A deep learning pipeline for automated classification of vocal fold polyps in flexible laryngoscopy

PURPOSE

To develop and validate a deep learning model for distinguishing healthy vocal folds (HVF) and vocal fold polyps (VFP) on laryngoscopy videos, while demonstrating the ability of a previously developed informative frame classifier in facilitating deep learning development.

METHODS

Following retrospective extraction of image frames from 52 HVF and 77 unilateral VFP videos, two researchers manually labeled each frame as informative or uninformative. A previously developed informative frame classifier was used to extract informative frames from the same video set. Both sets of videos were independently divided into training (60%), validation (20%), and test (20%) by patient. Machine-labeled frames were independently verified by two researchers to assess the precision of the informative frame classifier. Two models, pre-trained on ResNet18, were trained to classify frames as containing HVF or VFP. The accuracy of the polyp classifier trained on machine-labeled frames was compared to that of the classifier trained on human-labeled frames. The performance was measured by accuracy and area under the receiver operating characteristic curve (AUROC).

RESULTS

When evaluated on a hold-out test set, the polyp classifier trained on machine-labeled frames achieved an accuracy of 85% and AUROC of 0.84, whereas the classifier trained on human-labeled frames achieved an accuracy of 69% and AUROC of 0.66.

CONCLUSION

An accurate deep learning classifier for vocal fold polyp identification was developed and validated with the assistance of a peer-reviewed informative frame classifier for dataset assembly. The classifier trained on machine-labeled frames demonstrates improved performance compared to the classifier trained on human-labeled frames.

LEVEL OF EVIDENCE: 4

Effects of tofersen treatment in patients with SOD1-ALS in a "real-world" setting - a 12-month multicenter cohort study from the German early access program

Background

In April 2023, the antisense oligonucleotide tofersen was approved by the U.S. Food and Drug Administration (FDA) for treatment of SOD1-amyotrophic lateral sclerosis (ALS), after a decrease of neurofilament light chain (NfL) levels had been demonstrated.

Methods

Between 03/2022 and 04/2023, 24 patients with SOD1-ALS from ten German ALS reference centers were followed-up until the cut-off date for ALS functional rating scale revised (ALSFRS-R), progression rate (loss of ALSFRS-R/month), NfL, phosphorylated neurofilament heavy chain (pNfH) in cerebrospinal fluid (CSF), and adverse events.

Findings

During the observation period, median ALSFRS-R decreased from 38.0 (IQR 32.0-42.0) to 35.0 (IQR 29.0-42.0), corresponding to a median progression rate of 0.11 (IQR -0.09 to 0.32) points of ALSFRS-R lost per month. Median serum NfL declined from 78.0 pg/ml (IQR 37.0-147.0 pg/ml; n = 23) to 36.0 pg/ml (IQR 22.0-65.0 pg/ml; n = 23; p = 0.02), median pNfH in CSF from 2226 pg/ml (IQR 1061-6138 pg/ml; n = 18) to 1151 pg/ml (IQR 521-2360 pg/ml; n = 18; p = 0.02). In the CSF, we detected a pleocytosis in 73% of patients (11 of 15) and an intrathecal immunoglobulin synthesis (IgG, IgM, or IgA) in 9 out of 10 patients. Two drug-related serious adverse events were reported.

Interpretation

Consistent with the VALOR study and its Open Label Extension (OLE), our results confirm a reduction of NfL serum levels, and moreover show a reduction of pNfH in CSF. The therapy was safe, as no persistent symptoms were observed. Pleocytosis and Ig synthesis in CSF with clinical symptoms related to myeloradiculitis in two patients, indicate the potential of an autoimmune reaction.

Funding

No funding was received towards this study.

Novel Homozygous FA2H Variant Causing the Full Spectrum of Fatty Acid Hydroxylase-Associated Neurodegeneration (SPG35)

Fatty acid hydroxylase-associated neurodegeneration (FAHN/SPG35) is caused by pathogenic variants in FA2H and has been linked to a continuum of specific motor and non-motor neurological symptoms, leading to progressive disability. As an ultra-rare disease, its mutational spectrum has not been fully elucidated. Here, we present the prototypical workup of a novel FA2H variant, including clinical and in silico validation. An 18-year-old male patient presented with a history of childhood-onset progressive cognitive impairment, as well as progressive gait disturbance and lower extremity muscle cramps from the age of 15. Additional symptoms included exotropia, dystonia, and limb ataxia. Trio exome sequencing revealed a novel homozygous c.75C>G (p.Cys25Trp) missense variant in the FA2H gene, which was located in the cytochrome b5 heme-binding domain. Evolutionary conservation, prediction models, and structural protein modeling indicated a pathogenic loss of function. Brain imaging showed characteristic features, thus fulfilling the complete multisystem neurodegenerative phenotype of FAHN/SPG35. In summary, we here present a novel FA2H variant and provide prototypical clinical findings and structural analyses underpinning its pathogenicity.

Prescription medications with actionable pharmacogenomic recommendations in Veterans Health Administration patients

Aim: To evaluate the prevalence of medications with actionable pharmacogenomic (PGx) safety and efficacy recommendations in patients receiving care from the Veterans Health Administration. Materials & methods: Outpatient prescription data from 2011 to 2021 and any documented adverse drug reactions (ADRs) were reviewed for those who received PGx testing at one Veterans Administration location between November 2019 and October 2021. Results: Among the reviewed prescriptions, 381 (32.8%) were associated with an actionable recommendation based on the Clinical Pharmacogenetics Implementation Consortium (CPIC) prescribing guidelines, with 205 (17.7%) for efficacy concerns and 176 (15.2%) for safety concerns. Among those with a documented ADR for a PGx-impacted medication, 39.1% had PGx results that aligned with CPIC recommendations. Conclusion: Medications with actionable PGx recommendations for safety and efficacy concerns are received with similar frequency, and most patients who have undergone PGx testing at the Phoenix Veterans Administration have received medications that may be impacted by PGx testing.

