Complication rates and modes of short and medium-term failure in Motec total wrist arthroplasty: an international cohort study.

The aim of this study was to analyse the short- and medium-term complications of the Motec total wrist arthroplasty (TWA). Identifying exact modes of failure and their causes should allow surgeons to avoid or mitigate these risks in the future. Retrospective analysis of prospectively collected data from six hand surgeons at five international centres provided details of 171 Motec TWAs. The mean follow-up was 5.8 years (range 18 months to 12 years). There were 33 (19%) complications within our cohort, with a revision rate of 8.2% (14 revisions). There was no difference in complication rates between metal-on-metal and metal-on-polymer articulations. Failure of osseointegration was the most common complication. Problems with soft tissue balancing, implant impingement related osteolysis, bony impingement and metacarpal fracture were found to be other preventable causes of failure in this series. Elimination of these preventable complications will improve survival rates for this implant.Level of evidence: IV.

Assessment of the properties of aging biochar used as a substrate in constructed wetlands.

Biochar has gained global recognition as an effective tool for environmental remediation, and is increasingly being used as an alternative substrate in constructed wetlands (CWs). While, most studies have focused on the positive effects of biochar for the pollutant removal in CWs, less is known about aging and longevity of the embedded biochar. This study investigated the aging and stability of biochar embedded in CWs post-treating the effluent of a municipal and an industrial wastewater treatment plant. Litter bags containing biochar were inserted into two aerated horizontal subsurface flow CWs (350 m2 each), and retrieved on several dates (8-775 days after burial) for assessment of weight loss/gain and changes in biochar characteristics. Additionally, a 525-day laboratory incubation test was conducted to analyze biochar mineralization. The results showed that there was no significant biochar weight loss over time, but a slight increase in weight (2.3-3.0%) was observed at the end, likely due to mineral sorption. Biochar pH remained stable except for a sudden drop at the beginning (8.6-8.1), while the electrical conductivity continued to increase (96-256 µS cm-1) throughout the experiment. The sorption capacity of the aged biochar for methylene blue significantly increased (1.0-1.7 mg g-1), and a change in the biochar's elemental composition was also noted, with O-content increasing by 13-61% and C content decreasing by 4-7%. Despite these changes, the biochar remained stable according to the criteria of the European Biochar Foundation and International Biochar Initiative. The incubation test also showed negligible biochar mass loss (<0.02%), further validating the stability of the biochar. This study provides important insights into the evolution of biochar characteristics in CWs.

Outcomes of Allograft Medial Patellofemoral Ligament Reconstruction in Children and Adolescents with Hypermobility.

Introduction: Medial patellofemoral ligament (MPFL) reconstruction is used to treat patellofemoral instability either in isolation or in combination with other procedures. Use of allograft can preserve native tissue in children and can be advantageous in patients with connective tissue disorders, including ligamentous laxity. There is limited evidence regarding functional outcomes of allograft MPFL reconstruction in children and adolescents. This study aimed to assess the short to mid-term results of allograft MPFL reconstruction in children with hypermobility at a tertiary pediatric orthopedic center. Materials and Methods: We retrospectively reviewed all children and adolescents who had undergone allograft MPFL reconstruction over 4 years. The primary outcome measure was the validated Kujala score for patellofemoral disorders. The secondary outcome measures included complications such as redislocation of the patella needing revision surgery. Patients with hypermobility were quantified using Beighton criteria. Statistical analysis was performed using Graph Pad Prism (V6). Results: Between 2012 and 2016, the senior author performed 76 allograft MPFL reconstructions in 57 patients. Nineteen patients had bilateral surgery. The mean age was 14 (7-16) years with a female: male ratio of 3:1. The mean Beighton score was 7. Hypermobility was part of a syndrome in ten patients. The mean follow-up was 3 (1-4) years. Nine patients had trochleoplasty and six patients had tibial tubercle osteotomy, in addition to allograft MPFL reconstruction. These fifteen patients, who had additional procedures, were excluded during the analysis of the outcome measures. The mean Kujala score was 89 (80-100). The overall complication rate was 11% (9/76). These included two patella fractures and seven (9%) patients with recurrent instability needing revision surgery. There was no significant difference in complication rates between syndromic and nonsyndromic patients (P = 0.9). Conclusion: Our study shows excellent short to mid-term functional outcomes of allograft MPFL reconstruction in children and adolescents with hypermobility.

