Operative Management and Outcome of Idiopathic Rectal Necrosis in an Octogenarian

Idiopathic acute rectal necrosis (IARN) is a rare condition due to a robust rectal blood supply. This report describes an 83-year-old man presenting with septic shock due to distal sigmoid and complete rectal necrosis with perforation. He underwent emergent exploratory laparotomy, sigmoid and proximal rectum resection, and end sigmoid colostomy creation with delayed distal rectal evaluation. Bedside proctoscopy revealed pale, viable-appearing distal rectal mucosa on postoperative day 3. The patient had a protracted, complicated hospital stay but required no further operative intervention. Subsequent colostomy reversal was done 8 months postoperatively, and the patient did well and has been discharged with normal gastrointestinal function. Our successful conservative operative management of IARN deviates from previously described management in the literature which is emergent abdominoperineal resection. This conservative surgical strategy appears to have contributed to the patient's positive outcomes, highlighting the importance of considering a similar approach for future IARN cases.

Antithrombotics in the Fall Patient: Appropriateness and Risk-Benefit Analysis

Falls are the leading cause of hospitalizations following trauma nationwide, resulting in over 3 million admissions in 2020. This population is typically aged, and many are prescribed antithrombotic (AT) therapy. In this prospective study, we aimed to analyze fall history while assessing appropriateness of AT regimen relative to fall risk. Patients presenting following ground level fall (GLF) and meeting inclusion criteria during the study period were enrolled. Primary outcome was the relationship between AT therapy necessity (CHA2DS2-VASc) and fall risk (Morse Fall Risk). The cohort of 30 patients had an average age of 77. CHA2DS2-VASc and Morse Fall Risk showed a moderate-positive correlation (r = 0.47; P = 0.012); however, 17% of patients categorized as high fall risk had a <5% 1-year risk of VTE. This study demonstrates that risks of hemorrhage may outweigh thromboembolism prophylaxis in a significant number of patients and sheds light on the astonishing fall volume in this population.

Outcome of Seatbelt Education and Safety Program Among Teenagers

Despite the effectiveness of seatbelts, concerns persist about compliance, especially among teenagers. Survey data from a local high school and registry data from a level 1 trauma center were used to observe seatbelt and motor vehicle accident trends. The survey data was analyzed to gauge student's sentiments on seatbelt education. The trauma center data was analyzed to identify characteristics and trends among teenage motor vehicle accidents. Social media was the most common strategy selected for seatbelt safety awareness. Random seatbelt checks performed over 4 months revealed seatbelt compliance rates of 90%, 93.55%, and 96.94% after education intervention. Trauma center data showed that lack of seatbelt usage resulted in greater morbidity. These findings emphasize the need for targeted interventions. This study provides insights into creating effective education campaigns that can be used to enhance safety belt compliance and potentially reduce injury.

Application of the Geriatric Trauma Outcome Score in a Rural Setting

OBJECTIVE

To retrospectively apply the Geriatric Trauma Outcome (GTO) score to the patient population of a rural South Central Appalachian level 1 trauma center and identify the potential utility of the GTO score in guiding goals of care discussions.

METHODS

Trauma registry data was extracted for 5,627 patients aged 65+ from 2017 to 2021. GTO score was calculated for each patient. Descriptive statistics were calculated for age, Injury Severity Score (ISS), GTO score, receipt of red blood cells, discharge status, and code status. A simple logistic regression model was used to determine the relationship between GTO score and discharge status. The probability of mortality was then calculated using GTO score, and the distribution of code status among patients with ≤50, 51-75%, and >75% probability of mortality was examined.

RESULTS

For every 10-point increase in GTO score, odds of mortality increased by 79% (OR = 1.79; P < .001). Patients had an estimated 50% probability of mortality with a GTO score of 156, 75% with 174, and 99% with a score of 234, respectively. Seventeen patients had a GTO score associated with >75% probability of mortality. Of those 17 patients, four retained a full code status.

CONCLUSIONS

Our analysis demonstrates that the GTO score is a validated measure in a rural setting and can be an easily calculated metric to help determine a geriatric patient's probability of mortality following a trauma. The results of our study also found that GTO score can be used to inform goals of care discussions with patients.

Assessing Futile Trauma Transfers in Rural Appalachia Following a Regional Health Care System Consolidation

This study sought to define and analyze rates of futile trauma transfers (FTTs) after the consolidation of two rural level 1 trauma centers into one. Data was extracted from the regional trauma registry for a period of 5 years (2017-2022) for all trauma patients transferred into our level 1 trauma center (n = 3369). An FTT was defined as a transfer that (1) received no major interventions and (2) died or was discharged to a hospice facility within 72 hours. Out of the 3369 transfer patients analyzed during the 33-month pre-consolidation and 33-month post-consolidation periods, 34 patients met the criteria of an FTT within the transfer-to-discharge window. The pre-consolidation category contained 12, and the post-consolidation category contained 22. Chi-square analysis indicated no significant difference in FTT rate between categories. Furthermore, the post-consolidation FTT rate of 1.1% remained consistent with the estimated national average of 1.5%.

Impact of Trauma Resuscitation Emergency Care Nurse Deployment in Trauma Activations in a Rural Trauma Center

BACKGROUND

Although the role of a dedicated trauma nurse has been implemented in an urban setting, it has not been studied in the rural trauma setting. We instituted a trauma resuscitation emergency care (TREC) nurse role to respond to trauma activations at our rural trauma center.

OBJECTIVE

This study aims to determine the impact of TREC nurse deployment on the timeliness of resuscitation interventions in trauma activations.

