An Oncoplastic Approach to Primary Pediatric Pterygomaxillary Osteosarcoma

Osteosarcomas arising within the pterygomaxillary/infratemporal fossa region are rare among the pediatric population. Survival rates are most influenced by tumor resection with negative margins, which can be dependent on surgical accessibility of the tumor site. The pterygomaxillary/infratemporal fossa location poses several challenges to safe and adequate tumor resection, including proximity of the facial nerve and great vessels and scarring associated with traditional transfacial approaches. In this article, we present the case of a 6-year-old boy with an osteosarcoma of the left pterygomaxillary/infratemporal fossa region successfully managed with an "oncoplastic" approach, incorporating the use of CAD/CAM and mixed reality technologies.

Orthodontic and Orthognathic Surgical Treatment in a Patient with a Large Lymphatic Malformation of the Face: A Case Report

Lymphatic malformations (LMs) are congenital abnormalities in the development of the lymphatic system. They can damage other structures including the airway, blood vessels, nerves, or bones. LMs of the face can result in malocclusion, and many patients with LMs of the face require orthognathic surgery to correct the malocclusion. Surgery-first is a treatment modality which should be considered for individuals with LMs and is a protocol in which orthognathic surgery is performed prior to orthodontic treatment. This case report describes surgery-first and subsequent orthodontic treatment in a patient with a class III malocclusion due to a large facial LM.

Surgical approach to penile reconstruction for shaft skin excision from circumcision

PURPOSE

Circumcision is one of the most frequently performed surgical procedures. Complications are infrequent, including bleeding, though can be significant such as shaft skin excision. The aim of this study was to identify mechanism of injury and reconstructive techniques for skin excision using a full thickness skin graft (FTSG) or with the novel application of tissue expanders (TE).

METHODS

Patients who underwent penile reconstruction following shaft skin excision from an overzealous circumcision were retrospectively reviewed. The penis was covered using a FTSG, harvested from the groin/hip, or using TE, with expanders placed in residual shaft skin.

RESULTS

Twelve patients experienced significant skin loss (range 65-95%) including 2 with partial glans loss. Ten were reconstructed using a FTSG and 2 with TE. Injury was most frequently from a Mogen clamp (n = 9), or from a Gomco clamp, Plastibell device, and electrocautery burns. Six FTSG patients experienced complications with lymphedema (n = 3) most common.

CONCLUSION

Shaft skin excision is a devastating complication with risk greatest from Mogen clamp use. TE is preferred as this avoids donor site morbidity which reassures parents but requires sufficient residual skin that can be expanded. Both techniques effectively provide soft tissue coverage with acceptable appearance and long-term function.

Differences in Applicant Perceptions of Virtual Interviews Between Integrated Plastic Surgery and Subspecialty Fellowship Applicants

OBJECTIVE

We aim to survey and compare integrated plastic surgery and plastic surgery subspecialty fellowship applicants on their experiences with virtual interviews and to determine if there are differences between them.

DESIGN

An IRB-approved survey study was conducted using the Qualtrics platform.

SETTING

The study was conducted at the Johns Hopkins University and the R Adams Cowley Shock Trauma Center in Baltimore Maryland.

PARTICIPANTS

Applicants that applied to 1) the Johns Hopkins/University of Maryland or the University of California San Diego integrated plastic surgery residency programs, 2) craniofacial surgery fellowship, and 3) microsurgery, hand surgery, or burn surgery fellowship at the Johns Hopkins University were selected to participate in the survey.

RESULTS

A total of 94 surveys were completed by residency applicants and 55 by fellowship applicants. After the interview season, 80% of fellowship applicants recommended virtual interviews compared to 61.7% of residency applicants (p = 0.03). Fellowship applicants reported significantly less issues with self-advocacy and did not view the virtual interview process as significant of a detriment when meeting program residents/staff, viewing the hospital/surrounding area, and learning about the program (p < 0.05). A higher percentage of fellowship applicants interviewed at multiple programs during a single day compared to residency applicants (56.4% vs 27.7%; p < 0.001).

CONCLUSIONS

A higher proportion of fellowship applicants prefer virtual interviews, which associated with key differences in perceptions, expectations, and priorities. Our data supports that fellowship programs may wish to continue virtual interviews even after COVID-related restrictions are lifted, because fellows are equally able to self-advocate in a virtual format while benefiting from cost and time savings; fellowship programs would also gain the cost and time savings from this model as well.

Design of a Novel Orthodontic Appliance to Prevent Pedicle Trauma in Patients Undergoing Double-Opposing Buccal Flaps for Palatal Lengthening

OBJECTIVE

To describe a novel orthodontic appliance to prevent pedicle trauma in patients undergoing double-opposing buccal flap surgery for secondary palatal lengthening.

DESIGN

Case series.

SETTING

Cleft and craniofacial clinic, Johns Hopkins Children's Center.

PATIENTS, PARTICIPANTS

Four patients undergoing double-opposing buccal flap surgery for repair of velopharyngeal insufficiency.

INTERVENTIONS

Patients were fitted with the device, which consists of a lower lingual holding arch with acrylic bite blocks.

MAIN OUTCOME MEASURE

Presence of pedicle trauma postsurgery and tolerability of the device.

RESULTS

The appliance was well tolerated in all 4 patients and no biting trauma to the pedicles was observed.

CONCLUSIONS

A reliable appliance has been developed to prevent biting trauma to the pedicles in patients undergoing double-opposing buccal flap surgery in the permanent dentition stage.

