? We examined these questions by performing single-nuclear and single-cell RNA-Seq and ATAC-Seq in both developing and regenerating retinas. While MG reprogram to a state similar to late-stage retinal progenitors in developing retinas, there are transcriptional differences between reprogrammed MG/MGPCs and late progenitors, as well as reprogrammed MG in outer and inner retinal damage models. Validation of candidate genes confirmed that loss of different subtypes induces differences in transcription factor gene expression and regeneration outcomes. This work identifies major differences between gene regulatory networks activated following the selective loss of different subtypes of retina neurons, as well as between retinal regeneration and development.

Common and divergent gene regulatory networks control injury-induced and developmental neurogenesis in zebrafish retina

Following acute retinal damage, zebrafish possess the ability to regenerate all neuronal subtypes. This regeneration requires Müller glia (MG) to reprogram and divide asymmetrically to produce a multipotent Müller glia-derived neuronal progenitor cell (MGPC). This raises three key questions. First, does loss of different retinal cell subtypes induce unique MG regeneration responses? Second, do MG reprogram to a developmental retinal progenitor cell state? And finally, to what extent does regeneration recapitulate retinal development? We examined these questions by performing single-nuclear and single-cell RNA-Seq and ATAC-Seq in both developing and regenerating retinas. While MG reprogram to a state similar to late-stage retinal progenitors in developing retinas, there are transcriptional differences between reprogrammed MG/MGPCs and late progenitors, as well as reprogrammed MG in outer and inner retinal damage models. Validation of candidate genes confirmed that loss of different subtypes induces differences in transcription factor gene expression and regeneration outcomes. This work identifies major differences between gene regulatory networks activated following the selective loss of different subtypes of retina neurons, as well as between retinal regeneration and development.

Heterogeneous pdgfrb+ cells regulate coronary vessel development and revascularization during heart regeneration

Endothelial cells emerge from the atrioventricular canal to form coronary blood vessels in juvenile zebrafish hearts. We find that pdgfrb is first expressed in the epicardium around the atrioventricular canal and later becomes localized mainly in the mural cells. pdgfrb mutant fish show severe defects in mural cell recruitment and coronary vessel development. Single-cell RNA sequencing analyses identified pdgfrb+ cells as epicardium-derived cells (EPDCs) and mural cells. Mural cells associated with coronary arteries also express cxcl12b and smooth muscle cell markers. Interestingly, these mural cells remain associated with coronary arteries even in the absence of Pdgfrβ, although smooth muscle gene expression is downregulated. We find that pdgfrb expression dynamically changes in EPDCs of regenerating hearts. Differential gene expression analyses of pdgfrb+ EPDCs and mural cells suggest that they express genes that are important for regeneration after heart injuries. mdka was identified as a highly upregulated gene in pdgfrb+ cells during heart regeneration. However, pdgfrb but not mdka mutants show defects in heart regeneration after amputation. Our results demonstrate that heterogeneous pdgfrb+ cells are essential for coronary development and heart regeneration.

Inflammation Regulates the Multi-Step Process of Retinal Regeneration in Zebrafish

The ability to regenerate tissues varies between species and between tissues within a species. Mammals have a limited ability to regenerate tissues, whereas zebrafish possess the ability to regenerate almost all tissues and organs, including fin, heart, kidney, brain, and retina. In the zebrafish brain, injury and cell death activate complex signaling networks that stimulate radial glia to reprogram into neural stem-like cells that repair the injury. In the retina, a popular model for investigating neuronal regeneration, Müller glia, radial glia unique to the retina, reprogram into stem-like cells and undergo a single asymmetric division to generate multi-potent retinal progenitors. Müller glia-derived progenitors then divide rapidly, numerically matching the magnitude of the cell death, and differentiate into the ablated neurons. Emerging evidence reveals that inflammation plays an essential role in this multi-step process of retinal regeneration. This review summarizes the current knowledge of the inflammatory events during retinal regeneration and highlights the mechanisms whereby inflammatory molecules regulate the quiescence and division of Müller glia, the proliferation of Müller glia-derived progenitors and the survival of regenerated neurons.