7 tricks for 7 T CEST: Improving the reproducibility of multipool evaluation provides insights into the effects of age and the early stages of Parkinson's disease

The objective of the current study was to optimize the postprocessing pipeline of 7 T chemical exchange saturation transfer (CEST) imaging for reproducibility and to prove this optimization for the detection of age differences and differences between patients with Parkinson's disease versus normal subjects. The following 7 T CEST MRI experiments were analyzed: repeated measurements of a healthy subject, subjects of two age cohorts (14 older, seven younger subjects), and measurements of 12 patients with Parkinson's disease. A slab-selective, B 1 + -homogeneous parallel transmit protocol was used. The postprocessing, consisting of motion correction, smoothing, B 0 -correction, normalization, denoising, B 1 + -correction and Lorentzian fitting, was optimized regarding the intrasubject and intersubject coefficient of variation (CoV) of the amplitudes of the amide pool and the aliphatic relayed nuclear Overhauser effect (rNOE) pool within the brain. Seven "tricks" for postprocessing accomplished an improvement of the mean voxel CoV of the amide pool and the aliphatic rNOE pool amplitudes of less than 5% and 3%, respectively. These postprocessing steps are: motion correction with interpolation of the motion of low-signal offsets (1) using the amide pool frequency offset image as reference (2), normalization of the Z-spectrum using the outermost saturated measurements (3), B 0 correction of the Z-spectrum with moderate spline smoothing (4), denoising using principal component analysis preserving the 11 highest intensity components (5), B 1 + correction using a linear fit (6) and Lorentzian fitting using the five-pool fit model (7). With the optimized postprocessing pipeline, a significant age effect in the amide pool can be detected. Additionally, for the first time, an aliphatic rNOE contrast between subjects with Parkinson's disease and age-matched healthy controls in the substantia nigra is detected. We propose an optimized postprocessing pipeline for CEST multipool evaluation. It is shown that by the use of these seven "tricks", the reproducibility and, thus, the statistical power of a CEST measurement, can be greatly improved and subtle changes can be detected.

Linear projection-based chemical exchange saturation transfer parameter estimation

Isolated evaluation of multiparametric in vivo chemical exchange saturation transfer (CEST) MRI often requires complex computational processing for both correction of B0 and B1 inhomogeneity and contrast generation. For that, sufficiently densely sampled Z-spectra need to be acquired. The list of acquired frequency offsets largely determines the total CEST acquisition time, while potentially representing redundant information. In this work, a linear projection-based multiparametric CEST evaluation method is introduced that offers fast B0 and B1 inhomogeneity correction, contrast generation and feature selection for CEST data, enabling reduction of the overall measurement time. To that end, CEST data acquired at 7 T in six healthy subjects and in one brain tumor patient were conventionally evaluated by interpolation-based inhomogeneity correction and Lorentzian curve fitting. Linear regression was used to obtain coefficient vectors that directly map uncorrected data to corrected Lorentzian target parameters. L1-regularization was applied to find subsets of the originally acquired CEST measurements that still allow for such a linear projection mapping. The linear projection method allows fast and interpretable mapping from acquired raw data to contrast parameters of interest, generalizing from healthy subject training data to unseen healthy test data and to the tumor patient dataset. The L1-regularization method shows that a fraction of the acquired CEST measurements is sufficient to preserve tissue contrasts, offering up to a 2.8-fold reduction of scan time. Similar observations as for the 7-T data can be made for data from a clinical 3-T scanner. Being a fast and interpretable computation step, the proposed method is complementary to neural networks that have recently been employed for similar purposes. The scan time acceleration offered by the L1-regularization ("CEST-LASSO") constitutes a step towards better applicability of multiparametric CEST protocols in a clinical context.

Changes in Cough Airflow and Acoustics After Injection Laryngoplasty

OBJECTIVE/HYPOTHESIS

We explored the following hypotheses in a cohort of patients undergoing injection laryngoplasty: (1) glottic insufficiency affects voluntary cough airflow dynamics and restoring glottic competence may improve parameters of cough strength, (2) cough strength can be inferred from cough acoustic signal, and (3) glottic competence changes cough sounds and correlates with spectrogram morphology.

STUDY TYPE/DESIGN

Prospective interventional study.

METHODS

Subjects with glottic insufficiency secondary to unilateral vocal fold paresis, paralysis, or atrophy, and scheduled for injection laryngoplasty completed an instrumental assessment of voluntary cough airflow using a pneumotachometer and a protocolized voluntary cough sound recording. A Wilcoxon signed-rank test was used to compare the differences between pre- and post-injection laryngoplasty in airflow and acoustic measures. A Spearman rank-order correlation was used to evaluate the association between airflow and acoustic cough measures.

RESULTS

Twenty-five patients (13F:12M, mean age 68.8) completed voluntary cough airflow measurements and 22 completed cough sound recordings. Following injection laryngoplasty, patients had a statistically significant decreased peak expiratory flow rise time (PEFRT) (mean change: -0.03 s, SD: 0.06, p = 0.04) and increased cough volume acceleration (mean change: 13.1 L/s2 , SD: 33.9, p = 0.03), suggesting improved cough effectiveness. Correlation of cough acoustic measures with airflow measures showed a weak relationship between PEFRT and acoustic energy (coefficient: -0.31, p = 0.04) and peak power density (coefficient: -0.35, p = 0.02).

CONCLUSIONS

Our study thus indicates that injection laryngoplasty may help avert aspiration in patients with glottic insufficiency by improving cough effectiveness and that improved cough airflow measures may be tracked with cough sounds.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:S1-S14, 2023.

