Key lessons from the establishment of a nurse-led infection prevention and control program for COVID-19 in an Australian hotel quarantine and isolation service

BACKGROUND

A key aspect of Australia's response to the COVID-19 pandemic was to control transmission through legislated quarantine and isolation of overseas returning travellers and potentially infectious community members. In New South Wales, Special Health Accommodation (SHA) was rapidly established as a comprehensive health service for individuals that were at risk of having COVID-19, were confirmed to have COVID-19 or for those with complex health needs that were deemed inappropriate for management in Police managed Quarantine Hotels. SHA services were later expanded to care for community members who were COVID-19 positive and unable to effectively isolate, or contacts of individuals who were unable to quarantine effectively in their homes. SHA's unique nurse-led Infection Prevention and Control (IPC) program offers key lessons that may impact future programs.

METHODS

A reflection on the experience of leading an Infection Prevention and Control program in SHA was undertaken. This was supported by a review of SHA admission, workforce and transmission data and data obtained from a cross-sectional questionnaire aimed to better understand the experiences of a novel population of health workers (HW) in a comprehensive health-led quarantine and isolation service.

RESULTS

SHA program data demonstrates how its IPC program implementation prevented transmission of COVID-19 to SHA staff and patients. Responses from the questionnaire suggested staff felt safe and well-prepared through the IPC education they received. They also gained transferrable knowledge and skills, which they intend to use in future healthcare roles.

CONCLUSION

The SHA nurse-led IPC program offered successful quarantine and isolation for COVID-19 in non-purpose-built facilities. A review of IPC strategies and key lessons from the establishment of the SHA IPC program are of critical importance to planning and management of current and future pandemics.

Unusual Presentation of Synovial Lipomatosis Mimicking As Septic Arthritis of Knee: A Case Report

Synovial lipomatosis or lipoma arborescens is a very uncommon pseudo-tumorous lesion of the synovium which more commonly affects the knee joint. The most probable cause of this pathological lesion is degenerative articular disorders of the joint and improper fat accumulation. It is characterized by presence of villous proliferation of the synovium and replacement of the sub-synovial tissue by mature adipocytes which is infiltrated by dense chronic inflammatory cells like lymphocytes, plasma cells and eosinophils. This condition is rarely seen in smaller joints. Its aetiology is still unknown. We report a patient who presented with features of septic arthritis which on intraoperative and histopathological assessment showed features of synovial lipomatosis.

A Multicenter Study of Stellate Ganglion Block as a Temporizing Treatment for Refractory Ventricular Arrhythmias

BACKGROUND

Ventricular tachycardia (VT) and ventricular fibrillation (VF) are life-threatening conditions and can be refractory to conventional drug and device interventions. Stellate ganglion blockade (SGB) has been described as an adjunct, temporizing intervention in patients with refractory ventricular arrhythmia. We examined the association of SGB with VT/VF in a multicenter registry.

OBJECTIVES

This study examined the efficacy of SGB for treatment/temporization of refractory VT/VF.

METHODS

The authors present the first analysis from a multicenter registry of patients treated for refractory ventricular arrhythmia at a clinical site in the Czech Republic and the United States. Data were collected between 2016 and 2022. SGB was performed at the bedside by anesthesiologists and/or cardiologists. Outcomes of interest were VT/VF burden and defibrillations at 24 hours before and after SGB.

RESULTS

In total, there were 117 patients with refractory ventricular arrhythmias treated with SGB at Duke (n = 49) and the Institute for Clinical and Experimental Medicine (n = 68). The majority of patients were male (94.0%), were White (87.2%), and had an implantable cardioverter-defibrillator (70.1%). The most common etiology of heart disease was ischemic cardiomyopathy (52.1%), and monomorphic VT was the most common morphology (70.1%). Within 24 hours before SGB (0-24 hours), the median episodes of VT/VF were 7.5 (Q1-Q3: 3.0-27.0), and 24 hours after SGB, the median decreased to 1.0 (Q1-Q3: 0.0-4.5; P < 0.001). At 24 hours before SGB, the median defibrillation events were 2.0 (Q1-Q3: 0.0-8.0), and 24 hours after SGB, the median decreased to 0.0 (Q1-Q3: 0.0-1.0; P < 0.001).

