Meiosis in allopolyploid Arabidopsis suecica.

Polyploidy is a major force shaping eukaryote evolution but poses challenges for meiotic chromosome segregation. As a result, first-generation polyploids often suffer from more meiotic errors and lower fertility than established wild polyploid populations. How established polyploids adapt their meiotic behaviour to ensure genome stability and accurate chromosome segregation remains an active research question. We present here a cytological description of meiosis in the model allopolyploid species Arabidopsis suecica (2n = 4x = 26). In large part meiosis in A. suecica is diploid-like, with normal synaptic progression and no evidence of synaptic partner exchanges. Some abnormalities were seen at low frequency, including univalents at metaphase I, anaphase bridges and aneuploidy at metaphase II; however, we saw no evidence of crossover formation occurring between non-homologous chromosomes. The crossover number in A. suecica is similar to the combined number reported from its diploid parents Arabidopsis thaliana (2n = 2x = 10) and Arabidopsis arenosa (2n = 2x = 16), with an average of approximately 1.75 crossovers per chromosome pair. This contrasts with naturally evolved autotetraploid A. arenosa, where accurate chromosome segregation is achieved by restricting crossovers to approximately 1 per chromosome pair. Although an autotetraploid donor is hypothesized to have contributed the A. arenosa subgenome to A. suecica, A. suecica harbours diploid A. arenosa variants of key meiotic genes. These multiple lines of evidence suggest that meiosis in the recently evolved allopolyploid A. suecica is essentially diploid like, with meiotic adaptation following a very different trajectory to that described for autotetraploid A. arenosa.

The Use of Cryotherapy in the Early Postoperative Period after Total Hip Arthroplasty.

BACKGROUND: Recent evidence suggests that cryotherapy may be beneficial in reducing postoperative pain and blood loss in joint arthroplasty. The objective of this study was to review the use of cryotherapy in the early postoperative phase after total hip arthroplasty to assess the benefits in terms of pain relief and reduction in postoperative blood loss. MATERIAL AND METHODS: A prospective cohort study of the use of a cryotherapy device (Hilotherm) was performed in patients following total hip arthroplasty. The primary outcome measures were visual analogue score (VAS) for pain (at 24 and 48 hours postoperatively), and amount of postoperative blood loss, measured by change in haemoglobin (g/L). The secondary outcome measures were length of stay (days), duration of patient controlled analgesia (PCA) administered postoperatively (hours) and amount of analgesia used (mg) in the first 48 hours. RESULTS: 28 patients were recruited (n=13 Hilotherm; n= 15 non-Hilotherm). Hilotherm application reduced pain in the first 24 hours, non-significantly, (3.50±2.41 vs 4.90±2.95; p=0.185). This effect was not carried through at 48 hours postoperatively (5.68±1.94 vs 3.72±2.46; p=0.029). Hilotherm application significantly reduced postoperative blood loss (22.38±5.71 g/L vs 29.13±10.22 g/L; p=0.045). Hilotherm reduced length of stay by almost 1 day; however, this was not statistically significant (4.46±2.33 vs 5.20±3.55; p=0.528). There was no difference in the length of time PCA was administered (22.30±0.75 vs 22.02±3.26; p=0.763). Patients in the non-Hilotherm group required more paracetamol on average (p=0.001). CONCLUSIONS: 1. Hilotherm application does not appear to significantly reduce pain postoperatively but re-sults in less postoperative blood loss. 2. There may be a role for the continued use of cryotherapy in the early period of rehabilitation following total hip arthroplasty, as it appears to result in more rapid ambulatory rehabilitation in patients, resulting in reduced length of stay.

Can we reduce the number of MRSA screening site swabs in elective orthopedic patients?

