The Multifaceted Role of Cofilin in Neurodegeneration and Stroke: Insights into Pathogenesis and Targeting as a Therapy.

This comprehensive review explores the complex role of cofilin, an actin-binding protein, across various neurodegenerative diseases (Alzheimer's, Parkinson's, schizophrenia, amyotrophic lateral sclerosis (ALS), Huntington's) and stroke. Cofilin is an essential protein in cytoskeletal dynamics, and any dysregulation could lead to potentially serious complications. Cofilin's involvement is underscored by its impact on pathological hallmarks like Aß plaques and α-synuclein aggregates, triggering synaptic dysfunction, dendritic spine loss, and impaired neuronal plasticity, leading to cognitive decline. In Parkinson's disease, cofilin collaborates with α-synuclein, exacerbating neurotoxicity and impairing mitochondrial and axonal function. ALS and frontotemporal dementia showcase cofilin's association with genetic factors like C9ORF72, affecting actin dynamics and contributing to neurotoxicity. Huntington's disease brings cofilin into focus by impairing microglial migration and influencing synaptic plasticity through AMPA receptor regulation. Alzheimer's, Parkinson's, and schizophrenia exhibit 14-3-3 proteins in cofilin dysregulation as a shared pathological mechanism. In the case of stroke, cofilin takes center stage, mediating neurotoxicity and neuronal cell death. Notably, there is a potential overlap in the pathologies and involvement of cofilin in various diseases. In this context, referencing cofilin dysfunction could provide valuable insights into the common pathologies associated with the aforementioned conditions. Moreover, this review explores promising therapeutic interventions, including cofilin inhibitors and gene therapy, demonstrating efficacy in preclinical models. Challenges in inhibitor development, brain delivery, tissue/cell specificity, and long-term safety are acknowledged, emphasizing the need for precision drug therapy. The call to action involves collaborative research, biomarker identification, and advancing translational efforts. Cofilin emerges as a pivotal player, offering potential as a therapeutic target. However, unraveling its complexities requires concerted multidisciplinary efforts for nuanced and effective interventions across the intricate landscape of neurodegenerative diseases and stroke, presenting a hopeful avenue for improved patient care.

Ultracongruent Designs Compared to Posterior-Stabilized and Cruciate-Retaining Tibial Inserts - What Does the Evidence Tell Us? A Systematic Review and Meta-Analysis.

BACKGROUND: Posterior-stabilized (PS) and cruciate-retaining (CR) have been the most common tibial designs used in total knee arthroplasty. Ultra-congruent (UC) inserts are becoming popular because they preserve bone without relying on the posterior cruciate ligament balance and integrity. Despite increasing use, there is no consensus on how UC inserts perform versus PS and CR designs. METHODS: A comprehensive literature search of 5 online databases was performed for articles from January 2000 to July 2022 comparing the kinematic and clinical outcomes of PS or CR tibial inserts to UC inserts. There were nineteen studies included. There were 5 studies comparing UC to CR and 14 comparing UC to PS. Only one randomized controlled trial (RCT) was rated "good quality". RESULTS: For CR studies, pooled analyses showed no difference in knee flexion (n = 3, P = .33) or Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores (n = 2, P = .58). For PS studies, meta-analyses showed better anteroposterior stability (n = 4, P < .001) and more femoral rollback (n = 2, P < .001) for PS but no difference in knee flexion (n = 9, P = .55) or medio-lateral stability (n = 2, P = .50). There was no difference with WOMAC (n = 5, P = .26), Knee Society Score (n = 3, P = .58), Knee Society Knee Score (n = 4, P = .76), or Knee Society Function Score (n = 5, P = .51). CONCLUSION: Available data demonstrates there are no clinical differences between CR or PS and UC inserts in small short-term studies ending around 2 years after surgery. More importantly, high-quality research comparing all inserts is lacking, demonstrating a need for more uniform and longer-term studies beyond 5 years after surgery to justify increased UC usage.

Transfusion Rates in the Operative Treatment of Prosthetic Hip and Knee Infection.