CONCLUSIONS

In the largest cohort of patients with treatment-refractory ventricular arrhythmia, we demonstrate that SGB use was associated with a reduction in the ventricular arrhythmia burden and need for defibrillation therapy.

Development and validation of a questionnaire to assess commonality knowledge of traumatic dental injuries and management of emergencies

BACKGROUND

Dental trauma represents a significant public health problem, causing a burden for both individuals and society. The aim of this study is to systematically develop and validate a questionnaire on 'traumatic dental injuries and management of emergencies' (TIME) for assessing the knowledge, attitude and practice (KAP) for a commonality.

METHODS

The scale development phases included conceptual framework, systematic development of an item pool, refinement of the item pool by Focus-group discussion (n = 23), validity-testing using Content Validity Index (n = 5), translation and back-translation, Cognitive interviewing (n = 30,45), and reliability testing (n = 40). The conceptual framework was built based on six broad constructs, such as broken teeth, knocked-out (avulsion) teeth, pushed/moved-in and loosened teeth (luxation injuries), soft tissue injuries, follow-up and management, and prevention and protection.

RESULTS

Reviews of existing questionnaires significantly helped to generate an initial pool of 68 items (refined to 51 items). Lawshe's content validity was 0.92. High test-retest reliability was demonstrated (kappa value = 0.98). The questionnaire showed a high level of reliability (Cronbach's alpha = 0.86) with great internal consistency.

CONCLUSION

TIME is the first validated scale for recording knowledge, attitude and practices on traumatic dental injuries and management of emergencies for non-dental professionals. The 51-tem tool will allow dentists to evaluate KAP of commonality. KAP measured across the globe would have a significant impact on planning awareness programs by dentists and dental associations.

Splanchnic Nerve Modulation Effects on Surrogate Measures of Venous Capacitance

Background Splanchnic nerve modulation (SNM) is an emerging procedure to reduce cardiac filling pressures in heart failure. Although the main contributor to reduction in cardiac preload is thought to be increased venous capacitance in the splanchnic circulation, supporting evidence is limited. We examined changes in venous capacitance surrogates pre- and post-SNM. Methods and Results This is a prespecified analysis of a prospective, open-label, single-arm interventional study evaluating the effects of percutaneous SNM with ropivacaine in chronic heart failure with elevated filling pressures at rest and with exercise. Patients underwent cardiopulmonary exercise testing with invasive hemodynamic assessment pre- and post-SNM. Blood pressure changes with modified Valsalva maneuver and hemoconcentration, pre- and post-SNM were compared using a repeated measures model. Inferior vena cava diameter and collapsibility (>50% decrease in size with inspiration), and presence of bendopnea pre- and post-SNM were also compared. Fifteen patients undergoing SNM (age 58 years, 47% women, 93% with left ventricular ejection fraction ≤35%) were included. After SNM, changes in systolic blood pressure during Valsalva (peak-to-trough) were greater (41 versus 48 mm Hg, P=0.025). Exercise-induced hemoconcentration was unchanged (0.63 versus 0.43 g/dL, P=0.115). Inferior vena cava diameter was reduced (1.59 versus 1.30 cm, P=0.034) with higher collapsibility (33% versus 73%, P=0.014). Bendopnea was less (47% versus 13%, P=0.025). Conclusions SNM resulted in increased venous capacitance, associated decreased cardiac preload, and decreased bendopnea. Minimally invasive measures of venous capacitance could serve as markers of successful SNM. Long-term effects of SNM on venous capacitance warrant further investigation for heart failure management. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03453151.

Splanchnic Nerve Block Mediated Changes in Stressed Blood Volume in Heart Failure

OBJECTIVES

The authors estimated changes of stressed blood volume (SBV) induced by splanchnic nerve block (SNB) in patients with either decompensated or ambulatory heart failure with reduced ejection fraction (HFrEF).