Comparison of Different Techniques of Meatoplasty After Canal Wall Down Mastoidectomy.

To compare surgical outcomes with different meatoplasty techniques without removal of a cartilage piece in canal wall down mastoidectomy. Total 61 patients of canal wall down mastoidectomy included in the study where either inferior based flap technique or division in middle technique meatoplasty performed and 2 groups formed. Group A consisted of 33 patients and the inferior based flap technique of meatoplasty used in these patients. Group B consisted of 28 patients and the division in middle technique of meatoplasty used in these patients. Granulations, discharge or stenosis of canal were observed in less than 8% of cases in both the groups. Meatoplasty done without incision or excision of a piece of cartilage from pinna can be achieved with good success rates with either inferiorly based flap technique or division in middle technique.

Esophageal retention cyst: Esophagogastric junction outflow obstruction (EGJOO) as a potential etiology and management with endoscopic mucosal resection (EMR).

INTRODUCTION AND IMPORTANCE: Esophageal retention cysts are acquired cysts with no known etiology. They are characterized by dilation of the submucosal glands. Symptomatic cysts are traditionally managed by surgical resection. CASE PRESENTATION: We present a case of progressive dysphagia and chest pain secondary to esophageal retention cysts in the mid and distal esophagus with associated esophagogastric junction outflow obstruction (EGJOO) and jackhammer esophagus on high resolution manometry (HRM). The patient underwent staged endoscopic mucosal resection (EMR) with subsequent improvement in her symptoms. However, EGJOO persisted after resection, suggesting it was the primary pathology and not a consequence of the obstruction from the cysts. CLINICAL DISCUSSION: Esophageal retention cysts are rarely reported in the literature with most descriptions coming from incidental post-mortems. The presented case suggests EGJOO as a potential etiology of retention cysts. The proposed mechanism is that a significant rise in esophageal intraluminal pressure creates a state of stasis in the esophagus, ideal for the development of these cysts. Symptomatic or malignant retention cysts should be resected. We demonstrate the feasibility of EMR as an alternative to surgical resection. CONCLUSION: Esophageal retention cyst is a rare entity, which may arise as a result of EGJOO. The natural history and malignant potential of these cysts are unknown, and no formal guidelines have been established for follow-up for patients with asymptomatic retention cysts. Endoscopic mucosal resection can be used to successfully manage these cysts.

Fine wire versus locking plate fixation of type C pilon fractures.

PURPOSE: The successful treatment of high energy pilon fractures (AO-OTA 43C) can be achieved with a fine wire circular external fixator (CEF) or locking plate construct (ORIF). There is no consensus on whether ORIF or CEF achieves superior outcomes, and both have unique complications. We report early to mid-term outcomes comparing type C pilon fractures treated with ORIF and CEF. METHODS: An 8-year retrospective review was performed on all patients who underwent ORIF or CEF for closed 43C fractures in a tertiary orthoplastic centre. Outcomes included unplanned return to theatre prior to union including superficial and deep surgical site infections (SSI), non-union and post-traumatic osteoarthritis (PTOA) needing fusion. RESULTS: 76 patients underwent ORIF and 59 patients had CEF, with a mean follow-up of 2 years. 7/76 (9.2%) patients who underwent ORIF had a superficial SSI; 2 patients (2.6%) required a formal debridement for deep SSI; none required a flap. 13/59 patients (22%) had a pin track infection following CEF. With the numbers available, there was no significant difference in rates of unplanned return to theatre before bone healing (ORIF 7/76, 9.2%, CEF 9/59, 15.2%, p = 0.7), rates of mal-union (1.7% CEF, 3.9% ORIF, p = 0.7), deep SSI (p = 0.9), time to union (ORIF: 8.1 months v CEF 10.8 months, p = 0.51), non-union (p = 0.24) and fusion for PTOA (ORIF: 6/76, CEF 2/59, p = 0.46). CONCLUSION: With correct patient selection, both ORIF and CEF offer equivalent and favourable early to mid-term outcomes with regard to deep SSI, non-union, mal-union and PTOA. Although statistically insignificant, ORIF with more than 2 plates carries a risk of superficial and deep SSI, whilst CEF is associated with a 22% pin track infection rate. These unique risks must be discussed with the patient as part of a shared decision-making process.