Whole-mount Immunohistochemistry of Adult Zebrafish Retina for Advanced Imaging

Immunohistochemistry is a widely used technique to examine the expression and subcellular localization of proteins. This technique relies on the specificity of antibodies and requires adequate penetration of antibodies into tissues. The latter is especially challenging for thick specimens, such as embryos and other whole-mount preparations. Here we describe an improved method of immunohistochemistry for retinal whole-mount preparations. We report that a cocktail of three reagents, Triton X-100, Tween-20, and DMSO, in blocking and antibody dilution buffers strongly enhances immunolabeling in whole-mount retinas from adult zebrafish. In addition, we establish that in whole retinal tissues, a classic epitope retrieval method, based on citrate buffer, is effective for immunolabeling membrane-associated proteins. Overall, this simple modification allows precise and reproducible immunolabeling of proteins in retinal whole-mounts.

Defect patterns on the curved surface of fish retinae suggest a mechanism of cone mosaic formation

The outer epithelial layer of zebrafish retinae contains a crystalline array of cone photoreceptors, called the cone mosaic. As this mosaic grows by mitotic addition of new photoreceptors at the rim of the hemispheric retina, topological defects, called "Y-Junctions", form to maintain approximately constant cell spacing. The generation of topological defects due to growth on a curved surface is a distinct feature of the cone mosaic not seen in other well-studied biological patterns like the R8 photoreceptor array in the Drosophila compound eye. Since defects can provide insight into cell-cell interactions responsible for pattern formation, here we characterize the arrangement of cones in individual Y-Junction cores as well as the spatial distribution of Y-junctions across entire retinae. We find that for individual Y-junctions, the distribution of cones near the core corresponds closely to structures observed in physical crystals. In addition, Y-Junctions are organized into lines, called grain boundaries, from the retinal center to the periphery. In physical crystals, regardless of the initial distribution of defects, defects can coalesce into grain boundaries via the mobility of individual particles. By imaging in live fish, we demonstrate that grain boundaries in the cone mosaic instead appear during initial mosaic formation, without requiring defect motion. Motivated by this observation, we show that a computational model of repulsive cell-cell interactions generates a mosaic with grain boundaries. In contrast to paradigmatic models of fate specification in mostly motionless cell packings, this finding emphasizes the role of cell motion, guided by cell-cell interactions during differentiation, in forming biological crystals. Such a route to the formation of regular patterns may be especially valuable in situations, like growth on a curved surface, where the resulting long-ranged, elastic, effective interactions between defects can help to group them into grain boundaries.

Inflammation and matrix metalloproteinase 9 (Mmp-9) regulate photoreceptor regeneration in adult zebrafish

Brain injury activates complex inflammatory signals in dying neurons, surviving neurons, and glia. Here, we establish that inflammation regulates the regeneration of photoreceptors in the zebrafish retina and determine the cellular expression and function of the inflammatory protease, matrix metalloproteinase 9 (Mmp-9), during this regenerative neurogenesis. Following photoreceptor ablation, anti-inflammatory treatment suppresses the number of injury-induced progenitors and regenerated photoreceptors. Upon photoreceptor injury, mmp-9 is induced in Müller glia and Müller glia-derived photoreceptor progenitors. Deleting mmp-9 results in over production of injury-induced progenitors and regenerated photoreceptors, but over time the absence of Mmp-9 compromises the survival of the regenerated cones. At all time-points studied, the levels of tnf-α are significantly elevated in mutant retinas. Anti-inflammatory treatment in mutants rescues the defects in cone survival. These data provide a link between injury-induced inflammation in the vertebrate CNS, Mmp-9 function during neuronal regeneration and the requirement of Mmp-9 for the survival of regenerated cones.

