Comprehensive Biotransformation Analysis of Phenylalanine-Tyrosine Metabolism Reveals Alternative Routes of Metabolite Clearance in Nitisinone-Treated Alkaptonuria.

Metabolomic analyses in alkaptonuria (AKU) have recently revealed alternative pathways in phenylalanine-tyrosine (phe-tyr) metabolism from biotransformation of homogentisic acid (HGA), the active molecule in this disease. The aim of this research was to study the phe-tyr metabolic pathway and whether the metabolites upstream of HGA, increased in nitisinone-treated patients, also undergo phase 1 and 2 biotransformation reactions. Metabolomic analyses were performed on serum and urine from patients partaking in the SONIA 2 phase 3 international randomised-controlled trial of nitisinone in AKU (EudraCT no. 2013-001633-41). Serum and urine samples were taken from the same patients at baseline (pre-nitisinone) then at 24 and 48 months on nitisinone treatment (patients N = 47 serum; 53 urine) or no treatment (patients N = 45 serum; 50 urine). Targeted feature extraction was performed to specifically mine data for the entire complement of theoretically predicted phase 1 and 2 biotransformation products derived from phenylalanine, tyrosine, 4-hydroxyphenylpyruvic acid and 4-hydroxyphenyllactic acid, in addition to phenylalanine-derived metabolites with known increases in phenylketonuria. In total, we observed 13 phase 1 and 2 biotransformation products from phenylalanine through to HGA. Each of these products were observed in urine and two were detected in serum. The derivatives of the metabolites upstream of HGA were markedly increased in urine of nitisinone-treated patients (fold change 1.2-16.2) and increases in 12 of these compounds were directly proportional to the degree of nitisinone-induced hypertyrosinaemia (correlation coefficient with serum tyrosine = 0.2-0.7). Increases in the urinary phenylalanine metabolites were also observed across consecutive visits in the treated group. Nitisinone treatment results in marked increases in a wider network of phe-tyr metabolites than shown before. This network comprises alternative biotransformation products from the major metabolites of this pathway, produced by reactions including hydration (phase 1) and bioconjugation (phase 2) of acetyl, methyl, acetylcysteine, glucuronide, glycine and sulfate groups. We propose that these alternative routes of phe-tyr metabolism, predominantly in urine, minimise tyrosinaemia as well as phenylalanaemia.

Does Direct Surgical Decompression After Traumatic Spinal Cord Injury Influence Post-Traumatic Syringomyelia Rates? An 18-Year Single-Center Experience.

OBJECTIVE: Risk factors for post-traumatic syringomyelia (PTS) development after traumatic spinal cord injury (tSCI) are incompletely understood. This study aimed to investigate the influence of direct surgical decompression after tSCI, as well as demographic, clinical, and other management-related factors, on rates of PTS development. METHODS: A single-center case-control study was conducted on patients who presented with tSCI to a tertiary referral center over an 18-year period and received adequate follow-up. Cases were defined by both clinical suspicion and radiologic evidence of PTS. Demographic, clinical, and management-related data were collected and a multivariable logistic regression analysis performed. RESULTS: A total of 286 patients were analyzed, of whom 33 (11.5%) demonstrated PTS. Direct surgical decompression with or without stabilization was performed in 190 of 286 patients, stabilization alone in 47, and non-surgical management in 49. On multivariable analysis, no significant influence on PTS risk was demonstrated for method of acute management (P > 0.05). A ten-year increase in age at injury was shown to decrease PTS rates by 0.72 (P = 0.01). Neurologically complete injury was associated with an increased rate of PTS, though this association did not achieve significance (P = 0.08). When only surgically managed patients were considered (n = 237), no significant influence on PTS rates was demonstrated for anterior decompression (adjusted odds ratio = 1.13, 95% CI = 0.34-3.74, P = 0.84) and for stabilization alone (adjusted odds ratio = 1.19, 95% CI = 0.39-3.61, P = 0.76) relative to posterior decompression. CONCLUSIONS: Direct surgical decompression after tSCI was not demonstrated to significantly influence rates of PTS development. Age at injury and severity of injury should be considered as risk factors for PTS on follow-up.

Use of machine learning to model surgical decision-making in lumbar spine surgery.

