C-to-G editing generates double-strand breaks causing deletion, transversion and translocation.

Base editors (BEs) introduce base substitutions without double-strand DNA cleavage. Besides precise substitutions, BEs generate low-frequency 'stochastic' byproducts through unclear mechanisms. Here, we performed in-depth outcome profiling and genetic dissection, revealing that C-to-G BEs (CGBEs) generate substantial amounts of intermediate double-strand breaks (DSBs), which are at the centre of several byproducts. Imperfect DSB end-joining leads to small deletions via end-resection, templated insertions or aberrant transversions during end fill-in. Chromosomal translocations were detected between the editing target and off-targets of Cas9/deaminase origin. Genetic screenings of DNA repair factors disclosed a central role of abasic site processing in DSB formation. Shielding of abasic sites by the suicide enzyme HMCES reduced CGBE-initiated DSBs, providing an effective way to minimize DSB-triggered events without affecting substitutions. This work demonstrates that CGBEs can initiate deleterious intermediate DSBs and therefore require careful consideration for therapeutic applications, and that HMCES-aided CGBEs hold promise as safer tools.

Immediately sequential bilateral cataract surgery (ISBCS) adapted protocol during COVID-19.

OBJECTIVE: To describe the steps, hurdles, and recommendations for implementation of the immediately sequential bilateral cataract surgery (ISBCS) evidence-based protocol at a high-volume Canadian tertiary care centre. DESIGN: Quality-improvement study. PARTICIPANTS: A total of 406 patients who underwent ISBCS from July 2020 to December 2020. Patients were selected based on specific inclusion and exclusion criteria including psychosocial factors, refractive error and consent. This initiative impacted staff at all levels involved with cataract surgery. METHODS: The Model of Improvement framework was used and involved numerous discussions with multidisciplinary teams of ophthalmologists, nursing and support staff, management, pharmacists, and medical device reprocessing teams. This initiative was created and refined via a thorough review of the literature and current best practices. It was implemented in July 2020 after a nursing "huddle." Any adverse outcomes and overall impact were collected from various levels of staff involved. RESULTS: Each eye was treated as a separate surgery with a double time-out per bilateral case. Additional measures were taken to ensure different lot numbers for medications, equipment, and materials. This practice increased surgical volume by approximately 25% and reduced the number of patient visits by 50%, reducing potential COVID-19 exposure. CONCLUSIONS: The resulting protocol from our study may be useful to other centres wishing to integrate ISBCS as one example of successful implementation. Of the 406 cases of ISBCS performed, we report zero cases of toxic anterior segment syndrome or endophthalmitis. In times of decreased elective surgeries, ISBCS is a safe and effective option to supplement surgical volume and provide significant patient benefits.

Evaluation of the characteristics of primary iridociliary cysts using ultrasound biomicroscopy at a tertiary care centre.

OBJECTIVE: To evaluate the ultrasound biomicroscopic characteristics of primary iridociliary cysts presenting to a Canadian tertiary care centre. DESIGN: Retrospective study. PARTICIPANTS: A total of 189 patients (212 eyes) referred to the Sinai Health System (Toronto) for suspected iris abnormalities. METHODS: Clinical records of patients referred between March 2016 and October 2019 were reviewed. All patients were evaluated and received a diagnosis of an iridociliary cyst using ultrasound biomicroscopy (UBM). Data were collected for age, sex, involvement (iris vs ciliary body), laterality, size, and location on initial examination and subsequent follow-up. RESULTS: Of the 189 patients (212 eyes) with iridociliary cysts, more were female (65.1%) versus male (34.9%). The highest incidence occurred in females aged 21-30 years (13.2%). The iris pigment epithelium was involved in 84.4%, and only the ciliary body was involved in 3.8%. Both the iris pigment epithelium and the ciliary body were involved in 10.8%. The size of the cysts ranged between 0.5 and 4.41 mm in diameter. Cysts greater than 1 mm in diameter occurred in 78.7%, and 86.8% of cysts occurred unilaterally. Twelve percent were multicystic, and 8.5% were multiloculated, with 1% exhibiting both features. Twenty-three eyes (12.2%) were reviewed at 1 year of follow-up with UBM. Stable iridociliary cysts with no appreciable change in size were seen in 73.9% (n = 17). Iridociliary cyst growth was noted at 4 months in 1 patient. CONCLUSION: Information regarding iridociliary cysts is not easily available in the literature. UBM is a helpful clinical tool in the evaluation of iris abnormalities. Iridociliary cysts tend to be stable and compatible with a low rate of complications.