METHODS

This pre- and postintervention study at a rural Level I trauma center compared the time to resuscitation interventions before (August 2018 to July 2019) and after (August 2019 to July 2020) deploying TREC nurses to trauma activations.

RESULTS

A total of 2,593 participants were studied, of which 1,153 (44%) were in the pre-TREC group and 1,440 (56%) in the post-TREC group. After TREC deployment, the median (interquartile range [IQR]) emergency department times within the first hour decreased from 45 (31.23-53) to 35 (16-51) min ( p = .013). The median (IQR) time to the operating room within the first hour decreased from 46 (37-52) to 29 (12-46) min ( p = .001), and within the first 2 hr, decreased from 59 (43.8-86) to 48 (23-72) min ( p = .014).

CONCLUSION

Our study found that TREC nurse deployment improved resuscitation intervention timeliness during the first 2 hr (early phase) of trauma activations.

Poor Outcomes of Patients From Delayed Care After Ground Level Falls

BACKGROUND

Ground level falls are a common cause of morbidity and mortality in trauma patients. Delayed presentation in many conditions has been proven to lead to worsened outcomes. Currently, there are limited data on outcomes of those who have a delayed presentation after a ground level fall.

MATERIALS AND METHODS

This study was a retrospective analysis of the Trauma Registry at our center. Any adult patient who presented after a ground level fall was grouped based on their time to presentation post-injury: less than or greater than 24 h. Age, gender, hospital length of stay (LOS), intensive care unit (ICU) LOS, mechanical ventilation days, Injury Severity Score, and mortality were patient characteristics gathered. A Student's t-test and Chi-squared testing were utilized to determine the presence of significant differences between the groups. Significance was set at P < .05.

RESULTS

Two hundred of 4018 patients had delayed presentation. Those with delayed presentation were more likely to be male (P = .028), younger in age (71 vs 74 years old, P < .01), had greater hospital LOS (6 vs. 5, P < .01), ICU LOS (5 vs. 3, P < .01), and mechanical ventilation days (13 vs. 5 days, P < .01). They also had higher ISS (8 vs. 7, P < .01), and mortality was significantly higher in those who presented after 24 h (P = .034).

CONCLUSION

Patients with delayed presentation after a ground level fall have worsened Injury Severity Scores and outcomes to include hospital and ICU LOS, ventilator days, and overall mortality.

Sunken Skin Flap Syndrome: Neurological Dysfunction After Decompressive Craniectomy

Sunken Skin Flap Syndrome (or Syndrome of the Trephined) following a head trauma is rare, but most often results from complications after decompressive craniectomy. This syndrome is most often characterized by neurological dysfunction that improves with cranioplasty. Early diagnosis and treatment are critically important to long term neurological improvement. This is a case report of a 49-year-old male who fell down a flight of stairs and was found unresponsive. Initial imaging revealed extensive head trauma. Neurosurgery performed an emergency decompressive craniectomy, but his post-operative course was complicated by the development of sunken flap syndrome one month after his initial surgery, diagnosed by an acute neurological decline and emergent CT imaging. A review of the literature indicates that this is a rarely documented finding, and this case report discusses the critical components of diagnosis and treatment of this unusual and potentially lethal condition.

Lower Extremity Sandblast Injury: A Rarely Seen Injury Mechanism in the Civilian Population

Blast injuries are both complex and rare in the civilian population. This combination can often lead to missed opportunities for early, effective intervention. This is a case report of a 31-year-old male who suffered a lower extremity blast injury while using an industrial sandblaster. This blast injury presented as a closed degloving, or Morel-Lavallee lesion, which can easily be mistreated and lead to infection and further disability. Following assessment, identification, and confirmation of the Morel-Lavallee lesion via radiographic imaging, this patient underwent debridement surgery, wound vac therapy, and antibiotic treatment before being discharged home with no major physiologic or neurologic deficits. The purpose of this report is to highlight the importance of assessing for closed degloving injuries when presented with blast injury traumas in the civilian trauma setting, and outlines the process utilized for assessment and treatment.

Antibiotic prophylaxis for tube thoracostomy placement in trauma: a practice management guideline from the Eastern Association for the Surgery of Trauma

BACKGROUND

Antibiotic prophylaxis is routinely administered for most operative procedures, but their utility for certain bedside procedures remains controversial. We performed a systematic review and meta-analysis and developed evidence-based recommendations on whether trauma patients receiving tube thoracostomy (TT) for traumatic hemothorax or pneumothorax should receive antibiotic prophylaxis.

METHODS

Published literature was searched through MEDLINE (via PubMed), Embase (via Elsevier), Cochrane Central Register of Controlled Trials (via Wiley), Web of Science and ClinicalTrials.gov databases by a professional librarian. The date ranges for our literature search were January 1900 to March 2020. A systematic review and meta-analysis of currently available evidence were performed using the Grading of Recommendations Assessment, Development and Evaluation methodology.

RESULTS

Fourteen relevant studies were identified and analyzed. All but one were prospective, with eight being prospective randomized control studies. Antibiotic prophylaxis protocols ranged from a single dose at insertion to 48 hours post-TT removal. The pooled data showed that patients who received antibiotic prophylaxis were significantly less likely to develop empyema (OR 0.47, 95% CI 0.25 to 0.86, p=0.01). The benefit was greater in patients with penetrating injuries (penetrating OR 0.25, 95% CI 0.10 to 0.59, p=0.002, vs blunt OR 0.25, 95% CI 0.06 to 1.12, p=0.07). Administration of antibiotic prophylaxis did not significantly affect pneumonia incidence or mortality.