Bedeutung der Muskelsonographie in der Detektion von Faszikulationen bei der ALS

Bei der amyotrophen Lateralsklerose sind Faszikulationen häufig bereits in frühen Stadien in mehreren Körperregionen vorzufinden und haben daher Eingang in die entsprechenden Leitlinien und Diagnosekriterien gefunden. Während die invasive EMG-Diagnostik unverzichtbar zum Nachweis von akut- und chronisch-neurogenen Veränderungen des elektrischen Signalverhaltens motorischer Einheiten und zur Bestätigung von Faszikulationspotenzialen bleibt, bietet die Muskelsonographie ein hochsensitives Verfahren, um schnell und nicht-invasiv Faszikulationen in den verschiedenen Muskel-Etagen zu erfassen. In dieser Übersichtsarbeit stellen wir die bisherigen Daten zum Einsatz der Muskelsonographie zur Faszikulationsdetektion dar. Durch ihren Einsatz ermöglicht die Muskelsonographie im klinischen Alltag eine zielgerichtete und hierdurch aussagekräftigere EMG-Diagnostik. Aktuelle Forschungsstudien zielen darauf ab, Faszikulationen sonomorphologisch genauer zu charakterisieren, zu quantifizieren und als Verlaufsparameter zu untersuchen.

Parkinson's disease or multiple system atrophy: potential separation by quantitative susceptibility mapping

Background

Due to the absence of robust biomarkers, and the low sensitivity and specificity of routine imaging techniques, the differential diagnosis between Parkinson's disease (PD) and multiple system atrophy (MSA) is challenging. High-field magnetic resonance imaging (MRI) opened up new possibilities regarding the analysis of pathological alterations associated with neurodegenerative processes. Recently, we have shown that quantitative susceptibility mapping (QSM) enables visualization and quantification of two major histopathologic hallmarks observed in MSA: reduced myelin density and iron accumulation in the basal ganglia of a transgenic murine model of MSA. It is therefore emerging as a promising imaging modality on the differential diagnosis of Parkinsonian syndromes.

Objectives

To assess QSM on high-field MRI for the differential diagnosis of PD and MSA.

Methods

We assessed 23 patients (nine PDs and 14 MSAs) and nine controls using QSM on 3T and 7T MRI scanners at two academic centers.

Results

We observed increased susceptibility in MSA at 3T in prototypical subcortical and brainstem regions. Susceptibility measures of putamen, pallidum, and substantia nigra reached excellent diagnostic accuracy to separate both synucleinopathies. Increase toward 100% sensitivity and specificity was achieved using 7T MRI in a subset of patients. Magnetic susceptibility correlated with age in all groups, but not with disease duration in MSA. Sensitivity and specificity were particularly high for possible MSA, and reached 100% in the putamen.

Conclusion

Putaminal susceptibility measures, in particular on ultra-high-field MRI, may distinguish MSA patients from both, PD and controls, allowing an early and sensitive diagnosis of MSA.

Automatic classification of informative laryngoscopic images using deep learning

Objective

This study aims to develop and validate a convolutional neural network (CNN)‐based algorithm for automatic selection of informative frames in flexible laryngoscopic videos. The classifier has the potential to aid in the development of computer‐aided diagnosis systems and reduce data processing time for clinician‐computer scientist teams.

Methods

A dataset of 22,132 laryngoscopic frames was extracted from 137 flexible laryngostroboscopic videos from 115 patients. 55 videos were from healthy patients with no laryngeal pathology and 82 videos were from patients with vocal fold polyps. The extracted frames were manually labeled as informative or uninformative by two independent reviewers based on vocal fold visibility, lighting, focus, and camera distance, resulting in 18,114 informative frames and 4018 uninformative frames. The dataset was split into training and test sets. A pre‐trained ResNet‐18 model was trained using transfer learning to classify frames as informative or uninformative. Hyperparameters were set using cross‐validation. The primary outcome was precision for the informative class and secondary outcomes were precision, recall, and F1‐score for all classes. The processing rate for frames between the model and a human annotator were compared.

Results

The automated classifier achieved an informative frame precision, recall, and F1‐score of 94.4%, 90.2%, and 92.3%, respectively, when evaluated on a hold‐out test set of 4438 frames. The model processed frames 16 times faster than a human annotator.

Conclusion

The CNN‐based classifier demonstrates high precision for classifying informative frames in flexible laryngostroboscopic videos. This model has the potential to aid researchers with dataset creation for computer‐aided diagnosis systems by automatically extracting relevant frames from laryngoscopic videos.

Applications of Artificial Intelligence to Office Laryngoscopy: A Scoping Review

OBJECTIVES/HYPOTHESIS

This scoping review aims to provide a broad overview of the applications of artificial intelligence (AI) to office laryngoscopy to identify gaps in knowledge and guide future research.

STUDY DESIGN

Scoping Review.

METHODS

Searches for studies on AI and office laryngoscopy were conducted in five databases. Title and abstract and then full-text screening were performed. Primary research studies published in English of any date were included. Studies were summarized by: AI applications, targeted conditions, imaging modalities, author affiliations, and dataset characteristics.

RESULTS

Studies focused on vocal fold vibration analysis (43%), lesion recognition (24%), and vocal fold movement determination (19%). The most frequently automated tasks were recognition of vocal fold nodules (19%), polyp (14%), paralysis (11%), paresis (8%), and cyst (7%). Imaging modalities included high-speed laryngeal videos (45%), stroboscopy (29%), and narrow band imaging endoscopy (7%). The body of literature was primarily authored by science, technology, engineering, and math (STEM) specialists (76%) with only 30 studies (31%) involving co-authorship by STEM specialists and otolaryngologists. Datasets were mostly from single institution (84%) and most commonly originated from Germany (23%), USA (16%), Spain (9%), Italy (8%), and China (8%). Demographic information was only reported in 39 studies (40%), with age and sex being the most commonly reported, whereas race/ethnicity and gender were not reported in any studies.