Postnatal Progressive Craniosynostosis in Syndromic Conditions: Two Patients With Saethre-Chotzen Due to TWIST1 Gene Deletions and Review of the Literature

Saethre-Chotzen syndrome (SCS) is a known craniosynostosis syndrome with a variable presentation of craniofacial and somatic involvement. Congenital coronal craniosynostosis is most commonly observed in SCS; however, progressive postnatal craniosynostosis of other sutures has been reported. The authors present 2 infants with progressive postnatal craniosynostosis and SCS caused by chromosome 7p deletions including the TWIST1 gene. The evolution of their clinical features and a literature review of patients with syndromic, postnatal progressive craniosynostosis illustrate the importance of longitudinal observation and management of these patients.

The Impact of Payment Reform on Pediatric Craniofacial Fracture Care in Maryland

STUDY DESIGN

Retrospective, quasi-experimental difference-in-differences investigation.

OBJECTIVE

Pediatric craniofacial fractures are often associated with substantial morbidity and consumption of healthcare resources. Maryland's All Payer Model (APM) represents a unique case study of the health economics surrounding pediatric craniofacial fractures. The APM implemented global hospital budgets to disincentivize low-value care and encourage preventive, community-based efforts. The objective of this study was to investigate how this reform has impacted pediatric craniofacial fracture care in Maryland.

METHODS

Children (≤18 years) receiving inpatient craniofacial fracture-related care in Maryland between January, 2009 through December, 2016 were investigated. New Jersey was used for comparison. Data were abstracted from the Kid's Inpatient Database (Healthcare Cost and Utilization Project).

RESULTS

Between 2009-2016, 3,655 pediatric patients received inpatient care for craniofacial fractures in Maryland and New Jersey. Prior to APM implementation, around 20% of Maryland patients received care outside of urban teaching hospitals. After APM implementation, less than 6% of patients received care outside of urban teaching hospitals (p = 0.003). Implementation of the APM in Maryland also resulted in fewer pediatric craniofacial fracture admissions than New Jersey, though this only reached borderline significance (adjusted difference-in-differences estimate: -1.1 fewer admissions, 95% confidence interval: -2.1 to 0.0, p = 0.05). Inpatient costs for pediatric craniofacial care and mean did not change post-APM.

CONCLUSIONS

Maryland's APM consolidated pediatric craniofacial fracture inpatient care at urban, teaching hospitals. Inpatient costs and lengths of stay did not change after policy implementation, but overall admission rates decreased. Such considerations are important when considering national expansion of global hospital budgeting.

Interfacility Transfers for Isolated Craniomaxillofacial Trauma: Perspectives of the Facial Trauma Surgeon

STUDY DESIGN

Secondary overtriage is a burden to the medical system. Unnecessary transfers overload trauma centers, occupy emergency transfer resources, and delay definitive patient care. Craniomaxillofacial (CMF) trauma, especially in isolation, is a frequent culprit.

OBJECTIVE

The aim of this study is to assess the perspectives of facial trauma surgeons regarding the interfacility transfer of patients with isolated CMF trauma.

METHODS

A 31-item survey was developed using Likert-type scale and open-ended response systems. Internal consistency testing among facial trauma surgeons yielded a Cronbach's α calculation of .75. The survey was distributed anonymously to the American Society of Maxillofacial Surgeons, the North American Division of AO Craniomaxillofacial, and the American Academy of Facial Plastic and Reconstructive Surgery. Statistical significance in response plurality was determined by nonoverlapping 99.9% confidence intervals (P < .001). Sum totals were reported as means with standard deviations and z scores with P values of less than .05 considered significant.

RESULTS

The survey yielded 196 responses. Seventy-seven percent of respondents did not believe that most isolated CMF transfers required emergency surgery and roughly half (49%) thought that most emergency transfers were unnecessary. Fifty-four percent of respondents agreed that most patients transferred could have been referred for outpatient management and 87% thought that transfer guidelines could help decrease unnecessary transfers. Twenty-seven percent of respondents had no pre-transfer communication with the referring facility. Perspectives on the transfer of specific fracture patterns and their presentations were also collected.

CONCLUSION

Most facial trauma surgeons in this study believe that emergent transfer for isolated CMF trauma is frequently unnecessary. Such injuries rarely require emergent surgery and can frequently be managed in the outpatient setting without activating emergency transfer services. The fracture-specific data collected are a representation of the national, multidisciplinary opinion of facial trauma surgeons and correlate with previously published data on which specific types of facial fractures are most often transferred unnecessarily. The results of this study can serve as the foundation for interfacility transfer guidelines, which may provide a valuable resource in triaging transfers and decreasing associated health-care costs.

Public Perceptions of Physician Attire and Professionalism in the US

IMPORTANCE

In recent years, casual physician attire (fleece jackets and softshell jackets) has become increasingly popular, but to our knowledge, public perceptions of these garments have not been studied. Furthermore, gender biases may result in differing expectations and perceptions of female and male physicians and may be associated with patient rapport and trust building.

OBJECTIVE

To characterize public perceptions of casual physician attire and implicit gender biases in public assessment of physicians' professional attire.

DESIGN, SETTING, AND PARTICIPANTS

This survey study used a population-based survey administered via Amazon Mechanical Turk from May to June 2020 among individuals aged 18 years or older who were US residents and for whom English was the primary language.

INTERVENTION

Survey featuring photographs of a male or female model wearing various types of physician attire (white coat, business attire, and scrubs).

MAIN OUTCOMES AND MEASURES

Respondents' ratings of professionalism, experience, and friendliness of the male and female models in various attire and perceptions of the models' most likely health care profession. Preference scores for various outfits were calculated as the difference between the preference score for an outfit and the mean preference score for the outfit-role pairing.

