Outcomes of asymptomatic common bile duct stones detected at intraoperative cholangiography.

AIMS: The aim of this study was to investigate the outcome of common bile duct stones (CBDS) in asymptomatic patients at laparoscopic cholecystectomy (LC) and intra-operative cholangiogram (IOC). METHODS: All patients undergoing LC and IOC at Te Whatu Ora - Health New Zealand Waikato between January 2017 and January 2022 were retrospectively reviewed. Electronic records were screened for asymptomatic CBDS. Exclusion criteria were hyperbilirubinaemia, gallstone pancreatitis, cholangitis and imaging-detected CBDS. IOC reports were reviewed to determine presence of CBDS. A second blinded review was undertaken by a radiologist. Outcomes were use of endoscopic retrograde pancreatography (ERCP), complications and readmission with retained CBDS. RESULTS: Included were 1,297 patients undergoing LC and IOC. Of these, 150 (24.1%) patients had a positive IOC, of which 58 (38.7%) were asymptomatic. Attempted flushing of CBDS was employed in 49 cases, 10 successfully. Common duct exploration was successful in a further six out of seven cases. Of the remaining 42 patients, 18 were offered ERCP. Seven had no stone at endoscopy. Sixteen had imaging, revealing clear ducts in 14. The remaining two then had ERCP confirming choledocholithiasis. Eight patients were managed expectantly, of whom none required readmission with retained stones. CONCLUSION: Rates of retained asymptomatic stones after positive IOC were low. Acknowledging risks associated with intervention and low rates of readmission with retained CBDS, an expectant approach could be more readily considered.

AAST grade of liver injury is not the single most important consideration in decision making for liver trauma.

BACKGROUND: The liver is one of the most injured organs in both blunt and penetrating trauma. The aim of this study was to identify whether the AAST liver injury grade is predictive of need for intervention, risk of complications and mortality in our patient population, and whether this differs between blunt and penetrating-trauma mechanisms. METHODS: Retrospective review of all liver injuries from a single high-volume metropolitan trauma centre in South Africa from December 2012 to January 2022. Inclusion criteria were all adults who had sustained traumatic liver injury. Patients were excluded if they were under 15 years of age or had died prior to operation or assessment. Statistical analysis was undertaken using both univariate and multivariate models. RESULTS: 709 patients were included, of which 351 sustained penetrating and 358 blunt trauma. Only 24.3 % of blunt compared to 76.4 % of penetrating trauma patients underwent laparotomy (p< 0.001). In blunt trauma, increasing AAST grade correlated directly with rates of laparotomy with an odds ratio of 1.7 (p < 0.001). In penetrating trauma, there was no statistical significance between increasing AAST grade and the rate of laparotomy. The rate of bile leak was 4.5 % (32/709) and of rebleed was 0.7 % (5/709). Five patients underwent ERCP and endoscopic sphincterotomy for bile leak, and three required angio-embolization for rebleeding. Increasing AAST grades were significantly associated with the odds of bile leak in both blunt and penetrating trauma. There was a statistically significant increase in the odds of a rebleed with increasing AAST grade in penetrating trauma. Five patients rebled, of which three died. Seven patients developed hepatic necrosis. Seventy-six patients died (10 %). There were 34/358 (9 %) deaths in the blunt cohort and 42 /351 (11 %) deaths in the penetrating trauma cohort. CONCLUSION: AAST grade in isolation is not a good predictor of the need for operation in hepatic trauma. Increasing AAST grade was not found to correlate with increased risk of mortality for both blunt and penetrating hepatic trauma. In both blunt and penetrating trauma, increasing AAST grade is significantly associated with increased bile leak. The need for ERCP and endoscopic sphincterotomy to manage bile leak in our setting is low. Similarly, the rate of rebleeding and of angioembolization was low.

Structural maturation of SYCP1-mediated meiotic chromosome synapsis by SYCE3.

