Gene regulatory networks controlling temporal patterning, neurogenesis, and cell-fate specification in mammalian retina

Gene regulatory networks (GRNs), consisting of transcription factors and their target sites, control neurogenesis and cell-fate specification in the developing central nervous system. In this study, we use integrated single-cell RNA and single-cell ATAC sequencing (scATAC-seq) analysis in developing mouse and human retina to identify multiple interconnected, evolutionarily conserved GRNs composed of cell-type-specific transcription factors that both activate genes within their own network and inhibit genes in other networks. These GRNs control temporal patterning in primary progenitors, regulate transition from primary to neurogenic progenitors, and drive specification of each major retinal cell type. We confirm that NFI transcription factors selectively activate expression of genes promoting late-stage temporal identity in primary retinal progenitors and identify other transcription factors that regulate rod photoreceptor specification in postnatal retina. This study inventories cis- and trans-acting factors that control retinal development and can guide cell-based therapies aimed at replacing retinal neurons lost to disease.

A potential role for somatostatin signaling in regulating retinal neurogenesis

Neuropeptides have been reported to regulate progenitor proliferation and neurogenesis in the central nervous system. However, these studies have typically been conducted using pharmacological agents in ex vivo preparations, and in vivo evidence for their developmental function is generally lacking. Recent scRNA-Seq studies have identified multiple neuropeptides and their receptors as being selectively expressed in neurogenic progenitors of the embryonic mouse and human retina. This includes Sstr2, whose ligand somatostatin is transiently expressed by immature retinal ganglion cells. By analyzing retinal explants treated with selective ligands that target these receptors, we found that Sstr2-dependent somatostatin signaling induces a modest, dose-dependent inhibition of photoreceptor generation, while correspondingly increasing the relative fraction of primary progenitor cells. These effects were confirmed by scRNA-Seq analysis of retinal explants but abolished in Sstr2-deficient retinas. Although no changes in the relative fraction of primary progenitors or photoreceptor precursors were observed in Sstr2-deficient retinas in vivo, scRNA-Seq analysis demonstrated accelerated differentiation of neurogenic progenitors. We conclude that, while Sstr2 signaling may act to negatively regulate retinal neurogenesis in combination with other retinal ganglion cell-derived secreted factors such as Shh, it is dispensable for normal retinal development.

Multiplexed Analysis of Retinal Gene Expression and Chromatin Accessibility using scRNA-Seq and scATAC-Seq

Powerful next generation sequencing techniques offer robust and comprehensive analysis to investigate how retinal gene regulatory networks function during development and in disease states. Single-cell RNA sequencing allows us to comprehensively profile gene expression changes observed in retinal development and disease at a cellular level, while single-cell ATAC-Seq allows analysis of chromatin accessibility and transcription factor binding to be profiled at similar resolution. Here the use of these techniques in the developing retina is described, and MULTI-Seq is demonstrated, where individual samples are labeled with a modified oligonucleotide-lipid complex, enabling researchers to both increase the scope of individual experiments and substantially reduce costs.

Assessment of the Validity of the INR System for Patients with Liver Impairment

The INR system was developed to standardize PT reporting in patients on oral anticoagulants. We prospectively collected blood samples from 29 patients with liver impairment (INR 1.5-3.5). Control patients were on warfarin (n = 31). PT’s were measured on an ACL-300 with three thromboplastin reagents. INR’s were calculated using instrument specific ISI’s. Other tests performed were FDP’s, fibrinogen, aPTT, factors II, V, VII and X. The INR’s for each patient in the study population using the three thromboplastin reagents were significantly different (p = 0.0001). Those for the control population were not (p = 0.0658). Fibrinogen, factors V, II and X were different at the 5% level of significance between the populations. FDP’s were detected in 17 study subjects. The INR system is not valid for comparison of patients with liver impairment because different reagents do not give the same INR for the same sample. It is, however, no less valid than the use of PT with different thromboplastin reagents. Further study is recommended.