RESULTS

Of 522 surveys completed, 487 were included for analysis; the mean (SD) age of respondents was 36.2 (12.4) years, 260 (53.4%) were female, and 372 (76.4%) were White individuals. Respondents perceived models of health care professionals wearing white coats vs those wearing fleece or softshell jackets as significantly more experienced (mean [SD] experience score: white coat, 4.9 [1.5]; fleece, 3.1 [1.5]; softshell, 3.1 [1.5]; P < .001) and professional (mean [SD] professionalism score: white coat, 4.9 [1.6]; fleece, 3.2 [1.5]; softshell, 3.3 [1.5]; P < .001). A white coat with scrubs attire was most preferred for surgeons (mean [SD] preference index: 1.3 [2.3]), whereas a white coat with business attire was preferred for family physicians and dermatologists (mean [SD] preference indexes, 1.6 [2.3] and 1.2 [2.3], respectively; P < .001). Regardless of outerwear, female models in business attire as inner wear were rated as less professional than male counterparts (mean [SD] professionalism score: male, 65.8 [25.4]; female, 56.2 [20.2]; P < .001). Both the male and the female model were identified by the greater number of respondents as a physician or surgeon; however, the female model vs the male model was mistaken by more respondents as a medical technician (39 [8.0] vs 16 [3.3%]; P < .005), physician assistant (56 [11.5%] vs 11 [2.3%]; P < .001), or nurse (161 [33.1%] vs 133 [27.3%]; P = .050).

CONCLUSIONS AND RELEVANCE

In this survey study, survey respondents rated physicians wearing casual attire as less professional and experienced than those wearing a white coat. Gender biases were found in impressions of professionalism, with female physicians' roles being more frequently misidentified. Understanding disparate public perceptions of physician apparel may inform interventions to address professional role confusion and cumulative career disadvantages for women in medicine.

Academic Productivity Among Plastic Surgery Subspecialty Fellowship Applicants

INTRODUCTION

Plastic surgery subspecialty fellowships are highly competitive. Academic productivity is an objective metric that can be used to compare candidates. This study aims to evaluate intersubspecialty differences in academic profiles of plastic surgery fellows.

METHODS

We performed a cross-sectional analysis of the plastic surgery fellows in the United States from 2015 to 2019. We used the San Francisco Match website and individual program websites to obtain details of fellowship programs (microsurgery, aesthetic, hand, and craniofacial) and plastic surgery fellows. Bibliometric data at the time of fellowship application were obtained for each fellow.

RESULTS

A total of 235 fellows were included. There was a significant difference in the median number of publications (P = 0.0067) and h-index (P = 0.0229) across subspecialties. Multivariate analysis demonstrated that dedicated research time was predictive for a high publication count (odds ratio [OR], 3.59; P = 0.0007) and h-index (OR, 4.88; P < 0.0001) at the time of fellowship application. Although international residency and aesthetic fellowship application were predictive of a reduced number of publications (OR, 0.17; P < 0.0001, and OR, 0.43; P = 0.0190, respectively), H-index was increased by possession of an advanced degree (OR, 2.00; P = 0.0291) and decreased with international residency (OR, 0.26, P = 0.0021).

CONCLUSIONS

All plastic surgery fellows have highly qualified academic profiles at the time of fellowship application. Academic productivity differs between subspecialty fellowships. Those wishing to match into competitive subspecialties should consider taking dedicated time for research or attaining an advanced degree.

Design of a Novel Reproducible Cartilage-Sparing Autologous Technique for Microtia Repair

Microtia reconstruction through manual carving of autologous rib cartilage has a steep learning curve, is operator dependent, is time consuming, requires multiple stages, and frequently results in suboptimal results with poor patient satisfaction. The use of temporoparietal fascia over polypropylene implants achieves excellent cosmetic outcomes in a single stage, although is burdened by infection and extrusion in some cases. We describe the development of a hybrid technique with a novel device that allows for standardization of the cartilaginous construct, minimization of the need for donor cartilage and operative time, and minimization of the number of stages. Clinical Trial: NCT03624608.

Laryngoscopy Grade Improvement and Difficult Airway Resolution in Infants With Robin Sequence Undergoing Mandibular Distraction Osteogenesis: A Multi-Institutional Study

OBJECTIVE

Mandibular distraction osteogenesis (MDO) aims to relieve tongue-based airway obstruction in Robin Sequence (RS). We investigated direct laryngoscopy grade (DLG) improvement and difficult airway (DA) resolution following MDO.

DESIGN

Retrospective cohort analysis.

SETTING

Three tertiary care institutions.

PATIENTS

Sixty-four infants with RS who underwent a single MDO procedure in their first year of life were identified from January 2010 to January 2019.

MAIN OUTCOME MEASURES

The primary outcome was DLG pre- and post-MDO. Secondary outcomes included DA designation, pre- and post-MDO polysomnographic assessment for obstructive sleep apnea (OSA), length of stay, need for gastrostomy, and major/minor adverse events.

RESULTS

Median DLG improved from II pre-MDO to I at the time of distractor removal (n = 43, P < .001). No significant change was seen in patients with a third recorded time point (eg, palatoplasty; n = 78, P = .52). Twenty-six (47%) of 55 patients were designated as DA pre-MDO, and 10 (18%) of 55 patients retained the label post-MDO (P < .01). Five (50%) of these 10 patients appeared to be inappropriately retained. Median obstructive apnea-hypopnea index improved from 38.6 (range 31.2-62.8) pre-MDO to 2.9 (range 1-3.9) post-MDO (n = 12; P = .002).