In meiosis, a supramolecular protein structure, the synaptonemal complex (SC), assembles between homologous chromosomes to facilitate their recombination. Mammalian SC formation is thought to involve hierarchical zipper-like assembly of an SYCP1 protein lattice that recruits stabilizing central element (CE) proteins as it extends. Here we combine biochemical approaches with separation-of-function mutagenesis in mice to show that, rather than stabilizing the SYCP1 lattice, the CE protein SYCE3 actively remodels this structure during synapsis. We find that SYCP1 tetramers undergo conformational change into 2:1 heterotrimers on SYCE3 binding, removing their assembly interfaces and disrupting the SYCP1 lattice. SYCE3 then establishes a new lattice by its self-assembly mimicking the role of the disrupted interface in tethering together SYCP1 dimers. SYCE3 also interacts with CE complexes SYCE1-SIX6OS1 and SYCE2-TEX12, providing a mechanism for their recruitment. Thus, SYCE3 remodels the SYCP1 lattice into a CE-binding integrated SYCP1-SYCE3 lattice to achieve long-range synapsis by a mature SC.

Tex19.1 inhibits the N-end rule pathway and maintains acetylated SMC3 cohesin and sister chromatid cohesion in oocytes.

Age-dependent oocyte aneuploidy, a major cause of Down syndrome, is associated with declining sister chromatid cohesion in postnatal oocytes. Here we show that cohesion in postnatal mouse oocytes is regulated by Tex19.1. We show Tex19.1-/- oocytes have defects maintaining chiasmata, missegregate their chromosomes during meiosis, and transmit aneuploidies to the next generation. Furthermore, we show that mouse Tex19.1 inhibits N-end rule protein degradation mediated by its interacting partner UBR2, and that Ubr2 itself has a previously undescribed role in negatively regulating the acetylated SMC3 subpopulation of cohesin in mitotic somatic cells. Lastly, we show that acetylated SMC3 is associated with meiotic chromosome axes in mouse oocytes, and that this population of cohesin is specifically depleted in the absence of Tex19.1. These findings indicate that Tex19.1 regulates UBR protein activity to maintain acetylated SMC3 and sister chromatid cohesion in postnatal oocytes and prevent aneuploidy from arising in the female germline.

Dazl determines primordial follicle formation through the translational regulation of Tex14.

Deleted in azoospermia-like (DAZL) is a germ cell RNA-binding protein that is essential for entry and progression through meiosis. The phenotype of the Dazl knockout mouse has extensive germ cell loss because of incomplete meiosis. We have created a Dazl hypomorph model using short interfering RNA knockdown in mouse fetal ovary cultures, allowing investigation of Dazl function in germ cell maturation. Dazl hypomorph ovaries had a phenotype of impaired germ cell nest breakdown with a 66% reduction in total follicle number and an increase in the proportion of primordial follicles (PMFs), with smaller oocytes within these follicles. There was no significant early germ cell loss or meiotic delay. Immunostaining of intercellular bridge component testis-expressed protein (Tex)14 showed ∼59% reduction in foci number and size, without any change in Tex14 mRNA levels. TEX14 expression was also confirmed in the human fetal ovary across gestation. Using 3'UTR-luciferase reporter assays, translational regulation of TEX14 was demonstrated to be DAZL-dependant. Dazl is therefore essential for normal intercellular bridges within germ cell nests and their timely breakdown, with a major impact on subsequent assembly of PMFs.-Rosario, R., Crichton, J. H., Stewart, H. L., Childs, A. J., Adams, I. R., Anderson, R. A. Dazl determines primordial follicle formation through the translational regulation of Tex14.

An ancient germ cell-specific RNA-binding protein protects the germline from cryptic splice site poisoning.

Male germ cells of all placental mammals express an ancient nuclear RNA binding protein of unknown function called RBMXL2. Here we find that deletion of the retrogene encoding RBMXL2 blocks spermatogenesis. Transcriptome analyses of age-matched deletion mice show that RBMXL2 controls splicing patterns during meiosis. In particular, RBMXL2 represses the selection of aberrant splice sites and the insertion of cryptic and premature terminal exons. Our data suggest a Rbmxl2 retrogene has been conserved across mammals as part of a splicing control mechanism that is fundamentally important to germ cell biology. We propose that this mechanism is essential to meiosis because it buffers the high ambient concentrations of splicing activators, thereby preventing poisoning of key transcripts and disruption to gene expression by aberrant splice site selection.

Defects in meiotic recombination delay progression through pachytene in Tex19.1-/- mouse spermatocytes.