Reprogramming Müller Glia to Regenerate Retinal Neurons

In humans, various genetic defects or age-related diseases, such as diabetic retinopathies, glaucoma, and macular degeneration, cause the death of retinal neurons and profound vision loss. One approach to treating these diseases is to utilize stem and progenitor cells to replace neurons in situ, with the expectation that new neurons will create new synaptic circuits or integrate into existing ones. Reprogramming non-neuronal cells in vivo into stem or progenitor cells is one strategy for replacing lost neurons. Zebrafish have become a valuable model for investigating cellular reprogramming and retinal regeneration. This review summarizes our current knowledge regarding spontaneous reprogramming of Müller glia in zebrafish and compares this knowledge to research efforts directed toward reprogramming Müller glia in mammals. Intensive research using these animal models has revealed shared molecular mechanisms that make Müller glia attractive targets for cellular reprogramming and highlighted the potential for curing degenerative retinal diseases from intrinsic cellular sources.

P3468Tentative criteria of a combined RV3+SV3 voltage for early diagnosis of pediatric patients with hypertrophic cardiomyopathy

Background

A high voltage in midprecordial leads, termed the Katz-Wachtel sign, is a surrogate marker of left- or bi-ventricular hypertrophy. Asymmetrical interventricular hypertrophy is a characteristic feature of hypertrophic cardiomyopathy (HCM). In Japan, a school-based electrocardiographic (ECG) screening program was developed for all 1st, 7th, and 10th graders. Our hypothesis is that a combined voltage of RV3+SV3 {V3(R+S)} is a marker to screen pediatric HCM.

Purpose

[1] To develop V3(R+S) voltage criteria in 1st, 7th, and 10th graders at the screening program and [2] to determine whether the criteria are useful for the early diagnosis of HCM.

Methods

[1] Overall, 48,401 digitally stored ECGs from 16,773 1st graders (6-year-olds), 18,126 7th graders (12-year-olds), and 13,502 10th graders (15-year-olds) were obtained after excluding ECGs of subjects with underlying diseases, arrhythmias, and ST/T changes. The prevalence of HCM in children is estimated at 2.9 per 100,000 (1/34,000). The screening points were assumed to be between 1/2,000 and 1/5,000 to exclude the possibility of false negatives. [2] In 12 HCM patients (males/females=10/2) who were diagnosed after 12 years of age (one case was diagnosed at 9 years of age), the ECGs at the screening program of their first grade (at 6 years of age) were retrospectively examined.

Results

[1] The V3(R+S) criteria were 6.0 mV, 6.0 mV, and 5.5 mV for 1st, 7th, and 10th grader males, and 5.0 mV, 4.5 mV, and 4.0 mV for 1st, 7th, and 10th grade females, respectively. The number of subjects (and prevalence in parentheses) selected by the criteria were 2 (1/4175), 3 (1/2981), and 1 (1/6477) for 1st, 7th, and 10th grade males, and 2 (1/4212), 3 (1/3061), and 1 (1/3513) for 1st, 7th, and 10th grade females, respectively. [2] Four of 12 cases fulfilled the criteria. Of these, one suddenly died at 18 years of age, one experienced out-of-hospital cardiac arrest at 16 years of age, and one already had an interventricular thickness of 19 mm at 12 years of age.

Conclusions

These tentative V3(R+S) voltage criteria may be useful for the early diagnosis of pediatric HCM patients, particularly severe patients. The children and adolescents who were screened can be followed at 2–3-year intervals with ECGs and echocardiography. Early diagnosis and intervention including lifestyle modification and medication may prevent them expiring from out-of-hospital cardiac arrest or sudden death. Finally, the criteria should be validated in clinical settings.

Acknowledgement/Funding

A Health and Labour Sciences Grant from the Ministry of Health, Labour and Welfare of Japan (H27-019)

P4654Clinical and electrocardiographic features of restrictive cardiomyopathy in children

Introduction

Restrictive cardiomyopathy (RCM) is a rare myocardial disease with an impaired diastolic function and poor prognosis. The mean survival duration after a diagnosis of RCM is reported to be around 2 years in children and most need heart transplantations.