Surgery for prosthetic joint infection (PJI) can often lead to significant blood loss, necessitating allogeneic blood transfusion (ABT). The use of ABT is associated with higher rates of morbidity and death in revision total joint arthroplasty, particularly in the treatment of PJI. We compared ABT rates by procedure type among patients treated for PJI. We retrospectively reviewed 143 operative cases of hip and knee PJI performed at our institution between 2016 and 2018. Procedures were categorized as irrigation and debridement (I&D) with modular component exchange (modular component exchange), explantation with I&D and placement of an antibiotic spacer (explantation), I&D with antibiotic spacer exchange (spacer exchange), or antibiotic spacer removal and prosthetic reimplantation (reimplantation). Rates of ABT and the number of units transfused were assessed. Factors associated with ABT were assessed with a multilevel mixed-effects regression model. Of the cases, 77 (54%) required ABT. The highest rates of ABT occurred during explantation (74%) and spacer exchange (72%), followed by reimplantation (36%) and modular component exchange (33%). A lower preoperative hemoglobin level was associated with higher odds of ABT. Explantation, reimplantation, and spacer exchange were associated with greater odds of ABT. Antibiotic spacer exchange and explantation were associated with greater odds of multiple-unit transfusion. Rates of ABT remain high in the surgical treatment of PJI. Antibiotic spacer exchange and explantation procedures had high rates of multiple-unit transfusions, and additional units of blood should be made available. Preoperative anemia should be treated when possible, and further refinement of blood management protocols for prosthetic joint infection is necessary. [Orthopedics. 2022;45(6):353-359.].

Preoperative Patient Optimization in Total Joint Arthroplasty-The Paradigm Shift from Preoperative Clearance: A Narrative Review.

Background: Total joint arthroplasty (TJA) is one of the most common procedures performed in the United States. Outcomes of this elective procedure may be improved via preoperative optimization of modifiable risk factors. Purposes: We sought to summarize the literature on the clinical implications of preoperative risk factors in TJA and to develop recommendations regarding preoperative optimization of these risk factors. Methods: We searched PubMed in August 2019 with an update in September 2020 for English-language, peer-reviewed publications assessing the influence on outcomes in total hip and knee replacement of 7 preoperative risk factors-obesity, malnutrition, hypoalbuminemia, diabetes, anemia, smoking, and opioid use-and recommendations to mitigate them. Results: Sixty-nine studies were identified, including 3 randomized controlled trials, 8 prospective cohort studies, 42 retrospective studies, 6 systematic reviews, 3 narrative reviews, and 7 consensus guidelines. These studies described worse outcomes associated with these 7 risk factors, including increased rates of in-hospital complications, transfusions, periprosthetic joint infections, revisions, and deaths. Recommendations for strategies to screen and address these risk factors are provided. Conclusions: Risk factors can be optimized, with evidence suggesting the following thresholds prior to surgery: a body mass index <40 kg/m2, serum albumin ≥3.5 g/dL, hemoglobin A1C ≤7.5%, hemoglobin >12.0 g/dL in women and >13.0 g/dL in men, and smoking cessation and ≥50% decrease in opioid use by 4 weeks prior to surgery. Surgery should be delayed until these risk factors are adequately optimized.

Increased Patient-Level Payment After Removal of Total Knee Arthroplasty From the Inpatient-Only List.

BACKGROUND: In January 2018, the Centers for Medicare and Medicaid Services removed total knee arthroplasty (TKA) from the Inpatient Only (IPO) list. This study aimed to compare patient-level payments in TKA cases with a length of stay (LOS) <2 midnights before and after removal of TKA from IPO list. METHODS: In this retrospective cohort study, all Medicare patients who received a primary elective TKA from 2016-2019 with a LOS <2 midnights at an academic tertiary center were identified. Total and itemized charges and patient-level payments were compared between eligible TKA cases performed in 2016-2017 and those in 2018-2019. There were 351 eligible TKA cases identified: 151 in 2016-2017 and 200 in 2018-2019. RESULTS: The percentage of patients making any out-of-pocket payment increased in 2018-2019 from 2016-2017 (51.0% versus 10.6%), as did median patient-level payment ($7.30 [range, $0.00-$3,389] versus $0.00 [range, $0.00-$1,248], P < .001 for both). A greater proportion of patients in 2018-2019 paid $1-$50 than in 2016-2017 (37.5% versus 1.3%, P < .001) with no change in the proportion of patients who made payments >$50. Total charges were less in 2018-2019 than in 2016-2017 (P = .001). Charges for drugs, laboratory tests, admissions/floor, and therapies decreased in 2018-2019, whereas charges for the operating room and radiology increased (P < .001 for all). CONCLUSION: Patients receiving outpatient TKA in 2018-2019 were more likely to have out-of-pocket payments than patients with comparable hospital stay who were designated as inpatients, although most of these payments were less than $50.