CONCLUSION

More interdisciplinary collaboration between STEM and otolaryngology research teams improved demographic reporting especially of race and ethnicity to ensure broad representation, and larger and more geographically diverse datasets will be crucial to future research on AI in office laryngoscopy.

LEVEL OF EVIDENCE

N/A Laryngoscope, 2021.

Characteristics of prolonged noninvasive ventilation in emergency departments and impact upon effectiveness. Analysis of the VNICat registry

OBJECTIVE

To analyze the characteristics and variables associated with prolonged noninvasive ventilation performed completely in Emergency Departments (NIV-ED) and its influence upon effectiveness.

DESIGN

A prospective, multicenter, observational multipurpose cohort study was carried out.

SETTING

VNICAT Registry.

SUBJECTS

Patients in which NIV-ED was performed in 11 Catalan hospitals in the months of February or March 2015.

INTERVENTION

No.

VARIABLES

The study variable was NIV-ED, which as a function of time was defined as prolonged or not prolonged. The efficacy variable was the success of the technique in terms of patient improvement.

RESULTS

A total of 125 patients were included, with a median NIV-ED duration of 12 h, which was the cut-off point for the comparator groups. In 60 cases (48%) NIV-ED was not prolonged (<12 h), while in 65 cases (52%) ventilation was prolonged (≥12 h). Non-prolonged NIV-ED was associated to the indication of acute heart failure and prolonged ventilation to the presence of diabetes. There were no differences between non-prolonged and prolonged NIV-ED in terms of efficacy, and the success rate in terms of improvement was 68.3% and 76.9%, respectively, with an adjusted odds ratio of 1.49 (95%CI 0.61-3.60).

CONCLUSIONS

Prolonged NIV-ED is a frequent situation, but few variables associated to it have been studied. The presence of prolonged ventilation did not influence the success rate of NIV.

'We should classify pet obesity as a disease'

Alexander German, Ian Ramsey and Philip Lhermette address some of the concerns raised over calling pet obesity a disease and argue that this classification can bring many management opportunities.

Characteristics of prolonged noninvasive ventilation in emergency departments and impact upon effectiveness. Analysis of the VNICat registry

OBJECTIVE

To analyze the characteristics and variables associated with prolonged noninvasive ventilation performed completely in Emergency Departments (NIV-ED) and its influence upon effectiveness.

DESIGN

A prospective, multicenter, observational multipurpose cohort study was carried out.

SETTING

VNICat Registry.

SUBJECTS

Patients in which NIV-ED was performed in 11 Catalan hospitals in the months of February or March 2015.

INTERVENTION

No.

VARIABLES

The study variable was NIV-ED, which as a function of time was defined as prolonged or not prolonged. The efficacy variable was the success of the technique in terms of patient improvement.

RESULTS

A total of 125 patients were included, with a median NIV-ED duration of 12hours, which was the cut-off point for the comparator groups. In 60 cases (48%) NIV-ED was not prolonged (<12hours), while in 65 cases (52%) ventilation was prolonged (≥12hours). Non-prolonged NIV-ED was associated to the indication of acute heart failure and prolonged ventilation to the presence of diabetes. There were no differences between non-prolonged and prolonged NIV-ED in terms of efficacy, and the success rate in terms of improvement was 68.3% and 76.9%, respectively, with an adjusted odds ratio of 1.49 (95%CI 0.61-3.60).

CONCLUSIONS

Prolonged NIV-ED is a frequent situation, but few variables associated to it have been studied. The presence of prolonged ventilation did not influence the success rate of NIV.

Outcomes of pubertal development in girls as a function of pubertal onset age

BACKGROUND

The relationship between pubertal onset and tempo and pubertal growth is controversial. We hypothesized that the age at onset of girls' puberty predicts pubertal tempo and the rate of pubertal progression.

METHODS

We analysed the data of 380 girls from the prospective Study of Early Child Care and Youth Development (SECCYD), who were recruited in the USA from 1991-2006 and followed from birth to age 15.5 years. We used the following indicators: thelarche age (Tanner stage B2), pubarche age (P2), menarche age (M), the age when breast (B5) and pubic hair (P5) became fully mature, pubertal growth, pubertal duration (time from B2 to B5), pubertal progression (time from B2 to M). We clustered the girls according to B2 age into early onset (EO;<9.4 years), intermediate (IO;9.4-10.5 years), late onset (LO;>10.5 years).

RESULTS

All indicators of pubertal onset and conclusion occurred earlier in the EOs than in the LO; yet, the differences in the age at main pubertal milestones lessened as puberty progressed: two years for B2; -1.4 years for M; - one year for B5. In EO, puberty was one year (average) longer than in LO. Although EO grew 7 cm (average) more than LO, their heights at B5 were comparable. There was a significant relationship between the thelarche age and puberty tempo (r=0.23, P<0.0001).

CONCLUSIONS

The study highlights the predictive nature of variation in the onset age of puberty on its progression and duration. These results are reassuring in this context and will add to clinicians' and parental understanding of the expected milestones of puberty.

Assessment of pharmacists' self-reported preparedness to provide pharmacotherapy services to individuals with psychiatric disorders

Introduction:

The purpose of this study was to compare pharmacists' level of training and/or experience in psychiatric pharmacy to (1) their self-perceived preparedness to provide pharmacotherapy services to individuals with psychiatric disorders and (2) barriers to providing pharmacotherapy services to individuals with psychiatric disorders.

Methods:

This study used data from an Internet-based questionnaire. Respondents were divided into 2 groups: group A completed the Arizona Pharmacy Association's Psychiatric Certificate Program, and/or was board certified in psychiatric pharmacy, and/or was a member of the College of Psychiatric and Neurologic Pharmacists, and/or had completed a psychiatric pharmacy residency; group B had no specialized training and/or experience in psychiatric pharmacy. A Mann-Whitney U test was used to compare the scaled responses for each group.

