A systematic review of the performance of actigraphy in measuring sleep stages

The accuracy of actigraphy for sleep staging is assumed to be poor, but examination is limited. This systematic review aimed to assess the performance of actigraphy in sleep stage classification of adults. A systematic search was performed using MEDLINE, Web of Science, Google Scholar, and Embase databases. We identified eight studies that compared sleep architecture estimates between wrist-worn actigraphy and polysomnography. Large heterogeneity was found with respect to how sleep stages were grouped, and the choice of metrics used to evaluate performance. Quantitative synthesis was not possible, so we performed a narrative synthesis of the literature. From the limited number of studies, we found that actigraphy-based sleep staging had some ability to classify different sleep stages compared with polysomnography.

A case-control study to investigate the prevalence of obstructive sleep apnea and the utility of the PSQ-SRBD questionnaire in children and young people with epilepsy

STUDY OBJECTIVES

Epilepsy and obstructive sleep apnea syndrome (OSAS) are each relatively common in children. OSAS may affect cognition, such that recognition of OSAS is important for children and young people with epilepsy (CYPWE). Published pilot data reported 55% CYPWE had symptoms suggestive of OSAS, compared with 7% typically developing controls. The primary aim of this study was to ascertain OSAS prevalence by polysomnography (PSG) in CYPWE, with secondary aims being to evaluate the utility of sleep questionnaires in CYPWE.

METHODS

Children and young people with epilepsy and age- and sex-matched typically developing controls were studied. A single night of level I attended PSG was undertaken, along with questionnaires [Pediatric Sleep Questionnaire (PSQ-SRBD), Pittsburgh Sleep Quality Index (PSQI) and the childhood and adolescent Epworth Sleepiness Scale (ESS-CHAD)]. OSAS was defined as obstructive apnea-hypopnea index (oAHI) of ≥ 1 event/h.

RESULTS

Polysomnography was performed in 72 children including 48 CYPWE (60% male) and 24 controls (54% male). Mean age (11 years) was similar for CYPWE and controls, p= 0.42; with slightly higher BMI z scores (0.7 v 0.1, p=0.03) noted in CYPWE. Mean oAHI was 0.61 in CYPWE versus 0.42 (controls), p=0.62. Despite higher PSQ-SRBD scores in CYPWE (0.38 v 0.12, p<0.001), no difference in OSAS prevalence (10% vs. 4%, p=0.78) was found. Children and young people with epilepsy had higher ESS-CHAD (6 vs. 3.5, p=0.01) and PSQI (5 vs. 3.3, p=0.02) scores indicating greater levels of daytime sleepiness and poorer sleep quality.

CONCLUSIONS

The study found no evidence for increased OSAS prevalence in CYPWE, whilst the utility of the PSQ-SRBD in predicting OSAS appears limited for CYPWE. Children and young people with epilepsy are, however demonstrably sleepier with poorer sleep quality. The cause for these findings remains unclear.

CLINICAL TRIAL REGISTRATION

Investigation of Sleep Quality and Prevalence of Sleep-disordered Breathing in Children and Young People With Epilepsy; https://www.clinicaltrials.gov/study/NCT03103841.

Prevalence of obstructive sleep apnea (OSA) among preschool aged children in the general population: A systematic review

Untreated pediatric obstructive sleep apnea (OSA) is associated with significant morbidities affecting behavior, neurocognitive development, endocrine and metabolic health. This systematic review evaluated prevalence of OSA reported in population-based studies among preschoolers as early intervention may have positive effects on health and quality of life. Thirty studies were included. High degrees of heterogeneity in methods and definitions were observed between the studies. Seven studies confirmed OSA by implementing objective methods after screening for habitual snoring with only two studies utilizing polysomnography, the reference standard, testing 1.2% of the combined cohorts (n = 82/4575) to confirm disease. Diagnosis of OSA was based on utilizing retired thresholds of the apnea-hypopnea-index (AHI), AHI4%≥5/hour of sleep (hrSleep), reporting prevalence of 1.8% and 6.4%, respectively. The remaining five studies implemented relatively insensitive objective recording methods to confirm disease in a limited number of children (n = 449/2486; 18.0%), estimating prevalence in the range of 0.7%-13.0%. The remaining literature is based on implementing questionnaires only to evaluate OSA. Studies published before 2014 reported 3.3%-9.4% prevalence, while more recent studies published 2016-2023 report higher prevalence, 12.8%-20.4%, when excluding outliers. This trend suggests that prevalence of OSA may possibly have been increasing in preschoolers over the past decade.