Recombination, synapsis, chromosome segregation and gene expression are co-ordinately regulated during meiosis to ensure successful execution of this specialised cell division. Studies with multiple mutant mouse lines have shown that mouse spermatocytes possess quality control checkpoints that eliminate cells with persistent defects in chromosome synapsis. In addition, studies on Trip13mod/mod mice suggest that pachytene spermatocytes that successfully complete chromosome synapsis can undergo meiotic arrest in response to defects in recombination. Here, we present additional support for a meiotic recombination-dependent checkpoint using a different mutant mouse line, Tex19.1-/-. The appearance of early recombination foci is delayed in Tex19.1-/- spermatocytes during leptotene/zygotene, but some Tex19.1-/- spermatocytes still successfully synapse their chromosomes and we show that these spermatocytes are enriched for early recombination foci. Furthermore, we show that patterns of axis elongation, chromatin modifications and histone H1t expression are also all co-ordinately skewed towards earlier substages of pachytene in these autosomally synapsed Tex19.1-/- spermatocytes. We also show that this skew towards earlier pachytene substages occurs in the absence of elevated spermatocyte death in the population, that spermatocytes with features of early pachytene are present in late stage Tex19.1-/- testis tubules and that the delay in histone H1t expression in response to loss of Tex19.1 does not occur in a Spo11 mutant background. Taken together, these data suggest that a recombination-dependent checkpoint may be able to modulate pachytene progression in mouse spermatocytes to accommodate some types of recombination defect.

The role of splenic angioembolization as an adjunct to nonoperative management of blunt splenic injuries: A systematic review and meta-analysis.

BACKGROUND: Nonoperative management (NOM) of hemodynamically normal patients with blunt splenic injury (BSI) is the standard of care. Guidelines recommend additional splenic angioembolization (SAE) in patients with American Association for the Surgery of Trauma (AAST) Grade IV and Grade V BSI, but the role of SAE in Grade III injuries is unclear and controversial. The aim of this systematic review was to compare the safety and effectiveness of SAE as an adjunct to NOM versus NOM alone in adults with BSI. METHODS: A systematic literature search (Medline, Embase, and CINAHL) was performed to identify original studies that compared outcomes in adult BSI patients treated with SAE or NOM alone. Primary outcome was failure of NOM. Secondary outcomes included morbidity, mortality, hospital length of stay, and transfusion requirements. Bayesian meta-analyses were used to calculate an absolute (risk difference) and relative (risk ratio [RR]) measure of treatment effect for each outcome. RESULTS: Twenty-three studies (6,684 patients) were included. For Grades I to V combined, there was no difference in NOM failure rate (SAE, 8.6% vs NOM, 7.7%; RR, 1.09 [0.80-1.51]; p = 0.28), mortality (SAE, 4.8% vs NOM, 5.8%; RR, 0.82 [0.45-1.31]; p = 0.81), hospital length of stay (11.3 vs 9.5 days; p = 0.06), or blood transfusion requirements (1.8 vs 1.7 units; p = 0.47) between patients treated with SAE and those treated with NOM alone. However, morbidity was significantly higher in patients treated with SAE (SAE, 38.1% vs NOM, 18.6%; RR, 1.83 [1.20-2.66]; p < 0.01). When stratified by grade of splenic injury, SAE significantly reduced the failure rate of NOM in patients with Grade IV and Grade V splenic injuries but had minimal effect in those with Grade I to Grade III injuries. CONCLUSION: Splenic angioembolization should be strongly considered as an adjunct to NOM in patients with AAST Grade IV and Grade V BSI but should not be routinely recommended in patients with AAST Grade I to Grade III injuries. LEVEL OF EVIDENCE: Systematic review and meta-analysis, level III.

Tex19.1 promotes Spo11-dependent meiotic recombination in mouse spermatocytes.

Meiosis relies on the SPO11 endonuclease to generate the recombinogenic DNA double strand breaks (DSBs) required for homologous chromosome synapsis and segregation. The number of meiotic DSBs needs to be sufficient to allow chromosomes to search for and find their homologs, but not excessive to the point of causing genome instability. Here we report that the mammal-specific gene Tex19.1 promotes Spo11-dependent recombination in mouse spermatocytes. We show that the chromosome asynapsis previously reported in Tex19.1-/- spermatocytes is preceded by reduced numbers of recombination foci in leptotene and zygotene. Tex19.1 is required for normal levels of early Spo11-dependent recombination foci during leptotene, but not for upstream events such as MEI4 foci formation or accumulation of H3K4me3 at recombination hotspots. Furthermore, we show that mice carrying mutations in Ubr2, which encodes an E3 ubiquitin ligase that interacts with TEX19.1, phenocopy the Tex19.1-/- recombination defects. These data suggest that Tex19.1 and Ubr2 are required for mouse spermatocytes to accumulate sufficient Spo11-dependent recombination to ensure that the homology search is consistently successful, and reveal a hitherto unknown genetic pathway promoting meiotic recombination in mammals.