BACKGROUND

The splanchnic vascular capacity is a major determinant of the SBV, which in turn determines cardiac filling pressures and may be modifiable through SNB.

METHODS

We analyzed data from 2 prospective, single-arm clinical studies in decompensated HFrEF (splanchnic HF-1; resting hemodynamics) and ambulatory heart failure (splanchnic HF-2; exercise hemodynamics). Patients underwent invasive hemodynamics and short-term SNB with local anesthetics. SBV was simulated using heart rate, cardiac output, central venous pressure, pulmonary capillary wedge pressure, systolic and diastolic systemic arterial and pulmonary artery pressures, and left ventricular ejection fraction. SBV is presented as ml/70 kg body weight.

RESULTS

Mean left ventricular ejection fraction was 21 ± 11%. In patients with decompensated HFrEF (n = 11), the mean estimated SBV was 3,073 ± 251 ml/70 kg. At 30 min post-SNB, the estimated SBV decreased by 10% to 2,754 ± 386 ml/70 kg (p = 0.003). In ambulatory HFrEF (n = 14) patients, the mean estimated SBV was 2,664 ± 488 ml/70 kg and increased to 3,243 ± 444 ml/70 kg (p < 0.001) at peak exercise. The resting estimated SBV was lower in ambulatory patients with HFrEF than in decompensated HFrEF (p = 0.019). In ambulatory patients with HFrEF, post-SNB, the resting estimated SBV decreased by 532 ± 264 ml/70 kg (p < 0.001). Post-SNB, with exercise, there was no decrease of estimated SBV out of proportion to baseline effects (p = 0.661).

CONCLUSIONS

The estimated SBV is higher in decompensated than in ambulatory heart failure. SNB reduced the estimated SBV in decompensated and ambulatory heart failure. The reduction in estimated SBV was maintained throughout exercise. (Splanchnic Nerve Anesthesia in Heart Failure, NCT02669407; Abdominal Nerve Blockade in Chronic Heart Failure, NCT03453151).

Stellate Ganglion Blockade: an Intervention for the Management of Ventricular Arrhythmias

PURPOSE OF REVIEW

To highlight the indications, procedural considerations, and data supporting the use of stellate ganglion blockade (SGB) for management of refractory ventricular arrhythmias.

RECENT FINDINGS

In patients with refractory ventricular arrhythmias, unilateral or bilateral SGB can reduce arrhythmia burden and defibrillation events for 24-72 h, allowing time for use of other therapies like catheter ablation, surgical sympathectomy, or heart transplantation. The efficacy of SGB appears to be consistent despite the type (monomorphic vs polymorphic) or etiology (ischemic vs non-ischemic cardiomyopathy) of the ventricular arrhythmia. Ultrasound-guided SGB is safe with low risk for complications, even when performed on anticoagulation. SGB is effective and safe and could be considered for patients with refractory ventricular arrhythmias.

Integrating New Staff into Endovascular Stroke-Treatment Workflows in the COVID-19 Pandemic

A health care crisis such as the coronavirus disease 2019 (COVID-19) pandemic requires allocation of hospital staff and resources on short notice. Thus, new and sometimes less experienced team members might join the team to fill in the gaps. This scenario can be particularly challenging in endovascular stroke treatment, which is a highly specialized task that requires seamless cooperation of numerous health care workers across various specialties and professions. This document is intended for stroke teams who face the challenge of integrating new team members into endovascular stroke-treatment workflows during the COVID-19 pandemic or any other global health care emergency. It discusses the key strategies for smooth integration of new stroke-team members in a crisis situation: 1) transfer of key knowledge (simple take-home messages), 2) open communication and a nonjudgmental atmosphere, 3) strategic task assignment, and 4) graded learning and responsibility. While these 4 key principles should generally be followed in endovascular stroke treatment, they become even more important during health care emergencies such as the COVID-19 pandemic, when health care professionals have to take on new and additional roles and responsibilities in challenging working environments for which they were not specifically trained.