PURPOSE: The majority of lumbar spine surgery referrals do not proceed to surgery. Early identification of surgical candidates in the referral process could expedite their care, whilst allowing timelier implementation of non-operative strategies for those who are unlikely to require surgery. By identifying clinical and imaging features associated with progression to surgery in the literature, we aimed to develop a machine learning model able to mirror surgical decision-making and calculate the chance of surgery based on the identified features. MATERIAL AND METHODS: In total, 55 factors were identified to predict surgical progression. All patients presenting with a lumbar spine complaint between 2013 and 2019 at a single Australian Tertiary Hospital (n = 483) had their medical records reviewed and relevant data collected. An Artificial Neural Network (ANN) was constructed to predict surgical candidacy. The model was evaluated on its accuracy, discrimination, and calibration. RESULTS: Eight clinical and imaging predictive variables were included in the final model. The ANN was able to predict surgical progression with 92.1% accuracy. It also exhibited excellent discriminative ability (AUC = 0.90), with good fit of data (Calibration slope 0.938, Calibration intercept - 0.379, HLT > 0.05). CONCLUSION: Through use of machine learning techniques, we were able to model surgical decision-making with a high degree of accuracy. By demonstrating that the operating patterns of single centres can be modelled successfully, the potential for more targeted and tailored referrals becomes possible, reducing outpatient wait-list duration and increasing surgical conversion rates.

Expression of tyrosine pathway enzymes in mice demonstrates that homogentisate 1,2-dioxygenase deficiency in the liver is responsible for homogentisic acid-derived ochronotic pigmentation.

Alkaptonuria (AKU) is caused by homogentisate 1,2-dioxygenase (HGD) deficiency. This study aimed to determine if HGD and other enzymes related to tyrosine metabolism are associated with the location of ochronotic pigment. Liver, kidney, skin, bone, brain, eyes, spleen, intestine, lung, heart, cartilage, and muscle were harvested from 6 AKU BALB/c Hgd -/- (3 females, 3 males) and 4 male C57BL/6 wild type (WT) mice. Hgd, 4-hydroxyphenylpyruvate dioxygenase (4-Hppd), tyrosine hydroxylase (Th), and tyrosinase (Tyr) mRNA expression was investigated using qPCR. Adrenal gland and gonads from AKU Hgd tm1a -/- mice were LacZ stained, followed by qPCR analysis of Hgd mRNA. The liver had the highest expression of Hgd, followed by the kidney, with none detected in cartilage or brain. Low-level Hgd expression was observed within developing male germ cells within the testis and epididymis in Hgd tm1a -/-. 4-Hppd was most abundant in liver, with smaller amounts in kidney and low-level expression in other tissues. Th was expressed mainly in brain and Tyr was found primarily in the eyes. The tissue distribution of both Hgd and 4-Hppd suggest that ochronotic pigment in AKU mice is a consequence of enzymes within the liver, and not from enzymatic activity within ochronotic tissues. Excessive accumulation of HGA as ochronotic pigment in joints and other connective tissues originates from the circulation and therefore the extracellular fluid. The tissue distribution of both Th and Tyr suggests that these enzymes are not involved in the formation of HGA-derived ochronotic pigment.

Anatomical Distribution of Ochronotic Pigment in Alkaptonuric Mice is Associated with Calcified Cartilage Chondrocytes at Osteochondral Interfaces.

Alkaptonuria (AKU) is characterised by increased circulating homogentisic acid and deposition of ochronotic pigment in collagen-rich connective tissues (ochronosis), stiffening the tissue. This process over many years leads to a painful and severe osteoarthropathy, particularly affecting the cartilage of the spine and large weight bearing joints. Evidence in human AKU tissue suggests that pigment binds to collagen. The exposed collagen hypothesis suggests that collagen is initially protected from ochronosis, and that ageing and mechanical loading causes loss of protective molecules, allowing pigment binding. Schmorl's staining has previously demonstrated knee joint ochronosis in AKU mice. This study documents more comprehensively the anatomical distribution of ochronosis in two AKU mouse models (BALB/c Hgd-/-, Hgd tm1a-/-), using Schmorl's staining. Progression of knee joint pigmentation with age in the two AKU mouse models was comparable. Within the knee, hip, shoulder, elbow and wrist joints, pigmentation was associated with chondrons of calcified cartilage. Pigmented chondrons were identified in calcified endplates of intervertebral discs and the calcified knee joint meniscus, suggesting that calcified tissues are more susceptible to pigmentation. There were significantly more pigmented chondrons in lumbar versus tail intervertebral disc endplates (p = 0.002) and clusters of pigmented chondrons were observed at the insertions of ligaments and tendons. These observations suggest that loading/strain may be associated with increased pigmentation but needs further experimental investigation. The calcified cartilage may be the first joint tissue to acquire matrix damage, most likely to collagen, through normal ageing and physiological loading, as it is the first to become susceptible to pigmentation.