BACKGROUND: Deep infection after routine elective orthopedic procedures can be catastrophic, leading to further surgery, loss of limb, disability, and risk of mortality. Ring-fencing elective orthopedic ward has been shown to significantly reduce the incidence of all postoperative infections especially with methicillin-resistant Staphylococcus aureus (MRSA). Our hospital's current MRSA screening is a four-site MRSA swabs. OBJECTIVES: This study evaluates the possibility of reducing the number of MRSA swab sites as part of a quality improvement project. STUDY DESIGN AND METHODS: Patients on the waiting list for elective orthopedic procedure in our trust who had an MRSA-positive swab from either four sites were analyzed over the time period from January 2012 to December 2014. Those without swabs from all four areas (nose, throat, axilla, and groin) were excluded. Positive swabs of different regions were recorded and compared. RESULTS: There were 138 MRSA-positive patients, giving an incidence of 31 per 10,000 screen/year over that time period. Some patients ( n = 31, 22.5%) had a positive swab in more than one site. The positive sites were as follows: nose (69.60%, n = 96), groin (26.10%, n = 36), throat (25.30%, n = 35), and axilla (8.70%, n = 12). In our cohort, we would miss a significant proportion of positive patients if we change it to a two swab screening policy (26.8% for nose and axilla combination; 18.10% for nose and groin combination; and 15.20% for nose and throat). However, we would only miss 2.2% of cases for a nose, groin, and throat three-swab policy. There were also 11 instances, where a previously negative site become positive in the next swab. CONCLUSION: A three-swab combination of nasal, throat, and groin swabs improves pickup rate of MRSA significantly compared to a two-swab policy and misses only 2.2% compared to a four-swab policy. Axilla swabbing does not make a significant difference to the results. Based on this study, the policy has now been changed from a four-swab to three-swab screening in our trust. This has now been audited four times and they were all negative. This has helped to reduce cost in terms of staff time and resources. We would not recommend screening only the previous positive site for the next repeat screening swabs as there is an 8% chance of missing MRSA carrier status.

Mid-term clinical results of the cementless R3 cup and Polarstem total hip arthroplasty.

BACKGROUND: There has been a shift from cemented to uncemented hip arthroplasty. One popular uncemented combination is the R3 acetabular cup with Polarstem, having the lowest revision rate in the UK National Joint Registry. However, there are no medium-term clinical outcomes on this combination in the literature. The aim of this study is to review our centre's outcomes with this combination using conventional bearings with a minimum of 7-year follow-up. METHODS: Using our centre's arthroplasty database, we identified all patients that underwent a total hip arthroplasty using these implants from August 2009 to December 2010. One hundred and forty-four procedures were performed. The primary outcome was revision rate, and the secondary outcomes were clinical and radiological evaluation. RESULTS: The mean cohort age at surgery was 68.3 years. There were three revisions, of which only one underwent a cup revision. The mean Oxford Hip Score at 7-year follow-up was 38. Radiological evaluation of both acetabular and stem component did not show any radiolucency at 7-year follow-up. Kaplan-Meier survivorship analysis showed an implant survival rate of 97.69% at 7 years using revision for all causes as endpoint. The risk of revision was 1.47% at 7 years. CONCLUSION: Our revision rates are comparable to the UK's National Joint Registry, with excellent clinical and radiological outcome. Our results correlate with the allocated rating of 7A* by the Orthopaedic Data Evaluation Panel for both R3 acetabular cup and Polarstem.

A Comparative Study Between Uncemented and Hybrid Total Hip Arthroplasty in Octogenarians.

BACKGROUND: The aim of this prospective cohort study is to evaluate the outcome of octogenarian patients undergoing uncemented total hip arthroplasty (THA) with a control group of similarly aged patients undergoing hybrid THA with a minimum 5-year follow-up. METHODS: Clinical outcomes including intraoperative and postoperative complications, blood transfusion, revision rate, and mortality were recorded. Radiological analysis of preoperative and postoperative radiographs assessed bone quality, implant fixation, and any subsequent loosening. RESULTS: One hundred forty-three patients (mean age 86.2 years) were enrolled in the study. Seventy-six patients underwent uncemented THA and 67 underwent hybrid THA. The uncemented cohort had a significantly lower intraoperative complication rate (P = .017) and also a lower transfusion rate (P = .002). Mean hospital stay (P = .27) was comparable between the 2 groups. Two patients underwent revision surgery in each cohort. CONCLUSION: Our study demonstrates that uncemented THA is safe for the octogenarian patient and we recommend that age should not be a barrier to the choice of implant. However, intraoperative assessment of bone quality should guide surgeons to the optimum decision regarding uncemented and hybrid implants. LEVEL OF EVIDENCE: 3.

R3 Cup Does Not Have a High Failure Rate in Conventional Bearings: A Minimum of 5-Year Follow-Up.