DISCUSSION

In adult trauma patients who require TT insertion, we conditionally recommend antibiotic prophylaxis be given at the time of insertion to reduce incidence of empyema.

PROSPERO REGISTRATION NUMBER

CRD42018088759.

Bridging the Gap: How to Get Osteopathic Residents Into Fellowships

Introduction

The fellowship match process is convoluted, with each specialty having its match on its timeline- with some programs having a Post Graduate Year (PGY) 4^th-year or 5^th-year match.

This study aims to identify tangible recommendations for osteopathic surgery residents to use to improve their applications and, ultimately, the success rate for matching into post-graduate fellowship training.

Methods

In October 2021, as a part of the American College of Osteopathic Surgeons (ACOS) Strategic Planning efforts, the ACOS Resident Student Section sent a questionnaire to the listed email contact for each surgical fellowship program. Fellowship coordinators and program directors were included in the survey. The programs that were included in the study were vascular, thoracic (which included cardiothoracic), surgical critical care, endocrine, hepatobiliary, transplant, pediatric, surgical oncology, breast, minimally invasive, and colorectal surgery.

Results

Of the 108 programs that answered the survey, 36% of them reported they currently had an osteopathic fellow, and another 29% said they had an osteopathic fellow in the past. 35% of the programs listed that they had never had an osteopathic fellow in their program.

In regards to how residents can improve their application for fellowship matches the most common answer was research in the field, they were trying to match into. They wanted to see high scores on the United States Medical Licensing Examination (USMLE) and American Board of Surgery In-Training Examination (ABSITE) exams. They also noted that they wanted candidates from more well know residency programs, where they knew the residents would have gotten good training.

Conclusion

We recommend that any potential fellowship applicant focus on the following three areas increase competitiveness for matching into fellowship training: publication in the desired field, increased overall scholarly activity, and increased ABSITE scores.

Lessons learnt: Undertaking rapid reviews on public health and social measures during a global pandemic

Public health and social measures (PHSM) have been central to the COVID‐19 response. Consequently, there has been much pressure on decision‐makers to make evidence‐informed decisions and on researchers to synthesize the evidence regarding these measures. This article describes our experiences, responses and lessons learnt regarding key challenges when planning and conducting rapid reviews of PHSM during the COVID‐19 pandemic. Stakeholder consultations and scoping reviews to obtain an overview of the evidence inform the scope of reviews that are policy‐relevant and feasible. Multiple complementary reviews serve to examine the benefits and harms of PHSM across different populations and contexts. Conceiving reviews of effectiveness as adaptable living reviews helps to respond to evolving evidence needs and an expanding evidence base. An appropriately skilled review team and good planning, coordination and communication ensures smooth and rigorous processes and efficient use of resources. Scientific rigor, the practical implications of PHSM‐related complexity and likely time savings should be carefully weighed in deciding on methodological shortcuts. Making the best possible use of modeling studies represents a particular challenge, and methods should be carefully chosen, piloted and implemented. Our experience raises questions regarding the nature of rapid reviews and regarding how different types of evidence should be considered in making decisions about PHSM during a global pandemic. We highlight the need for readily available protocols for conducting studies on the effectiveness, unintended consequences and implementation of PHSM in a timely manner, as well as the need for rapid review standards tailored to “rapid” versus “emergency” mode reviewing.

Effects of Trauma Center Consolidation on Pediatric Trauma at an Appalachian Pediatric Hospital

With the increase in hospital consolidation over the past decade, multiple studies have been performed evaluating patient outcomes after consolidation. To date, there have not been studies performed to assess outcomes in pediatric trauma patients. The goal was to assess pediatric patient outcomes in a children's hospital after consolidation of two Level 1 Trauma centers in a rural Appalachian health system. A retrospective analysis of data from the Trauma Registry between October 2015 - September 2020 was performed. The variables included in analysis were age, injury severity score (ISS), hospital days, intensive care unit days, ventilator days, mortality, discharge disposition, consults, and hospital visit cost. Despite increased ISS, there was no difference in in-patient outcomes. However, these patients were more likely to require orthopedic evaluation and further outpatient care after discharge, suggesting more severely injured patients were evaluated by the trauma service post consolidation.

Before Disaster Strikes: A Pilot Intervention to Improve Pediatric Trainees' Knowledge of Disaster Medicine

OBJECTIVE

Because training in pediatric disaster medicine (PDM) is neither required nor standardized for pediatric residents, we designed and integrated a PDM course into the curriculum of a pediatric residency program and assessed if participation increased participants' knowledge of managing disaster victims.

METHODS

We adapted and incorporated a previously studied PDM course into a small-sized pediatric residency program. The curriculum consisted of didactic lectures and experiential learning via simulation with structured debriefing. With IRB approval, the authors conducted a longitudinal series of pretests and posttests to assess knowledge and perceptions.

RESULTS

Sixteen eligible residents completed the intervention. Before the course, none of the residents reported experience treating disaster victims. Pairwise comparison of scores revealed a 35% improvement in scores immediately after completing the course (95% confidence interval, 22.73%-47.26%; P < 0.001) and a 23.73% improvement 2 months later (95% confidence interval, 7.12%-40.34%; P < 0.01).

CONCLUSIONS

Residents who completed this course increased their knowledge of PDM with moderate retention of knowledge gained. There was a significant increase in perceived ability to manage patients in a disaster situation after this educational intervention and the residents' confidence was preserved 2 months later. This PDM course may be used in future formulation of a standardized curriculum.