New IR imaging modalities for cancer detection and for intra-cell chemical mapping with a sub-diffraction mid-IR s-SNOM

We present two new modalities for generating chemical maps. Both are mid-IR based and aimed at the biomedical community, but they differ substantially in their technological readiness. The first, so-called "Digistain", is a technologically mature "locked down" way of acquiring diffraction-limited chemical images of human cancer biopsy tissue. Although it is less flexible than conventional methods of acquiring IR images, this is an intentional, and key, design feature. It allows it to be used, on a routine basis, by clinical personnel themselves. It is in the process of a full clinical evaluation and the philosophy behind the approach is discussed. The second modality is a very new, probe-based "s-SNOM", which we are developing in conjunction with a new family of tunable "Quantum Cascade Laser" (QCL) diode lasers. Although in its infancy, this instrument can already deliver ultra-detailed chemical images whose spatial resolutions beat the normal diffraction limit by a factor of ∼1000. This is easily enough to generate chemical maps of the insides of single cells for the first time, and a range of new possible scientific applications are explored.

Variation in the circularly polarized light reflection of Lomaptera (Scarabaeidae) beetles

An extended spectroscopic study on the left-through-left circularly polarized reflection spectra of a large number of beetles from the Australasian Scrabaeidae:Cetoniinae of the Lomaptera genus was undertaken. We have obtained a five-category spectral classification. The principal spectral features, which even within the genus range from blue to infrared, are related to structural chirality in the beetle shells. The detailed features of each spectral classification are related to different structural perturbations of the helix, including various pitch values and abrupt twist defects. These spectral characteristics and associated shell structures are confirmed on the basis of simple modelling. An important conclusion from our study is that the simple helical structure resulting in a single symmetric Bragg peak is not the dominant spectral type. Rather the reality is a rich tapestry of spectral types. One intriguing specimen is identified via a scanning electron micrograph to consist of a double interstitial helix leading to a particular double-peak spectrum.

Clinical signs and symptoms of oropharyngeal aspiration and dysphagia in children

The diagnostic value of various signs and symptoms (clinical markers) in predicting oropharyngeal aspiration (OPA) or swallowing dysfunction has not been established in children. The present retrospective study was undertaken to: 1) identify specific clinical markers associated with radiographic evidence of OPA, isolated laryngeal penetration (ILP) and post-swallow residue (PSR); 2) determine the sensitivity and specificity of clinical markers associated with OPA; and 3) determine the influence of age and neurological impairment on clinical markers of OPA. In total, 11 clinical markers of dysphagia were compared with the videofluoroscopic swallow study (VFSS) results (OPA, ILP and PSR) in 150 children on diets of thin fluid and purée consistencies. Chi-squared and logistic regression were used to analyse the association between clinical markers and VFSS-identified swallowing dysfunction. In children with OPA, wet voice (odds ratio (OR) 8.90, 95% confidence interval (CI) 2.87-27.62), wet breathing (OR 3.35, 95% CI 1.09-10.28) and cough (OR 3.30, 95% CI 1.17-9.27) were significantly associated with thin fluid OPA. Predictive values included: wet voice (sensitivity 0.67; specificity 0.92); wet breathing (sensitivity 0.33; specificity 0.83); and cough (sensitivity 0.67; specificity 0.53). No clinical markers were significantly associated with OPA, ILP or PSR on the purée consistency. Cough was significantly associated with PSR on thin fluids (OR 3.59, 95% CI 1.22-10.55). Differences were found for age. Wet voice, wet breathing and cough were good clinical markers for children with oropharyngeal aspiration on thin fluid but not on purée. Age and neurological status influenced the significance of these clinical markers.