10-year anniversary of the European Somnologist examination - A historic overview and critical appraisal

The European Somnologist certification programme was developed by the European Sleep Research Society to improve patient care in sleep medicine by providing an independent evaluation of theoretical and practical knowledge. The examination of eligible experts plays a key role in this procedure. A process was started more than 15 years ago to create the European sleep medicine curriculum, eligibility criteria for certification, and sleep centre accreditation criteria. The process was characterised by interdisciplinary collaboration, consensus, and achieving new solutions. During the past 10 years, experience has been gained by the examination and certification of more than 1000 sleep medicine experts from more than 50 countries. The process has continuously been improved. However, as the programme was designed and administered mainly by medical experts in the field, systematic influence from teaching and pedagogic experts was partially underrepresented. The current critical appraisal pinpoints several missing links in the process – mainly as a missing constructive alignment between learning objectives, learning and teaching activities, and the final assessment. A series of suggestions has been made to further improve the ESRS certification programme.

The association between obstructive sleep apnoea and wound healing: a systematic review

Purpose

Obstructive sleep apnoea (OSA) is a common, significantly underdiagnosed sleep-related breathing disorder, characterised by upper airway collapse and resultant intermittent hypoxia. Oxygen plays an important role in collagen synthesis and as a result in wound healing. An association between OSA and wound healing has not been clearly delineated. A systematic review was performed to understand this association.

Methods

Randomised controlled trials, cohort, cross-sectional and case–control studies evaluating the relationship between OSA or OSA-related symptoms and wound healing in adult populations were searched in the systematic review using electronic databases PubMed, EMBASE and Ovid MEDLINE.

Main results

A total of 11 cohort studies and 1 case–control study with a total of 58,198,463 subjects were included. Most studies suggest that patients diagnosed with OSA or who are at high risk of having OSA are more likely to suffer from wound complications. Patients with OSA have been found to be at higher risk for post-operative wound infection and wound dehiscence. Contradictory results were obtained on time to heal, with one study concluding that individuals with OSA were more likely to heal earlier when compared to patients without OSA. Quality of evidence, however, was deemed very low due to high risk of bias.

Conclusions

This systematic review did identify an association between OSA and wound healing. However, due to the very low-quality evidence, further research is warranted to better characterise this association and investigate whether or not treating OSA can indeed affect wound healing.

Acoustic Screening for Obstructive Sleep Apnea in Home Environments Based on Deep Neural Networks

Obstructive sleep apnea (OSA) is a chronic and prevalent condition with well-established comorbidities. However, many severe cases remain undiagnosed due to poor access to polysomnography (PSG), the gold standard for OSA diagnosis. Accurate home-based methods to screen for OSA are needed, which can be applied inexpensively to high-risk subjects to identify those that require PSG to fully assess their condition. A number of methods that analyse speech or breathing sounds to screen for OSA have been previously investigated. However, these methods have constraints that limit their use in home environments (e.g., they require specialised equipment, are not robust to background noise, are obtrusive or depend on tightly controlled conditions). This paper proposes a novel method to screen for OSA, which analyses sleep breathing sounds recorded with a smartphone at home. Audio recordings made over a whole night are divided into segments, each of which is classified for the presence or absence of OSA by a deep neural network. The percentage of segments predicted as containing evidence of OSA is then used to screen for the condition. Audio recordings made during home sleep apnea testing from 103 participants for 1 or 2 nights were used to develop and evaluate the proposed system. When screening for moderate OSA the acoustics based system achieved a sensitivity of 0.79 and a specificity of 0.80. The sensitivity and specificity when screening for severe OSA were 0.78 and 0.93, respectively. The system is suitable for implementation on consumer smartphones.