Tibial Plateau Fracture with Avulsion Fracture of Tibial Tuberosity: A Case Report and Review of Literature

Tibial tuberosity fractures are usually seen in the adolescent age group and are very rare in adults. Here we describe a case of knee injury following a road traffic accident. The patient had tibial tuberosity avulsion along with tibial plateau fracture. He was treated with open surgical reduction and internal fixation. His rehabilitation was quite successful, resulting in a good range of motion and functional outcome. This study aims to present this unusual case of tibial tuberosity avulsion fracture associated with tibial plateau fracture and its appropriate management.

Stellate Ganglion Blockade for the Treatment of Refractory Ventricular Arrhythmias

OBJECTIVES

This study sought to describe our institutional experience with establishing a neurocardiology service in an attempt to provide autonomic modulation as a treatment for ventricular arrhythmias (VAs).

BACKGROUND

Treatment-refractory VAs are commonly driven and exacerbated by heightened sympathetic tone.

METHODS

Among patients referred to the neurocardiology service (August 2016 to December 2018), we performed ultrasound-based, bilateral, temporary stellate ganglion blockade (SGB) in 20 consecutive patients. We analyzed outcomes of interest including sustained VA or VA requiring defibrillation in the 24 and 48 h before and 24 and 48 h after SGB.

RESULTS

The majority of patients were men (n = 19, 95%), with a mean age of 58 ± 14 years. At the time of SGB, 10 (50%) were on inotropic support and 9 (45%) were on mechanical circulatory support. Besides 1 case of hoarseness, there were no apparent procedural complications. SGB was associated with a reduction in the number of VA episodes from the 24 h before (median 5.5 [interquartile range (IQR): 2.0 to 15.8]) to 24 h after SGB (median 0 [IQR: 0 to 3.8]) (p < 0.001). The number of defibrillation events decreased from 2.5 (IQR: 0 to 10.3) to 0 (IQR: 0 to 2.5) (p = 0.002). Similar findings were observed over the 48-h period before and after the SGB. Overall, 9 of 20 (45%) patients had a complete response with no recurrence of ventricular tachycardia (VT) or ventricular fibrillation (VF) for 48 h after SGB. Four (20%) patients had no recurrent VT or VF following SGB through discharge. Similar response rates were observed in those with ischemic (median 6 [IQR: 1.8 to 18.8] to 0.5 [IQR: 0 to 5.3] events; p = 0.031) and nonischemic (median 3.5 [IQR: 1.8 to 6.8] to 0 [IQR: 0 to 1.3] events; p = 0.012) cardiomyopathy.

CONCLUSIONS

Minimally invasive, ultrasound-guided bilateral SGB appears safe and provides substantial reduction in VA burden with approximately 1 in 2 patients exhibiting complete suppression of VT or VF for 48 h.

The ASOS Surgical Risk Calculator: development and validation of a tool for identifying African surgical patients at risk of severe postoperative complications

BACKGROUND

The African Surgical Outcomes Study (ASOS) showed that surgical patients in Africa have a mortality twice the global average. Existing risk assessment tools are not valid for use in this population because the pattern of risk for poor outcomes differs from high-income countries. The objective of this study was to derive and validate a simple, preoperative risk stratification tool to identify African surgical patients at risk for in-hospital postoperative mortality and severe complications.

METHODS

ASOS was a 7-day prospective cohort study of adult patients undergoing surgery in Africa. The ASOS Surgical Risk Calculator was constructed with a multivariable logistic regression model for the outcome of in-hospital mortality and severe postoperative complications. The following preoperative risk factors were entered into the model; age, sex, smoking status, ASA physical status, preoperative chronic comorbid conditions, indication for surgery, urgency, severity, and type of surgery.

RESULTS

The model was derived from 8799 patients from 168 African hospitals. The composite outcome of severe postoperative complications and death occurred in 423/8799 (4.8%) patients. The ASOS Surgical Risk Calculator includes the following risk factors: age, ASA physical status, indication for surgery, urgency, severity, and type of surgery. The model showed good discrimination with an area under the receiver operating characteristic curve of 0.805 and good calibration with c-statistic corrected for optimism of 0.784.