Results:

Compared with pharmacists without training and/or experience in psychiatry (N = 235), respondents with specialized training and/or experience in psychiatric pharmacy (N = 38) reported more frequent interactions with patients with psychiatric disorders and provided more counseling and drug information, monitoring for adverse drug reactions, screening for treatment issues, and both pharmacologic and nonpharmacologic treatment recommendations (P < .05). Pharmacists trained in psychiatry reported being more prepared to provide all pharmacotherapy services (P < .003), except in addressing nonadherence, utilizing online resources, and providing pharmacotherapy services to patients with attention deficit hyperactivity disorder. They reported fewer barriers to providing pharmacotherapy services (P < .005), except for time to provide services, having a private consultation area, and reimbursement for patient care activities.

Discussion:

This study found that responding pharmacists without psychiatric training/experience may need additional education and training after graduation and that they perceive more barriers in providing services to the population with psychiatric disorders.

Event data recorders in the analysis of frontal impacts

Evaluations of crash protection safety features require measures for quantifying impact severity. Velocity change (delta-V) is the major descriptor of collision severity used in most real-world crash databases. One of the limitations of delta-V is that it does not account for the time over which the crash pulse occurs (delta-t). Late model GM vehicles equipped with event data recorders capture the cumulative delta-V in 10 ms intervals over the crash pulse. Deceleration can be readily calculated from these data and provides a complementary measure of severity that has not previously been available for real world crashes. The relationship between maximum delta-V and deceleration was examined for different vehicle platforms involved in real world frontal impacts and frontal crash tests. Maximum deceleration was observed to be closely correlated to the maximum delta-V.

Clinical and Autopsy Diagnoses of Visceral Affections of Patients Who Died Because of Complicated Burns with Multi-organ Failure

The anatomicopathological investigations carried out in a total number of 186 cadavers during the last decade were reviewed. In these retrospective studies of necropsy protocols related to different affections of visceral organ systems that evolved asymptomatically, 30.1% involved the neurological system, 36.0% the uropoiesis system, 34.4% the gastrointestinal system, 52.0% the hepatobiliary system, and 39.7% the cardiovascular system, with a prevalence in the pulmonary system of 64.2%. A comparative analysis of the incidence of affections detected in various visceral organs (on the basis of necropsy data in the 186 burn patients) and the incidence of their clinical manifestations showed that in 35% of patients with extensive and deep burns all of these conditions developed asymptomatically and were diagnosed only through autopsy.

Rhinitis/Bronchopneumonia Syndrome in Irish Wolfhounds

This study describes the clinical, immunologic, genetic, and pathologic features of Irish Wolfhounds with rhinitis/bronchopneumonia syndrome. The dogs examined were from Belgium, The Netherlands, UK, Canada, Germany, and Switzerland. Signs included transient to persistent mucoid or mucopurulent rhinorrhea, cough, and respiratory dyspnea. Radiographic, rhinoscopic, and bronchoscopic findings were variable. Analysis of ciliary ultrastructure was performed in 5 affected dogs, but no characteristic primary ciliary defects (primary ciliary dyskinesia) were detected. Serum and bronchoalveolar lavage fluid (BALF) concentrations of IgA, IgG, and IgM were determined in some affected dogs and clinically normal Irish Wolfhounds. Serum IgA concentration was below the reference range in 5 of 8 affected dogs tested, whereas BALF IgA concentration was above the normal range in 2 affected adult dogs. The CD4 to CD8 lymphocyte subset ratio (CD4:CD8) in peripheral blood was tested in 3 affected dogs and was within the normal range. BALF CD4:CD8 was tested in 1 affected dog and was higher than the normal range. Decreased neutrophil phagocytosis was observed in 1 of the 4 dogs tested. Analysis of pedigrees of the Belgian, Canadian, German, and Swiss dogs revealed common ancestry, suggesting a heritable syndrome.

Antibody responses of naive cattle to two inactivated bovine viral diarrhoea virus vaccines, measured by indirect and blocking ELISAS and virus neutralisation

Two groups of naive heifers were given primary courses of two inactivated bovine viral diarrhoea (BVD) virus vaccines licensed for use in the UK. Their humoral responses in serum and milk were assayed by means of an indirect ELISA detecting antibodies to structural viral glycoproteins, a blocking ELISA specific for antibodies to the non-structural protein NS2-3 and the virus neutralisation test (VNT). For each assay, the numbers of serum or milk samples testing positive at each sample point and the mean values were determined. In both vaccine groups, serum antibody responses were detected by the indirect ELISA and the VNT, with both the numbers of seropositive animals and mean values peaking five weeks after the second vaccination. In the 23 heifers vaccinated with Bovilis BVD, the mean NS2-3-specific ELISA values remained low throughout the trial, with no serum or milk samples testing positive. In the 24 heifers vaccinated with Bovidec, the mean NS2-3 responses peaked below the level of positivity five weeks after the second vaccination, before declining again; NS2-3-specific antibodies were detected in one serum sample and one milk sample from two heifers in this group. A pooled milk sample from each vaccine group tested negative by both ELISAS 12 weeks after the second vaccination.

Children in crashes: mechanisms of injury and restraint systems

OBJECTIVES

To explore the levels of protection offered to children involved in motor vehicle collisions.

DESIGN

A joint study by the Children's Hospital of Eastern Ontario (CHEO) and Transport Canada, Ottawa, conducted in 2 phases: retrospective from 1990 to 1997 and prospective from 1998 to 2000.

SETTING

CHEO, a university affiliated tertiary care centre.

PATIENTS

Children admitted to CHEO between 1990 and 2000 with spinal trauma due to motor vehical crashes (MVCs). Phase I of the study involved analysis, in a series of 45 children after MVAs, by location of spinal injury versus belt type. Phase 2 was a prospective study of 22 children injured in 15 MVAs.