Purpose

This study aimed to determine the 12-lead electrocardiogram (ECG) diagnostic criteria of RCM based on the initial diagnostic electrocardiogram.

Methods

ECGs in pediatric cardiomyopathy patients were collected from 15 institutes in Japan between 1979 and 2013. We compared the ECG findings, especially of the P wave, in RCM patients between the cardiomyopathy group and healthy children group separately for each gender and the age. The ECGs in the healthy group were obtained from school heart screening in Japan of first-graders, and seventh-graders. Statistical significance was determined as p<0.001.

Results

Among 376 registered cardiomyopathy patients, 63 had hypertrophic cardiomyopathy (HCM) (36%), 91 (24%) dilated cardiomyopathy (DCM), 106 (28%) a left ventricular myocardial noncompaction (LVNCs), 25 (7%) restrictive cardiomyopathy (RCM), 14 (4%) arrhythmogenic right ventricular cardiomyopathy (ARVC), and 5 (1%) other cardiomyopathies. Of the 25 RCM patients (9.9±3.4 years old, F:M=11:14), 36% were discovered during school heart screening. The first onset was an abnormal ECG in 9, symptoms of heart failure in 6, respiratory tract infections in 3, syncope in 1, and 6 with other. Of those patients, 2 (8%) had a family history of RCM, 24 (92%) no family history. A genetic diagnosis was performed in 5 of the 25 cases, and 3 had genetic abnormalities related to RCM. The mean follow-up period was 65±95 months (mean±standard deviation). During follow up, 19 patients (76%) survived, 6 (24%) died, 7 (28%) had heart transplantations, and 3 (12%) were waiting for heart transplantations with a left ventricular assist device.

The P wave was bimodal in lead I or biphasic in lead V1 in 15 patients (93%), and 13 (81%) patients had both variations. We evaluated the duration and amplitude of the first and second component of the P wave as P1 and P2. The number of control and RCM patients (control/RCM), duration of P1+P2, and sum total absolute value of the amplitude of P1+P2 in lead V1 were 8350/5, 90±9/116±10ms, and 72±28/528±278μV in first grade boys, 8423/3, 91±10/120±22ms, and 66±28/326±229μV in first grade girls, 8943/1, 97±1/100ms, and 71±31/328μV in seventh grade boys, and 9183/5, 98±11/112±10ms, and 55±27/315±56μV in seventh grade girls. Although the number of patients in the RCM group was small, sum total absolute value of the amplitude of P1+P2 in lead V1 showed a significant difference in any group.

Conclusion

The ECG in children with RCM exhibits P wave abnormalities in almost all patients. In particular, not the P wave interval but P wave shape in I and V1 and the sum total absolute value of the amplitude of P1+P2 in lead V1 were observed differences.

P6544A real world study of high frequency atrial anti-tachycardia pacing in new algorithm for atrial arrhythmia

Background

Advanced pacemakers feature atrial antitachycardia pacing (aATP) therapies for terminating atrial arrhythmia. Previous studies showed the efficacy of combined atrial preventive pacing and aATP in patients with pacemakers. The independent effect of aATP and the impact for patients outside the clinical trials has not been well elucidated.

Methods

In a single center, prospective, all-comers trial, we enrolled 567 patients implanted cardiac devices with Reactive ATP function. History of permanent atrial fibrillation (AF) was not included. After device interrogation of the AF burden and the longest AF duration in the last 6 months, aATP was programmed as a bit more aggressive setting than MINERVA trial (time interval was set as every 2 hours). As for newly implanted devices, aATP was activated after at least 3 months run-in period. Primary and secondary outcomes were the longest AF duration and cumulative percentage of progression into permanent AF, respectively.