Use of Collagen Sheets as Graft Material for Myringoplasty.

The purpose of the study is to investigate how Collagen sheet used as graft material in Myringoplasty improves hearing and tympanic membrane tissue repair in patients with tympanic membrane perforation (TMP) in an office based procedure. Total 50 cases included in the study where Collagen sheet used as graft material for myringoplasty in small to moderate size tympanic membrane perforations(TMP) and procedure performed in an office based set up with the help of a High definition endoscope and camera. Cases followed up regularly and results observed in terms of graft uptake and complete closure of TMP and hearing improvement. Out of 50, complete closure of TMP observed in 39 cases and an average hearing gain of 9.9 db noted in these cases. Success rate of 78% achieved and failed cases were subjected to traditional post auricular method of myringoplasty under microscopic guidance. Myringoplasty with the help of collagen sheet material in an office based set up is an easy, minimally invasive and effective technique and it avoids need for major invasive intervention in a significant number of patients.

Appendiceal carcinoma presenting as a rapidly enlarging abdominal mass.

INTRODUCTION: Appendiceal adenocarcinomas, although rare, usually present as slow-growing masses. Rarely, do they rapidly enlarge into large abdominal masses over a short period of time. Generally, we attribute rapidly growing abdominal masses to sarcomas, desmoid tumors, or gynecological masses. We present a case of a rapidly growing appendiceal adenocarcinoma in an elderly patient. CASE PRESENTATION: We report a case of an 83-year-old-male who presented with a one-month history of abdominal pain. A computer tomography (CT) scan identified a lower pelvic mass measuring 7.39 cm × 5.40 cm. A biopsy was done which revealed appendiceal carcinoma. A plan for radiotherapy to reduce the tumor size was made and the patient was discharged. However, the patient returned after three weeks due to worsening abdominal pain and a CT scan identified a significant enhancement in the tumor size. The patient underwent debulking surgery. Pathology of the specimen identified adenocarcinoma of the appendix. DISCUSSION: A rapidly growing carcinoma of the appendix is rare as they are known to have a slow growth rate. A swift diagnosis and intervention are required as these rapidly enhancing neoplasms in the abdomen can become unresectable and metastasize. Although there are various methods of treatment for appendiceal carcinomas, the rapid growth rate and lack of response to radiation required debulking surgery. CONCLUSION: There exist a myriad of differential diagnoses for a rapidly growing mass in the abdomen. We are presenting the first documented case of a rapidly growing appendiceal adenocarcinoma. Surgeons should be aware of the variety of differentials in such cases.

Functional outcomes & metal ion levels following ceramic on metal total hip arthroplasty: 9 Year follow-up.

In this study, we evaluate the mid-term functional and radiological outcomes of Ceramic on Metal Total Hip Arthroplasty (CoM THA) THA. 66 CoM THAs were performed between 2008 and 2010. These were evaluated and followed up in 2017-18, at a mean follow-up of 9 years to record the Oxford Hip Score [OHS] and whole blood Cobalt and Chrome levels. Our all cause revision rate was 4.5% (3 out of 66). At mid-term follow up, patients with CoM THAs are mostly asymptomatic with reasonable functional outcomes, we have reported similar revision rates in conjunction with raised blood metal ion levels and frequency of radiolucent lines.

Outcome of revision surgery in recurrent dislocation of primary total hip arthroplasty.