CONCLUSIONS

This simple preoperative risk calculator could be used to identify high-risk surgical patients in African hospitals and facilitate increased postoperative surveillance.

CLINICAL TRIAL REGISTRATION

NCT03044899.

The rising tide of opioid use and abuse: the role of the anesthesiologist

Opioid use has risen dramatically in the past three decades. In the USA, opioid overdose has become a leading cause of unintentional death, surpassing motor vehicle accidents. A patient's first exposure to opioids may be during the perioperative period, a time where anesthesiologists have a significant role in pain management. Almost all patients in the USA receive opioids during a surgical encounter. Opioids have many undesirable side effects, including potential for misuse, or opioid use disorder. Anesthesiologists and surgeons employ several methods to decrease unnecessary opioid use, opioid-related adverse events, and side effects in the perioperative period. Multimodal analgesia, enhanced recovery pathways, and regional anesthesia are key tools as we work towards optimal opioid stewardship and the ideal of effective analgesia without undesirable sequelae.

Stellate ganglion blockade for the treatment of refractory ventricular arrhythmias: A systematic review and meta-analysis

INTRODUCTION

Treatment refractory ventricular arrhythmias (VAs) are often driven and exacerbated by heightened sympathetic tone. We aim to conduct a systematic review and meta-analysis of published studies of a temporary percutaneous stellate ganglion block (SGB) on VA burden and defibrillation episodes in patients with treatment refractory VAs.

METHODS

Relevant studies from January 1960 through May 2017 were identified in PubMed and Google Scholar. We performed a patient-level analysis using Student's t-test to compare outcomes before and after SGB.

RESULTS

We identified 22 unique case series with a total of 35 patients. Patients were 57 ± 17 years old and 69% were males with a high burden of VA. A unilateral (left)-sided SGB was used in 85.7% (30 of 35) of cases and the remaining were bilateral SGB. The use of a unilateral or bilateral SGB resulted in a significant reduction of VA episodes (24-hours pre: mean 16.5 [CI 9.7-23.1] events vs. post: mean 1.4 [CI 0.85-2.01] events; P = 0.0002) and need for defibrillation (24-hours pre: mean 14.2 [CI 6.8-21.6] vs. post: mean 0.6 [CI 0.3-0.9]; P = 0.0026). Furthermore, SGB was significantly associated with a reduction of VA burden regardless of etiology of cardiomyopathy, type of ventricular rhythm, and degree of contractile dysfunction. SGB was followed by surgical sympathectomy in 21% of cases.

CONCLUSIONS

Early experience suggests that SGB is associated with an acute reduction in the VA burden and offers potential promise for a broader use in high-risk populations. Randomized controlled studies are needed to confirm the safety and efficacy of this therapy.

Efficient routeing in Poisson small-world networks

In a recent paper, Kleinberg (2000) considered a small-world network model consisting of a d-dimensional lattice augmented with shortcuts. The probability of a shortcut being present between two points decays as a power, r-α, of the distance, r, between them. Kleinberg showed that greedy routeing is efficient if α = d and that there is no efficient decentralised routeing algorithm if α ≠ d. The results were extended to a continuum model by Franceschetti and Meester (2003). In our work, we extend the result to more realistic models constructed from a Poisson point process wherein each point is connected to all its neighbours within some fixed radius, and possesses random shortcuts to more distant nodes as described above.

Sensitizing undergraduate medical students to consultation skills: A pilot study

BACKGROUND

Good consultation skills help physicians to diagnose the problems of the patient more accurately, and foster a therapeutic relationship. We describe a pilot study that used role-play with peers as a method to sensitize first clinical year medical students to consultation skills Methods. Students were divided into groups of three where one acted as a doctor, the second as a patient and the third as an observer. Students were asked to perform a role-play of a prepared clinical scenario where the patient had a hidden fear of malignancy. Observations were recorded in a simplified Calgary-Cambridge consultation checklist. Students' feedback and their emotions written after the role-play were analysed and discussed. Assessment of their learning was done with an objective structured clinical examination.