Reversal of ochronotic pigmentation in alkaptonuria following nitisinone therapy: Analysis of data from the United Kingdom National Alkaptonuria Centre.

BACKGROUND: Increased homogentisic acid (HGA) causes ochronosis. Nitisinone decreases HGA. The aim was to study the effect of nitisinone on the ochronosis progression. METHODS: Photographs of the eyes and ears were acquired from patients attending the National Alkaptonuria Centre (NAC) at V-1 (pre-baseline visit), V0 (baseline visit when 2 mg nitisinone was commenced), and yearly at V1, V2, and V3 visits. Photographs were inspected for evolution of ochronotic pigment and also scored categorically to derive eye, ear, and combined ochronosis scores. An ear cartilage biopsy was also carried out at V0 and one year after V3 (V4) and ochronotic pigment was assessed and quantitated. Visits were compared for changes in pigment. Fasting blood and 24-hour urine samples were collected for measurement of HGA. RESULTS: There were 80 AKU patients at V0, and 52, 47, and 40 at V1, V2, and V3 in the group with variable numbers (VAR Group) respectively; 23 patients attended once before V0, in the V-1 visit. Photographs of patients show increase in eye pigment between V-1 and V0, followed by decrease post-nitisinone at V1, V2, and V3. Ear and combined ochronosis semiquantitative scoring showed an increase between V-1 and V0 (P < .01), followed by a decrease at V1, V2, and V3, in the VAR group (P < .01). Ochronotic pigment in ear biopsy between V0 and V4 showed a 19.1% decrease (P < .05). CONCLUSIONS: Nitisinone decreases HGA and partially reverses ochronosis.

Seed size, number and strategies in annual plants: a comparative functional analysis and synthesis.

BACKGROUND AND AIMS: Plants depend fundamentally on establishment from seed. However, protocols in trait-based ecology currently estimate seed size but not seed number. This can be rectified. For annuals, seed number should simply be a positive function of vegetative biomass and a negative function of seed size. METHODS: Using published values of comparative seed number as the 'gold standard' and a large functional database, comparative seed yield and number per plant and per m2 were predicted by multiple regression. Subsequently, ecological variation in each was explored for English and Spanish habitats, newly calculated C-S-R strategies and changed abundance in the British flora. KEY RESULTS: As predicted, comparative seed mass yield per plant was consistently a positive function of plant size and competitive ability, and largely independent of seed size. Regressions estimating comparative seed number included, additionally, seed size as a negative function. Relationships differed numerically between regions, habitats and C-S-R strategies. Moreover, some species differed in life history over their geographical range. Comparative seed yield per m2 was positively correlated with FAO crop yield, and increasing British annuals produced numerous seeds. Nevertheless, predicted values must be viewed as comparative rather than absolute: they varied according to the 'gold standard' predictor used. Moreover, regressions estimating comparative seed yield per m2 achieved low precision. CONCLUSIONS: For the first time, estimates of comparative seed yield and number for >800 annuals and their predictor equations have been produced and the ecological importance of these regenerative traits has been illustrated. 'Regenerative trait-based ecology' remains in its infancy, with work needed on determinate vs. indeterminate flowering ('bet-hedging'), C-S-R methodologies, phylogeny, comparative seed yield per m2 and changing life history. Nevertheless, this has been a positive start and readers are invited to use estimates for >800 annuals, in the Supplementary data, to help advance 'regenerative trait-based ecology' to the next level.