Results

Of 541 eligible patients, aged 75.3±10.7 years, 356 pacemaker, 82 ICD and 103 CRT patients, the longest single episode of AF lasted ≤6 min in 439 patients (81.1%), >6 min to 6 h in 43 (8.0%), >6–24 h in 33 (6.1%), and >24 h in 26 (4.8%) at the enrollment. During mean follow-up of 1.9 years, the longest AF episode lasted >24 h in 49 patients (9.1%) and 14 patients (2.6%) progressed into permanent AF. According with baseline longest single episode of AF, patients with AF ≤6 min developed an episode >24 h in 0.8% at 1 year and 3.2% at 2 years follow up; patients with AF >6 min to 6 h developed an episode >24 h in none at 1 year and 7% at 2 years follow up; and patients with AF >6–24 h developed an episode >24 h in 19% at 1 year and 42% at 2 years follow up, respectively. In a subgroup analysis of in 192 patients with at least 1 aATP, 46 patients with high efficacy (>44%) did not developed an episode >24 h. Only one patient developed into permanent AF without aATP therapy. On multivariate analysis, neither ICD nor CRT was independent risk factor for developing the longest AF episode >24 h.

Conclusions

The independent use of aATP without atrial preventive pacing was effective for preventing AF progression in a real world cohort. Even without the previous AF episodes, aATP could prevent AF development, especially in patients showing high aATP efficacy. Future research is required to enhance the aATP success rate.

Novel Animal Model of Crumbs-Dependent Progressive Retinal Degeneration That Targets Specific Cone Subtypes

Purpose

Human Crb1 is implicated in some forms of retinal degeneration, suggesting a role in photoreceptor maintenance. Multiple Crumbs (Crb) polarity genes are expressed in vertebrate retina, although their functional roles are not well understood. To gain further insight into Crb and photoreceptor maintenance, we compared retinal cell densities between wild-type and Tg(RH2-2:Crb2b-sf^EX/RH2-2:GFP)^pt108b transgenic zebrafish, in which the extracellular domain of Crb2b-short form (Crb2b-sf^EX) is expressed in the retina as a secreted protein, which disrupts the planar organization of RGB cones (red, green, and blue) by interfering with Crb2a/2b-based cone-cone adhesion.

Methods

We used standard morphometric techniques to assess age-related changes in retinal cell densities in adult zebrafish (3 to 27 months old), and to assess effects of the Crb2b-sf^EX transgene on retinal structure and photoreceptor densities. Linear cell densities were measured in all retinal layers in radial sections with JB4-Feulgen histology. Planar (surface) densities of cones were determined in retinal flat-mounts. Cell counts from wild-type and pt108b transgenic fish were compared with both a “photoreceptor maintenance index” and statistical analysis of cell counts.

Results

Age-related changes in retinal cell linear densities and cone photoreceptor planar densities in wild-type adult zebrafish provided a baseline for analysis. Expression of Crb2b-sf^EX caused progressive and selective degeneration of RGB cones, but had no effect on ultraviolet-sensitive (UV) cones, and increased numbers of rod photoreceptors.

Conclusions

These differential responses of RGB cones, UV cones, and rods to sustained exposure to Crb2b-sf^EX suggest that Crb-based photoreceptor maintenance mechanisms are highly selective.

Anisotropic Müller glial scaffolding supports a multiplex lattice mosaic of photoreceptors in zebrafish retina

Background

The multiplex, lattice mosaic of cone photoreceptors in the adult fish retina is a compelling example of a highly ordered epithelial cell pattern, with single cell width rows and columns of cones and precisely defined neighbor relationships among different cone types. Cellular mechanisms patterning this multiplex mosaic are not understood. Physical models can provide new insights into fundamental mechanisms of biological patterning. In earlier work, we developed a mathematical model of photoreceptor cell packing in the zebrafish retina, which predicted that anisotropic mechanical tension in the retinal epithelium orients planar polarized adhesive interfaces to align the columns as cone photoreceptors are generated at the retinal margin during post-embryonic growth.