CONCLUSION

Mandibular distraction osteogenesis allowed for DLG improvement that was stably maintained as well as functional improvement in OSA, with minimal morbidity. Difficult airway designation persisted in the electronic record of some infants despite clinical resolution.

Mandibular Reconstruction Following Central Giant Cell Granuloma Resection in Primary Dentition: A Case for the Use of a Costochondral Graft

Central giant cell granuloma is a benign, intraosseous lesion that may affect the pediatric craniofacial skeleton, particularly the mandible. When surgery is indicated, the role of the craniofacial surgeon is to ameliorate the sequelae of ablative surgery by restoring facial symmetry, ensuring appropriate postoperative occlusion, and allowing for adequate interincisal opening, all in the setting of a growing craniofacial skeleton. Herein, we report the case of a 3-year-old female presenting for reconstruction after resection of the right hemimandible proximal to the unerupted first permanent molar. We highlight the various reconstructive challenges associated with mandibular reconstruction during primary dentition and make a case for the use of a costochondral graft, with a successful outcome demonstrated at 2 years of follow-up.

Postoperative Drain Use in Cranial Vault Remodeling: A Survey of Craniofacial Surgeon Practices and a Review of the Literature

BACKGROUND

The use of subgaleal drains following primary cranioplasty for craniosynostosis has undergone limited investigation. Proposed benefits include prevention of seroma, detection of postoperative bleeding, and cerebrospinal fluid leak. We conducted a systematic review of the literature and surveyed craniofacial surgeons to ascertain the current evidence pertaining to drain use following primary cranioplasty for craniosynostosis and to determine surgical practice patterns.

METHODS

PubMed and Embase databases were searched to identify relevant articles. Abstracts were reviewed by 2 investigators, and a Cohen κ statistic was calculated. Patient demographic and outcome data were extracted and compared. A 9-question survey was e-mailed to active and associate members of the American Society of Craniofacial Surgeons.

RESULTS

A total of 7395 unique citations were identified. Only 2 retrospective chart reviews met inclusion criteria. All objective parameters demonstrated no difference between patients with and without drains. A subjective benefit of limiting facial swelling was proposed without objective analysis. Fifty (32.5%) of the 154 craniofacial surgeons responded to the survey. Forty-two percent used postoperative drains. A significant association (P = .01) was found between the belief that drains limited facial swelling and their use.

CONCLUSIONS

The literature examining postoperative drain use in primary cranioplasty for craniosynostosis is restricted. The current studies show no definite benefit to drain use but are limited in their assessment of key outcomes. There is wide variability among surgeons regarding drain use, and this seems to be motivated by belief and tradition.

Cleft and Craniofacial Team Orthodontic Care in the United States: A Survey of the ACPA

Objective:

To better understand the capacity for orthodontic care, service features, and finances among members of the American Cleft Palate-Craniofacial Association (ACPA).

Design:

Cross-sectional survey.

Setting:

ACPA-approved multidisciplinary cleft teams.

Participants:

Cleft team coordinators.

Interventions:

Coordinators were asked to complete the survey working together with their orthodontists.

Main Outcome Measure:

Model for orthodontic care.

Results:

Coordinators from 82 out of 167 teams certified by ACPA completed the survey (response rate = 49.1%). Most orthodontists were private practice volunteers (48%) followed by university/hospital employed (22.8%). Care was often delivered in community private practice facilities (44.2%) or combination of university and private practice facilities (39.0%). Half of teams reported offering presurgical infant orthopedics (PSIO), with nasoalveolar molding being the most common. Cleft/craniofacial patients typically comprise 25% or less of the orthodontists’ practices. The presence of a university/hospital-based orthodontist was associated with higher rates of offering PSIO ( P < .001) and an increased percentage dedication of their practice to cleft/craniofacial care ( P < .001).

Conclusion:

Orthodontic models across ACPA-certified teams are highly varied. The employment of full-time craniofacial orthodontists is less common but is highly correlated with a practice with a high percentage of cleft care and the offering of advanced services such as PSIO. Future work should focus on how to effectively promote such roles for orthodontists to ensure high-level care for cleft/craniofacial patients requiring treatment from infancy through skeletal maturity.

Parasitic rachipagus conjoined twin: case report

A parasitic twin represents a rare developmental anomaly in which an asymmetrical, nonviable conjoined twin is attached to the host body at the time of birth. Rachipagus is among the rarest of conjoined twin subtypes and typically features a parasitic twin mass attached at the spine. Herein, the authors review the literature and describe the case of a 9-month-old girl presenting with a rachipagus parasitic twin consisting of a fully developed set of lower extremities originating from the midline upper back. After a complete workup to delineate parasite and autosite anatomy, the parasitic twin mass was successfully excised by a multidisciplinary team of surgeons, and the resulting defect was closed in a single stage.

Equivalent effects of topically-delivered adipose-derived stem cells and dermal fibroblasts in the ischemic rabbit ear model for chronic wounds

BACKGROUND

Mesenchymal stem cells (MSC) have garnered considerable attention in plastic surgery. Via proliferation/differentiation or the elaboration of paracrine factors, MSC and their adipose-derived stem cell counterparts (ADSC) have been suggested to stimulate cutaneous wound healing. Previous reports have been limited by a lack of appropriate controls and the lack of a clinically-relevant context or ability to extrapolate to human wound healing.

OBJECTIVES

The authors qualitatively and quantitatively evaluate the ability of ADSC to improve wound healing in an ischemic variant of their well-established rabbit ear wound model.