Dietary restriction of tyrosine and phenylalanine lowers tyrosinemia associated with nitisinone therapy of alkaptonuria.

Alkaptonuria (AKU) is caused by homogentisate 1,2-dioxygenase deficiency that leads to homogentisic acid (HGA) accumulation, ochronosis and severe osteoarthropathy. Recently, nitisinone treatment, which blocks HGA formation, has been effective in AKU patients. However, a consequence of nitisinone is elevated tyrosine that can cause keratopathy. The effect of tyrosine and phenylalanine dietary restriction was investigated in nitisinone-treated AKU mice, and in an observational study of dietary intervention in AKU patients. Nitisinone-treated AKU mice were fed tyrosine/phenylalanine-free and phenylalanine-free diets with phenylalanine supplementation in drinking water. Tyrosine metabolites were measured pre-nitisinone, post-nitisinone, and after dietary restriction. Subsequently an observational study was undertaken in 10 patients attending the National Alkaptonuria Centre (NAC), with tyrosine >700 µmol/L who had been advised to restrict dietary protein intake and where necessary, to use tyrosine/phenylalanine-free amino acid supplements. Elevated tyrosine (813 µmol/L) was significantly reduced in nitisinone-treated AKU mice fed a tyrosine/phenylalanine-free diet in a dose responsive manner. At 3 days of restriction, tyrosine was 389.3, 274.8, and 144.3 µmol/L with decreasing phenylalanine doses. In contrast, tyrosine was not effectively reduced in mice by a phenylalanine-free diet; at 3 days tyrosine was 757.3, 530.2, and 656.2 µmol/L, with no dose response to phenylalanine supplementation. In NAC patients, tyrosine was significantly reduced (P = .002) when restricting dietary protein alone, and when combined with tyrosine/phenylalanine-free amino acid supplementation; 4 out of 10 patients achieved tyrosine <700 µmol/L. Tyrosine/phenylalanine dietary restriction significantly reduced nitisinone-induced tyrosinemia in mice, with phenylalanine restriction alone proving ineffective. Similarly, protein restriction significantly reduced circulating tyrosine in AKU patients.

Conditional targeting in mice reveals that hepatic homogentisate 1,2-dioxygenase activity is essential in reducing circulating homogentisic acid and for effective therapy in the genetic disease alkaptonuria.

Alkaptonuria is an inherited disease caused by homogentisate 1,2-dioxygenase (HGD) deficiency. Circulating homogentisic acid (HGA) is elevated and deposits in connective tissues as ochronotic pigment. In this study, we aimed to define developmental and adult HGD tissue expression and determine the location and amount of gene activity required to lower circulating HGA and rescue the alkaptonuria phenotype. We generated an alkaptonuria mouse model using a knockout-first design for the disruption of the HGD gene. Hgd tm1a -/- mice showed elevated HGA and ochronosis in adulthood. LacZ staining driven by the endogenous HGD promoter was localised to only liver parenchymal cells and kidney proximal tubules in adulthood, commencing at E12.5 and E15.5 respectively. Following removal of the gene trap cassette to obtain a normal mouse with a floxed 6th HGD exon, a double transgenic was then created with Mx1-Cre which conditionally deleted HGD in liver in a dose dependent manner. 20% of HGD mRNA remaining in liver did not rescue the disease, suggesting that we need more than 20% of liver HGD to correct the disease in gene therapy. Kidney HGD activity which remained intact reduced urinary HGA, most likely by increased absorption, but did not reduce plasma HGA nor did it prevent ochronosis. In addition, downstream metabolites of exogenous 13C6-HGA, were detected in heterozygous plasma, revealing that hepatocytes take up and metabolise HGA. This novel alkaptonuria mouse model demonstrated the importance of targeting liver for therapeutic intervention, supported by our observation that hepatocytes take up and metabolise HGA.

Endonasal endoscopic pituitary surgery in the elderly.