BACKGROUND: The R3 cementless acetabular system was first marketed in Australia and Europe in 2007. Previous papers have shown high failure rates of the R3 cup with up to 24% with metal-on-metal bearing. There are currently no medium term clinical results on this cup. The aim of the study is to review our results of the R3 acetabular cup with conventional bearings with a minimum of 5-year follow-up. METHODS: Patients who were implanted with the R3 acetabular cup were identified from our center's arthroplasty database. A total of 293 consecutive total hip arthroplasties were performed in 286 patients. The primary outcome was revision. The secondary outcomes were the Oxford Hip Scores (OHS) and radiographic evaluation. RESULTS: The mean age of the patients was 69.4 years. The mean preoperative OHS was 23 (range 10-34) and the mean OHS was 40 (range 33-48) at the final follow-up. Radiological evaluation showed an excellent ARA score in all patients at 5 years. None of the R3 cups showed osteolysis at the final follow-up. There were 3 revisions in our series, of which 2 R3 cups were revised. The risk of revision was 1.11% at 5 years. CONCLUSION: Our experience of using the R3 acetabular system with conventional bearings showed high survivorship and is consistent with the allocated Orthopaedic Data Evaluation Panel rating of 5A* as rated in 2015 in the United Kingdom.

Popliteal Artery Pseudoaneurysm After Total Knee Arthroplasty.

BACKGROUND: Popliteal artery pseudoaneurysm is a rare complication after total knee arthroplasty. Early recognition is imperative in its management to prevent the subsequent development of compartment syndrome and soft tissue ischemia. The aim of this study was to evaluate the complication rate, recognition, and management of symptomatic popliteal artery pseudoaneurysm after total knee arthroplasty. METHODS: Between January 2004 and October 2014, 7937 consecutive total knee arthroplasties were identified from the Theatre Management (Ormis) System and cross-referenced against 1304 radiology reports containing the key words "popliteal" and "aneurysm' identified from the Patient Archiving Communication System. RESULTS: Seven patients (0.088%) were found to have had a symptomatic popliteal artery pseudoaneurysm. The median (range) interval between total knee arthroplasty and the radiological diagnosis of a pseudoaneurysm was 15 (7-27) days. Popliteal artery pseudoaneurysm was diagnosed on duplex imaging (n = 4), arteriogram (n = 2), and computed tomography angiogram (n = 1). Fasciotomies were undertaken in 3 patients. CONCLUSION: The complication rate of popliteal artery pseudoaneurysm was comparable to the literature. Recognition was identified as a problem. An appreciation of the mechanisms of injury and an awareness of this potential complication among orthopedic surgeons are imperative in reducing the complication rate and interval to diagnosis. Popliteal artery pseudoaneurysm should be included in the differential diagnosis for patients with a clinical presentation of postoperative compartment syndrome or deep vein thrombosis, and examination of the popliteal pulse should be undertaken early.

Early failure of the Polarstem total hip arthroplasty--can the Australian NJR tell us the full story?

The Australian NJR 2012 has reported that the Polarstem/R3 Total hip arthroplasty has a higher than anticipated revision rate with a three year cumulative percentage of 3%. Out of the 733 Polarstem femoral components, 18 had to be revised within 3 years. Our unit has been using this system since 2009. The aim of this prospective study is to report the clinical outcome of the PolarStem in our cohort of 646 stems with 100% follow up, compared to the Australian registry. Of the 646 hips, 5 returned to theater for a further operation for any reason. The cumulative 3 year survival rate was 99.7%, with revision for any reason as the endpoint. Our 3 year cumulative revision rate for all revisions in the Polarstem femoral stem is 0.15%, which is 20 times less as compared to the 3% reported by the Australian registry.

Common femoral vein thrombosis caused by a metal-on-metal hip arthroplasty-related pseudotumor.

We present a case of a pseudotumor causing a deep femoral vein thrombosis 16 months after undergoing a metal-on-metal total hip arthroplasty. There is increasing concern over the effect of metal ions that are produced by wear in metal-on-metal hip arthroplasty systems. Recently, a number of articles have reported the development of an inflammatory pseudotumor causing a number of different problems early on in the lifespan of the implant necessitating revision surgery. This case reports the first presentation of a pseudotumor causing a serious venous thrombosis due to pressure effect and indicates further possible evidence for caution when considering metal-on-metal bearing hip arthroplasty.

CPR for children: one hand or two?