METHODS

To incorporate ischemia, a major pathophysiologic factor in human chronic wounds, into our model, two of the three main arteries to the rabbit ear were ligated before wounding. Green fluorescent protein (GFP)-labeled ADSC or rabbit dermal fibroblasts (RDF) were then applied to wounds and histologic parameters of healing quantified.

RESULTS

At Postoperative Day (POD) 1, both cell types were present in a uniform distribution across wounds and positive for the proliferation marker Ki-67. By POD 7 and continuing through POD 10, ADSC and RDF contributed similarly to the accumulation of stratified "neogranulation" across the wound bed. No statistically-significant differences were observed between ADSC and RDF in terms of this positive effect on granulation (P=.2-.3 for comparison of mean granulation tissue gaps and areas).

CONCLUSIONS

ADSC and RDF can be delivered topically to wounds, resulting in a high level of engraftment in the ischemic background. Cellular wound therapy holds promise for chronic wound healing as well as other antiscarring therapies, but further studies are warranted before full clinical translation.

Reevaluating the role of LTD in cerebellar motor learning

Long-term depression at parallel fiber-Purkinje cell synapses (PF-PC LTD) has been proposed to be required for cerebellar motor learning. To date, tests of this hypothesis have sought to interfere with receptors (mGluR1) and enzymes (PKC, PKG, or αCamKII) necessary for induction of PF-PC LTD and thereby determine if cerebellar motor learning is impaired. Here, we tested three mutant mice that target the expression of PF-PC LTD by blocking internalization of AMPA receptors. Using three different cerebellar coordination tasks (adaptation of the vestibulo-ocular reflex, eyeblink conditioning, and locomotion learning on the Erasmus Ladder), we show that there is no motor learning impairment in these mutant mice that lack PF-PC LTD. These findings demonstrate that PF-PC LTD is not essential for cerebellar motor learning.

Persistent inflammation induces GluR2 internalization via NMDA receptor-triggered PKC activation in dorsal horn neurons

Spinal cord GluR2-lacking AMPA receptors (AMPARs) contribute to nociceptive hypersensitivity in persistent pain, but the molecular mechanisms underlying this event are not completely understood. We report that complete Freund's adjuvant (CFA)-induced peripheral inflammation induces synaptic GluR2 internalization in dorsal horn neurons during the maintenance of CFA-evoked nociceptive hypersensitivity. This internalization is initiated by GluR2 phosphorylation at Ser(880) and subsequent disruption of GluR2 binding to its synaptic anchoring protein (GRIP), resulting in a switch of GluR2-containing AMPARs to GluR2-lacking AMPARs and an increase of AMPAR Ca(2+) permeability at the synapses in dorsal horn neurons. Spinal cord NMDA receptor-mediated triggering of protein kinase C (PKC) activation is required for the induction and maintenance of CFA-induced dorsal horn GluR2 internalization. Moreover, preventing CFA-induced spinal GluR2 internalization through targeted mutation of the GluR2 PKC phosphorylation site impairs CFA-evoked nociceptive hypersensitivity during the maintenance period. These results suggest that dorsal horn GluR2 internalization might participate in the maintenance of NMDA receptor/PKC-dependent nociceptive hypersensitivity in persistent inflammatory pain.

Targeted In Vivo Mutations of the AMPA Receptor Subunit GluR2 and Its Interacting Protein PICK1 Eliminate Cerebellar Long-Term Depression

Cerebellar long-term depression (LTD) is a major form of synaptic plasticity that is thought to be critical for certain types of motor learning. Phosphorylation of the AMPA receptor subunit GluR2 on serine-880 as well as interaction of GluR2 with PICK1 have been suggested to contribute to the endocytic removal of postsynaptic AMPA receptors during LTD. Here, we show that targeted mutation of PICK1, the GluR2 C-terminal PDZ ligand, or the GluR2 PKC phosphorylation site eliminates cerebellar LTD in mice. LTD can be rescued in cerebellar cultures from mice lacking PICK1 by transfection of wild-type PICK1 but not by a PDZ mutant or a BAR domain mutant deficient in lipid binding, indicating the importance of these domains in PICK1 function. These results demonstrate that PICK1-GluR2 PDZ-based interactions and GluR2 phosphorylation are required for LTD expression in the cerebellum.

N-ethylmaleimide-sensitive factor is required for the synaptic incorporation and removal of AMPA receptors during cerebellar long-term depression

Cerebellar long-term depression (LTD) is a persistent attenuation of synaptic transmission at the parallel fiber-Purkinje cell synapse mediated by the removal of GluR2 subunit-containing alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. The removal of AMPA receptors requires protein kinase C phosphorylation of the GluR2 subunit within its carboxyl-terminal PSD-95/Discs Large/Zona Occludens-1 (PDZ) ligand and binding of the PDZ domain-containing protein, PICK1. The sequence of the GluR2 subunit is similar to that of the GluR3 and GluR4c subunits, which also contain PDZ ligands and protein kinase C consensus sites. Although GluR3 and GluR4c are also expressed in Purkinje cells, we have previously shown that cerebellar LTD is absent in GluR2(-/-) mice, suggesting that these subunits are unable to substitute functionally for GluR2. Here, we examine the apparent difference in the regulation of these AMPA receptor subunits by attempting to rescue LTD in GluR2(-/-) Purkinje cells with WT and mutant GluR2 and GluR3 subunits. Our results show that the selective interaction of the GluR2 subunit with the N-ethylmaleimide-sensitive factor protein is required for synaptic, but not extrasynaptic, incorporation of AMPA receptors as well as for their competence to undergo LTD. In addition, perfusion of a synthetic peptide that acutely disrupts the interaction of GluR2 with N-ethylmaleimide-sensitive factor selectively depletes GluR2-containing receptors from synapses and occludes LTD. These findings demonstrate that interaction of AMPA receptors with N-ethylmaleimide-sensitive factor plays a critical role in incorporation of AMPA receptors into synapses and for their subsequent removal during cerebellar LTD.