Does This Patient With Acute Infectious Conjunctivitis Have a Bacterial Infection?: The Rational Clinical Examination Systematic Review.

Importance: Acute infectious conjunctivitis is characterized by ocular redness and discharge, and is a common clinical entity. Evidence-based tools to aid the clinical diagnosis of viral vs bacterial conjunctivitis are lacking and may contribute to overprescribing of topical antibiotics. Objective: To determine the relative prevalence of viral vs bacterial conjunctivitis in adults and children, and to determine which symptoms or signs are suggestive of a viral vs bacterial etiology. Data Sources: A MEDLINE search (January 1946-March 2022) yielded 1891 articles. Included articles were rated using a quality score based on a modified Rational Clinical Examination grading system. Methodological quality levels 1 through 4 required a microbiological reference standard for diagnosis, whereas quality level 5 (the lowest quality) used a clinical reference standard for diagnosis. Study Selection: Consecutive series of patients presenting with acute infectious conjunctivitis and case series of viral or bacterial conjunctivitis alone. Thirty-two studies were included in a meta-analysis to determine prevalence and diagnostic accuracy measures; 27 used a microbiological reference standard for diagnosis and 5 used a clinical reference standard for diagnosis. Results: In studies involving children (5 studies; 881 patients; mean age, 4.7 years [age range, 1 month-18 years]), the prevalence of bacterial conjunctivitis was higher than viral conjunctivitis (71% vs 16%, respectively, P = .01). In the only study of adults (n = 207 patients; mean age, 25.7 years), the prevalence of viral conjunctivitis was higher than bacterial conjunctivitis (78% vs 16%, respectively, P < .001). For the primary analysis of level 1 (n = 6) and level 2 (n = 5) studies (1725 patients total), the clinical findings that best distinguished a viral etiology for conjunctivitis from a bacterial etiology included pharyngitis (sensitivity range, 0.55-0.58; specificity range, 0.89-0.94; positive likelihood ratio [LR] range, 5.4-9.9), preauricular lymphadenopathy (sensitivity range, 0.17-0.31; specificity range, 0.93-0.94; positive LR range, 2.5-5.6), and contact with another person with red eye (sensitivity, 0.18 [95% CI, 0.14-0.22]; specificity, 0.93 [95% CI, 0.90-0.95]; positive LR, 2.5 [95% CI, 1.6-3.7]). Mucopurulent ocular discharge (sensitivity, 0.76 [95% CI, 0.60-0.87); specificity, 0.66 [95% CI, 0.58-0.73]; positive LR, 2.1 [95% CI, 1.7-2.6]) and otitis media (sensitivity, 0.24 [95% CI, 0.20-0.29]; specificity, 0.91 [95% CI, 0.85-0.94]; positive LR, 2.5 [95% CI, 1.5-4.4]) were associated with the presence of bacterial conjunctivitis. Conclusions and Relevance: In this review, bacterial conjunctivitis was more common than viral conjunctivitis in children and viral conjunctivitis was more common than bacterial conjunctivitis in adults, although the prevalence estimates were based on limited evidence. Symptoms and signs associated with a higher likelihood of viral conjunctivitis in adults and children included concomitant pharyngitis, an enlarged preauricular node, and contact with another person with red eye, and signs associated with a higher likelihood of bacterial conjunctivitis included the presence of mucopurulent discharge and otitis media, but no single symptom or sign differentiated the 2 conditions with high certainty.