Arthroscopic "Remplissage" for shoulder instability: a systematic review.

PURPOSE: Large Hill-Sachs lesions engaging the glenoid rim predispose to recurrent anterior instability and failure of isolated labrum repairs. In arthroscopic remplissage, the posterior capsule and infraspinatus are sutured into the humeral defect to limit such engagement. This systematic review assessed the outcomes and complications of arthroscopic remplissage for anterior shoulder instability. METHODS: A search of the MEDLINE, EMBASE and evidence-based medicine Cochrane databases was conducted. Data were extracted by two reviewers in a standardised manner. Redislocation, instability and complication rates were calculated and expressed as percentages with 95 % confidence intervals. RESULTS: Of 4,284 studies identified, eight articles with a total of 207 patients were analysed. Mean redislocation rate was 4.2 ± 3.9 % (range 0-15 %), and mean recurrent instability rate 3.2 ± 3.8 % (0-15 %). Posterosuperior shoulder pain and stiffness were the only complications described. Overall, there was a mean reduction in external rotation in adduction of 5.6° (-40 to +30), reduction in external rotation in abduction of 11.3° (-50 to +7) and reduction in internal rotation of 0.9 (-4 to 0) vertebral levels. CONCLUSIONS: Arthroscopic remplissage alongside anterior labrum repair seems successful in treating recurrent shoulder instability in the presence of large or engaging Hill-Sachs lesion. However, the available literature consists mainly of heterogeneous case series. There is a need for a high-quality randomised trial to compare remplissage with other commonly used techniques for recurrent instability associated with substantial Hill-Sachs defects such as the Latarjet procedure. LEVEL OF EVIDENCE: Systematic review, Level IV.

Oocyte development, meiosis and aneuploidy.

Meiosis is one of the defining events in gametogenesis. Male and female germ cells both undergo one round of meiotic cell division during their development in order to reduce the ploidy of the gametes, and thereby maintain the ploidy of the species after fertilisation. However, there are some aspects of meiosis in the female germline, such as the prolonged arrest in dictyate, that appear to predispose oocytes to missegregate their chromosomes and transmit aneuploidies to the next generation. These maternally-derived aneuploidies are particularly problematic in humans where they are major contributors to miscarriage, age-related infertility, and the high incidence of Down's syndrome in human conceptions. This review will discuss how events that occur in foetal oocyte development and during the oocytes' prolonged dictyate arrest can influence meiotic chromosome segregation and the incidence of aneuploidy in adult oocytes.

The role of chromatin modifications in progression through mouse meiotic prophase.

Meiosis is a key event in gametogenesis that generates new combinations of genetic information and is required to reduce the chromosome content of the gametes. Meiotic chromosomes undergo a number of specialised events during prophase to allow meiotic recombination, homologous chromosome synapsis and reductional chromosome segregation to occur. In mammalian cells, DNA physically associates with histones to form chromatin, which can be modified by methylation, phosphorylation, ubiquitination and acetylation to help regulate higher order chromatin structure, gene expression, and chromosome organisation. Recent studies have identified some of the enzymes responsible for generating chromatin modifications in meiotic mammalian cells, and shown that these chromatin modifying enzymes are required for key meiosis-specific events that occur during meiotic prophase. This review will discuss the role of chromatin modifications in meiotic recombination, homologous chromosome synapsis and regulation of meiotic gene expression in mammals.

Defending the genome from the enemy within: mechanisms of retrotransposon suppression in the mouse germline.

The viability of any species requires that the genome is kept stable as it is transmitted from generation to generation by the germ cells. One of the challenges to transgenerational genome stability is the potential mutagenic activity of transposable genetic elements, particularly retrotransposons. There are many different types of retrotransposon in mammalian genomes, and these target different points in germline development to amplify and integrate into new genomic locations. Germ cells, and their pluripotent developmental precursors, have evolved a variety of genome defence mechanisms that suppress retrotransposon activity and maintain genome stability across the generations. Here, we review recent advances in understanding how retrotransposon activity is suppressed in the mammalian germline, how genes involved in germline genome defence mechanisms are regulated, and the consequences of mutating these genome defence genes for the developing germline.