OBJECTIVE Pituitary adenomas are benign, slow-growing tumors that cause symptoms either through mass effect or hormone overproduction. The decision to operate on a healthy young person is relatively straightforward. In the elderly population, however, the risks of complications may increase, rendering the decision more complex. Few studies have documented the risks of surgery using the endonasal endoscopic approach in a large number of elderly patients. The purpose of this study was to audit a single center's data regarding outcomes of purely endoscopic endonasal transsphenoidal resection of pituitary adenomas in elderly patients and to compare them to the current literature. METHODS A retrospective review of a prospectively acquired database of all endonasal endoscopic surgeries done by the senior authors was queried for patients aged 60-69 years and for those aged 70 years or older. Demographic and radiographic preoperative data were reviewed. Outcomes with respect to extent of resection and complications were examined and compared with appropriate statistical tests. RESULTS A total of 135 patents were identified (81 aged 60-69 years and 54 aged 70 years or older [70+]). The average tumor diameter was slightly larger for the patients in the 70+ age group (mean [SD] 25.7 ± 9.2 mm) than for patients aged 60-69 years (23.1 ± 9.8 mm, p = 0.056). There was no significant difference in intraoperative blood loss (p > 0.99), length of stay (p = 0.22), or duration of follow-up (p = 0.21) between the 2 groups. There was a 7.4% complication rate in patients aged 60-69 years (3 nasal and 3 medical complications) and an 18.5% complication rate in patients older than 70 years (4 cranial, 3 nasal, 1 visual, and 2 medical complications; p = 0.05 overall and 0.013 for cranial complications). Cranial complications in the 70+ age category included 2 postoperative hematomas, 1 pseudoaneurysm formation, and 1 case of symptomatic subdural hygromas. CONCLUSIONS Endonasal endoscopic surgery in elderly patients is safe, but there is a graded increase in complication rates with increasing age. The decision to operate on an asymptomatic or mildly symptomatic patient in these age groups should take this increasing complication rate into account. The use of a lumbar drain or lumbar punctures should be weighed against the risk of subdural hematoma in patients with preexisting atrophy.

Corrigendum: Whole-genome landscape of pancreatic neuroendocrine tumours.

This corrects the article DOI: 10.1038/nature21063.

Trade-offs between seed and leaf size (seed-phytomer-leaf theory): functional glue linking regenerative with life history strategies and taxonomy with ecology?

Background and Aims: While the 'worldwide leaf economics spectrum' (Wright IJ, Reich PB, Westoby M, et al. 2004. The worldwide leaf economics spectrum. Nature : 821-827) defines mineral nutrient relationships in plants, no unifying functional consensus links size attributes. Here, the focus is upon leaf size, a much-studied plant trait that scales positively with habitat quality and components of plant size. The objective is to show that this wide range of relationships is explicable in terms of a seed-phytomer-leaf (SPL) theoretical model defining leaf size in terms of trade-offs involving the size, growth rate and number of the building blocks (phytomers) of which the young shoot is constructed. Methods: Functional data for 2400+ species and English and Spanish vegetation surveys were used to explore interrelationships between leaf area, leaf width, canopy height, seed mass and leaf dry matter content (LDMC). Key Results: Leaf area was a consistent function of canopy height, LDMC and seed mass. Additionally, size traits are partially uncoupled. First, broad laminas help confer competitive exclusion while morphologically large leaves can, through dissection, be functionally small. Secondly, leaf size scales positively with plant size but many of the largest-leaved species are of medium height with basally supported leaves. Thirdly, photosynthetic stems may represent a functionally viable alternative to 'small seeds + large leaves' in disturbed, fertile habitats and 'large seeds + small leaves' in infertile ones. Conclusions: Although key elements defining the juvenile growth phase remain unmeasured, our results broadly support SPL theory in that phytometer and leaf size are a product of the size of the initial shoot meristem (≅ seed mass) and the duration and quality of juvenile growth. These allometrically constrained traits combine to confer ecological specialization on individual species. Equally, they appear conservatively expressed within major taxa. Thus, 'evolutionary canalization' sensu Stebbins (Stebbins GL. 1974. Flowering plants: evolution above the species level . Cambridge, MA: Belknap Press) is perhaps associated with both seed and leaf development, and major taxa appear routinely specialized with respect to ecologically important size-related traits.

Whole-genome landscape of pancreatic neuroendocrine tumours.