The Effect of Single Accreditation on Medical Student Match Rates in Surgical Specialties

Introduction The year 2020 marked the first year in which a match under single accreditation took place. Both osteopathic (DO) and allopathic (MD) students would participate in the first match cycle without a dedicated DO match system. Our primary objective was to investigate how single accreditation has impacted the DO applicants attempting to match into surgical specialties. Our secondary objective was to investigate the impact of single accreditation at the program director (PD) level and whether or not this process would see a change in DO PD distribution in previously American Osteopathic Association (AOA)-approved programs. Method Information on number of applicants and post-match positions was gathered from AOA and National Residency Match Program (NRMP) websites. Credentials of PDs were obtained from the Accreditation Council on Graduate Medical Education website. Based on the available data, the following surgical specialties were compared for the years 2020, 2018, and 2016: General Surgery, Neurological Surgery (NSGY), Orthopedic Surgery, Otolaryngology/ENT (ENT), Plastic Surgery, and Thoracic Surgery. Data from 2016 were not included in the results as the AOA match results analysis was insufficient and unable to be directly compared to the NRMP data. Results of matched DO and MD applicants were compared using bivariate analysis. A p-value of <0.05 was considered significant. Results From the year 2018 to 2020, the DO applicants saw a decrease of 3% in the total number of matched postgraduate year 1 spots in surgical specialties. NRMP results from 2020 saw that 51.7% of DO applicants matched and 67.7% (p < 0.001) of MD applicants matched for the specialties examined. Percent of matched:applied for DO applicants was lower than MD applicants in the fields of NSGY (p < 0.001), ENT (p < 0.001), Plastic Surgery (p < 0.001), General Surgery (p < 0.001), and Thoracic Surgery (p = 0.011). After evaluating 60 former AOA General Surgery programs, 56% were found to have MD as PD. Another 26 former AOA surgical programs were investigated, and 58% were found to have MD PD.  Conclusion Single accreditation has impacted the match process now that a large number of both MD and DO applicants are using the NRMP match system for postgraduate placement. Based on the available data, our results indicate that in the examined surgical specialties, there is a statistically significant difference in the number of MD and DO residents.

Proficiency of surgical faculty and residents with ethical dilemmas: is modeling enough?

OBJECTIVE

Professionalism, an Accreditation Commission for Graduate Medical Education (ACGME) competency, embraces the concept of adherence to ethical principles. Despite this, most surgical residencies do not currently include ethics as part of their core curriculum. Further, expertise in effectively managing ethical dilemmas is frequently obtained via modeling after the attending physician. This study evaluated surgical faculty (SF) and residents (SR) on their understanding of basic ethical principles and their overall confidence in translation of these principles into clinical practice. The objective was to determine if there are any differences in the overall levels of knowledge and confidence in ethics between SR and SF.

DESIGN AND SETTING

Immediately before the first session of a Kamangar Grant supported monthly Ethics Forum, all SF and SR completed a Pre-Curriculum Questionnaire (PCQ) on their knowledge about ethical principles and their confidence in dealing with ethical issues. PQC contained 13 multiple-choice and true/false knowledge questions and 8 questions evaluating confidence rated on a 5-point Likert scale.

PARTICIPANTS

Surgical faculty (SF) (n = 16) and SR (n = 36). Knowledge and confidence scores were compared between SR and SF, using Student t-test analysis to evaluate differences between groups.

RESULTS

No significant differences were found in ethical knowledge scores between faculty and residents. Faculty confidence is higher than resident (p < 0.05). Further, female faculty confidence is higher than that of their male counterparts (p < 0.05).

CONCLUSIONS

While SF are more confident in their ethical decision-making, their fundamental knowledge base in ethics is not different from that of SR. Female SF report greater self-confidence over their male counterparts. In total, SF may not possess the foundation to effectively mentor residents in appropriate ethical principles and their translation to clinical practice. This study supports the need for both SR and SF to engage in an integrated education program in ethics to promote on-going dialogue in this complex topic.

Daclizumab phase II trial in relapsing and remitting multiple sclerosis: MRI and clinical results

OBJECTIVE

Daclizumab is an interleukin 2 receptor alpha chain specific humanized monoclonal antibody that has shown promising therapeutic effects in multiple sclerosis (MS). Daclizumab treatment in patients with relapsing and remitting MS was administered to determine effects on MRI and clinical outcomes.

METHODS

Patients with MS on interferon (IFN) therapy but with continuing relapses and contrast enhancing lesions (CEL) were selected. Patients were evaluated with monthly MRI scans and clinical rating scales starting 3 months prior to treatment and then at 0.5 to 27.5 months during treatment. Daclizumab (1 mg/kg IV) was administered twice in the first month (initiated and administered again in 2 weeks), followed by treatments every 4 weeks. IFN was continued until 5.5 months after daclizumab was initiated. Patients were then placed on daclizumab monotherapy. Patients with recurrent CEL were restarted on IFN with daclizumab therapy at (1.5 mg/kg IV) every 28 days.

RESULTS

Nine patients qualified for inclusion and completed the trial. Efficacy measured by both total CEL and new CEL (p < 0.001), relapses, timed ambulation, Expanded Disability Status Scale, and Neurologic Rating Scale (p < 0.05 to p < 0.01) was observed.

CONCLUSION

Daclizumab was effective in reducing contrast enhancing lesions and improving clinical scores in patients with relapsing and remitting multiple sclerosis with active disease not controlled by interferon therapy. These results provide evidence for long-term efficacy and support further clinical development of daclizumab.