Intraoperative and Postoperative Iron Supplementation in Elective Total Joint Arthroplasty: A Systematic Review.

INTRODUCTION: Postoperative anemia is associated with substantial morbidity and mortality in total joint arthroplasty (TJA). Our primary objective was to determine whether perioperative iron supplementation improves postoperative hemoglobin levels in TJA. Secondary objectives were to determine the effects of perioperative iron on adverse events, quality of life, and functional measures in TJA. METHODS: We conducted a systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using six databases. We included English-language, randomized controlled trials investigating intraoperative or postoperative iron supplementation in elective TJA that reported postoperative hemoglobin levels in patients aged 18 years or older. Seven eligible studies were identified, among which substantial heterogeneity was noted. Bias risk was low in four studies, unclear in two studies, and high in one study. Three studies assessed oral iron supplementation, three assessed intravenous iron supplementation, and one compared oral and intravenous iron supplementation. All intravenous iron was administered intraoperatively, except in the oral versus intravenous comparison. RESULTS: Postoperative oral iron supplementation had no effect on postoperative hemoglobin levels. Intraoperative and postoperative intravenous iron supplementation was associated with higher postoperative hemoglobin levels and greater increases in hemoglobin levels. Two studies reported rates of anemia and found that intraoperative and postoperative intravenous iron supplementation reduced rates of postoperative anemia at postoperative day 30. No adverse events were associated with iron supplementation. One study found that intravenous iron improved quality of life in TJA patients with severe postoperative anemia compared with those treated with oral iron. Perioperative iron had no effects on functional outcomes. DISCUSSION: We found no evidence that postoperative oral iron supplementation improves hemoglobin levels, quality of life, or functional outcomes in elective TJA patients. However, intraoperative and postoperative intravenous iron supplementation may accelerate recovery of hemoglobin levels in these patients. LEVEL OF EVIDENCE: Level I, systematic review of randomized controlled trials.

Factors Associated With Perioperative Transfusion in Lower Extremity Revision Arthroplasty Under a Restrictive Blood Management Protocol.

INTRODUCTION: Approximately 37% of patients undergoing lower extremity revision total joint arthroplasty (TJA) receive allogeneic blood transfusions (ABTs), which are associated with increased risk of morbidity and death. It is important to identify patient factors associated with needing ABT because the health of higher-risk patients can be optimized preoperatively and their need for ABT can be minimized. Our goal was to identify the patient and surgical factors independently associated with perioperative ABT in revision TJA. METHODS: We included all 251 lower extremity revision TJA cases performed at our academic tertiary care center from January 1, 2016, to December 31, 2018. We assessed the following factors for associations with perioperative ABT: patient age, sex, race, body mass index, preoperative hemoglobin level, and infection status (ie, infection as indication for revision TJA); use of vasopressors, tranexamic acid (TXA), surgical drains, tourniquets, and intraoperative cell salvage; and procedure type (hip versus knee), procedure complexity (according to the number of components revised), and surgical time. Multivariable regression was used to identify factors independently associated with perioperative ABT. RESULTS: The following characteristics were independently associated with greater odds of perioperative ABT: preoperative hemoglobin level (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.5 to 2.2), infectious indication for revision (OR, 3.6; 95% CI, 1.3 to 9.7), and procedure complexity. TXA use was a negative predictor of ABT (OR, 0.47; 95% CI, 0.23 to 0.98). Compared with polyethylene liner exchanges, single-component revisions (OR, 14; 95% CI, 3.6 to 56) and dual-component revisions (OR, 7.8; 95% CI, 2.3 to 26) were associated with greater odds of ABT. DISCUSSION: Patients with preoperative anemia, those undergoing revision TJA because of infection, those who did not receive TXA, and those undergoing more complex TJA procedures may have greater odds of requiring ABT. We recommend preoperative optimization of the health of these patients to reduce the need for ABT. LEVEL OF EVIDENCE: Level III, prognostic study.

Routine Basic Metabolic Panels Are Not Needed in All Patients After Primary Total Joint Arthroplasty: An Opportunity for Cost Reduction.