Differences in Metabolic Profiles of Healthy Dogs Fed a High-Fat vs. a High-Starch Diet.

Obesity is a common problem in dogs and overconsumption of energy-rich foods is a key factor. This study compared the inflammatory response and fecal metabolome of dogs fed a high-fat vs. a high-starch diet. Ten healthy lean adult beagles were equally allocated into two groups in a cross-over design. Each group received two diets in which fat (horse fat) and starch (pregelatinized corn starch) were exchanged in an isocaloric way to compare high fat vs. high starch. There was a tendency to increase the glucose and glycine concentrations and the glucose/insulin ratio in the blood in dogs fed with the high-fat diet, whereas there was a decrease in the level of Non-esterified fatty acids and a tendency to decrease the alanine level in dogs fed with the high-starch diet. Untargeted analysis of the fecal metabolome revealed 10 annotated metabolites of interest, including L-methionine, which showed a higher abundance in dogs fed the high-starch diet. Five other metabolites were upregulated in dogs fed the high-fat diet, but could not be annotated. The obtained results indicate that a high-starch diet, compared to a high-fat diet, may promote lipid metabolism, anti-oxidative effects, protein biosynthesis and catabolism, mucosal barrier function, and immunomodulation in healthy lean dogs.

Uncovering a conserved vulnerability site in SARS-CoV-2 by a human antibody.

An essential step for SARS-CoV-2 infection is the attachment to the host cell receptor by its Spike receptor-binding domain (RBD). Most of the existing RBD-targeting neutralizing antibodies block the receptor-binding motif (RBM), a mutable region with the potential to generate neutralization escape mutants. Here, we isolated and structurally characterized a non-RBM-targeting monoclonal antibody (FD20) from convalescent patients. FD20 engages the RBD at an epitope distal to the RBM with a KD of 5.6 nM, neutralizes SARS-CoV-2 including the current Variants of Concern such as B.1.1.7, B.1.351, P.1, and B.1.617.2 (Delta), displays modest cross-reactivity against SARS-CoV, and reduces viral replication in hamsters. The epitope coincides with a predicted "ideal" vulnerability site with high functional and structural constraints. Mutation of the residues of the conserved epitope variably affects FD20-binding but confers little or no resistance to neutralization. Finally, in vitro mode-of-action characterization and negative-stain electron microscopy suggest a neutralization mechanism by which FD20 destructs the Spike. Our results reveal a conserved vulnerability site in the SARS-CoV-2 Spike for the development of potential antiviral drugs.

Serum symmetric dimethylarginine shows a relatively consistent long-term concentration in healthy dogs with a significant effect of increased body fat percentage.

Symmetric dimethylarginine (SDMA) is a promising renal marker that correlates well with the glomerular filtration rate and could allow earlier detection of impaired renal function. The main objectives of this study were to assess the long-term variability of SDMA in healthy dogs and examine the influence of an increased body fat percentage on the level of SDMA. Sixteen lean Beagles were randomly assigned to the control group or weight-change group in age- and gender-matched pairs. The energy intake of the control group (n = 8) was strictly regulated to maintain an ideal body weight for 83 weeks, while the weight-change group (n = 8) was fed to induce weight gain (week 0-47), to maintain stable excessive body weight (week 47-56) and to lose weight (week 56-83), consecutively. At 8 specified time points, the body condition score, body composition, glomerular filtration rate, serum concentration of SDMA and creatinine were analyzed. In the control group, the within-subject coefficient of variation, between-subject coefficient of variation, reference change value (type I error = 5%) and index of individuality were 0.16, 0.22, 0.43 and 0.73, respectively. The control group and weight-change group did not differ significantly in SDMA concentration. SDMA showed a significant negative association (coefficient = -0.07) with body fat percentage (p<0.01) in the weight-change group and a significant positive association (coefficient = 7.79) with serum creatinine (p<0.01) in the entire study population. In conclusion, SDMA concentration has high long-term stability in healthy adult dogs. For the evaluation of SDMA concentrations, subject-specific reference values are preferred over a population-based reference value seen their higher sensitivity. Moreover, an increased body fat percentage does seem to affect the serum SDMA concentration of otherwise healthy dogs, but its clinical relevance has to be clarified in further research.