Restriction of oral intake of water for aspiration lung disease in children

BACKGROUND

Primary aspiration of food and fluid is commonly seen in children with feeding and swallowing difficulties associated with a range of diseases and complex medical conditions. Respiratory sequelae and pneumonia are known to be associated with primary aspiration of ingested material, however causality between primary aspiration of specific food and fluid types and pulmonary effects in children is yet to be established in controlled trials. The relative pulmonary morbidity of aspiration of ingested food and fluid materials versus other causes of respiratory disease such as viral and bacterial causes, secondary aspiration of gastrointestinal contents and predisposing lung conditions such as chronic neonatal lung disease in a developing immune system is also unclear. Current management decisions for children who aspirate have to optimise oral nutrition and hydration, while reducing the risk of aspiration to preserve pulmonary integrity. This generally includes restricting aspirated food or fluids and providing texture-modified diets and thickened fluids. Young children frequently refuse thickened fluids providing a management dilemma for both families and health professionals.

OBJECTIVES

Our objective was to evaluate the efficacy of restriction of oral water ingestion on the pulmonary status of children with thin fluid aspiration demonstrated on a modified barium swallow study.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Airways Collaborative Review Group Specialised Register, MEDLINE, EMBASE and CINAHL databases were searched by the Cochrane Airways Group. The latest search was performed in January 2005.

SELECTION CRITERIA

All randomised controlled trials comparing restriction of oral intake of water with unlimited oral water ingestion were eligible to be included.

DATA COLLECTION AND ANALYSIS

Results of searches were reviewed against a pre-determined criteria for inclusion. No eligible trials were identified for a paediatric population and thus no data were available for analysis. One trial in an adult population was identified and reported.

MAIN RESULTS

No randomised controlled trials examining the efficacy of restriction of oral intake of water in the management of children with thin fluid aspiration were found. In a single study in an adult population with stroke, no significant differences were seen between a control group of oral water restriction and the experimental group of unlimited oral water ingestion on outcomes such as pneumonia, total oral fluid intake and dehydration.

AUTHORS' CONCLUSIONS

There are no trials that have adequately evaluated the pulmonary effects of allowing or restricting oral water ingestion in children known to have primary aspiration of thin fluids. Thus, there is currently an absence of evidence to support a strict approach of full restriction of oral intake of water or support a more liberal approach of allowing oral water ingestion in children with primary aspiration of thin fluids.

Number of viable CD34(+) cells reinfused predicts engraftment in autologous hematopoietic stem cell transplantation

Reduced CD34(+) cell viability due to cryopreservation has unknown effects on subsequent hematopoietic engraftment in autologous transplantation. Thirty-six consecutive autologous peripheral stem cell collections were analyzed for absolute viable CD34(+) cell numbers at the time of stem cell collection and prior to re-infusion. Viable CD34(+) cells were enumerated using single platform flow cytometry and the molecular exclusion dye 7-amino actinomycin D. The median number of viable CD34(+) cells was 3.6 x 10(6)/kg at the time of harvest and 2.0 x 10(6)/kg after thawing. When viable CD34(+)cells enumerated after thawing were <2.0, 2.0-5.0, or >5.0 x 10(6)/kg, the median time to platelet engraftment was 17, 12 and 10 days, respectively (P < 0.05 for comparison of the group with <2.0 x 10(6)/kg and the other two groups), and the median time to neutrophil engraftment was 13, 14 and 12 days, respectively (P = NS). A minimum of 2.0 x 10(6) CD34(+) cells/kg was harvested in 33 of 36 patients (92%) but only 19 of 36 (52%) patients met this threshold at the time of reinfusion. The reduced numbers of viable CD34(+) cells measured prior to re-infusion is associated with time to platelet engraftment and may be useful in monitoring stem cell loss during processing and identifying patients at risk of graft failure.