INTERVENTIONS

A biomechanical assessment of the vehicle and its influence on the injuries sustained.

MAIN OUTCOME MEASURES

The nature and extent of the injuries sustained, and the vehicle dynamics and associated occupant kinematics.

RESULTS

The odds ratio of sustaining a spinal injury while wearing a 2-point belt versus a 3-point belt was 24 (95% confidence interval 2.0-2.45, p < 0.1), indicating a much higher incidence with a lap belt than a shoulder strap.

CONCLUSIONS

Proper seat-belt restraint reduces the morbidity in children involved in MVCs. Children under the age of 12 years should not be front-seat passengers until the sensitivity of air bags has been improved. Three-point pediatric seat belts should be available for family automobiles to reduce childhood trauma in MVCs.

Testing of bulk tank milk from Northern Ireland dairy herds for viral RNA and antibody to bovine viral diarrhoea virus

Bulk tank milk samples collected from 929 Northern Ireland dairy herds were classified according to their geographical location, somatic cell count and milk yield. Each sample was tested by ELISA for antibody levels to bovine viral diarrhoea virus (BVDV) and the herds were assigned to four groups with increasing antibody levels. In nine herds (1 per cent) no antibodies were detectable in the milk samples (group 1) and they were detectable at low levels in the milk from 90 herds (9.7 per cent, group 2), at moderate levels in 369 herds (39.7 per cent, group 3), and at high levels in the remaining 461 herds (49.6 per cent, group 4). The testing of samples from 90 herds in groups 1 and 2 after an interval of 12 months showed that the annual incidence risk for new infections with BVDV was in the range 0.133 to 0.477. There were significant relationships (P < 0.001) between the mean corrected optical density in the ELISA and herd location and somatic cell count, but not yield; the relationship with somatic cell count was linear (P < 0.01). Forty-three group 3 herds and 49 group 4 herds were selected at random and bulk milk samples were tested for BVDV by reverse transcriptase polymerase chain reaction. None of the group 3 herds was positive, but five group 4 herds were positive.

Pestiviral infections in sheep and pigs in Northern Ireland

Serological surveys were carried out to determine the prevalence of pestiviral infections in sheep and pigs in Northern Ireland. Sera from 918 ewes in 92 flocks from 10 regions were tested by ELISA for antibodies to border disease virus and positive results were obtained from 49 ewes (5.3 per cent) in 28 flocks (30.4 per cent). There were highly significant geographical variations in its flock prevalence ranging from 0 per cent in the Enniskillen region to 70 per cent in the Coleraine region. There was no significant association between the proportion of seropositive flocks and the presence of cattle on the farm (P = 0.583). In the positive flocks, the average rate of seroprevalence was 17.5 per cent, and the highest was 40 per cent. Comparative neutralisation studies on 14 positive sera with bovine viral diarrhoea virus type I (BVDV I) and border disease virus revealed higher titres (> or = four-fold) to BVDV I in all cases. Only one positive result was obtained when fluids from 186 aborted ovine fetuses were tested for border disease virus by ELISA. Serum samples from 680 pigs in 46 herds were tested for virus neutralising antibodies to border disease virus. Twenty sera (2.9 per cent) were cytotoxic, and only one of the remaining 660 sera gave a positive result. This sample tested negative for classical swine fever by ELISA, and comparative neutralisation studies showed that it had a four-fold higher titre to BVDV I than to border disease virus.

Spectroscopic studies of pr(3+) ions in silver halide crystals

The luminescence of AgBr and AgBrCl crystals doped with Pr(3+) rare-earth ions was investigated in the visible and infrared spectral ranges. We measured the excitation, emission, and absorption spectra as well as the kinetic parameters over a broad temperature range. The strong influence of the silver halide composition on Pr(3+) ions spectroscopic properties was revealed. We calculated useful optical parameters for Pr:AgBr crystals by using the Judd-Ofelt approximation. Good agreement between the theoretical and the measured parameters was obtained.

Evaluation of an immunofluorescent antibody test to detect bovine herpesvirus 1-specific IgM

An indirect immunofluorescent antibody test (IIFAT) was developed to detect bovine herpesvirus 1 (BHV-1)-specific IgM. All sera were treated with protein-G agarose prior to testing to eliminate the possibility of false-positive results due to IgM-isotype rheumatoid factor (IgM-RF). Specific IgM was first detected 8 days after experimental infection of 3 calves free of maternally derived antibody, with peak responses occurring 2-7 days later. Seroconversion was detected in all 3 calves using a single-dilution enzyme-linked immunosorbent assay. Following reinfection at 30 days postinfection, a low-level IgM response was detected in only 1 calf. Seroconversion was detected in 2 calves. There was no evidence of activation of IgM-RF by infection or reinfection with BHV-1. When 87 acute and convalescent serum pairs collected from 21 outbreaks of respiratory disease were tested, specific IgM was detected in 58 animals (66.6%) from 19 (90.5%) outbreaks. Seroconversion was detected in 44 of these animals (50.6%) from 17 outbreaks (81.0%). The correlations between these 2 assays on a calf and outbreak basis were 79.3% and 90.5%, respectively. Specific IgM was detected in 17/20 sera (85.0%) collected from an additional outbreak. No virus was detected by virus isolation or immunofluorescent staining in nasal mucus samples collected at the same time. Detection of specific IgM by IIFAT is a useful technique for the serodiagnosis of BHV-1 infection.