RESULTS

Students' feedback revealed that they were sensitized to the importance of starting the consultation with an open question, listening to the opening statement, non-verbal.

Prospective randomized observer-blinded study comparing the analgesic efficacy of ultrasound-guided rectus sheath block and local anaesthetic infiltration for umbilical hernia repair

BACKGROUND

Umbilical hernia repair, a common day-surgery procedure in children, is associated with considerable postoperative discomfort. Possible modes of postoperative analgesia for umbilical hernia repair are rectus sheath block (RSB) and local anaesthetic infiltration of the surgical site (LAI).

METHODS

We undertook an observer-blinded, randomized, prospective, observational study to compare the efficacy of ultrasound-guided RSB and LAI in providing postoperative analgesia for umbilical hernia repair. Our primary objective was to compare the use of opioid medication between patients who receive RSB and those who receive LAI. Our secondary objectives were to compare the duration of analgesia based on time to first rescue analgesic, to compare the quality of analgesia based on revised FACES scale, and to determine the incidence of side-effects.

RESULTS

Fifty-two patients (26 in each group) completed the study. There was a statistically significant difference in the perioperative opioid medication consumption between the LAI group [mean: 0.13 mg kg(-1), confidence interval (0.09-0.17 mg kg⁻¹)] and the RSB group [mean: 0.07 mg kg⁻¹, confidence interval (0.05-0.09 mg kg⁻¹)] (P=0.008). When we compared the postoperative opioid consumption between the LAI group [mean: 0.1 mg kg⁻¹, 95% confidence interval (0.07-0.13 mg kg⁻¹)] and the RSB group [mean: 0.07 mg kg(-1), 95% confidence interval (0.05-0.09 mg kg⁻¹)] (P=0.09), there was a trend towards statistical significance between the two groups. The difference in time to rescue analgesic administration between the RSB group [49.7 (36.9) min] and the LAI group [32.4 (29.4) min] was not statistically significant (P=0.11).

CONCLUSIONS

This study demonstrates that ultrasound-guided RSB provides superior analgesia in the perioperative period compared with infiltration of the surgical site after umbilical hernia repair. In comparing only the postoperative period, analgesia provided by an ultrasound-guided RSB showed a trend towards statistically significant improvement compared with infiltration of the surgical site.

Spatial learning-induced egr-1 expression in telencephalon of gold fish Carassius auratus

The immediate-early gene (egr-1) expression was used to examine the neuron's response in telencephalon of goldfish during spatial learning in small space. Fishes were pre-exposed in the experimental apparatus and trained to pick food from the tray in a rectangular-shaped arena. The apparatus was divided into identical compartments comprising three gates to provide different spatial tasks. After the fish learned to pass through the gate one, two more gates were introduced one by one. Fish made more number of attempts and took longer time (P < 0.05) to pass through the first gate than the gate two or three. This active learning induces the expression of egr-1 in telencephalon as established by western blot analysis. Subsequently, the fish learn quickly to cross the similar type of second and third gate and make fewer errors with a corresponding decline in the level of egr-1 expression. As the fish learned to pass through all the three gates, third gate was replaced by modified gate three. Interestingly, the level of egr-1 expression increased again, when the fish exhibit a high exploratory behavior to cross the modified gate three. The present study shows that egr-1 expression is induced in the telencephalon of goldfish while intensively acquiring geometric spatial information to pass through the gates.

Olfactory bulb serotonin level modulates olfactory recognition in the neonate rat

Role of serotonin in olfactory recognition was tested by depleting the olfactory bulb serotonin during postnatal day (PND) 1 - 4 following administration of 5,7-dihydroxytryptamine. Significant difference in the olfactory recognition test was observed during PND5-7; control pups successfully recognized and oriented towards their mother; whereas treated pups failed to recognize their mother odour. Later on, during PND12-14, both group of pups responded equally in the recognition test. Levels of olfactory bulb serotonin were depleted (53.3%) in the treated pups on PND-8, which was restored on PND-14 with only 15% variation. Further analysis demonstrated that depletion of serotonin in olfactory bulb did not affect the normal suckling and weight gain, it only modulates olfactory recognition.