Body weight does not predict for anti-Xa levels after fixed dose prophylaxis with enoxaparin after orthopedic surgery

Enoxaparin after joint arthroplasty is effective prophylaxis against venous thromboembolism. This is usually given as a fixed dose without monitoring of anti-Xa levels. This study assesses the relationship between trough anti-Xa levels, body weight, and venous thromboembolism. Consenting patients at three institutions were treated with Enoxaparin 30 mg subcutaneously bis in die postoperatively until discharge. Chromogenic anti-Xa levels were measured on the fifth postoperative day by the method of Stachrome (Diagnostica Stago). All patients had bilateral compression doppler ultrasonography on day 10 or discharge and were followed for 12 weeks for evidence of venous thromboembolism. Eleven patients developed objectively confirmed venous thromboembolism during the study. In this study, there was poor correlation between weight and anti-Xa levels. In addition, body weight and anti-Xa levels of patients who developed venous thromboembolism were compared to those who did not and there were no significant differences between the two groups. In conclusion, this study shows that there is poor correlation of trough anti-Xa levels with body weight. Recognizing the low overall event rate this study does not support the need to monitor anti-Xa levels or adjusting the dose according to weight.

Single platform flow cytometric absolute CD34+ cell counts based on the ISHAGE guidelines. International Society of Hematotherapy and Graft Engineering

In concert with the International Society of Hematotherapy and Graft Engineering (ISHAGE), we previously described a set of guidelines for detection of CD34+ cells based on a four-parameter flow cytometry method (CD45 FITC/CD34 PE staining, side and forward angle light scatter). With this procedure, an absolute CD34+ count is generated by incorporating the leukocyte count from an automated hematology analyser (two-platform method). In the present study, we modified the basic ISHAGE method with the addition of a known number of Flow-Count fluorospheres. To reduce errors inherent to sample washing/centrifugation, we implemented ammonium chloride lyse, no-wash no-fix sample processing. These modifications convert the basic protocol into a single-platform method to determine the absolute CD34 count directly from a flow cytometer and form the basis of the Stem-Kit from Coulter/Immunotech. A total of 72 samples of peripheral blood, apheresis packs, and cord blood were analysed and compared using the ISHAGE protocol with or without the addition of fluorescent microspheres. Comparison of methods showed a high correlation coefficient (r=0.99), with no statistically significant difference or bias between methods (P > 0.05). Linearity of the absolute counting method generated an R2 value of 1.00 over the range of 0-250/microl. Precision of the absolute counting method measured at three concentrations of CD34+-stabilised KG1 a cells (Stem-Trol, COULTER) generated a coefficient of variation (C.V.) ranging from 4% to 9.9%. In a further modification of the single-platform method, the viability dye 7-amino actinomycin D was included and demonstrated that both viable and nonviable CD34+ cells could be identified and quantitated. Together, these modifications combine the accuracy and sensitivity of the original ISHAGE method with the ability to produce an absolute count of viable CD34+ cells. It is the accurate determination of this value that is most clinically relevant in the transplant setting. These modifications may improve the interlaboratory reproducibility of CD34 determinations due to the reduction in sample handling and calculation of results.

Silicone gel enhances the development of autoimmune disease in New Zealand black mice but fails to induce it in BALB/cAnPt mice

Anecdotal evidence links silicone gel breast implants with the development of autoimmune connective tissue disease in women. To investigate whether silicone gel is capable of directly inducing and/or enhancing the development of autoimmune disease, female BALB/cAnPt (BALB/c) and New Zealand Black (NZB) mice were injected subcutaneously with silicone gel, pristane, a nonmetabolizable substance that can cause plasmacytomas in BALB/c and NZB mice, or saline and monitored for the development of glomerulonephritis and autoantibody production. NZB, but not BALB/c, mice spontaneously develop autoantibodies and an autoimmune hemolytic anemia by 12 months of age. Over a period of 10 months, biweekly screening for proteinuria revealed increases in urinary protein in NZB mice that received multiple injections of either silicone gel or pristane. In contrast, urinary protein was unaffected in identically treated BALB/c mice. Although, silicone gel had no effect on serum titers of antierythrocyte antibodies in NZB mice, the hematocrits were significantly decreased. Moreover, silicone gel both increased the concentration of IgM anti-type I collagen antibodies and skewed the immunofluorescent staining pattern of serum autoantibodies on HEp-2 cells. In contrast, silicone gel failed to induce the production of anti-erythrocyte or antinuclear antibodies in BALB/c mice and induced only slight increases in IgG anti-type I collagen antibodies. These results suggest that silicone gel can exacerbate the development of autoimmune disease in autoimmune NZB mice, but fails to induce disease in normal BALB/c mice. This is consistent with several epidemiological studies failing to demonstrate an increase in the incidence of autoimmune disease in women with breast implants. However, because silicone gel was able to exacerbate autoimmune disease in NZB mice, it may play a similar role in the development of autoimmune disease in a small percentage of women who are genetically susceptible to such diseases.