AIMS: Current guidelines for chest compressions in CPR advocate a one handed technique in children (1-8 years old) and a two handed technique in adults (>8 years old). No previous study has examined whether these two techniques generate different compression pressures. This study assesses the relative difference in intrathoracic compression pressures generated by one- and two handed chest compression techniques in a paediatric manikin. METHODS: Randomised crossover design. Subjects performed both types of chest compressions on an adapted paediatric resuscitation manikin connected to a pressure transducer and personal computer. Ethical approval was granted. RESULTS: A 30 volunteer subjects (9 male, 21 female) participated in the study. Their mean age was 30.8 years (S.D. 8.6), and mean weight was 70.5 kg (S.D. 12.8). The mean compression pressure was 86.6 mmHg (S.D. 13.68) for two handed and 75.1 mmHg (S.D. 12.02) for one handed (P < 0.001, paired t-test). The average peak compression pressure was 133.5 mmHg (S.D. 26.36) for two handed and 116.8 mmHg (S.D. 21.48) for one handed (P = 0.001, paired t-test); 29 found the two handed technique easier to perform. CONCLUSION: Two handed chest compression CPR seems to be easier to perform on a paediatric resuscitation manikin and produces significantly higher mean and peak pressures. Further work is needed to determine the comparative effects on children and which technique produces better clinical outcomes.

Multifocal electroretinographic features of central retinal vein occlusion.

PURPOSE: To determine the features of wide-field multifocal electroretinography (WF-mfERG) recorded in patients with central retinal vein occlusion (CRVO) and to compare WF-mfERG responses of the affected and fellow eyes. In addition, WF-mfERG responses were also compared by using standard electroretinography (ERG). METHODS: WF-mfERG and ERG responses were recorded from both eyes of 56 patients with CRVO. The WF-mfERG responses, obtained using a custom-built system were grouped into central and peripheral rings. The P1 amplitudes, and P1 and N1 implicit times were grouped and averaged within both rings. Nonparametric statistical analysis was used to compare the ERG results from the affected and fellow eyes. The results were also compared with normative data (5% to 95% confidence limits). RESULTS: CRVO markedly affected all the parameters of the WF-mfERG. In the affected eyes, 98% of the central and 91% of the peripheral P1 implicit times fell outside the normal range, as opposed to 35% of the 30-Hz flicker implicit times. The WF-mfERG responses obtained from eyes with CRVO were significantly different (P<0.01) from those derived from the fellow eye. The central and peripheral P1 implicit times were also abnormal in 59.2% and 46.9% of the fellow eyes, respectively. CONCLUSIONS: WF-mfERG is more susceptible than the standard ERG to changes in the nonlinear dynamics of the eye due to the multiple frequencies of stimulation used to record WF-mfERG responses. WF-mfERG could be a sensitive indicator of the underlying disease affecting the retina in eyes with CRVO and may have a role in the clinical setting.

The multifocal ERG: unmasked by selective cross-correlation.

The purpose of this paper is to provide the reader with a better insight into the mechanisms of multifocal ERG (mfERG) recording. The construction of the first and second order mfERG responses were examined by recovering the response to specific pulse trains embedded in the m-sequence.A custom built pc based multifocal system driving a LED stimulator was used to record a 61 element mfERG and a global ERG. The global ERG recording was used to enable the recovery of different pulse trains embedded in the m-sequence. Summation of these individual pulse trains was performed and the results compared with the standard full cross-correlation. An isolated pulse response is defined as a flash of light that has no other flashes within two m-sequence base periods before or after the flash. This isolated pulse response was recovered from the raw data and this response input into a simple superposition model to predict the waveform shape for specific pulse trains. The superposition model was compared with the actual selective cross-correlation for a particular pulse train. The summations of the selective cross-correlation components give identical responses to the full cross-correlation. The superposition model also predicts the waveform shapes recovered by the selective cross-correlation procedure. The mfERG response is a complex composite response from a number of different pulse trains. Examination of the individual waveform shapes provides some insight into the origin of the mfERG waveform. The main contributions to the P1 component are the same as for an isolated response and as with the standard ERG this component is likely to be dominated by the mid retina. The N1 component is also likely to have similar origins to that of the isolated response but the amplitude is dominated by contributions from pulse trains where there is no change of state and therefore includes a component from the interaction between two consecutive stimuli. The N2 component is a composite response dominated by the interaction between two successive stimuli two base periods apart and the P1 component of a second stimulus delayed one frame from the first stimulus.