High prevalence of obstructive sleep apnea in pregnant women with class III obesity: a prospective cohort study

STUDY OBJECTIVES

To determine the prevalence of obstructive sleep apnea (OSA) in a cohort of women with class III obesity, and a comparator lean group, in the second and third trimesters of pregnancy. Secondary objectives were to compare characteristics of women with obesity with and without OSA and to assess factors that were predictive of OSA.

METHODS

We performed a prospective cohort study involving 33 women with class III obesity (mean body mass index 43.5 ± 3.9 kg/m2) and 39 lean women (body mass index 22.0 ± 1.7 kg/m2) with singleton pregnancies. Participants completed 2 level 3 sleep studies between 12-22 weeks and 32-38 weeks gestation. OSA was defined as a respiratory event index ≥ 5 events/h (≥ 3% desaturation criteria). Levels of interleukin-6, glucose, and C-peptide were quantified in maternal blood. Logistic regression analysis was performed to determine predictors of OSA.

RESULTS

OSA was identified in 12 (37.5%) and 14 (50.0%) women with obesity and in 1 (2.6%) and 3 (9.1%) lean women in the second and third trimesters, respectively. Women with obesity with OSA were older than those with no OSA but otherwise had similar characteristics. In unadjusted analysis of women with obesity, increased age, body mass index, homeostatic model assessment of insulin resistance, and history of nonsmoking were associated with increased odds of OSA. In multivariable analysis, only increased age remained significantly associated with OSA.

CONCLUSIONS

OSA is highly prevalent in pregnant women with class III obesity. Further research is required to establish effective management strategies for the growing number of women in this high-risk group.

CITATION

Johns EC, Hill EA, Williams S, et al. High prevalence of obstructive sleep apnea in pregnant women with class III obesity: a prospective cohort study. J Clin Sleep Med. 2022;18(2):423-432.

Objective and Subjective Prevalence of Obstructive Sleep Apnoea/Hypopnoea Syndrome in UK Adults with Down Syndrome: A Strong Marker for Diurnal Behavioural Disturbances

Prior to this study, the prevalence of obstructive sleep apnoea/hypopnoea syndrome (OSAHS) in adults with Down syndrome was unknown. We hypothesized that unrecognised OSAHS could have an additional deleterious impact on mood and behavioural disturbances in this group of people.

AIMS

To assess the prevalence of OSAHS in adults with Down syndrome in the United Kingdom, subjectively and objectively, and ascertain its association with diurnal behavioural disturbances.

METHOD

Cross-sectional questionnaire study with home sleep apnoea testing (HSAT) during 2011-2015 across the four nations of the United Kingdom. Participants were adults aged ≥16 years with Down syndrome. Main outcome measures were: self- or caregiver-completed questionnaire data, including the Pictorial Epworth Sleepiness Scale (pESS), selected domains of the Developmental Behavioural Checklist for Adults (DBC-A), anthropometric measures, and symptoms of OSAHS. Objective prevalence was undertaken in a sample of responders using HSAT.

RESULTS

Responses were received from 1321/5270 participants (25%), with 1105 valid responses (21%). Eighty-one participants (7%) reported a prior diagnosis of OSA, of whom 38 were receiving therapy. Using validated algorithms, a diagnosis of OSAHS was probable in 366 participants (35%), who were younger, with higher BMI and higher mean total pESS (p < 0.0001). A total of 23% of participants had a pESS > 10. OSAHS was a strong marker for behavioural disturbances on the DBC-A depression, disruption and anti-social subscales (p < 0.001). Of 149 individuals who underwent HSAT, 42% were diagnosed with OSAHS.

CONCLUSIONS

Untreated OSAHS in Down syndrome is common and associated with behavioural and mood disturbances. Improving awareness of OSAHS amongst adults with Down syndrome, their families and healthcare professionals is essential.