Smartphone Compatible versus Conventional Ophthalmoscope: A Randomized Crossover Educational Trial.

Objective The aim of the study is to compare performance and ease-of-use (EOU) of optic disk assessment using a smartphone direct ophthalmoscope attachment (D-EYE) to the gold standard direct ophthalmoscope (DO). Design The type of study involved is prospective, randomized, crossover, and educational trial. Participants The participants involved were first year medical students inexperienced in ophthalmoscopy. Methods Optic disks of standardized and volunteer patients were examined using the D-EYE and a conventional DO. Optic disk identification, EOU ratings of the devices, self-reported confidence level in their examination with the devices, and estimation of vertical cup-to-disk ratio (VCDR) were compared. Analyses included Chi-square tests, independent samples t -tests, correlations, and multivariable linear regression. Results Forty-four medical students voluntarily participated in the study. Students using the DO required more attempts (3.57 vs. 2.69, p = 0.010) and time (197.00 vs. 168.02 seconds, p = 0.043) to match the patient's fundus to the correct photograph. Overall EOU between the devices (6.40 vs. 4.79, p < 0.001) and overall confidence in examination (5.65 vs. 4.49, p = 0.003) were greater when using the D-EYE. There were no statistically significant differences in accuracy of VCDR estimations between the two ophthalmoscopes. Conclusion Smartphone ophthalmoscopy could offer additional learning opportunities in medical education and may be considered in clinical practice by non-specialist physicians given its greater EOU and increased success in visualizing the optic disk.

The development of neutralizing antibodies against SARS-CoV-2 and their common features.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a worldwide severe coronavirus disease 2019 (COVID-19) pandemic since December 2019. There is a great demand for effective therapies for the prevention and treatment of COVID-19. Developing therapeutic neutralizing antibodies (NAbs), which could block viral infection, is such a promising approach, as NAbs have been successfully applied to the treatment of other viral infections. The recent advances of antibody technology have greatly accelerated the discovery of SARS-CoV-2 NAbs, and many of which are now actively tested in clinical trials. Here, we review the approaches applied for SARS-CoV-2 NAb development, and discuss the emerging technologies underlining the antibody discovery. We further summarize the common features of these antibodies including the shared neutralizing epitopes and sequence features.

ERCC6L2 promotes DNA orientation-specific recombination in mammalian cells.

Programmed DNA recombination in mammalian cells occurs predominantly in a directional manner. While random DNA breaks are typically repaired both by deletion and by inversion at approximately equal proportions, V(D)J and class switch recombination (CSR) of immunoglobulin heavy chain gene overwhelmingly delete intervening sequences to yield productive rearrangement. What factors channel chromatin breaks to deletional CSR in lymphocytes is unknown. Integrating CRISPR knockout and chemical perturbation screening we here identify the Snf2-family helicase-like ERCC6L2 as one such factor. We show that ERCC6L2 promotes double-strand break end-joining and facilitates optimal CSR in mice. At the cellular levels, ERCC6L2 rapidly engages in DNA repair through its C-terminal domains. Mechanistically, ERCC6L2 interacts with other end-joining factors and plays a functionally redundant role with the XLF end-joining factor in V(D)J recombination. Strikingly, ERCC6L2 controls orientation-specific joining of broken ends during CSR, which relies on its helicase activity. Thus, ERCC6L2 facilitates programmed recombination through directional repair of distant breaks.

Weight-gain induced changes in renal perfusion assessed by contrast-enhanced ultrasound precede increases in urinary protein excretion suggestive of glomerular and tubular injury and normalize after weight-loss in dogs.