Measurement of up- and down-lead fiber sensitivity caused by the lead in a multimode fiber in an interferometric system

The results of a comparative experimental study on the effect of the modal noise induced by lead-in fibers in an extrinsic interferometric system, illuminated by high- and low-coherence light sources, respectively, are reported. When the up-lead fiber was subject to a perturbation, the sensitivity of the system was reduced by 20.9 dB through the use of a high-coherence source, and by 1.8 dB through the use of a low-coherence source. When the down-lead fiber was perturbed, the sensitivity dropped by 30.3 dB and 4.9 dB for high- and low-coherence sources, respectively. The results from the experimental analysis supported qualitatively by simple theory show that the use of a low-coherence light source can greatly suppress the modal noise induced in both the up- and down-lead fibers, if the coherence length of the light source used is less than the optical path difference between two adjacent fiber modes. This shows the practicality of the use of niultimode fibers in an interferometric system with a suitable lig t source.

Optimized multiwavelength combination sources for interferometric use

We present the use of multiwavelength combination sources in a direct method for improved central fringe identification in a white-light interferometric system. The optimum wavelength combinations of such sources can be obtained by the use of the results of a simple analysis. We find that this multiwavelength technique can greatly reduce the minimum signal-to-noise ratio required by the systemwhen used to identify the central fringe, and thus it offers an increased signal resolution. As a result, it is suitable for high-precision measurement purposes as well as for applications in coherence multiplexed interferometric sensor systems.

Assessment of the validity of the INR system for patients with liver impairment

The INR system was developed to standardize PT reporting in patients on oral anticoagulants. We prospectively collected blood samples from 29 patients with liver impairment (INR 1.5-3.5). Control patients were on warfarin (n = 31). PT's were measured on an ACL-300 with three thromboplastin reagents. INR's were calculated using instrument specific ISI's. Other tests performed were FDP's, fibrinogen, aPTT, factors II, V, VII and X. The INR's for each patient in the study population using the three thromboplastin reagents were significantly different (p = 0.0001). Those for the control population were not (p = 0.0658). Fibrinogen, factors V, II and X were different at the 5% level of significance between the populations. FDP's were detected in 17 study subjects. The INR system is not valid for comparison of patients with liver impairment because different reagents do not give the same INR for the same sample. It is, however, no less valid than the use of PT with different thromboplastin reagents. Further study is recommended.

Relation between the coherence length and modal noise in a graded-index multimode fiber for white-light interferometric systems

The results of a comparative experimental study on the effect of modal noise induced by the modal coupling effect in a graded-index multimode fiber that is illuminated by a light source with a tunable coherence length are reported. It has been shown that, in the coherence-length region of 30-80 microm, the value of the signal-to-noise ratio in an interferometric system could be reduced by the perturbation-induced modal noise, and, as the coherence length increases, the more the signal-to-noise ratio decreases. However, when the value of the coherence length is in the region of 80 microm and upward, the value of the corresponding signal-to-noise ratio reduction is seen to vary in only a very small range (<2 dBV). Under this condition the modal noise induced in the fiber cannot be suppressed by the incoherent nature of the light source, thus showing the practical limitation of the use of multimode fibers in an interferometric system with a low-coherence light source.

Characteristics of synthesized light sources for white-light interferometric systems

Results of a study on the use of synthesized light sources in white-light interferometry are presented. The optimum wavelength combination with a pair of multimode laser diodes used to generate a synthetic wavelength source was simulated theoretically and verified experimentally. Using the best wavelength combination, we found that the lowest signal-to-noise ratio required by the system was 18.1 dB in theory and 22.1 dB from experiment. The relationships between the wavelengths of the two diodes used, their coherence lengths, and the signal-to-noise ratio required by the system are shown and discussed.