Isolation of CD45RO+, memory T cells recognizing proteolipid protein from neurologically normal subjects

Previous studies provide evidence for in vivo activation of MBP-reactive T cells in subjects with multiple sclerosis. In general, in vivo activation occurs less frequently in healthy control subjects. In the current study we examined the T cell response to proteolipid protein in PBMC isolated from 9 control subjects. We used CD45 isotypes as markers for memory and naïve T cells to assess in vivo activation of CD4+ T cells reactive with PLP. In contrast to the results obtained using MBP, we found that approximately 50% of PLP-reactive T cells were derived from the CD45RO+ memory subpopulation of T cells isolated from these control subjects. These results indicate that some myelin-reactive T cells have undergone activation in vivo in neurologically intact individuals. This suggests that immunoregulatory mechanisms may be present that prevent overt disease in spite of in vivo activation of PLP-reactive T cells.

The design and performance of a 2.5-GHz telecommand link for wireless biomedical monitoring

This paper details the implementation and operational performance of a minimum-power 2.45-GHz pulse receiver and a companion on-off keyed transmitter for use in a semi-active, duplex RF biomedical transponder. A 50-ohm microstrip stub-matched zero-bias diode detector forms the heart of a body-worn receiver that has a (CMOS baseband amplifier consuming 20 microA from +3 V and achieves a tangential sensitivity of -53 dBm. The base transmitter generates 0.5 W of peak RF output power into 50 ohms. Both linear and right-hand circularly polarized Tx-Rx antenna sets were employed in system reliability trials carried out in a hospital Coronary Care Unit. For transmitting antenna heights between 0.3 and 2.2 m above floor level, transponder interrogations were 95% reliable within the 67-m2 area of the ward, falling to an average of 46% in the surrounding rooms and corridors. Overall, the circular antenna set gave the higher reliability and lower propagation power decay index.

In vivo reduction of telomere length in human antigen-reactive memory T cells

There is a reduction in the average telomere lengths of CD4+ "memory" T cells, defined by the CD45RO+ phenotype, compared to CD54RA+ "naive" T cells. However, other studies suggest that telomerase activity often is sufficient to maintain the telomere length of certain B and T cell populations following immune activation in vivo. Thus it is uncertain whether genuine memory CD4+ T cells, defined by an immune response to specific recall antigens, would display telomeres of reduced length, or whether telomere size would be maintained. Therefore, we examined the telomere lengths of T cells responding to two common recall antigens, tetanus toxoid and Candida albicans. Telomere terminal restriction fragment length was assessed by Southern blots or by flow cytometry following in situ hybridization with telomere-specific peptide nucleic acid probes. For the five subjects tested, the Candida- or tetanus-reactive memory T cell populations demonstrated a significant reduction of telomere length even when compared to the phenotypically defined memory CD45RO+ T cell populations isolated from peripheral blood mononuclear cells. This finding suggests that telomerase activity does not fully compensate for the effects of in vivo activation and proliferation of some antigen-specific CD4+ T cell populations. This may contribute to immune senescence.

A dynamical-systems model for Parkinson's disease

The juxtaposition of hypokinetic and hyperkinetic symptoms in Parkinson's disease (PD) presents a challenge in modeling the basal ganglia. We propose a model of the striatum that can account for the mixture of symptoms seen in PD. In the model, the problem of motor planning is cast in terms of a particle in a potential, where potentials are generated internally in striatal modules, subject to afferent control. Planned movement is governed by Hamilton's equations, where potential energy is supplied by potentials expressed in the striatum. To test the model in realistic situations, a dynamic simulation of a two-link robot arm was used. Normal movement is modeled and shown to exhibit observed experimental properties. Symptoms of PD are reproduced by modeling hypothetical consequences of PD pathology.

Radiowave propagation from a tissue-implanted source at 418 MHz and 916.5 MHz

Tissue-implanted ultra-high frequency (UHF) radio devices are being employed in both humans and animals for telemetry and telecommand applications. This paper describes the experimental measurement and electromagnetic modeling of propagation from 418-MHz and 916.5-MHz sources placed in the human vagina. Whole-body homogeneous and semi-segmented software models were constructed using data from the Visible Human Project. Bodyworn radiation efficiencies for a vaginally placed 418-MHz source were calculated using finite-difference time-domain and ranged between 1.6% and 3.4% (corresponding to net body losses of between 14.7 and 18.0 dB). Greater losses were encountered at 916.5 MHz, with efficiencies between 0.36% and 0.46% (net body loss ranging between 23.4 and 24.4 dB). Practical measurements were in good agreement with simulations, to within 2 dB at 418 MHz and 3 dB at 916.5 MHz. The degree of tissue-segmentation for whole-body models was found to have a minimal effect on calculated azimuthal radiation patterns and bodyworn radiation efficiency, provided the region surrounding the implanted source was sufficiently detailed.

Enterogastric reflux mimicking gallbladder disease: detection, quantitation and potential significance

OBJECTIVE

Visualization of enterogastric reflux (EGR) may be present during hepatobiliary imaging. Reflux of bile may damage the gastric mucosa, altering its function, and cause such symptoms as epigastric pain, heartburn, nausea, intermittent vomiting and abdominal fullness. These symptoms also are associated with gallbladder disease. The aim of this study was to quantitate the EGR index (EGRI) and to determine if a difference exists in normal and abnormal responses using standard cholecystokinin (CCK)-augmented hepatobiliary imaging.

METHODS

This study used 129 patients. LAO dynamic data on a 128 x 128 matrix at a rate of 1 frame/min were obtained. After the gallbladder ejection fraction (GBEF) was determined, the EGRI (%) was calculated by relating the counts in the gastric ROI to the counts in the hepatobiliary ROI at a specified time. The results were compared with the patient's final clinical diagnosis.