BACKGROUND: As the incidence of total joint arthroplasty (TJA) increases, identifying methods for cost reduction is essential. Basic metabolic panels (BMPs) are obtained routinely after TJA. We aimed at assessing the prevalence of intervention secondary to abnormal BMPs after primary TJA and at identifying predictors of the need for postoperative BMPs. METHODS: We reviewed 802 cases (758 patients) of primary lower-extremity TJA performed from January 1 through December 31, 2018, at our tertiary care medical center. Patient characteristics, preoperative and postoperative BMPs, comorbidities, current medications, and in-hospital interventions were recorded. Age-adjusted Charlson Comorbidity Index (AA-CCI) values were calculated. Institutional costs of 1 BMP and of all BMPs not prompting intervention were calculated. We used multiple regression to identify independent predictors of in-hospital interventions secondary to abnormal postoperative BMPs. RESULTS: Our institutional BMP cost was $36. A total of 1032 postoperative BMPs were ordered; 958 (93%) prompted no intervention. This equated to $34,488 of avoidable BMP costs. We identified 27 cases (3.4%) requiring intervention secondary to abnormal BMPs. Independent predictors of intervention were preoperative renal dysfunction (ie, abnormal creatinine or glomerular filtration rate <60 mL/min) (odds ratio [OR], 7.8; 95% confidence interval [CI], 2.8-22), number of current nephrotoxic medications (OR, 1.9; 95% CI, 1.3-2.9), and AA-CCI value (OR, 1.2; 95% CI, 1.0-1.5). CONCLUSION: Routine postoperative BMPs are unwarranted for most patients undergoing primary TJA. Testing may be reserved for those with renal dysfunction, those taking multiple nephrotoxic medications, or those with a high AA-CCI value.

Published Operative Times Do Not Reflect Surgeon Effort: A Novel Approach for Calculating Operative Times in Total Hip Arthroplasty to Better Quantify Surgeon Work.

BACKGROUND: Current estimates of operative time (OT) for total hip arthroplasty (THA) are reported as the mean OT across all procedures. This method does not reflect variability among surgeons and surgical settings and should not be used to infer individual surgeon work. We hypothesized that this method would underestimate the time it takes individual surgeons to perform THA. Therefore, we compared the mean OT for all THA cases ("overall OT") with the mean OT for individual surgeons ("individual surgeon OT") and examined which factors were associated with each. METHODS: Mean OT was calculated for 3972 primary THA cases ("overall OT") by 41 surgeons from 2015 to 2018 in a single health system. The mean OT for each surgeon was determined ("individual surgeon OT"), averaged across surgeons, and compared with overall OT. Overall OT and individual surgeon OT were assessed for associations with surgeon-related (adult reconstruction fellowship training, THA volume, years' experience), hospital-related (hospital type, trainee presence), and patient-related (age, body mass index category, American Society of Anesthesiologists physical status classification) factors (alpha = 0.05). RESULTS: Mean individual surgeon OT was significantly longer (106 ± 21 minutes) than overall OT (96 ± 28 minutes) (P = .03), with 73% of individual surgeon OTs being greater than overall OT. Although all surgeon-, hospital-, and patient-related factors were associated with significant differences in overall OT, only hospital type was associated with differences in individual surgeon OT. CONCLUSION: Individual surgeon OT was longer than overall OT for most surgeons and provides a better estimate of surgeon work.

Can Baseline Computed Tomography Scans Be Used to Identify Patients at High Risk of Vision Loss due to Terson Syndrome?

PURPOSE: To determine if routinely performed computed tomographic (CT) scanning in patients with aneurysmal subarachnoid hemorrhages (aSAHs) is sufficient to identify patients at high risk of vision loss due to Terson syndrome (TS). METHODS: Consecutive patients with a diagnosis of aSAH admitted to the neurologic intensive care unit of a regional referral hospital over a 3-year period were prospectively evaluated. Head CT scans performed in the emergency department were assessed for the presence of a "crescent sign" (evidence of significant subinternal limiting membrane hemorrhage). Dilated funduscopic examinations were performed by an ophthalmologist, masked to the results of the CT scan, to identify retinal and vitreous hemorrhages consistent with TS. Retinal hemorrhages were categorized according to size-those smaller than 2 mm in diameter were deemed low risk (lrTS) for vision loss and those larger than 2 mm in diameter were deemed high risk (hrTS) for vision loss. RESULTS: One hundred seventeen patients with aSAH were enrolled in the study. The overall incidence of TS was 24.9% (29 of 117 patients; 12 were bilateral). Compared to patients without TS, those with TS had a higher Fisher Hemorrhage Grade and a lower mean (±standard deviation) GCS score (8.66 ± 4.97 vs 12.09 ± 1.10; P < 0.001). The CT crescent sign was positive in 7 patients (6.0%), 6 (5.1%; 2 were bilateral) of whom were found to have hrTS. Of the 110 patients without a CT crescent sign, 88 (75.1%) patients did not have TS, 21 had lrTS, and 1 patient had hrTS in one eye. The CT crescent sign was highly sensitive (85.7%) and specific (99.1%) for diagnosing hrTS. CONCLUSION: The CT crescent sign is a highly sensitive and specific marker for hrTS. CT scanning may replace routine ophthalmologic examinations to identify patients at risk of vision loss due to aSAH.