Sleep medicine catalogue of knowledge and skills - Revision

The 'catalogue of knowledge and skills' for sleep medicine presents the blueprint for a curriculum, a textbook, and an examination on sleep medicine. The first catalogue of knowledge and skills was presented by the European Sleep Research Society in 2014. It was developed following a formal Delphi procedure. A revised version was needed in order to incorporate changes that have occurred in the meantime in the International Classification of Sleep Disorders, updates in the manual for scoring sleep and associated events, and, most important, new knowledge in sleep physiology and pathophysiology. In addition, another major change can be observed in sleep medicine: a paradigm shift in sleep medicine has taken place. Sleep medicine is no longer a small interdisciplinary field in medicine. Sleep medicine has increased in terms of recognition and importance in medical care. Consequently, major medical fields (e.g. pneumology, cardiology, neurology, psychiatry, otorhinolaryngology, paediatrics) recognise that sleep disorders become a necessity for education and for diagnostic assessment in their discipline. This paradigm change is considered in the catalogue of knowledge and skills revision by the addition of new chapters.

Prospective Trial of CPAP in Community-Dwelling Adults with Down Syndrome and Obstructive Sleep Apnea Syndrome

Adults with Down syndrome (DS) are predisposed to obstructive sleep apnoea (OSA), but the effectiveness and acceptability of continuous positive airway pressure treatment (CPAP) in this group has rarely been formally assessed. This study was designed as a pilot randomised, parallel controlled trial for one month, continuing as an uncontrolled cohort study whereby the control group also received the intervention. Symptomatic, community-dwelling DS individuals exhibiting ≥10 apnoeas/hypopneas per hour in bed on a Type 3 home sleep study were invited to participate in this study, with follow-up at 1, 3, 6, and 12 months from baseline. Measurements of sleepiness, behaviour, cognitive function and general health were undertaken; the primary outcome was a change in the pictorial Epworth Sleepiness Scale (pESS) score. Twenty-eight participants (19 male) were enrolled: age 28 ± 9 year; body mass index 31.5 ± 7.9 kg/m2; 39.6 ± 32.2 apnoeas/hypopneas per hour in bed; pESS 11 ± 6/24. The pilot randomised controlled trial at one month demonstrated no change between the groups. At 12 months, participant (p = 0.001) pESS and Disruptive (p < 0.0001), Anxiety/Antisocial (p = 0.024), and Depressive (p = 0.008) behaviour scores were reduced compared to baseline. Improvement was noted in verbal (p = 0.001) and nonverbal intelligence scores (p = 0.011). General health scores also improved (p = 0.02). At the end of the trial, 19 participants continued on treatment. Use of CPAP in adults with DS and OSA led to a number of significant, sustained improvements in sleepiness and behavioural/emotional outcomes at 12 months.

Behavioural and emotional disturbances associated with sleep-disordered breathing symptomatology in children with Down's syndrome

BACKGROUND

Down's syndrome (DS) predisposes to sleep-disordered breathing (SDB). In children with DS, behavioural and emotional disturbances secondary to SDB are often assumed to result from cognitive impairment alone. Our aim was to explore the relationship of behavioural and emotional disturbances with SDB in a population of children with DS.

METHODS

A modified sleep questionnaire, Epworth Sleepiness Scale (ESS), Paediatric ESS and the short form of the developmental behaviour checklist (DBC-P24) were sent to 261 carers of children aged 4 to 15 years with DS in 2012.

RESULTS

Of 120 participants, 25% had probable SDB. In children with probable SDB compared to those without nocturnal symptoms, the total behaviour problem score (TBPS) was significantly higher (20.3 ± 8.6/48 vs. 12 ± 7.5/48; P = 0.002) as was the PaedESS (7.7 ± 5.6/24 vs. 2.8 ± 3.5/24; P = 0.002). For every increase in frequency of choking attacks, snoring and night awakenings, the TBPS increased by 1.37, 1.28 and 1.75 points, respectively, indicating worsening behaviour. The TBPS was found to decrease by 1.31 points for every hour more of self-reported sleep duration (r = -0.25, P = 0.017).