RESULTS

Normal responders (GBEF > or = 35%) had a higher EGRI than abnormal responders with a P = 0.001 EGR observed in 75 patients (58.1%). Significant reflux (EGRI > or = 14.2% at 15 min) was observed in 29 additional patients (22.5%). Patients with EGRI > or = 24.5% showed a strong association with the pathophysiologic syndrome of gastritis, alkaline reflux, gastric ulcer and gastro esophageal reflux disease. There was no EGR observed in the remaining 25 patients (19.4%).

CONCLUSION

This simple addition to the CCK-augmented hepatobiliary imaging may both detect and quantitate abnormal EGR as the cause of the patient's symptoms in the presence of a normal GBEF result, and/or those patients with risk factors for gastritis.

FDTD analysis of close-coupled 418 MHz radiating devices for human biotelemetry

This paper describes the finite-difference time-domain (FDTD) analysis of antenna-body interaction effects occurring when chest-mounted 418 MHz radio transmitters are used for medical telemetry applications. Whole-body software models (homogeneous, layered and tissue-segmented) were developed for an adult male subject. Using an electrically small (300 mm2) planar loop antenna, calculated radiation efficiencies ranged between 33.5% and 39.2% for a whole-body model, and between 60.7% and 66.1% for a torso; radiation patterns were found to be largely independent of model composition. The computed radiation efficiency for a 21.5 kg phantom representing a six-year-old female was within 1.1 dB of measured results (actual body mass 28 kg) and well-correlated azimuthal radiation patterns were noted.

Modulation of immune system function by measles virus infection: role of soluble factor and direct infection

Measles virus infection can result in a variety of immunologic defects. We have begun studies to determine the basis for the lack of immune responsiveness to antigen and mitogen following infection. Here we present data showing that Epstein-Barr virus-transformed B-cell lines infected with measles virus produce a soluble factor that can inhibit antigen-specific T-cell proliferation and inhibit the proliferation of uninfected B cells. The soluble factor was neither interleukin-10, transforming growth factor beta, nor alpha/beta interferon. B cells infected with measles virus or treated with the soluble factor were unable to present antigen to T cells in a manner that supported antigen-specific proliferation. This could represent one mechanism of how measles virus limits T-cell expansion. However, we found that once CD4(+) or CD8(+) T cells were activated, their cytolytic activity was intact whether infected with measles virus or treated with soluble factor. Thus, while slow to be generated these cytoxic cells could participate in viral clearance.

On the design and assessment of a 2.45 GHz radio telecommand system for remote patient monitoring

This paper discusses the design and operational assessment of a minimum-power, 2.45 GHz portable pulse receiver and associated base transmitter comprising the interrogation link in a duplex, cross-band RF transponder designed for short-range, remote patient monitoring. A tangential receiver sensitivity of - 53 dBm was achieved using a 50 ohms microstrip stub-matched zero-bias diode detector and a CMOS baseband amplifier consuming 20 microA from + 3 V. The base transmitter generated an on-off keyed peak output of 0.5 W into 50 ohms. Both linear and right-hand circularly-polarised antennas were employed in system evaluations carried out within an operational Coronary Care Unit ward. For transmitting antenna heights of between 0.3 and 2.2 m above floor level. transponder interrogations were 95% reliable within the 82 m2 area of the ward, falling to an average of 46% in the surrounding rooms and corridors. Separating the polarisation modes, using the circular antenna set gave the higher overall reliability.

Suppression of antigen-specific T cell proliferation by measles virus infection: role of a soluble factor in suppression

Measles virus infection causes a profound immunosuppression. The basis for this immunosuppression is not known. This immunosuppression could be due to virus acting directly on lymphoid cells, the production of an immunosuppressive viral product, or a lymphoid product. We have developed an antigen-specific T cell system to study measles virus-T-cell interactions. We demonstrate that as few as five infectious viral particles added to 1000 T cells results in profound inhibition of antigen-specific T cell proliferation. Supernates taken from measles virus-infected T cells suppress the proliferation of uninfected T cells. Measles-virus-infected HeLa or Vero cells do not produce the factor. The antiproliferative effects of the supernates cannot be attributed to infectious virus, IL-10 or TGF-beta. The soluble factor appears to be larger than 100 kDa, yet retains antiproliferative activity following trypsin digestion with a size less than 10 kDa. Loss of activity is seen following heat treatment at 56 degrees C. The factor is lymphoid cell specific and exhibits cytokine-like behavior yet appears not to be a known cytokine. This soluble factor may be responsible for the overt clinical immunosuppression seen in man and a previously undescribed cytokine induced by measles virus infection of human lymphocytes.

Measles virus infection of human T cells modulates cytokine generation and IL-2 receptor alpha chain expression

Measles virus (MV) suppresses specific functions in cells of the immune system and causes a generalized immunosuppression by mechanisms which remain undefined. It has been previously established that mitogen-induced proliferation of peripheral blood mononuclear cells (PBMC) is suppressed by infection with MV. Our current study demonstrates that MV infection inhibits antigen-specific proliferation of T lymphocytes. The inhibition of proliferation was not due to a decrease in IL-2 production. IL-2 production in cultures of infected and uninfected antigen-specific T cells was similar. In contrast, we found that expression of the IL-2R alpha subunit was decreased in mitogen-stimulated, MV-infected PBMC and antigen-stimulated, MV-infected T lymphocytes compared to stimulated but noninfected T cells. However, the expression of the IL-2R beta subunit was not altered in MV-infected T cells. We also examined the influence of MV infection on the production of the cytokines IL-4, IL-6, IL-10, and IFN-gamma by T lymphocytes. By comparing infected versus uninfected antigen-specific T cell lines, we found that MV infection of antigen-specific activated T cells caused no substantial change in generation of IFN-gamma, IL-6, or IL-10. There was a 50% reduction in IL-4 generation following MV infection. These data indicate that the immunosuppression by acute MV infection is not associated with a generalized inhibition of cytokine production. One mechanism for the suppression of proliferation following acute MV infection may be a block in the expression of the IL-2R alpha subunit by activated T cells.