BACKGROUND: The cause of recurrent dislocation following primary total hip arthroplasty (THA) is multifactorial. A re-dislocation rate of up-to 34% following revision is reported. The aim of this study was to determine the re-dislocation rates following revision for recurrent THR dislocation. METHODOLOGY: Patients who underwent revision for recurrent dislocation between January 2008 and January 2015 were identified. We identified the date and type of primary implant, overall number and reasons for dislocation, revision implant details and complication data. RESULTS: Over an 8-year period, 24 patients underwent revision. The median age was 77 (68-85) years, median time to first dislocation was 78 (23-160) months and median number of dislocations was 3 (2-4) with a mean follow-up of 18 months. Socket Mal-Orientation (10) and Abductor deficiency (5) were the main causes of recurrent dislocation. 21 patients (88%) underwent revision of both components, 1 patient underwent isolated cup revision and 2 patients had revision of acetabular component with insertion of a BioBall. There were no dislocations within 90 days of revision surgery. 4 patients had late dislocations (3 recurrent, 1 isolated). There was no significant increase risk of dislocation after revision surgery in the neck of femur group (p = 0.467). CONCLUSIONS: We report favourable outcomes for revision of both components for recurrent dislocation with no dislocations within 90 days. The overall late dislocation rate was 16.7%, however, these patients have settled following closed reduction. Due to its multifactorial aetiology, both component revision can be considered in this patient population.

A Study Comparing the Outcomes of Transverse Ulnar Shortening Osteotomy Fixed with a DCP to Oblique Osteotomy Fixed with a Procedure Specific Plate.

Background: Ulnar shortening osteotomy (USO) is a well-established procedure for ulnar impaction syndrome. Various types of osteotomies have been described. Methods: A retrospective cohort study was conducted to compare the results of transverse osteotomy (TO) fixed with a small fragment dynamic compression plate (Synthes, Pennsylvania, USA), to oblique osteotomy (OO) fixed with a procedure specific plate and instrumentation system (Acumed LLC, Oregon, USA). A total of 39 patients underwent TO and 62 patients underwent OO between 2007 and 2016. The main outcomes compared were rate of union, duration of radiological healing, implant removal rate and other complications. Results: The two groups were comparable with regards to demographics, side operated and smoking status (p > 0.05). Amongst the TO group; 36 out of 39 patients (92.3%) achieved union, 3 patients (7.7%) developed non-union. Six out of the 36 healed TO (16.6%) required removal of hardware due to implant-related pain. No other complications were recorded amongst TO group needing surgical intervention. Amongst the OO group, 2 of the early cohort of 62 patients (3.2%) sustained acute failure of the metalwork due to technical error. One of the remaining 60 patients (1.6%) developed non-union giving an overall union rate of 95.2%. Two patients out of 59 healed OO (3.3%) required removal of hardware. Conclusions: Although there were 2 early failures, there was a trend towards improved union rate with OO, but this did not reach statistical significance (p > 0.05). There was a significantly higher hardware removal rate recorded in TO group (p = 0.023). The OO showed shorter duration for radiological healing than TO (p < 0.05). USO performed with an OO and fixed with procedure specific plate has lower implant removal rate, a shorter duration for radiological healing and comparable union rate to TO fixed with DCP, but needs careful attention to detail.

Ulnar tunnel syndrome: pathoanatomy, clinical features and management.

Ulnar tunnel syndrome is compression of the ulnar nerve at the level of the wrist within Guyon's canal. It is most commonly caused by a ganglion cyst but may also be secondary to fractures, inflammatory conditions, neoplasm, vascular anomalies, aberrant musculature or a combination of these. Assessment should include a detailed history focusing on duration, site and progression of symptoms. The level of compression can be estimated clinically on examination by assessing motor and sensory changes in the hand. Investigations are used to confirm diagnosis or to clarify the underlying cause. X-rays and computed tomography can be used to exclude fractures. Ultrasound is used to diagnose ganglion cysts and vascular anomalies, and can localise the level of compression. Nerve conduction studies can be used to support the diagnosis and look for proximal compression. Mild symptoms can be managed non-operatively. Surgical exploration and decompression is the gold standard treatment for neuro-compressive causes with largely good outcomes.