Isotype- and subclass-specific responses to infection and reinfection with parainfluenza-3 virus: comparison of the diagnostic potential of ELISAs detecting seroconversion and specific IgM and IgA

Isotype- and subclass-specific indirect enzyme-linked immunosorbent assays were developed to detect parainfluenza-3 virus-specific IgG1, IgG2, IgM, and IgA responses. Sera were treated with protein G-agarose prior to testing for specific IgM and IgA to eliminate the possibility of false-positive results due to IgM-rheumatoid factor and to remove interisotypic competition due to specific IgG. IgM and IgA absorbance values were expressed as a percentage of the absorbance values of positive reference sera included on each plate (S/P%), and respective positive/negative threshold values of 15.0% and 28.0% were determined. The mean interval between experimental infection of 3 calves and initial detection of specific IgG1 and IgG2 responses was 8.0 and 9.3 days respectively, rising rapidly to an initial plateau 13.7 and 11.0 days postinfection (dpi). Reinfection of these calves at 30 dpi resulted in further rapid increases, with higher plateau values reached 13.0 (IgG1) and 13.7 (IgG2) days later. The mean interval between infection and the first positive IgM and IgA responses was 6.7 and 12.3 days, respectively. IgM S/P% values peaked at 13.0 dpi, with all 3 calves showing a secondary anamnestic response to reinfection, peaking 4.7 days later. The IgA response to initial infection was weak, with only 2 calves showing an obvious peak response at 15.0 dpi. A strong anamnestic IgA response to reinfection occurred in 2 calves, with a peak response 9.5 days later. Apparent biphasic and triphasic IgM and IgA responses were evident in some calves. Acute and convalescent serum samples from 80 calves involved in 17 outbreaks of respiratory disease were tested for specific IgM and IgA. Positive IgM results were detected in 15 outbreaks, with 71 sera from 44 calves testing positive. Although IgA-positive results were detected in the same 15 outbreaks, only 42 sera from 31 calves were positive. In a previous study, seroconversion was detected in 21 of these calves from 10 outbreaks. Thus the diagnostic potential of the assays was in the order IgM > IgA > seroconversion. The correlations between IgM and IgA, IgM and seroconversion, and IgA and seroconversion results for each calf were 73.8%, 58.8% and 62.5%, respectively.

Air bags and children: a potentially lethal combination

Air bags have been responsible for saving thousands of lives since their introduction in the early 1970s. Now, however, it has become apparent that under certain conditions, these restraint mechanisms designed to save lives have in fact been the cause of needless morbidity and mortality in children. We reviewed 13 children injured by air bags in Canada, where seat belt wear is mandatory for all occupants. Although 12 of the children sustained relatively minor air bag trauma, one child was killed by the air bag deployment, sustaining an occipital-C1 dislocation. The pediatric population is at particular risk as many parents continue to unwittingly place their children in the front seat and thus in jeopardy of sustaining air bag-induced injuries should a collision occur.

Evaluation of the suitability of a commercial bovine viral diarrhoea virus antigen capture ELISA for diagnostic testing

The suitability of a commercial bovine viral diarrhoea virus (BVDV) antigen capture enzyme-linked immunosorbent assay (ELISA) for routine diagnostic testing of bovine serum samples was evaluated by comparing the ELISA results of 214 sera with those obtained after two passages in roller tube cultures of fetal bovine lung cells and immunofluorescent staining using fluorescein isothiocyanate-conjugated hyperimmune BVDV anti-serum. In addition, 208 of these samples were tested by virus isolation in a microtitre system followed by indirect immunoperoxidase staining using a pool of two non-competing pestivirus specific monoclonal antibodies. The sensitivity of the ELISA compared with virus isolation followed by immunofluorescent and immunoperoxidase staining was 47.8 and 45.8%, respectively. The corresponding figures of specificity and overall correlation were 95.3 and 95.1%, and 90.2 and 89.4%. Twenty-two of 24 pestivirus isolates from the positive blood samples were typed as BVDV-like by monoclonal antibodies, indicating that the poor sensitivity of the ELISA was not due to the presence of atypical pestiviruses in the test sample. These results suggest that this ELISA is not suitable for testing blood samples for BVDV in a diagnostic laboratory.

Silver-halide fiber tip as a beam homogenizer for infrared hollow waveguides

A beam-homogenizing device consisting of a short tip of silver-halide infrared fiber eliminates the low-order multimode effect generated by bending of hollow guides. A series of experiments with a CO(2) laser shows that the solid fiber functions as a homogenizer with a small insertion loss of 0.2dB.

Airbag deployments: the Canadian experience

Transport Canada is undertaking an in-depth study of motor vehicle collisions involving airbag deployments. University-based collision investigation teams across Canada are used to collect crash data. The primary objective of the study is to gain a better understanding of the injuries and the injury mechanisms associated with airbag deployments among both restrained and unrestrained occupants. Preliminary results show an exceptionally high level of seatbelt use in conjunction with the supplemental air cushion restraints. Most crashes are, however, of only minor to moderate severity, in which the seatbelt systems alone would be expected to provide adequate occupant protection. Initial findings indicate that, at the lower end of the collision severity spectrum, deployment of an airbag may, in some circumstances, increase the overall likelihood of injury to a restrained occupant. This suggests that the current deployment threshold is set too low, at least for belted occupants.

High-cycle fatigue of silver halide infrared fibers

The transmission of CO(2) laser radiation by silver halide infrared fibers was measured during cyclic bending of the fibers. High-cycle fatigue of the fibers was investigated. The fibers were found to transmit without significant deterioration after more than 10(7) cycles. The fatigue-stress limit, based on 10(7) bending cycles, was estimated to be approximately 75 MPa.

Fatal injuries to restrained passenger car occupants in Canada: crash modes and kinematics of injury

Passenger car collisions with other vehicles and with fixed objects were studied from a representative sample of fatal and injury-producing collisions collected according to a prescribed sampling plan. This paper describes our analysis of accidents involving restrained passenger car occupants who are fatally injured in collisions. Lateral collisions were found to be predominant, and both lateral and frontal collisions were associated with marked intrusion into the occupant compartment, causing direct, severe injuries to the head and chest of these occupants. Multiple severe injuries to more than one body region were common, and 90% of these victims died within one hour of the collision. The seat belt generally offered no protection to these fatally injured occupants. Reducing the incidence of fatal injury to properly restrained passenger car occupants will necessitate diminishing these very severe intrusion forces, especially from heavy trucks and fixed vertical hazards. For vehicle design modifications to be effective, it appears likely that roadway and roadside design and management must be included in the safety equation. Excessive speeds, inadequate traffic control, and unforgiving roadside hazards are playing a major role in the incidence of fatal injuries documented in this study.