Retinal degeneration slow (rds) in mouse results from simple insertion of a t haplotype-specific element into protein-coding exon II

Retinal degeneration slow (rds) is a semidominant mutation of mice that causes dysplasia and degeneration of rod and cone photoreceptors. Mutations in RDS, the human ortholog of the rds gene, are responsible for several inherited retinal dystrophies including a subset of retinitis pigmentosa. The normal rds locus encodes rds/peripherin, an integral membrane glycoprotein present in outer segment discs. Genomic libraries from wildtype and rds/rds mice were screened with an rds cDNA, and phage lambda clones that span the normal and mutant loci were mapped. We show that in mice, rds is caused by the insertion into exon II of a 9.2-kb repetitive genomic element that is very similar to the t haplotype-specific element in the H-2 complex. The entire element is included in the RNA products of the mutant locus. We present evidence that rds in mice represents a null allele.

Uptake of systemically administered human anticerebellar antibody by rat Purkinje cells following blood-brain barrier disruption

Paraneoplastic cerebellar degeneration accompanying gynecological or breast malignancies is frequently associated with an autoantibody response, termed "type I" or "anti-Yo" directed against cytoplasmic antigens of cerebellar Purkinje cells. The role of this antibody response in the pathogenesis of paraneoplastic cerebellar degeneration is unknown; however, it is also not known whether anti-Purkinje cell antibodies from the systemic circulation bind to target Purkinje cell antigens under the conditions of brain inflammation and blood-brain barrier disruption, which are frequently present at the onset of cerebellar symptoms. Inbred Lewis rats received intraperitoneal injections of type I or normal IgG in the setting of blood-brain barrier disruption induced by adoptive transfer of experimental allergic encephalomyelitis (EAE) and were killed after 24, 48, and 96 h. Brains of these animals were studied histologically for evidence of EAE and immunohistochemically for binding of human or endogenous rat IgG to target neurons. Rat IgG was detected around vessels and in Purkinje cells of all animals studied. Human IgG was detected around vessels of all animals. In animals examined 96h after receiving type I human IgG, human IgG was identified within processes of Purkinje cells and within occasional Purkinje cell bodies. Uptake of type I IgG by other cell types was not observed, and neuronal uptake of IgG was not seen in brains of animals receiving normal human IgG. Our data demonstrate that circulating type I IgG is internalized by cerebellar Purkinje cells in the setting of blood-brain barrier disruption and suggest a mechanism by which an antibody response directed against cytoplasmic antigens of Purkinje cells may reach target antigens at the onset of paraneoplastic cerebellar degeneration.

Fading characteristics of a 2.3 GHz radio telemetry channel in a hospital building

This paper reports on radio path attenuation measurements made in a hospital complex at a spot frequency of 2.340 GHz. Power loss figures for fixed path propagation in a variety of building types have been determined for proposed telemetry use in operational ward situations. Throughout the hospital, the radio paths assessed all exhibited a loss in excess of that calculated for free-space communications. Modern buildings had external wall losses of 10-25 dB, with dividing walls in wards contributing an additional 5 dB. Received signal strength levels indicated a Rayleigh distribution for obstructed paths. Temporal testing was used to find the rate and depth of signal fades caused by the movement of personnel and equipment during normal ward usage; signal level reductions of greater than 35 dB were common during busy periods.

Primary central nervous system lymphoma following transfer of human peripheral blood lymphocytes into SCID mice

Severe combined immunodeficiency (SCID) mice are genetically deficient in both B and T cells. To study immune-mediated phenomena in the CNS, myelin basic protein-reactive T cell clones, admixed with peripheral blood lymphocytes as a source of antigen-presenting cells, derived from a healthy human donor, were injected intracerebrally (IC) into 10 SCID mice. One mouse developed quadriplegia 2 months after the last injection. Autopsy revealed marked meningeal and parenchymal infiltration by large cell lymphoma. There was no evidence of lymphoma outside of the CNS. The majority of the tumor cells were positive for L26 (a human pan B cell marker), with some cells positive for UCHL-1 (a human pan T cell marker). The majority of the tumor cells were also positive for Epstein-Barr virus (EBV) genome by in situ hybridization. Thus, primary CNS, EBV-positive B cell lymphoma can be produced in SCID mice by IC injection of nontransformed human peripheral blood lymphocytes. This phenomenon can be used as a model system for the study of primary CNS lymphomas under immunodeficiency conditions.

A new striatal model and its relationship to basal ganglia diseases

A new model of the striatum has recently been proposed. This model suggests that the somatotopic regions of the striatum correspond to state spaces governing various aspects of organism behavior (e.g., reaching, egomotion, task planning). The model is reviewed, and shown to be applicable to sequencing tasks. The model is also discussed in the context of some basal ganglia diseases.

A model for the functioning of the striatum

A model is presented for the operation of the striatum. The model posits that the basal ganglia are responsible for driving smooth transitions of state for an organism. We propose that this is accomplished through the computation of a potential function within the striatum on which a gradient descent is performed toward the goal state. The model suggests that various somatotopic regions of the striatum correspond to state spaces, each of which pertains to a different aspect of the organism. This paper discusses this model only in the context of motor control, i.e., egomotion and limb movement. The model appears to account for a variety of experimental results, and for some unusual properties of the striatum.