Methods

With cell-specific fluorescent reporters and in vivo imaging of the growing retinal margin in transparent juvenile zebrafish we provide the first view of how cell packing, spatial arrangement, and cell identity are coordinated to build the lattice mosaic. With targeted laser ablation we probed the tissue mechanics of the retinal epithelium.

Results

Within the lattice mosaic, planar polarized Crumbs adhesion proteins pack cones into a single cell width column; between columns, N-cadherin-mediated adherens junctions stabilize Müller glial apical processes. The concentration of activated pMyosin II at these punctate adherens junctions suggests that these glial bands are under tension, forming a physical barrier between cone columns and contributing to mechanical stress anisotropies in the epithelial sheet. Unexpectedly, we discovered that the appearance of such parallel bands of Müller glial apical processes precedes the packing of cones into single cell width columns, hinting at a possible role for glia in the initial organization of the lattice mosaic. Targeted laser ablation of Müller glia directly demonstrates that these glial processes support anisotropic mechanical tension in the planar dimension of the retinal epithelium.

Conclusions

These findings uncovered a novel structural feature of Müller glia associated with alignment of photoreceptors into a lattice mosaic in the zebrafish retina. This is the first demonstration, to our knowledge, of planar, anisotropic mechanical forces mediated by glial cells.

Electronic supplementary material

The online version of this article (10.1186/s13064-017-0096-z) contains supplementary material, which is available to authorized users.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Block of postjunctional muscle-type acetylcholine receptors in vivo causes train-of-four fade in mice

BACKGROUND

Train-of-four (TOF) fade during nerve-mediated muscle contraction is postulated to be attributable to inhibition of prejunctional nicotinic α3β2 acetylcholine receptors (nAChRs), while decrease of twitch tension is attributable to block of postjunctional muscle nAChRs. The validity of these presumptions was tested using specific prejunctional and postjunctional nAChR antagonists, testing the hypothesis that fade is not always a prejunctional phenomenon.

METHODS

Pentobarbital anaesthetized mice had TOF fade measured after administration of: either 0.9% saline; the prejunctional α3β2 nAChR antagonist, dihydro-β-erythroidine (DHβE); the postjunctional nAChR antagonists, α-bungarotoxin (α-BTX) or α-conotoxin GI; and a combination of α-BTX and DHβE; or a combination of α-conotoxin GI and DHβE.

RESULTS

Saline caused no neuromuscular changes. Administration of muscle nAChR antagonists, α-BTX or α-conotoxin GI caused significant decrease of twitch tension and TOF fade compared with baseline (P<0.01). DHβE alone caused no change of twitch tension or fade even after 90 min, but its coadministration with α-BTX or α-conotoxin GI significantly accelerated the onset of paralysis and degree of fade compared with α-BTX or α-conotoxin GI alone (P<0.01).

CONCLUSIONS

Occupation of postjunctional nAChRs alone by α-BTX or α-conotoxin GI causes fade. As the prejunctional effects of DHβE on fade became manifest only when co-administered with α-BTX or α-conotoxin GI, specific inhibition of prejunctional nAChR alone is not necessary and sufficient to cause fade. Fade observed during repetitive nerve stimulation can be because of block of either postjunctional nAChRs alone, or block of prejunctional and postjunctional nAChRs together.

Clinical efficacy and treatment persistence of monthly minodronate for osteoporotic patients unsatisfied with, and shifted from, daily or weekly bisphosphonates: the BP-MUSASHI study

This multi-center, prospective, open-label, observational study evaluated the effects of once-monthly minodronate (50 mg) on treatment persistence, bone turnover markers, bone mineral density, low back pain, and upper gastrointestinal symptoms in outpatients with osteoporosis previously treated with daily or weekly bisphosphonate products.

INTRODUCTION

The purposes of this study were to investigate the effects of once-monthly oral minodronate (MIN 50 mg) on bone turnover markers and bone mineral density, low back pain, and upper gastrointestinal symptoms, as well as preference for and treatment persistence of MIN 50 mg among Japanese osteoporosis patients currently treated with daily or weekly bisphosphonates.