Early detection of obesity-related glomerulopathy in humans is challenging as it might not be detected by routine biomarkers of kidney function. This study's aim was to use novel kidney biomarkers and contrast-enhanced ultrasound (CEUS) to evaluate the effect of obesity development and weight-loss on kidney function, perfusion, and injury in dogs. Sixteen healthy lean adult beagles were assigned randomly but age-matched to a control group (CG) (n = 8) fed to maintain a lean body weight (BW) for 83 weeks; or to a weight-change group (WCG) (n = 8) fed the same diet to induce obesity (week 0-47), to maintain stable obese weight (week 47-56) and to lose BW (week 56-83). At 8 time points, values of systolic blood pressure (sBP); serum creatinine (sCr); blood urea nitrogen (BUN); serum cystatin C (sCysC); urine protein-to-creatinine ratio (UPC); and urinary biomarkers of glomerular and tubular injury were measured. Glomerular filtration rate (GFR) and renal perfusion using CEUS were assayed (except for week 68). For CEUS, intensity- and time-related parameters representing blood volume and velocity were derived from imaging data, respectively. At 12-22% weight-gain, cortical time-to-peak, representing blood velocity, was shorter in the WCG vs. the CG. After 37% weight-gain, sCysC, UPC, glomerular and tubular biomarkers of injury, urinary immunoglobulin G and urinary neutrophil gelatinase-associated lipocalin, respectively, were higher in the WCG. sBP, sCr, BUN and GFR were not significantly different. After 23% weight-loss, all alterations were attenuated. Early weight-gain in dogs induced renal perfusion changes measured with CEUS, without hyperfiltration, preceding increased urinary protein excretion with potential glomerular and tubular injury. The combined use of routine biomarkers of kidney function, CEUS and site-specific urinary biomarkers might be valuable in assessing kidney health of individuals at risk for obesity-related glomerulopathy in a non-invasive manner.

Histiocytic sarcoma of the eyelid.

Histiocytic Sarcoma is a rare malignant hematopoietic neoplasm that can present in extranodal sites including lymph nodes, skin, gastrointestinal tract, and the central nervous system. Only 10% of cases manifest as skin lesions and very few are reported in the head and neck. The authors report a case of histiocytic sarcoma of the eyelid in a 72-year-old male that was clinically diagnosed as a chalazion. Initial excision was not sent for routine histopathological assessment and the patient was subsequently lost to follow up. Recurrence occurred at the eyelid site and additional lesions were found on the forearms, abdomen, and right knee. Histopathological assessment of one of these other sites confirmed the diagnosis of histiocytic sarcoma. To our knowledge, this is the first reported case of disseminated histiocytic sarcoma that originally presented in the ocular adnexa (eyelid). And, as the initial lesion was not sent to Pathology and therefore potentially missed, this case highlights the importance of submitting tissue, including chalazia, for pathologic evaluation.

Establishment of a biobank for human lung tissues of congenital diaphragmatic hernia and congenital pulmonary airway malformation.

BACKGROUND: Human tissue samples are an invaluable and little available source of information for translational studies of congenital lung diseases such as Congenital Diaphragmatic Hernia (CDH) or Congenital Pulmonary Airway Malformation (CPAM). PURPOSE: We aimed to establish a human lung tissue biobank of CDH and CPAM patients together with age-matched controls, coupled with a clinical database. METHODS: Pathology records from autopsies or surgical specimens for CDH and CPAM cases between 1980 and 2017 were reviewed. For surviving individuals, clinical patient data was obtained from corresponding pediatric surgery reports. Formalin-fixed, paraffin-embedded tissues of patients and age-matched controls were systematically stored for further translational studies. RNA integrity was determined on selected CDH blocks. RESULTS: A total of 16 CDH and 18 CPAM and age-matched control lung tissue blocks were included in our biobank. Ages ranged from 22 to 41 weeks of gestation (GA) in CDH (33.9 ±â€¯6.35 weeks) and 26 weeks (GA) and 12 years in CPAM (2.3 ±â€¯3.7 y). RNA isolation from CDH and control blocks yielded good RNA quality (OD 260/280 ratio: 2.01-2.09, OD 260/230 ratio: 2.04-2.09). CONCLUSION: We established a unique human biobank for CDH and CPAM tissues. The combination with clinical patient data will allow us to design future translational studies to improve our understanding of the disease pathogenesis of these congenital malformations.