Outcomes of Intramedullary Nailing with Cerclage Wiring in Subtrochanteric Femoral Fractures.

AIMS: The aim of this study was to compare the outcomes of closed reduction against open reduction with cerclage wires in patients with subtrochanteric fractures treated with intramedullary nailing (IMN). MATERIALS AND METHODS: We identified 141 patients who had an IMN over a 4-year period. They were classified into three groups based on fracture pattern and whether open or closed reduction was performed. Type I was a transverse fracture, type II, a spiral fracture with an intact posterior and medial wall in the proximal fragment, and a type III fracture without intact posterior or medial walls. The primary outcome measure was a revision surgery for implant failure. Secondary outcome measures were related to fracture reduction and radiological union scores of the hip (RUSH). RESULTS: There were 35 patients who had a type I fracture, 26 patients with a type II fracture, and 80 patients with a type III fracture. The mean follow-up was 7 months. Closed reduction in type III fractures was associated with a significantly increased risk of mechanical complications (p = 0.005) and unplanned returns to theatre for implant failure (p = 0.04) as compared to open reduction. Open reduction in type III fractures was associated with a significantly higher mean RUSH scores (p = 0.0006). There was no significant difference in mean operative time between open and closed reduction in type III fractures (p = 0.12). CONCLUSION: We recommend open reduction with cerclage wiring in type III subtrochanteric fractures in order to reduce the risk of implant failure, nonunion, and need for further surgery. HOW TO CITE THIS ARTICLE: Mehta NJ, Goldsmith T, Lacey A, et al. Outcomes of Intramedullary Nailing with Cerclage Wiring in Subtrochanteric Femoral Fractures. Strategies Trauma Limb Reconstr 2019;14(1):29-33.

Pharmacological manipulation of the olfactory bulb modulates beta oscillations: testing model predictions.

The mammalian olfactory bulb (OB) generates gamma (40-100 Hz) and beta (15-30 Hz) local field potential (LFP) oscillations. Gamma oscillations arise at the peak of inhalation supported by dendrodendritic interactions between glutamatergic mitral cells (MCs) and GABAergic granule cells (GCs). Beta oscillations are induced by odorants in learning or odor sensitization paradigms, but their mechanism and function are still poorly understood. When centrifugal OB inputs are blocked, beta oscillations disappear, but gamma oscillations persist. Centrifugal inputs target primarily GABAergic interneurons in the GC layer (GCL) and regulate GC excitability, suggesting a causal link between beta oscillations and GC excitability. Our previous modeling work predicted that convergence of excitatory/inhibitory inputs onto MCs and centrifugal inputs onto GCs increase GC excitability sufficiently to produce beta oscillations primarily through voltage dependent calcium channel-mediated GABA release, independently of NMDA channels. We test some of the predictions of this model by examining the influence of NMDA and muscarinic acetylcholine (ACh) receptors, which affect GC excitability in different ways, on beta oscillations. A few minutes after intrabulbar infusion, scopolamine (muscarinic antagonist) suppressed odor-evoked beta in response to a strong stimulus but increased beta power in response to a weak stimulus, as predicted by our model. Pyriform cortex (PC) beta power was unchanged. Oxotremorine (muscarinic agonist) suppressed all oscillations, likely from overinhibition. APV, an NMDA receptor antagonist, suppressed gamma oscillations selectively (in OB and PC), lending support to the model's prediction that beta oscillations can be supported independently of NMDA receptors. NEW & NOTEWORTHY Olfactory bulb local field potential beta oscillations appear to be gated by GABAergic granule cell excitability. Reducing excitability with scopolamine reduces beta induced by strong odors but increases beta induced by weak odors. Beta oscillations rely on the same synapse as gamma oscillations but, unlike gamma, can persist in the absence of NMDA receptor activation. Pyriform cortex beta oscillations maintain power when olfactory bulb beta power is low, and the system maintains beta band coherence.