Glutamate receptor subunit 2 Serine 880 phosphorylation modulates synaptic transmission and mediates plasticity in CA1 pyramidal cells

The cytoplasmic C termini of AMPA receptor subunits contain PDZ (postsynaptic density 95/Discs large/zona occludens 1) ligand domains that can control their synaptic trafficking during plasticity. The glutamate receptor subunit 2 (GluR2) PDZ ligand domain can be phosphorylated at serine 880 (S880), and this disrupts interactions with GRIP/ABP (glutamate receptor-interacting protein/AMPA-binding protein) but not with PICK1 (PKC-interacting protein 1). Here, the impact of GluR2 S880 phosphorylation on synaptic transmission and plasticity was explored by expressing, in hippocampal slice cultures, GluR2 subunits containing point mutations that mimic or prevent phosphorylation at this residue. Our results indicate that mimicking GluR2 S880 phosphorylation excludes these receptors from synapses, depresses transmission, and partially occludes long-term depression (LTD). Conversely, mutations that prevent phosphorylation reduce LTD. Disruption of the interaction between GluR2 and GRIP/ABP by S880 phosphorylation may thus facilitate removal of synaptic AMPA receptors and mediate some forms of activity-dependent synaptic depression.

Requirement of AMPA receptor GluR2 phosphorylation for cerebellar long-term depression

Cerebellar long-term depression (LTD) is a model of synaptic memory that requires protein kinase C (PKC) activation and is expressed as a reduction in the number of postsynaptic alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors. LTD was absent in cultured cerebellar Purkinje cells from mutant mice lacking the AMPA receptor GluR2 subunit and could be rescued by transient transfection with the wild-type GluR2 subunit. Transfection with a point mutant that eliminated PKC phosphorylation of Ser880 in the carboxy-terminal PDZ ligand of GluR2 failed to restore LTD. In contrast, transfection with a point mutant that mimicked phosphorylation at Ser880 occluded subsequent LTD. Thus, PKC phosphorylation of GluR2 Ser880 is a critical event in the induction of cerebellar LTD.

Disseminated acanthamebiasis in a renal transplant recipient with osteomyelitis and cutaneous lesions: case report and literature review

Disseminated acanthamebiasis is a rare disease that occurs predominantly in patients with human immunodeficiency virus (HIV) infection or acquired immunodeficiency syndrome but also in immunosuppressed transplant recipients. Few reports have focused on non-HIV-infected patients, in whom the disease is more likely to go unsuspected and undiagnosed before death. We describe a renal transplant recipient with Acanthamoeba infection and review the literature. The patient presented with osteomyelitis and widespread cutaneous lesions. No causative organism was identified before death, despite multiple biopsies with detailed histological analysis and culture. Disseminated Acanthamoeba infection was diagnosed after death, when cysts were observed in histological examination of sections of skin from autopsy, and trophozoites were found in retrospectively reviewed skin biopsy and surgical bone specimens. In any immunosuppressed patient, skin and/or bone lesions that fail to show improvement with broad-spectrum antibiotic therapy should raise the suspicion for disseminated acanthamebiasis. Early recognition and treatment may improve clinical outcomes.

Sparse 2-D array design for real time rectilinear volumetric imaging

Several sparse 2-D arrays for real time rectilinear volumetric imaging were investigated. All arrays consisted of 128x128=16,384 elements with lambda spacing operating at 5 MHz. Because of system limitations, not all of the elements could be used. From each array, 256 elements were used as transmitters, and 256 elements were used as receivers. These arrays were compared by computer simulation using Field II. For each array, beamplots for the on-axis case and an illustrative off-axis case were obtained. For the off-axis case, the effects of receive mode dynamic focusing were studied to maintain the beam perpendicular to the transducer face. Main lobe widths, side lobe heights, clutter floor levels, and pulse-echo sensitivities were quantified for each array. The sparse arrays, including a vernier periodic array, a random array, and a Mills cross array, were compared with a fully sampled array that served as the "gold standard". The Mills cross design showed the best overall performance under the current system constraints.

Changes in endogenous TPO levels during mobilization chemotherapy are predictive of CD34+ megakaryocyte progenitor yield and identify patients at risk of delayed platelet engraftment post-PBPC transplant