Renal perfusion parameters measured by contrast-enhanced ultrasound in healthy dogs demonstrate a wide range of variability in the long-term.

Contrast-enhanced ultrasound may be helpful for detecting early renal microvascular damage and dysfunction in dogs. However, before this noninvasive imaging method can be tested as an early-stage screening tool in clinical patients, an improved understanding of long-term variation in healthy animals is needed. In this prospective, secondary, longitudinal, serial measurements study, variability of contrast-enhanced ultrasound renal perfusion parameters was described for eight healthy dogs, using seven time points and a period of 83 weeks. Dogs were sedated with butorphanol (0.4 mg/kg), and contrast-enhanced ultrasound of each kidney was performed after an intravenous bolus injection of a microbubble contrast agent (0.04 mL/kg). Time-intensity curves were created from regions-of-interest drawn in the renal cortex and medulla. Intensity-related parameters representing blood volume and time-related parameters representing blood velocity were determined. A random-effects model using restricted maximum likelihood was used to estimate variance components. Within-dog coefficient of variation was defined as the ratio of the standard deviation over the mean. Time-related parameters such as time-to-peak, rise and fall time had lowest within-dog variability. Intensity-related parameters such as peak enhancement, wash-in and wash-out area under the curve, total area under the curve, and wash-in and washout rates had high within-dog variability (coefficient of variation > 45%). Authors therefore recommend the use of time-related parameters for future studies of renal perfusion. Within-dog variability for bilateral kidney measurements was extremely low, therefore contrast-enhanced ultrasound may be particularly useful for detecting unilateral changes in renal perfusion. Future studies are needed to compare contrast-enhanced ultrasound findings in healthy dogs versus dogs with renal disease.

Intrinsic Nucleotide Preference of Diversifying Base Editors Guides Antibody Ex Vivo Affinity Maturation.

Base editors (BEs) are emerging tools used for precision correction or diversifying mutation. It provides a potential way to recreate somatic hypermutations (SHM) for generating high-affinity antibody, which is usually screened from antigen-challenged animal models or synthetic combinatorial libraries. By comparing somatic mutations in the same genomic context, we screened engineered deaminases and CRISPR-deaminase coupling approaches and updated diversifying base editors (DBEs) to generate SHM. The deaminase used in DBEs retains its intrinsic nucleotide preference and mutates cytidines at its preferred motifs. DBE with AID targets the same hotspots as physiological AID does in vivo, while DBE with other deaminases generates distinct mutation profiles from the same DNA substrate. Downstream DNA repair pathways further diversified the sequence, while Cas9-nickase restricted mutation spreading. Finally, application of DBE in an antibody display system achieved antibody affinity maturation ex vivo. Our findings provide insight of DBE working mechanism and an alternative antibody engineering approach.

The response of canine faecal microbiota to increased dietary protein is influenced by body condition.

BACKGROUND: High protein diets shift the faecal microbiota into a more unfavourable composition in obese humans. In lean dogs, higher protein consumption is accompanied with increased production of putrefactive fermentation products, whereas obese dogs have a different gut microbiota compared to lean dogs. Still, the impact of high dietary protein on gut microbiota in obese dogs remains unclear. The aim of this study was to investigate faecal microbial changes in lean and obese dogs in response to two different levels of dietary protein. Six healthy lean and six obese Beagles were fed a high protein diet (HP) and a low protein diet (LP) for 28 days each in a crossover design. Denaturing gradient gel electrophoresis and quantitative PCR were performed on faecal samples for microbial profiling. Plasma acylcarnitine and fermentation metabolites were measured. RESULTS: Dogs fed HP had higher concentrations of protein fermentation metabolites including faecal ammonia, isovalerate, isobutyrate, phenol, indole, serum indoxyl sulphate and plasma 3-OH isovalerylcarnitine compared to dogs fed LP, whereas no changes in faecal concentrations of acetate and butyrate were observed. The abundances of clostridial clusters IV and XIVa, covering the majority of butyrate-producing bacteria, and of the butyrate kinase gene, one of the terminal genes of the butyrate synthesis pathway were higher in dogs on HP compared to LP. Significant interactions between diet and body condition were found for the abundance of Firmicutes, Lactobacillus and clostridial cluster I. The similarity coefficient of faecal microbiota between the two diets was smaller in obese dogs than in lean dogs. CONCLUSIONS: High protein diet increased the abundance and activity of butyrate-producing bacteria in Beagles independent of the body condition. In addition, increasing dietary protein content had a greater overall impact on faecal microbiota in obese compared to lean dogs.