The diagnosis of pancreatic neuroendocrine tumours (PanNETs) is increasing owing to more sensitive detection methods, and this increase is creating challenges for clinical management. We performed whole-genome sequencing of 102 primary PanNETs and defined the genomic events that characterize their pathogenesis. Here we describe the mutational signatures they harbour, including a deficiency in G:C > T:A base excision repair due to inactivation of MUTYH, which encodes a DNA glycosylase. Clinically sporadic PanNETs contain a larger-than-expected proportion of germline mutations, including previously unreported mutations in the DNA repair genes MUTYH, CHEK2 and BRCA2. Together with mutations in MEN1 and VHL, these mutations occur in 17% of patients. Somatic mutations, including point mutations and gene fusions, were commonly found in genes involved in four main pathways: chromatin remodelling, DNA damage repair, activation of mTOR signalling (including previously undescribed EWSR1 gene fusions), and telomere maintenance. In addition, our gene expression analyses identified a subgroup of tumours associated with hypoxia and HIF signalling.

Hypermutation In Pancreatic Cancer.

Pancreatic cancer is molecularly diverse, with few effective therapies. Increased mutation burden and defective DNA repair are associated with response to immune checkpoint inhibitors in several other cancer types. We interrogated 385 pancreatic cancer genomes to define hypermutation and its causes. Mutational signatures inferring defects in DNA repair were enriched in those with the highest mutation burdens. Mismatch repair deficiency was identified in 1% of tumors harboring different mechanisms of somatic inactivation of MLH1 and MSH2. Defining mutation load in individual pancreatic cancers and the optimal assay for patient selection may inform clinical trial design for immunotherapy in pancreatic cancer.

c-Fos induction by gut hormones and extracellular ATP in osteoblastic-like cell lines.

It is widely accepted that the c-Fos gene has a role in proliferation and differentiation of bone cells. ATP-induced c-Fos activation is relevant to bone homeostasis, because nucleotides that are present in the environment of bone cells can contribute to autocrine/paracrine signalling. Gut hormones have previously been shown to have an effect on bone metabolism. In this study, we used the osteoblastic Saos-2 cell line transfected with a c-Fos-driven reporter stimulated with five gut hormones: glucose inhibitory peptide (GIP), glucagon-like peptide-1 (GLP-1), glucagon-like peptide-2 (GLP-2), ghrelin and obestatin, in the presence or absence of ATP. In addition, TE-85 cells were used to determine the time course of c-Fos transcript induction following stimulation with GLP-1, and GLP-2 with or without ATP, using reverse transcription qPCR. The significant results from the experiments are as follows: higher level of c-Fos induction in presence of GIP, obestatin (p = 0.019 and p = 0.011 respectively), and GIP combined with ATP (p < 0.001) using the luciferase assay; GLP-1 and GLP-2 combined with ATP (p = 0.034 and p = 0.002, respectively) and GLP-2 alone (p < 0.001) using qPCR. In conclusion, three of the gut peptides induced c-Fos, providing a potential mechanism underlying the actions of these hormones in bone which can be directed or enhanced by the presence of ATP.

Genomic analyses identify molecular subtypes of pancreatic cancer.

Integrated genomic analysis of 456 pancreatic ductal adenocarcinomas identified 32 recurrently mutated genes that aggregate into 10 pathways: KRAS, TGF-ß, WNT, NOTCH, ROBO/SLIT signalling, G1/S transition, SWI-SNF, chromatin modification, DNA repair and RNA processing. Expression analysis defined 4 subtypes: (1) squamous; (2) pancreatic progenitor; (3) immunogenic; and (4) aberrantly differentiated endocrine exocrine (ADEX) that correlate with histopathological characteristics. Squamous tumours are enriched for TP53 and KDM6A mutations, upregulation of the TP63∆N transcriptional network, hypermethylation of pancreatic endodermal cell-fate determining genes and have a poor prognosis. Pancreatic progenitor tumours preferentially express genes involved in early pancreatic development (FOXA2/3, PDX1 and MNX1). ADEX tumours displayed upregulation of genes that regulate networks involved in KRAS activation, exocrine (NR5A2 and RBPJL), and endocrine differentiation (NEUROD1 and NKX2-2). Immunogenic tumours contained upregulated immune networks including pathways involved in acquired immune suppression. These data infer differences in the molecular evolution of pancreatic cancer subtypes and identify opportunities for therapeutic development.