Platform for ergonomic intraoral photodynamic therapy using low-cost, modular 3D-printed components: Design, comfort and clinical evaluation.

Oral cancer prevalence is increasing at an alarming rate worldwide, especially in developing countries which lack the medical infrastructure to manage it. For example, the oral cancer burden in India has been identified as a public health crisis. The high expense and logistical barriers to obtaining treatment with surgery, radiotherapy and chemotherapy often result in progression to unmanageable late stage disease with high morbidity. Even when curative, these approaches can be cosmetically and functionally disfiguring with extensive side effects. An alternate effective therapy for oral cancer is a light based spatially-targeted cytotoxic therapy called photodynamic therapy (PDT). Despite excellent healing of the oral mucosa in PDT, a lack of robust enabling technology for intraoral light delivery has limited its broader implementation. Leveraging advances in 3D printing, we have developed an intraoral light delivery system consisting of modular 3D printed light applicators with pre-calibrated dosimetry and mouth props that can be utilized to perform PDT in conscious subjects without the need of extensive infrastructure or manual positioning of an optical fiber. To evaluate the stability of the light applicators, we utilized an endoscope in lieu of the optical fiber to monitor motion in the fiducial markers. Here we showcase the stability (less than 2 mm deviation in both horizontal and vertical axis) and ergonomics of our applicators in delivering light precisely to the target location in ten healthy volunteers. We also demonstrate in five subjects with T1N0M0 oral lesions that our applicators coupled with a low-cost fiber coupled LED-based light source served as a complete platform for intraoral light delivery achieving complete tumor response with no residual disease at initial histopathology follow up in these patients. Overall, our approach potentiates PDT as a viable therapeutic option for early stage oral lesions that can be delivered in low resource settings.

Recurrent corneal erosion: a comprehensive review.

PURPOSE: To comprehensively review the literature regarding recurrent corneal erosion (RCE) and to present treatment options and recommendations for management. OVERVIEW: RCE usually presents with sharp, unilateral pain upon awakening, in an eye with an underlying basement membrane dystrophy, prior ocular trauma, stromal dystrophy or degeneration, or prior surgery for refractive errors, cataracts, or corneal transplantation. Making the correct diagnosis requires a careful slit-lamp examination of both eyes coupled with a high degree of suspicion. Several treatments are commonly used for RCE but new therapies have been introduced recently. Conservative treatment consists of antibiotic and preservative-free lubricating drops, with topical cycloplegics and oral analgesics to control pain. Patients who are unresponsive to these therapies may benefit from therapeutic bandage contact lenses (BCL). Newer therapies include oral matrix metalloproteinase (MMP) inhibitors, blood-derived eye drops, amniotic membrane graft application, and judicious application of topical corticosteroids. Once the epithelium is healed, a course of hypertonic saline solution and/or ointment can be used. Surgical procedures may be performed in patients who fail conservative therapy. Punctal occlusion with plugs increases the tear film volume. Epithelial debridement with diamond burr polishing (DBP), anterior stromal puncture (ASP), or alcohol delamination should be considered in selected patients. DBP can be used for patients with basement membrane dystrophies and is the preferred treatment overall due to a low recurrence rate. ASP can be used for erosions outside the central visual axis. Excimer laser phototherapeutic keratectomy is an attractive option in eyes with central RCE since it precisely removes tissue while preserving corneal transparency. In patients with RCE who are also candidates for refractive surgery, photorefractive keratectomy can be considered. SUMMARY: Newly introduced therapies for RCE enable therapy to be individualized and lower the recurrence rate.

Quantification of shoulder muscle intramuscular fatty infiltration on T1-weighted MRI: a viable alternative to the Goutallier classification system.