Light-induced COP9 signalosome expression in the Indian false vampire bat Megaderma lyra

The COP9 signalosome (CSN) is a multi-subunit protein complex conserved in plants and animals. CSN subunits have been identified as light-mediated master regulators of eukaryotic circadian clocks from fungi to animals. The Indian false vampire bat Megaderma lyra is completely adapted to an anthropic biotope and behavioral studies have reported that M. lyra exhibits light-sampling behavior to assess environmental light. LC-MS-MS results for a 36 kDa protein were analyzed using the Sequest search engine, and COP9 signalosome subunit 5 (CSN5) was pinpointed as having the highest score with 6 matching peptides. To confirm the presence of CSN5, up-regulated cDNA was amplified, sequenced, and identified as CSN5. Furthermore, semi-quantitative RT-PCR analysis demonstrated that the level of induction of CSN5 was regulated by environmental light. We estimated the level of expression across a light-dark cycle and observed a higher level of expression at the end of the light phase. Similarly, when the animal was shifted from continuous dark to light, CSN5 expression was induced. Correspondingly, we detected the similar pattern of translated protein with JAB1 antibody. Knowledge about the circadian rhythm and its molecular mechanism in Chiroptera is very limited and this study suggests that CSN5 might be involved in the M. lyra light-signaling process.

Spread of Epidemics and Rumours with Mobile Agents

We propose a simple model of infection that enables to study the coincidence time of two random walkers on an arbitrary graph. By studying the coincidence time of a susceptible and an infected individual both moving in the graph we obtain estimates of the infection probability. The main result of this paper is to pinpoint the impact of the network topology on the infection probability.

Exponential Random Graphs as Models of Overlay Networks

In this paper we give an analytic solution for graphs withnnodes andE=cnlognedges for which the probability of obtaining a given graphGisµn(G) = exp (-β∑i=1ndi2), wherediis the degree of nodei. We describe how this model appears in the context of load balancing in communication networks, namely peer-to-peer overlays. We then analyse the degree distribution of such graphs and show that the degrees are concentrated around their mean value. Finally, we derive asymptotic results for the number of edges crossing a graph cut and use these results (i) to compute the graph expansion and conductance, and (ii) to analyse the graph resilience to random failures.

[Post-traumatic inflammation with an intraocular foreign body]

BACKGROUND

To report on the diagnosis and management of a"firecracker" injury presenting with a post-traumatic intraocular inflammation.

CASE REPORT

A 10-year-old boy sustained a penetrating 16-mm cornea-sclera blast injury to his left eye with uveal prolapse and hemophthalmus and doubtful light perception. The cranial computed tomography revealed a metallic intraocular foreign body (IOFB), retinal detachment, and subretinal and subchoroidal hemorrhage. After primary wound closure and antibiotic treatment for 1 week, increasing cell infiltration and amaurosis developed, and a lensectomy, pars plana vitrectomy, and extraction of the 17x7x7-mm encapsulated IOFB via a scleral tunnel was indicated.

RESULTS

A vitreous specimen did not reveal microbial growth; however, plenty of polymorphonuclear cells, macrophages, and lymphocytes were observed. Spectroscopy of the IOFB showed copper, zinc, silicon, lead, and other metals. A diagnosis of noninfectious inflammation due to heavy metals, primarily copper (=chalcosis), was made. The postoperative course was unremarkable, the intraocular lens in place, fundus CDR 0.2, retina and macula attached, intraocular pressure 9 mmHg. Three weeks after surgery, the flash VEP showed absent potentials.

CONCLUSIONS

Large projectiles or parts should be removed from the eye immediately in order to prevent complications from toxic metallosis and early fibrotic reactions.