Anti-platelet agents reduce morphological changes of chronic hypoxic pulmonary hypertension

The pathophysiologic mechanism by which chronic hypoxia causes pulmonary hypertension is unknown. If anti-platelet agents, or other pharmacologic interventions, altered the pulmonary vascular changes induced by hypoxia, information concerning the pathogenesis of the pulmonary hypertension or the potential therapeutic usefulness of the drugs might be obtained. In Study 1, rats exposed to chronic hypobaric hypoxia (PB = 520 mmHg) had a pulmonary arterial medial thickness of 6.7 +/- 0.6 mu compared to 4.1 +/- 0.2 mu* for control, normoxic rats (*p less than 0.05). Administration of dipyridamole (2mg/kg/day), or sulfinpyrazone (11 mg/kg/day) in the drinking water reduced the medial thickness to 5.0 +/- 0.3 mu* and 5.4 +/- 0.5 mu* respectively, thus suggesting the possible involvement of platelets in the response of the media to chronic hypoxia. In Study 2, hypoxic rats treated with the calcium blocker, flunarizine, were found to have less medial hypertrophy than a control group of hypoxic rats. This observation suggests that a decrease in transmembrane calcium flux may also reduce medial hypertrophy.

Elimination of artifactual acetaldehyde in the measurement of human blood acetaldehyde by the use of polyethylene glycol and sodium azide: normal blood acetaldehyde levels in the dog and human after ethanol

A new procedure is described for the preparation of human blood samples for analysis of acetaldehyde and ethanol by head space gas chromatography. High concentrations of polyethylene glycol were used to remove the hemoglobin and approximately 50% of the plasma protein. Artifactual formation of acetaldehyde from ethanol was inhibited by sodium azide. Using this method, no artifactual acetaldehyde was detectable in human, dog, sheep, and rat blood when spiked with ethanol in final concentrations of 65 mM. The recovery of added acetaldehyde was approximately 80% for human dog, and sheep blood, whereas it was only 30% for rat blood. Following ethanol administration, acetaldehyde levels were determined in blood taken from the pulmonary artery and descending aorta of the dog and human, and also from the hepatic vein of the latter. The relative blood acetaldehyde concentrations at these sites were hepatic vein greater than pulmonary artery greater than descending aorta.

Night and day wetting among a population of three-year-olds

An epidemiological study of the emotional and intellectual development of 705 three-year-old children was used to estimate the prevalence of day and night wetting and to examine some factors associated with continence. 56 per cent of boys and 40 per cent of girls were stated to be wet at night. 22 per cent of boys and 12 per cent of girls were wet by day. These prevalence rates are higher than those reported in most other studies, and the possible reasons for this are discussed. Wetting at this age seems to be largely under the control of maturational factors, there being minimal evidence of an association between wetting status and a wide variety of social, emotional and physical stresses.

Acute onset of autistic features following brain damage in a ten-year-old

We report the case of a 10-year-old boy who, following a prolonged period of unconsciousness, displayed severe eye-to-eye gaze avoidance, sensory inattention, and some other behavioral symptoms normally associated with the syndrome of infantile autism. The symptoms lasted only a few months and were associated with the more permanent behavioral changes of postencephalitic psychosis. Serial computerized tomography scans were taken during his illness and recovery. The relevance of this case to the etiology of infantile autism is discussed.

Psychological factors in feeding disorders occurring in mentally or multiply handicapped children

This is a discussion of the psychological aspects of non-organic feeding problems occurring in infancy and early childhood. There are particular difficulties caused by parental responses to a handicapped child and these increase the likelihood of feeding problems. The temperament and personality of the child can pose additional problems. Early counselling for families of handicapped babies can facilitate normal mourning and the mobilization of practical help, and reduce the incidence of non-organic feeding problems.