Deviations from the expected relationship between serum FGF23 and other markers in children with CKD: a cross-sectional study.

BACKGROUND: High levels of fibroblast growth factor-23 (FGF23) are associated with mortality. In chronic kidney disease (CKD), FGF23 levels rise as renal function declines. We analyzed the contribution of laboratory values to the variance of FGF23 levels in relationship to a curve of expected FGF23 levels for a given GFR. METHODS: Following approval by the research ethics boards, we measured FGF23, CysC eGFR, creatinine, urea, albumin, calcium, phosphate, vitamin D metabolites, PTH, alkaline phosphatase, CRP, and venous gases in 141 pediatric CKD patients (45, 37, 32, 13 and 14 CKD stages I, II, III, IV, and V, respectively). Data were expressed as median (25th, 75th percentile). RESULTS: FGF23 correlated significantly with CysC, CysC eGFR, PTH, 1.25 (OH)2 vitamin D, phosphate, and pH. The correlation of the latter three remained significant in the multivariate analysis. We calculated a formula for the expected FGF23 value for a given level of eGFR which reads Y = 1295 * e-0.07247*X + 38.35. Deviation by more than 20% from the curve also depended on phosphate, 1.25 (OH)2 vitamin D and pH. CONCLUSIONS: Our data emphasize the importance of phosphate and 1.25 (OH)2 vitamin D levels. The impact of acidosis on FGF23 warrants further studies.

Does canine inflammatory bowel disease influence gut microbial profile and host metabolism?

BACKGROUND: Inflammatory bowel disease (IBD) refers to a diverse group of chronic gastrointestinal diseases, and gut microbial dysbiosis has been proposed as a modulating factor in its pathogenesis. Several studies have investigated the gut microbial ecology of dogs with IBD but it is yet unclear if this microbial profile can alter the nutrient metabolism of the host. The aim of the present study was to characterize the faecal bacterial profile and functionality as well as to determine host metabolic changes in IBD dogs. Twenty-three dogs diagnosed with IBD and ten healthy control dogs were included. Dogs with IBD were given a clinical score using the canine chronic enteropathy clinical activity index (CCECAI). Faecal short-chain fatty acids (SCFA) and ammonia concentrations were measured and quantitative PCR was performed. The concentration of plasma amino acids, acylcarnitines, serum folate, cobalamin, and indoxyl sulfate was determined. RESULTS: No significant differences in the abundance of a selection of bacterial groups and fermentation metabolites were observed between the IBD and control groups. However, significant negative correlations were found between CCECAI and the faecal proportion of Lactobacillus as well as between CCECAI and total SCFA concentration. Serum folate and plasma citrulline were decreased and plasma valine was increased in IBD compared to control dogs. Increased plasma free carnitine and total acylcarnitines were observed in IBD compared with control dogs, whereas short-chain acylcarnitines (butyrylcarnitine + isobutyrylcarnitine and, methylmalonylcarnitine) to free carnitine ratios decreased. Dogs with IBD had a higher 3-hydroxyisovalerylcarnitine + isovalerylcarnitine to leucine ratio compared to control dogs. CONCLUSIONS: Canine IBD induced a wide range of changes in metabolic profile, especially for the plasma concentrations of short-chain acylcarnitines and amino acids, which could have evolved from tissue damage and alteration in host metabolism. In addition, dogs with more severe IBD were characterised by a decrease in faecal proportion of Lactobacillus.