Functional polymorphisms in the P2X7 receptor gene are associated with stress fracture injury.

Military recruits and elite athletes are susceptible to stress fracture injuries. Genetic predisposition has been postulated to have a role in their development. The P2X7 receptor (P2X7R) gene, a key regulator of bone remodelling, is a genetic candidate that may contribute to stress fracture predisposition. The aim of this study is to evaluate the putative contribution of P2X7R to stress fracture injury in two separate cohorts, military personnel and elite athletes. In 210 Israeli Defense Forces (IDF) military conscripts, stress fracture injury was diagnosed (n = 43) based on symptoms and a positive bone scan. In a separate cohort of 518 elite athletes, self-reported medical imaging scan-certified stress fracture injuries were recorded (n = 125). Non-stress fracture controls were identified from these cohorts who had a normal bone scan or no history or symptoms of stress fracture injury. Study participants were genotyped for functional SNPs within the P2X7R gene using proprietary fluorescence-based competitive allele-specific PCR assay. Pearson's chi-squared (χ (2)) tests, corrected for multiple comparisons, were used to assess associations in genotype frequencies. The variant allele of P2X7R SNP rs3751143 (Glu496Ala-loss of function) was associated with stress fracture injury, whilst the variant allele of rs1718119 (Ala348Thr-gain of function) was associated with a reduced occurrence of stress fracture injury in military conscripts (P < 0.05). The association of the variant allele of rs3751143 with stress fractures was replicated in elite athletes (P < 0.05), whereas the variant allele of rs1718119 was also associated with reduced multiple stress fracture cases in elite athletes (P < 0.05). The association between independent P2X7R polymorphisms with stress fracture prevalence supports the role of a genetic predisposition in the development of stress fracture injury.

Trends in Acute Primary Angle-Closure Glaucoma, Peripheral Iridotomy and Cataract Surgery in Scotland, 1998-2012.

PURPOSE: We present rates of acute primary angle-closure glaucoma (APACG), peripheral iridotomy (PI) and cataract surgery in Scotland between 1998 and 2012. METHODS: The number of patients in Scotland with APACG in each of the years between 1998 and 2012 was obtained from Information Service Division (ISD) Scotland. Data was also obtained for patients who had undergone laser PI and cataract surgery. The annual rates of APACG, PI and cataract surgery were calculated using Scotland's population data during each of these years. RESULTS: Between 1998 and 2012 the rate of APACG in National Health Service patients decreased by 46.4% (from 46.7 to 25.0 per million, p < 0.005). The rate of PI increased overall by 116.3% (from 38.0 to 82.2 per million), but demonstrated a decrease of 48.2% (38.0 to 19.7 per million, p = 0.002) between 1998 and 2008, and an increase of 317.3% (19.7 to 82.2 per million, p = 0.005) between 2008 and 2012. Over the same 15-year period, cataract surgery increased by 73.4% (from 354.2 to 615.2 per 100,000, p < 0.005). In this timeframe, mid-year Scottish population estimates increased by 4.6%. CONCLUSION: Our results demonstrate a significant reduction in the rate of APACG in the Scottish population between 1998 and 2012, along with a rising rate of PI and cataract surgery. The trend of decreasing APACG may be due to the increasing rate of cataract surgery in the same time period. This parallels patterns seen in other European countries. We discuss these findings together with other related epidemiological factors.

Annular Salzmann degeneration: Avoiding perturbations and pitfalls in phacoemulsification surgery.

UNLABELLED: We highlight potential problems and pitfalls in cases of Salzmann nodular degeneration by reporting the case of an 84-year-old man with reduced visual acuity due to particularly extensive bilateral Salzmann nodules and moderate cataracts. Large annular Salzmann lesions were removed by superficial keratectomy in each eye. The reproducibility and accuracy of keratometry and biometry improved significantly, and uneventful phacoemulsification cataract surgery was performed 4 weeks after the keratectomy. The phacoemulsification procedures were routine other than the development of pronounced epithelial bullae in the area of Salzmann nodule excision. At final review, the uncorrected distance visual acuity was 20/20 in the right eye and 20/25 in the left eye. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.