Patients with delayed platelet recovery post-PBPC transplant (PBPCT) are a high-risk group for thrombocytopenic bleeding and platelet transfusion dependence. Total CD34+ cell dosage has been proposed as the most important factor influencing the rate of platelet recovery. To achieve the shortest time to platelet engraftment, a minimum leukapheresis target of 10x10(6) CD34+ cells/kg was established for 30 patients. Of the 29 evaluable patients, 62% had rapid (group I: time to platelets >20x10(9)/l < or =10 days and 50x10(9)/l < or =14 days) platelet recoveries while 38% had delayed (group II: 20x10(9)/l >10 days and 50x10(9)/l >14 days) recoveries. Groups I and II were compared for: (1) pretreatment variables; (2) mobilizing capability of CD34+ cells and subsets including megakaryocyte (Mk) progenitors; (3) infused dose of these cells at transplant; (4) changes in endogenous levels of Mpl ligand (or TPO) during mobilization and myeloablative chemotherapy. Group II patients received significantly more platelet transfusions (6 vs. 2.1, P = 0.002) post-PBPCT, had a higher proportion of patients with a prior history of BM disease (64% vs. 6%, P = 0.001), and showed a reduced ability to mobilize differentiated (CD34+/38+, CD34+/DR+) and Mk progenitors (CD34+/42a+, CD34+/61+). Only the number of Mk progenitors reinfused at transplant was significantly different between the groups (group II vs. group I: CD34+/42a+ = 1.02 vs. 2.56x10(6)/kg, P = 0.013; CD34+/61+ = 1.12 vs. 2.70x10(6)/kg, P = 0.015). The ability to mobilize Mk progenitors correlated with percentage changes in endogenous levels of TPO from baseline to platelet nadir during mobilization chemotherapy (CD34+/42a+: r = 0.684, P = 0.007; CD34+/61+: r = 0.684, P = 0.007), with group II patients experiencing lower percentage changes. An inverse trend but no correlation was observed between serial TPO levels and platelet counts. TPO levels remained elevated in group II patients throughout a prolonged period of thrombocytopenia (median days to 50x10(9)/l = 25 vs. 11 for group I), indicating that delayed engraftment was not due to a deficiency of TPO but to a lack of Mk progenitor target cells. Our results show that the number of reinfused Mk progenitors is a better predictor of platelet engraftment than total CD34+ cell dosage. Small changes in endogenous TPO levels during mobilization predict for low Mk progenitor yields.

Indinavir crystalluria: identification of patients at increased risk of developing nephrotoxicity

OBJECTIVE

To determine whether the protease inhibitor indinavir sulfate, which is extremely insoluble at physiologic pH levels and which is known to be associated with nephrolithiasis, is associated with crystalluria at a usual therapeutic dose.

METHODS

Freshly voided urine from 27 male human immunodeficiency virus patients being treated with indinavir at a dose of 800 mg, tid, in an outpatient setting and from 20 healthy subjects undergoing routine physical examination was subjected to dipstick urinalysis and microscopic examination of urinary sediments.

RESULTS

Three (11%) of 27 patients treated with indinavir developed highly characteristic crystalluria during the course of therapy. No such crystals were observed in the urine of the 20 healthy subjects.

CONCLUSION

Indinavir crystalluria was identified in asymptomatic patients treated with usual therapeutic doses of the drug. Screening urines of patients taking indinavir may be useful in identifying patients at risk for developing nephrotoxicity.

Exogenous Neisseria meningitidis endophthalmitis

PURPOSE

To report a case of Neisseria meningitidis endophthalmitis in association with a leaking filtering bleb and to consider antibiotic prophylaxis of those people with whom the patient had contact.

METHOD

We treated an 81-year-old man who had a chronic, leaking filtering bleb and who developed exogenous N meningitidis endophthalmitis.

RESULT

N meningitidis endophthalmitis was controlled with antibiotic therapy. Antibiotic prophylaxis for those with whom the patient had contact was not recommended.

CONCLUSION

In this case, the N meningitidis strain was not considered invasive because the bacteria apparently entered the eye through a leaky filtering bleb and not through the bloodstream. Recovery of noninvasive N meningitidis does not require prophylaxis for patient contacts. In cases of endogenous or idiopathic N meningitidis endophthalmitis, antibiotic prophylaxis of close patient contacts may be warranted.

Nosocomial and community-acquired Staphylococcus aureus bacteremias from 1980 to 1993: impact of intravascular devices and methicillin resistance

The rate of nosocomial bacteremia due to Staphylococcus aureus has increased over the past decade, but trends in community-acquired S. aureus bacteremia are less certain. This hospital-based observational study compares nosocomial and community-acquired S. aureus bacteremias during 1980-1983 and 1990-1993. The rate of nosocomial S. aureus bacteremia increased from 0.75 to 2.80 cases per 1,000 discharges, while the rate of community-acquired S. aureus bacteremia increased from 0.84 to 2.43 cases per 1,000 discharges. The number of nosocomial device-related bacteremias increased eightfold; 56% of S. aureus bacteremias were associated with devices during 1990-1993. Intravascular devices were associated with no community-acquired S. aureus bacteremias during 1980-1983 but with 22% during 1990-1993. Methicillin-resistant S. aureus (MRSA) seldom caused bacteremia during 1980-1983. From 1990 to 1993, MRSA caused 32% and 18.5% of nosocomial and community-acquired S. aureus bacteremias, respectively. The rates of both community-acquired and nosocomial S. aureus bacteremias have increased significantly since 1980. In addition to their role in nosocomial infections, MRSA and intravascular device-related S. aureus bacteremias are emerging problems in the nonhospital setting.

Osteomyelitis of the sternum caused by Apophysomyces elegans

Apophysomyces elegans, a member of the family Mucoraceae, was found to infect the chest wall and sternum of an immunocompetent man following minor trauma. As in previous cases, amphotericin B therapy alone was inadequate. Extensive surgical debridement was required in order to eradicate the infection.

Culture isolation of Acanthamoeba species and leptomyxid amebas from patients with amebic meningoencephalitis, including two patients with AIDS

Acanthamoeba species and leptomyxid organisms are free-living amebas that cause meningoencephalitis, primarily in immunocompromised patients. We report the isolation and culture of Acanthamoeba species and leptomyxid amebas from four patients with fatal amebic meningoencephalitis. Acanthamoeba species were cultured from brain abscess specimens from three immunocompromised patients (including two patients with AIDS). In the case of the fourth patient, who had no identifiable immunodeficiency, leptomyxid amebas were cultured from a specimen from a subcutaneous nodule and were identified in amebic granulomas in brain tissue by the indirect immunofluorescence test. Persons with advanced infection due to the human immunodeficiency virus may be at increased risk for amebic meningoencephalitis, but the diagnosis should be considered in the differential diagnosis of any immunocompromised patient with cerebral abscesses.