METHODS

Study patients were allocated based on their preference to either the Switch group (patients willing to switch over to MIN 50 mg) or the Continue group (patients wanting to continue their current therapies). Patients' treatment persistence and satisfaction levels with the therapies were assessed using a self-administered questionnaire. The study endpoints were serum TRACP-5b, serum P1NP, bone mineral density, upper gastrointestinal symptoms, and low back pain.

RESULTS

In total, 264 and 133 patients were allocated into the Switch and Continue groups, respectively. Approximately, 65 % of patients were willing to switch to MIN 50 mg, with the predominant reason being "less frequent dosing more convenient." Treatment persistence was significantly higher in the Switch group (MIN 50 mg) than the Continue group. Almost all patients with abnormal bone metabolism markers demonstrated normalization after switchover. MIN 50 mg alleviated low back pain and upper gastrointestinal symptoms induced by prior bisphosphonate use.

CONCLUSIONS

MIN 50 mg alleviates low back pain, reduces bone turnover markers and increases bone density, and induces fewer upper gastrointestinal symptoms after switchover from prior bisphosphonate products, and therefore, it may provide patients with a more convenient treatment option and enhance long-term treatment persistence.

Upregulation of leukemia inhibitory factor (LIF) during the early stage of optic nerve regeneration in zebrafish

Fish retinal ganglion cells (RGCs) can regenerate their axons after optic nerve injury, whereas mammalian RGCs normally fail to do so. Interleukin 6 (IL-6)-type cytokines are involved in cell differentiation, proliferation, survival, and axon regrowth; thus, they may play a role in the regeneration of zebrafish RGCs after injury. In this study, we assessed the expression of IL-6-type cytokines and found that one of them, leukemia inhibitory factor (LIF), is upregulated in zebrafish RGCs at 3 days post-injury (dpi). We then demonstrated the activation of signal transducer and activator of transcription 3 (STAT3), a downstream target of LIF, at 3–5 dpi. To determine the function of LIF, we performed a LIF knockdown experiment using LIF-specific antisense morpholino oligonucleotides (LIF MOs). LIF MOs, which were introduced into zebrafish RGCs via a severed optic nerve, reduced the expression of LIF and abrogated the activation of STAT3 in RGCs after injury. These results suggest that upregulated LIF drives Janus kinase (Jak)/STAT3 signaling in zebrafish RGCs after nerve injury. In addition, the LIF knockdown impaired axon sprouting in retinal explant culture invitro; reduced the expression of a regeneration-associated molecule, growth-associated protein 43 (GAP-43); and delayed functional recovery after optic nerve injury invivo. In this study, we comprehensively demonstrate the beneficial role of LIF in optic nerve regeneration and functional recovery in adult zebrafish.

Patterning the cone mosaic array in zebrafish retina requires specification of ultraviolet-sensitive cones

Cone photoreceptors in teleost fish are organized in precise, crystalline arrays in the epithelial plane of the retina. In zebrafish, four distinct morphological/spectral cone types occupy specific, invariant positions within a regular lattice. The cone lattice is aligned orthogonal and parallel to circumference of the retinal hemisphere: it emerges as cones generated in a germinal zone at the retinal periphery are incorporated as single-cell columns into the cone lattice. Genetic disruption of the transcription factor Tbx2b eliminates most of the cone subtype maximally sensitive to ultraviolet (UV) wavelengths and also perturbs the long-range organization of the cone lattice. In the tbx2b mutant, the other three cone types (red, green, and blue cones) are specified in the correct proportion, differentiate normally, and acquire normal, planar polarized adhesive interactions mediated by Crumbs 2a and Crumbs 2b. Quantitative image analysis of cell adjacency revealed that the cones in the tbx2b mutant primarily have two nearest neighbors and align in single-cell-wide column fragments that are separated by rod photoreceptors. Some UV cones differentiate at the dorsal retinal margin in the tbx2b mutant, although they are severely dysmorphic and are eventually eliminated. Incorporating loss of UV cones during formation of cone columns at the margin into our previously published mathematical model of zebrafish cone mosaic formation (which uses bidirectional interactions between planar cell polarity proteins and anisotropic mechanical stresses in the plane of the retinal epithelium to generate regular columns of cones parallel to the margin) reproduces many features of the pattern disruptions seen in the tbx2b mutant.