Can zero-hour cortical biopsy predict early graft outcomes after living donor renal transplantation?

INTRODUCTION: The aim of this study was to identify relevance of subclinical pathological findings in the kidneys of living donors and correlate these with early graft renal function. METHODS: This was a prospective study on 84 living donor kidney transplant recipients over a period of two years. In all the donors, cortical wedge biopsy was taken and sent for assessment of glomerular, mesangial, and tubule status. The graft function of patients with normal histology was compared with those of abnormal histological findings at one, three, and six months, and one year post-surgery. RESULTS: Most abnormal histological findings were of mild degree. Glomerulosclerosis (GS, 25%), interstitial fibrosis (IF, 13%), acute tubular necrosis (ATN 5%), and focal tubal atrophy (FTA, 5%) were the commonly observed pathological findings in zero-hour biopsies. Only those donors who had histological changes of IF and ATN showed progressive deterioration of renal function at one month, three months, six months, and one year post-transplantation. In donors with other histological changes, no significant effect on graft function was observed. CONCLUSIONS: Zero-hour cortical biopsy gave us an idea of the general status of the donor kidney and presence or absence of subclinical pathological lesions. A mild degree of subclinical and pathological findings on zero-hour biopsy did not affect early graft renal function in living donor kidney transplantation. Zero-hour cortical biopsy could also help in discriminating donor-derived lesions from de novo alterations in the kidney that could happen subsequently.

Task-Dependent Behavioral Dynamics Make the Case for Temporal Integration in Multiple Strategies during Odor Processing.

Differing results in olfactory-based decision-making research regarding the amount of time that rats and mice use to identify odors have led to some disagreements about odor-processing mechanics, including whether or not rodents use temporal integration (i.e., sniffing longer to identify odors better). Reported differences in behavioral strategies may be due to the different types of tasks used in different laboratories. Some researchers have reported that animals performing two-alternative choice (TAC) tasks need only 1-2 sniffs and do not increase performance with longer sampling. Others have reported that animals performing go/no-go (GNG) tasks increase sampling times and performance for difficult discriminations, arguing for temporal integration. We present results from four experiments comparing GNG and TAC tasks over several behavioral variables (e.g., performance, sampling duration). When rats know only one task, they perform better in GNG than in TAC. However, performance was not statistically different when rats learned and were tested in both tasks. Rats sample odors longer in GNG than in TAC, even when they know both tasks and perform them in the same or different sessions. Longer sampling is associated with better performance for both tasks in difficult discriminations, which supports the case for temporal integration over ≥2-6 sniffs in both tasks. These results illustrate that generalizations from a single task about behavioral or cognitive abilities (e.g., processing, perception) do not capture the full range of complexity and can significantly impact inferences about general abilities in sensory perception.SIGNIFICANCE STATEMENT Behavioral tasks and training and testing history affect measured outcomes in cognitive tests. Rats sample odors longer in a go/no-go (GNG) than in a two-alternative choice (TAC) task, performing better in GNG unless they know both tasks. Odor-sampling time is extended in both tasks when the odors to be discriminated are very similar. Rats may extend sampling time to integrate odor information up to ∼0.5 s (2-6 sniffs). Such factors as task, task parameters, and training history affect decision times and performance, making it important to use multiple tasks when making inferences about sensory or cognitive processing.

Is device-assisted reduction prior to semi-extended intramedullary nailing of distal tibial fractures necessary?