Fibroblast growth factor-23 and calcium phosphate product in young chronic kidney disease patients: a cross-sectional study.

BACKGROUND: Fibroblast growth factor-23 (FGF-23), a novel marker of bone disease in chronic kidney disease (CKD) has been shown to correlate with vascular calcifications. We aimed to describe the effect of the calcium phosphate product (Ca*P) on FGF-23 concentrations in children and young adults without confounding cardiovascular disease. METHODS: Pediatric and young adult patients with CKD stages I-V were recruited in this cross sectional study to measure FGF-23, cystatin C, vitamin D-metabolites and other serum markers of bone metabolism. FGF-23 levels were determined with an enzyme-linked immunosorbent assay. The association between FGF-23 and (Ca*P) was assessed using non-parametric methods. Patients were divided into two age groups, less than 13 years of age and greater than 13 years of age. RESULTS: This cross-sectional study measured serum FGF-23, in 81 patients (42 females, 51.9%) at London Health Sciences Centre, aged 2 to 25 years, with various stages of CKD (Cystatin C estimated glomerular filtration rate, eGFR=10.7-213.0 ml/min). For the whole entire group of patients, FGF-23 levels were found to correlate significantly with age (Spearman r= 0.26, p=0.0198), Cystatin C eGFR (Spearman r=-0.40 p=0.0002), CKD stage (Spearman r=0.457, p<0.0001), PTH (Spearman r=0.330, p=0.0039), ionized calcium (Spearman r=-0.330, p=0.0049), CysC (Spearman r= 0.404, p=0.0002) and 1,25-dihydroxyvitamin D (Spearman r=-0.345, p=0.0034) concentrations. No significant correlation was found between FGF-23 levels and calcium phosphate product (Spearman r= 0.164, p=0.142). Upon classification of patients into two age groups, less than 13 years of age and more than 13 years of age, correlational results differed significantly. FGF-23 correlated with CysC eGFR( Spearman r= -0.633, p<0.0001), CKD stage (Spearman r=0.731, p<0.0001), phosphate (Spearman r= 0.557, p<0.0001), calcium phosphate product (Spearman r=0.534, p<0.0001), 125(OH)2 Vit D (Spearman r=-0.631, p<0.0001), PTH (Spearman r= 0.475, p=0.0017) and ionized calcium (Spearman r= -0.503, p=0.0015) only in the older group. The relationship between FGF-23 and Ca*P for the older group could be expressed by the exponential model FGF-23= 38.15 e0.4625Ca*P. CONCLUSION: Abnormal values of FGF-23 in adolescents and young adults with CKD correlate with Ca* P in the absence of vascular calcifications, and may serve as a biomarker for the risk of cardiovascular calcifications.

Caffeine in bronchiolitis associated apnea: A retrospective cohort study.

Young infants with bronchiolitis commonly present with apnea. Caffeine is effective in treating apnea of prematurity and has been used to treat apnea associated with bronchiolitis. To evaluate whether caffeine administration to infants presenting with apnea in the setting of bronchiolitis was associated with a decreased rate of endotracheal intubation and mechanical ventilation, compared to infants who did not receive caffeine. Retrospective cohort study. University affiliated tertiary care children's hospital. Twenty-eight infants less than 3 months of age, 13 of whom received caffeine. Fewer infants who received caffeine required endotracheal intubation and invasive mechanical ventilation (OR = 0.30 95% CI 0.07 to 1.4, p = 0.15), but this was not statistically significant. Infants who received caffeine were more likely to be treated with non-invasive ventilation than infants in the control group (OR = 14; 95% CI 2.1 to 98 p = 0.01). Only one patient who was initially managed with non-invasive ventilation was subsequently intubated. There was no difference in the duration of total respiratory support, duration of invasive mechanical ventilation, hospital and pediatric critical care unit stay. All infants survived. This study does not provide adequate evidence to support or refute the routine use of caffeine in bronchiolitis associated apnea.