BACKGROUND: Quantification of rotator cuff intramuscular fatty infiltration is important for clinical decision-making in patients with rotator cuff tear. The semi-quantitative Goutallier classification system is the most commonly used method, but has limited reliability. Therefore, we sought to test a freely available fuzzy C-means segmentation software program for reliability of the quantification of shoulder intramuscular fatty infiltration on T1-weighted MR images and for correlation with fat fraction by six-point Dixon MRI. MATERIALS AND METHODS: We performed a prospective cross-sectional study to measure visible intramuscular fat area percentage on oblique sagittal T1 MR images by fuzzy C-means segmentation and fat fraction maps by six-point Dixon MRI for 42 shoulder muscles. Intra- and inter-observer reliability were determined. Correlative analysis for fuzzy C-means and six-point Dixon intramuscular fatty infiltration measures was also performed. RESULTS: We found that inter-observer reliability for the quantification of visible intramuscular fat area percentage by fuzzy C-means segmentation and fat fraction by six-point Dixon MRI was 0.947 and 0.951 respectively. The intra-observer reliability for the quantification of visible intramuscular fat area percentage by fuzzy C-means segmentation and fat fraction by six-point Dixon MRI was 0.871 and 0.979 respectively. We found a strong correlation between fuzzy C-means segmentation and six-point Dixon techniques; r = 0.850, p < 0.001 by individual muscle; and r = 0.977, p < 0.002 by study subject. CONCLUSION: Quantification of intramuscular fatty infiltration by fuzzy C-means segmentation on T1-weighted sequences demonstrates excellent reliability and strong correlation with fat fraction by six-point Dixon MRI. Quantitative fuzzy C-means segmentation is a viable alternative to the semi-quantitative Goutallier classification system.

Pseudohyperkalemia: To Treat or not to Treat.

Chronic lymphocytic leukemia (CLL) is characterized by excessive production of abnormal lymphocytes in the bone marrow. It usually presents as hepatosplenomegaly and lymphadenopathy along with constitutional symptoms of fever, tiredness, and weight loss. Pseudohyperkalemia may occur in patients with extreme leukocytosis. High serum and plasma potassium levels have been seen in pseudohyperkalemia. Whole blood potassium determination will usually help lead to a correct diagnosis. It is important to diagnose this condition early so that the patients are not inappropriately treated. We aim to highlight that hyperkalemia in CLL patients should only be treated if the patient is symptomatic or if the patient shows cardiac effects of hyperkalemia on electrocardiogram.

Isolation and characterization of a Rhodococcus strain able to degrade 2-fluorophenol.

A pure bacterial culture able to utilize 2-fluorophenol (2-FP) as sole carbon and energy source was isolated by selective enrichment from sediments collected from a contaminated site in Northern Portugal. 16S rRNA gene analysis showed that the organism (strain FP1) belongs to the genus Rhodococcus. When grown aerobically on 2-FP, growth kinetics of strain FP1 followed the Luong model. An inhibitory effect of increasing 2-FP concentrations was observed with no growth occurring at 2-FP levels higher than ca. 4 mM. Rhodococcus strain FP1 was able to degrade a range of other organofluorine compounds, including 2-fluorobenzoate, 3-fluorobenzoate, 4-fluorobenzoate, 3-fluorophenol, 4-fluorophenol, 3-fluorocatechol, and 4-fluorocatechol, as well as chlorinated compounds such as 2-chlorophenol and 4-chlorophenol. Experiments with cell-free extracts and partially purified enzymes indicated that the first step of 2-fluorophenol metabolism was conversion to 3-fluorocatechol, suggesting an unusual pathway for fluoroaromatic metabolism. To our knowledge, this is the first time that utilization of 2-FP as a growth substrate by a pure bacterial culture is reported.

Biodegradation kinetics of 4-fluorocinnamic acid by a consortium of Arthrobacter and Ralstonia strains.

Arthrobacter sp. strain G1 is able to grow on 4-fluorocinnamic acid (4-FCA) as sole carbon source. The organism converts 4-FCA into 4-fluorobenzoic acid (4-FBA) and utilizes the two-carbon side-chain for growth with some formation of 4-fluoroacetophenone as a dead-end side product. We also have isolated Ralstonia sp. strain H1, an organism that degrades 4-FBA. A consortium of strains G1 and H1 degraded 4-FCA with Monod kinetics during growth in batch and continuous cultures. Specific growth rates of strain G1 and specific degradation rates of 4-FCA were observed to follow substrate inhibition kinetics, which could be modeled using the kinetic models of Haldane-Andrew and Luong-Levenspiel. The mixed culture showed complete mineralization of 4-FCA with quantitative release of fluoride, both in batch and continuous cultures. Steady-state chemostat cultures that were exposed to shock loadings of substrate responded with rapid degradation and returned to steady-state in 10-15 h, indicating that the mixed culture provided a robust system for continuous 4-FCA degradation.