INTRODUCTION: Traditional methods of nailing distal tibial fractures have an unacceptable risk of mal-alignment due to difficulty in obtaining and maintaining reduction intra-operatively. Methods to obtain and maintain reduction when nailing these fractures, and therefore reducing the risk of Mal-alignment include modified external fixators, distractors and commercial reduction tools. Semi-extended intramedullary nailing of distal tibial fractures via a supra-patellar approach is now being used more commonly. The aim of this study was to assess whether a commercial reduction device (Staffordshire Orthopaedic Reduction Machine - STORM, Intelligent Orthopaedics, Stafffordshire, UK) is necessary to reduce the risk of mal-alignment in patients undergoing semi-extended nailing for distal tibial fractures. METHODOLOGY: A case-control study was conducted in 20 patients who had STORM-assisted reduction of distal tibial fractures prior to intramedullary nailing and 20 controls without STORM. The control group was matched for age, sex, fracture type (AO/OTA), ASA and gender. All patients had an intramedullary nail (IMN) using the semi-extended system. Primary outcome measures were coronal and sagittal mal-alignment. Secondary outcome measure was unplanned return to theatre for complications and problems with fracture healing. RESULTS: There was no difference in post-operative mal-alignment in both groups. There was no significant difference in time to union in both groups Both groups had equal number of patients requiring unplanned return to theatre. The STORM group was associated with a significantly increased operative time [p=0.007, 130.3min (SD 49.4) STORM vs 95.6 mins (SD 22.9) Control]. CONCLUSION: Intraoperative use of STORM significantly increases operative time with no difference in outcome. The superior orthogonal views and manual control obtained during semi-extended nailing via a supra-patellar approach obviate the need for additional methods: of intraoperative reduction for this fracture group.

Gamma and Beta Oscillations Define a Sequence of Neurocognitive Modes Present in Odor Processing.

UNLABELLED: Olfactory system beta (15-35 Hz) and gamma (40-110 Hz) oscillations of the local field potential in mammals have both been linked to odor learning and discrimination. Gamma oscillations represent the activity of a local network within the olfactory bulb, and beta oscillations represent engagement of a systemwide network. Here, we test whether beta and gamma oscillations represent different cognitive modes using the different demands of go/no-go and two-alternative choice tasks that previously were suggested to favor beta or gamma oscillations, respectively. We reconcile previous studies and show that both beta and gamma oscillations occur in both tasks, with gamma dominating the early odor sampling period (2-4 sniffs) and beta dominating later. The relative power and coherence of both oscillations depend separately on multiple factors within both tasks without categorical differences across tasks. While the early/gamma-associated period occurs in all trials, rats can perform above chance without the later/beta-associated period. Longer sampling, which includes beta oscillations, is associated with better performance. Gamma followed by beta oscillations therefore represents a sequence of cognitive and neural states during odor discrimination, which can be separately modified depending on the demands of a task and odor discrimination. Additionally, fast (85 Hz) and slow (70 Hz) olfactory bulb gamma oscillation sub-bands have been hypothesized to represent tufted and mitral cell networks, respectively (Manabe and Mori, 2013). We find that fast gamma favors the early and slow gamma the later (beta-dominated) odor-sampling period and that the relative contributions of these oscillations are consistent across tasks. SIGNIFICANCE STATEMENT: Olfactory system gamma (40-110 Hz) and beta (15-35 Hz) oscillations of the local field potential indicate different neural firing statistics and functional circuits. We show that gamma and beta oscillations occur in stereotyped sequence during odor sampling in associative tasks, with local gamma dominating the first 250 ms of odor sniffing, followed by systemwide beta as behavioral responses are prepared. Oscillations and coupling strength between brain regions are modulated by task, odor, and learning, showing that task features can dramatically adjust the dynamics of a cortical sensory system, which changes state every ∼250 ms. Understanding cortical circuits, even at the biophysical level, depends on careful use of multiple behavioral contexts and stimuli.

Leiomyosarcoma Presenting as a Scrotal Mass.

Scrotal leiomyosarcoma is a rare tumor arising from the dartos layer of the scrotum presenting as firm, rubbery, non-tender, irregular mass. To date about 37 cases of leiomyosarcoma of scrotum have so far been reported. Treatment involves wide surgical excision with tumor free margins. We report a case of scrotal leiomyosarcoma in a 48-year-old man which was treated by a wide surgical excision and follow up of 14 months showed no recurrence of tumor.