Microarray analysis of LTR retrotransposon silencing identifies Hdac1 as a regulator of retrotransposon expression in mouse embryonic stem cells.

Retrotransposons are highly prevalent in mammalian genomes due to their ability to amplify in pluripotent cells or developing germ cells. Host mechanisms that silence retrotransposons in germ cells and pluripotent cells are important for limiting the accumulation of the repetitive elements in the genome during evolution. However, although silencing of selected individual retrotransposons can be relatively well-studied, many mammalian retrotransposons are seldom analysed and their silencing in germ cells, pluripotent cells or somatic cells remains poorly understood. Here we show, and experimentally verify, that cryptic repetitive element probes present in Illumina and Affymetrix gene expression microarray platforms can accurately and sensitively monitor repetitive element expression data. This computational approach to genome-wide retrotransposon expression has allowed us to identify the histone deacetylase Hdac1 as a component of the retrotransposon silencing machinery in mouse embryonic stem cells, and to determine the retrotransposon targets of Hdac1 in these cells. We also identify retrotransposons that are targets of other retrotransposon silencing mechanisms such as DNA methylation, Eset-mediated histone modification, and Ring1B/Eed-containing polycomb repressive complexes in mouse embryonic stem cells. Furthermore, our computational analysis of retrotransposon silencing suggests that multiple silencing mechanisms are independently targeted to retrotransposons in embryonic stem cells, that different genomic copies of the same retrotransposon can be differentially sensitive to these silencing mechanisms, and helps define retrotransposon sequence elements that are targeted by silencing machineries. Thus repeat annotation of gene expression microarray data suggests that a complex interplay between silencing mechanisms represses retrotransposon loci in germ cells and embryonic stem cells.

Mechanisms of traumatic shoulder injury in elite rugby players.

BACKGROUND: Shoulder injuries in rugby players are common, but the mechanisms of injury are less well understood. This study aims to elucidate common mechanisms of injury and identify the patterns of injury they produce. MATERIALS AND METHODS: Twenty-four elite rugby players, referred to the senior author for diagnosis and management of shoulder injuries, were selected. Videos of the injuries were independently reviewed by rugby-medical experts to describe the mechanisms of injury. The mechanisms reported were collated and analysed to determine the level of agreement between reviewers and conclude an overall description of injury mechanisms. RESULTS: The authors identified three mechanisms of shoulder injury from the video analysis. These are the 'Try-Scorer', characterised by hyperflexion of the outstretched arm such as when scoring a try; the 'Tackler', extension of the abducted arm behind the player while tackling; and the 'Direct Impact', a direct blow to the arm or shoulder when held by the side in neutral or slight adduction. The Try Scorer and Tackler mechanisms both involve a levering force on the glenohumeral joint (GHJ). These mechanisms predominantly cause GHJ dislocation, with Bankart, reverse Bankart and superior labrum anterior-posterior tears. The Try-Scorer Mechanism also caused the majority (83%) of rotator cuff tears. The Direct Hit mechanism resulted in GHJ dislocation and labral injury in 37.5% of players and was most likely to cause acromioclavicular joint dislocation and scapula fractures, injuries that were not seen with the other mechanisms. CONCLUSION: Greater understanding of the mechanisms involved in rugby shoulder injury is useful in understanding the pathological injuries, guiding treatment and rehabilitation and aiding the development of injury-prevention methods.

The anatomy of the short head of biceps - not a tendon.

BACKGROUND: The short head of biceps brachii has been the subject of little investigation when compared to the long head or distal biceps tendons. The aim of this study was to dissect and describe the origin and proximal portion of the short head of biceps brachii. MATERIALS AND METHODS: Three left and two right (n = 5) fresh-frozen human cadaver shoulders were dissected and the proximal short head was measured and photographed. RESULTS: The origin of the short head of biceps consisted of muscle fibres attaching directly to the tip of the coracoid process, with a thin, tendinous aponeurosis covering its anterior surface, rather than a true tendon as previously described. CONCLUSION: The short head of biceps does not attach to the coracoid process via a true tendon. These findings have implications for procedures that utilise the short head of biceps. LEVEL OF EVIDENCE: Basic science study.