Human T lymphocytes reactive with whole myelin recognize predominantly myelin basic protein

Human T-cell lines and clones reactive with whole human myelin were isolated from three normal subjects by in vitro sensitization techniques. The CD4+ T-cell lines were maintained in long-term culture by periodic antigen restimulation with myelin and use of interleukin-2. Although myelin basic protein (MBP) represents only about 10% of the dry weight of myelin and the myelin-reactive T-cell populations were never exposed to purified MBP, each of the three cell lines responded to in vitro stimulation with both MBP and whole myelin. Seventeen of 18 T-cell clones derived from the myelin-reactive cell lines also responded to MBP. One myelin-reactive T-cell clone did not recognize MBP or the major myelin lipids but responded to delipidated myelin proteins suggesting that this clone recognized another myelin protein antigen. These results indicate that MBP is the predominant antigen in whole myelin recognized by human T cells under the culture conditions described. However, there is at least one additional protein antigen in myelin that is also immunogenic.

A quantitative immunohistochemical comparison of actively versus adoptively induced experimental allergic encephalomyelitis in the Lewis rat

A quantitative immunohistochemical comparison of actively and adoptively induced experimental allergic encephalomyelitis (EAE) in the Lewis rat was performed. Since the methods of EAE induction of these two systems and the kinetics of disease appearance are different, while the histopathology, disease manifestations, duration, and severity are similar, this study sought to identify any differences which exist at the level of the target organ. The number of cells expressing the T helper (W3/25) or suppressor/cytotoxic (OX-8) phenotypes and the number of Ia-positive cells found in the spinal cord of animals given EAE by one of the two methods were compared at two time points at which maximal similarities should exist. The results show that during acute adoptively induced EAE the inflammatory infiltrate contains a larger number of T helper (TH) cells per unit area than in acute active EAE. With the resolution of clinical signs of EAE, the disappearance of cells from the spinal cord is more rapid in adoptive EAE. In contrast, the inflammatory infiltrate and Ia-positive parenchymal cells persist in active EAE following recovery. These results suggest that actively and adoptively induced EAE may differ with respect to the effector mechanisms and/or the mechanisms of recovery at the level of the target organ.

Search for antibodies to galactocerebroside in the serum and cerebrospinal fluid in human demyelinating disorders

To determine if galactocerebroside (GalC) is a target antigen in the human demyelinating disorders multiple sclerosis, Guillain-Barré syndrome, and chronic demyelinating inflammatory polyneuropathy, we examined the serum and cerebrospinal fluid from patients with these disorders and from control subjects using four assay systems. In none of these assays could we detect significant differences in anti-GalC antibody titer between patients with demyelinating diseases and normal subjects or patients with other neurological disorders. Our data suggest that there is no humoral immune response to GalC in human demyelinating disorders.

Products of activated lymphocytes stimulate Schwann cell mitosis in vitro

Culture of Schwann cells and endoneurial fibroblasts from newborn rat sciatic nerves in the presence of supernatants obtained from concanavalin A (Con-A)-stimulated rat mononuclear cells resulted in proliferation of both cell types. Con-A did not induce Schwann cell or fibroblast proliferation. Supernatant from a Gibbon T-cell lymphoma and chromatographically purified rat interleukin-2 (IL-2) induced fibroblast but not Schwann cell proliferation, and cloned human IL-2 did not induce proliferation of either cell type. Proliferation of Schwann cells and endoneurial fibroblasts induced by activated mononuclear inflammatory cells may be important in inflammatory demyelinative neuropathies.

Transfer of experimental allergic neuritis with P2-reactive T-cell lines

Experimental allergic neuritis (EAN) was induced in normal Lewis rats by systemic passive transfer of T-cell lines responding to P2 protein. These cells had predominantly helper phenotype and could induce EAN within 7 days following adoptive transfer. There was no anti-P2 antibody response in the recipients of the P2-reactive cells recovered from donors with high anti-P2 antibody levels. This study provides direct evidence that T cells are important for the induction of EAN. Furthermore, there was no evidence of a pathogenic role for anti-P2 antibody in passive EAN.

Immune responses to myelin antigens in multiple sclerosis

Multiple sclerosis is considered to be a putative immunopathologic disease and there has been considerable effort over the years to prove an autoimmune etiology for it. To date, the evidence is all indirect and there is no proof of either antibody and/or cell-mediated hypersensitivity to any single identifiable CNS constituent whether a constituent of normal CNS or specific to the CNS of MS patients.

Long-term growth in vitro of human cerebrospinal fluid T lymphocytes

Investigations of central nervous system cellular immune reactivity in human disease, as reflected in the responses of cerebrospinal fluid lymphocytes, have been limited primarily due to the low numbers of cerebrospinal fluid lymphocytes available during routine diagnostic lumbar punctures in normal individuals and most patients with demyelinating diseases. We report the use of a T-cell growth factor generated by by phytochemagglutinin-stimulated, irradiated normal peripheral blood lymphocytes to maintain long-term proliferating cultures of human cerebrospinal fluid lymphocytes. Cerebrospinal fluid lymphocytes. Cerebrospinal fluid T-cell cultures were initiated from 10 to 14 cerebrospinal fluid samples with up to 5000-fold expansion of initial cell numbers. Few, if any, macrophage or surface immunoglobulin-bearing cells were present, while 80 to 90% of the cultured cells were T cells as demonstrated by rosette formation with sheep red blood cells. Mixed lymphocyte cultures with cultured cerebrospinal fluid T cells and irradiated, freshly isolated allogeneic peripheral blood lymphocytes yielded a positive response in four of the five cultures tested.