Suppurative cervical lymphadenitis after Yersinia enterocolitica bacteremia

Yersinia enterocolitica is increasingly recognized as a pathogen causing diverse complications. We have reported the case of a man with fever, abdominal tenderness, and Y enterocolitica bacteremia. After antibiotic therapy, his condition improved initially, but later, suppurative cervical lymphadenitis developed. This suggests that the hematogenous spread of Y enterocolitica to a distal lymphatic focus of infection is a possible complication of Y enterocolitica bacteremia.

The nature of insulin secretory defect in aging rats

We have attempted to define the nature of insulin secretory defect(s) in aged animals. In these studies, pancreatic islets were isolated from 2- and 18-mo-old Fischer 344 rats. Margination of secretion vesicles during exocytosis was assessed by measuring the recruitment of somatostatin (SRIF) receptors to the surface membrane. Section vesicle lysis was studied by measuring insulin release into the incubation media. Submaximal and maximal glucose-induced insulin secretion was significantly greater in islets isolated from younger rats (P less than 0.01). SRIF receptor recruitment was stimulated by glucose in both younger and older Fischer 344 rats. However, an increase in SRIF receptor recruitment was reduced in islets isolated from older animals (from 2.14 +/- 0.4 to 4.6 +/- 0.4 fmol/10 islets) (P less than 0.01) as compared with islets from younger animals (from 2.6 +/- 0.2 to 6.2 +/- 0.4 fmol/10 islets). When secretion vesicle lysis was inhibited by the presence of sodium isethionate in the incubation media, glucose (300 mg/dl) failed to stimulate secretion vesicle margination to the plasma membrane. In contrast, glyburide (0.6 micrograms/ml) continued to stimulate directly secretion vesicle margination in islets from aged animals (from 2.1 +/- 0.3 to 6.0 +/- 0.3 fmol/10 islets). We conclude that glucose-induced margination of secretion vesicles at the plasma membrane is impaired by the aging process. This impairment results in lower submaximal and maximal insulin secretory response to glucose. The fact that glyburide is capable of stimulating secretion vesicle margination suggests that glucose signal recognition and/or stimulus-secretion coupling may be the locus of impairment in the process of insulin secretion in older animals.

Control of secretion vesicle margination and lysis by glucose, IBMX, and glyburide

We have attempted to define the effect of glucose, glyburide, and isobutylmethylxanthine (IBMX) upon secretion vesicle margination to the plasma membrane and granule lysis. Margination of secretion vesicles during exocytosis was assessed by measuring the recruitment of somatostatin (SRIF) receptors. Secretion vesicle lysis was studied by measuring insulin release into the incubation media. Our observations suggest that glucose directly affects both secretion vesicle margination and lysis. Both events are rapidly influenced by this secretagogue (within 10 min of incubation). Trifluoperazine (TFP) and removal of Ca2+ from the incubation media significantly reduced glucose-induced margination of secretion vesicles and their lysis (P less than 0.001). IBMX primarily influences the lysis of secretion vesicles and not their margination. IBMX caused a rapid increase in insulin secretion within 10 min without recruitment of SRIF receptors. Neither TFP nor the absence of extracellular Ca2+ affected IBMX-induced insulin release. Late enhancement in margination of secretion vesicles (30 min of incubation with IBMX) is probably related to the initial event of secretion vesicle lysis and is independent of extracellular calcium. Glyburide exerts its action in a manner similar to glucose, affecting both the lysis of secretion vesicles and their margination. However, the action of glyburide is independent of extracellular calcium and partially dependent upon calmodulin.

Calmodulin and cyclic AMP. Possible different sites of action of these two regulatory agents in exocytotic hormone release

It may now be possible to identify certain intracellular events that impact specifically on secretion-granule fusion to the plasma membrane or on granule lysis. Secretion vesicles in isolated rat islets appear to translocate somatostatin (SRIF) receptors from the Golgi apparatus to the plasma membrane. We have proposed that secretion granule fusion to the plasma membrane can be determined by measuring recruitment of SRIF receptors to the surface membrane. Granule lysis can be assessed by measuring insulin release. To activate cyclic AMP (cAMP)-dependent pathways, we employed isobutylmethylxanthine (IBMX, 400 microM), glucagon (10 microM), and forskolin (20 microM), a diterpene activator of adenylate cyclase. These agents evoked rapid release of insulin (from 0.41 +/- 0.02 to 1.88 +/- 0.02; 0.41 +/- 0.02 to 1.93 +/- 0.08; and 0.41 +/- 0.02 to 1.66 +/- 0.03 microU/islet/min, respectively, P less than 0.001). There was no concomitant recruitment of SRIF receptors. Somatostatin (10 micrograms/ml), which inhibits cAMP-stimulated protein phosphorylation, suppresses insulin release evoked by IBMX, glucagon, or forskolin (inhibition: 80, 75, or 82%, respectively). In contrast, trifluoperazine (10 microM), an inhibitor of calmodulin, did not suppress insulin release induced through cAMP-dependent pathways. Trifluoperazine suppresses glucose-induced insulin release and the recruitment of SRIF receptors to the surface membrane, suggesting the possible role of calmodulin in promoting secretion-granule fusion with the plasma membrane.(ABSTRACT TRUNCATED AT 250 WORDS)