Prevalence of cervical lesions in rheumatoid arthritis: cross-sectional study on 263 patients

Abstract Spinal lesions in upper and sublaxilar cervical vertebrae were studied radiologically in 263 patients (25 men and 238 women) with rheumatoid arthritis (RA). Their average age was 58.9 years, and their disease duration was ranged from 6 months to 24 years (mean 13 years). Functional lateral views of the cervical spine were made. Atlantaxial subluxation (AAS) and vertical subluxation (VS) were evaluated as upper cervical lesions. Subaxilar subluxation (SAS) and endplate erosion were evaluated as subaxilar cervical lesions. One hundred and seventy-eight (67.7%) of the patients had a cervical lesion. Upper and subaxilar cervical abnormalities were recognized in 136 (51.7%) and 113 (43.0%) patients, respectively. There was no linkage between upper and subaxilar cervical lesions. While the prevalence of these lesions increased with time, the frequency was found to be over 50% within only 5 years from onset in patients with mutilating deformity. This prevalence tended to be associated with disease activity.

Genome-wide association study identifies a potent locus associated with human opioid sensitivity

Opioids, such as morphine and fentanyl, are widely used as effective analgesics for the treatment of acute and chronic pain. In addition, the opioid system has a key role in the rewarding effects of morphine, ethanol, cocaine and various other drugs. Although opioid sensitivity is well known to vary widely among individual subjects, several candidate genetic polymorphisms reported so far are not sufficient for fully understanding the wide range of interindividual differences in human opioid sensitivity. By conducting a multistage genome-wide association study (GWAS) in healthy subjects, we found that genetic polymorphisms within a linkage disequilibrium block that spans 2q33.3-2q34 were strongly associated with the requirements for postoperative opioid analgesics after painful cosmetic surgery. The C allele of the best candidate single-nucleotide polymorphism (SNP), rs2952768, was associated with more analgesic requirements, and consistent results were obtained in patients who underwent abdominal surgery. In addition, carriers of the C allele in this SNP exhibited less vulnerability to severe drug dependence in patients with methamphetamine dependence, alcohol dependence, and eating disorders and a lower 'Reward Dependence' score on a personality questionnaire in healthy subjects. Furthermore, the C/C genotype of this SNP was significantly associated with the elevated expression of a neighboring gene, CREB1. These results show that SNPs in this locus are the most potent genetic factors associated with human opioid sensitivity known to date, affecting both the efficacy of opioid analgesics and liability to severe substance dependence. Our findings provide valuable information for the personalized treatment of pain and drug dependence.

A self-renewing division of zebrafish Müller glial cells generates neuronal progenitors that require N-cadherin to regenerate retinal neurons

Müller glia function as retinal stem cells in adult zebrafish. In response to loss of retinal neurons, Müller glia partially dedifferentiate, re-express neuroepithelial markers and re-enter the cell cycle. We show that the immunoglobulin superfamily adhesion molecule Alcama is a novel marker of multipotent retinal stem cells, including injury-induced Müller glia, and that each Müller glial cell divides asymmetrically only once to produce an Alcama-negative, proliferating retinal progenitor. The initial mitotic division of Müller glia involves interkinetic nuclear migration, but mitosis of retinal progenitors occurs in situ. Rapidly dividing retinal progenitors form neurogenic clusters tightly associated with Alcama/N-cadherin-labeled Müller glial radial processes. Genetic suppression of N-cadherin function interferes with basal migration of retinal progenitors and subsequent regeneration of HuC/D(+) inner retinal neurons.