Examination and analysis of seat belt loading marks

In moderate to severe collisions, large decelerations and hence large forces are generated. Various components of the seat belt system are loaded, and physical evidence of this loading may be observed long after the collision event. Such witness marks result from interaction between different components of the restraint system, or between the restraint and portions of the vehicle interior. Detailed examination and analysis of such marks can establish whether or not the seat belt was in use, and also the precise manner in which the seat belt was worn. Such investigative techniques are critical for evaluating the collision performance of occupant restraint systems, and for positively identifying cases of restraint system misuse. This paper reviews the types of physical evidence which may be observed to determine restraint usage.

Immunity to tetanus: tetanus antitoxin and anti-BIIb in human sera

Immunity to tetanus was investigated in 157 individuals aged between 1 and 77 years using, for the evaluation of both tetanus antitoxin and antibody to fragment BIIb (anti-BIIb), an easily performed ELISA that gave reproducible results. Among these people 72% were protected against tetanus (tetanus antitoxin titres greater than 0.06 IU ml-1). Anti-BIIb titres greater than 0.15 U ml-1 were found in 75% of the males vs 57% of the females (P less than 0.02) with marked variations according to age. Furthermore, 13 out of 41 individuals with antitoxin titres less than 0.06 IU ml-1 (not protected against tetanus) were found to have anti-BIIb titres greater than 0.15 U ml-1. These data raise questions as to the significance and protective effect of anti-BIIb against tetanus.

Relation between protective potency and specificity of antibodies in sera of tetanus immunized individuals

Out of 157 human sera analyzed for antitetanus antibody content by ELISA, 13 turned out to contain only anti-BIIb antibodies, of which 8 proved to be neutralizing. Of these, the 3 sera 303, 306 and 312 together with a commercially available standard preparation of human antitetanus immunoglobulins were further analyzed as to their antibody composition by ELISA using plates sensitized with either the toxoid or various tetanus toxin-derived fragments. It was verified that the protective potency of these antisera was related mainly to their anti-BIIb antibody content. Adsorption experiments confirmed that anti-BIIb antibodies were primarily involved in toxin neutralization, although the presence of high levels of both anti-alpha and anti-Ibc antibodies could confer neutralizing capacity on the sera. A rabbit antiserum raised with the BIIb fragment resulted in a neutralizing antiserum that allowed us to calibrate the ELISA with the anti-BIIb antibodies as International Units.

Role of interferon, antibodies and macrophages in the protective effect of Corynebacterium parvum on encephalomyocarditis virus-induced disease in mice

Treatment of mice with Corynebacterium parvum enhances their resistance to encephalomyocarditis (EMC) virus infection. In EMC-virus-infected mice, pretreated with C. parvum, neither interferon production nor antibody responses were increased. A decrease of virus recovery was observed in cultures of macrophages taken from the peritoneum of mice early after injection of C. parvum and infected with EMC-virus in vitro. The data suggest that C. parvum acts by increasing intrinsic antiviral activity of macrophages.

Inhibition of [14C]aminopyrine uptake in rat isolated gastric mucosal cells by two classes of psychotropic agents

Certain CNS-active compounds decrease gastric acid secretion in vivo. In this study a number of tricyclic antipsychotic or antidepressant compounds together with haloperidol, a nontricyclic antipsychotic agent, were shown to inhibit dibutyryl-cAMP-stimulated [14C]aminopyrine uptake, an index of acid secretory activity in a rat isolated gastric mucosal cell preparation. The observed order of potency was: thioridazine greater than chlorpromazine greater than haloperidol approximately equal to desipramine approximately equal to imipramine greater than clozapine. Comparison of these potencies with those of the known (H+ + K+)ATPase inhibitors timoprazole and omeprazole revealed that the potency of timoprazole was similar to the one of clozapine while omeprazole was intermediate between thioridazine and chlorpromazine. Pirenzepine was ineffective.

[Digestive and cutaneous colonization of Staphylococcus aureus, Pseudomonas aeruginosa and Corynebacterium xerosis in germ-free hairless mice]

Regardless of the method of germ-free HRS mouse contamination, the kinetics of Staphylococcus aureus and Pseudomonas aeruginosa cutaneous colonization was parallel to the kinetics of intestinal colonization; Corynebacterium xerosis, however, was unable to colonize the skin or the gastrointestinal tract. There was little variability in intestinal and cutaneous colonization; this was quite different from observations in man and hairless holoxenic mice. It is possible to use these experimental models to standardize the measurement of antiseptic bactericidal activity in vivo.

[Digestive and cutaneous colonization of Staphylococcus epidermidis in hairless axenic mice]

In order to determine the cutaneous and digestive colonization of S. epidermidis in germ-free HRS mice, several groups of animals were contaminated with this strain according to different methods. The bacterial cutaneous enumerations were performed after preliminary crushing of the cutaneous biopsy. In this study, whatever the method of contamination of germ-free HRS mice, the kinetics of S. epidermidis cutaneous colonization was parallel to the kinetics of intestinal colonization. The isolation of bacteria on skin was possible only when microorganisms were eliminated in faeces (6 h after contamination). During a single experiment, there was only slight variability in colonization, whether intestinal or cutaneous. Some differences could be found from one experiment to another, but all animals in the same trial showed the same cutaneous bacterial count. This experimental model is characterized by an interrelation between the intestinal and cutaneous ecosystems.