Complete biodegradation of 4-fluorocinnamic acid by a consortium comprising Arthrobacter sp. strain G1 and Ralstonia sp. strain H1.

A consortium of the newly isolated bacterial strains Arthrobacter sp. strain G1 and Ralstonia sp. strain H1 utilized 4-fluorocinnamic acid for growth under aerobic conditions. Strain G1 converted 4-fluorocinnamic acid into 4-fluorobenzoic acid and used the two-carbon side chain for growth, with some formation of 4-fluoroacetophenone as a dead-end side product. In the presence of strain H1, complete mineralization of 4-fluorocinnamic acid and release of fluoride were obtained. Degradation of 4-fluorocinnamic acid by strain G1 occurred through a ß-oxidation mechanism and started with the formation of 4-fluorocinnamoyl-coenzyme A (CoA), as indicated by the presence of 4-fluorocinnamoyl-CoA ligase. Enzymes for further transformation were detected in cell extract, i.e., 4-fluorocinnamoyl-CoA hydratase, 4-fluorophenyl-ß-hydroxy propionyl-CoA dehydrogenase, and 4-fluorophenyl-ß-keto propionyl-CoA thiolase. Degradation of 4-fluorobenzoic acid by strain H1 proceeded via 4-fluorocatechol, which was converted by an ortho-cleavage pathway.

Analysis of two gene clusters involved in the degradation of 4-fluorophenol by Arthrobacter sp. strain IF1.

Arthrobacter sp. strain IF1 is able to grow on 4-fluorophenol (4-FP) as a sole source of carbon and energy. To clone the 4-FP degradation genes, DNA libraries were constructed and screened with a probe obtained by PCR using primers designed on the basis of conserved regions of aromatic two-component monooxygenases. Sequencing of positive clones yielded two gene clusters, each harboring a gene encoding a monooxygenase with high sequence similarity to the oxygenase component of 4-nitrophenol and 4-chlorophenol monooxygenase systems. Both these monooxygenase genes were differentially expressed during growth on 4-FP, as revealed by Northern blotting and reverse transcription-PCR. One cluster also contained a gene for a flavin reductase. The monooxygenase and reductase were purified from Escherichia coli cells expressing the corresponding genes, and together they catalyzed NADH-dependent hydroxylation and dehalogenation of 4-halophenols. The results indicate that strain IF1 transforms 4-FP to hydroquinone by a two-component monooxygenase system of which one component provides reduced flavin adenine dinucleotide at the expense of NADH and the other catalyzes para-hydroxylation of 4-FP and other 4-substituted phenols.

Arthroscopic and open Bankart repairs provide similar outcomes.

UNLABELLED: Recurrent instability after arthroscopic Bankart repair has decreased, largely because of improvements in surgical technique. We wanted to know whether there were differences in functional outcomes (using a validated outcomes measure) in patients who had arthroscopic Bankart repair or open Bankart repair for recurrent anterior glenohumeral instability. We retrospectively reviewed 106 patients who had a Bankart repair for recurrent anterior glenohumeral instability from 1998-2001. Of the 93 patients included, 69 patients had arthroscopic Bankart repair and 24 patients had open Bankart repair. The indications for surgery in the two groups were similar. The average age of the patients was 29.9 years (arthroscopic Bankart repair, 31 years; open Bankart repair, 28 years). The followup ranged from 24-77 months. The average modified American Shoulder and Elbow Surgeons score (PENN score) for pain, satisfaction, and function were 26.3, 8.5, and 55.1, respectively, in the arthroscopic Bankart repair group and 26.6, 8.8, and 54.2, respectively, in the open Bankart repair group. The total score was 90 in the arthroscopic Bankart repair group and 89.5 in the open Bankart repair group. Recurrent instability occurred in one patient in each group. We found no difference in outcomes between the arthroscopic and open Bankart repair groups using patient-assessed outcomes. LEVEL OF EVIDENCE: Therapeutic Study, Level III (retrospective comparative study). See the Guidelines for Authors for a complete description of levels of evidence.