CONCLUSIONS

SDB symptoms and shorter self-reported sleep duration are highly prevalent among children with DS and are independently associated with worsening behaviour using the TBPS.

A Cross-Sectional Comparison of the Prevalence of Obstructive Sleep Apnea Symptoms in Adults With Down Syndrome in Scotland and Japan

Small studies in Western populations report a high prevalence of obstructive sleep apnea (OSA) in adults with Down syndrome. To date, ethnic differences have not been explored. A questionnaire sent to 2,752 adults with Down syndrome aged ≥16 years in Scotland and Japan (789 valid responses) estimated OSA prevalence based on reported symptoms. Symptoms were common in both countries, with snoring (p = 0.001) and arousals (p = 0.04) more prevalent in Japan. Estimated OSA prevalence in adults with Down syndrome was similar in the two countries, and raised in comparison with the general adult population (19.6% in Scotland and 14.3% in Japan; p = 0.08), though BMI was a confounder. Identification and treatment of OSA is recommended in adults with Down syndrome, regardless of ethnicity.

0573 Screening for Obstructive Sleep Apnea at Home Based on Deep Learning Features Derived from Respiration Sounds

Introduction

Analysis of sleep breathing sounds has been employed to screen obstructive sleep apnea (OSA). However, most current methods rely on specialized equipment (e.g., tracheal microphones), require additional physiological data (e.g., oxygen saturation), are rule-based, or are trained on data collected in-lab, making them less suitable for home use. In this study, deep learning methods were leveraged to explore the hypothesis that sleep audio recordings collected via smartphones can be used alone to screen for OSA by exploiting the temporal pattern of respiration sounds.

Methods

Adult participants with suspected sleep-disordered breathing of varying degrees of severity were recruited from the general population and from GP referrals to sleep clinic. Audio recordings were collected via smartphones during home sleep apnea testing (HSAT). HSAT data were scored by a registered polysomnographic technologist in accordance with current international guidelines (AASM V2.5, 2018) and used as reference. To exploit acoustic respiration temporal pattern, time interval histograms were computed for sequences of audio-words that were automatically learned from spectral features with a deep neural network. Means and standard deviations of the time intervals for each audio-word were employed by a Gaussian mixture model to classify 2-minute audio recording segments as either containing OSA events or not.

Results

Preliminary data from 4 valid nights’ recordings obtained from 2 consented participants was analysed. 550 segments were used for training, with 180 segments used for evaluation. Audio recording demonstrated a sensitivity of 0.71 and specificity of 0.66 when compared with manually-scored HSAT.

Conclusion

Preliminary results suggest that an approach to OSA screening based on deep learning with inter-audio-word intervals to capture information about respiration temporal pattern may be a useful tool in diagnosis of OSA. Further model development is underway using data collected from up to 200 patients and full study data will be presented.

Support

The project is supported by an Innovate UK grant (project number 157358). HR is supported by a joint scholarship from Passion for Life Healthcare Ltd and University of Sheffield. LH acknowledges the financial support of NHS Research Scotland (NRS), through NHS Lothian.

Utility of the pictorial Epworth sleepiness scale in the adult down syndrome population

OBJECTIVE/BACKGROUND

The utility of the pictorial Epworth sleepiness scale (pESS) has been assessed by only a few studies in a clinical population. Some of its questions may be inappropriate in certain patient groups. The aim of this study was to assess the utility of the pESS in the adult Down syndrome (DS) population in the United Kingdom (UK).

PATIENTS/METHODS

A modified sleep questionnaire including the pESS was administered to 5430 adults with DS living in the UK. Standard statistical analysis was undertaken.

RESULTS

Of 1105 valid responses (20.35%), the pESS was incomplete in 129 (11.67%) cases. Of the incomplete responses, "Q1. Likelihood of dozing/falling sleep while sitting and reading?" was most frequently missed (63.6% of 129 responses).

CONCLUSIONS

The pESS may not be entirely appropriate in certain populations such as those with intellectual disability where literacy levels may be low. Question modification may be necessary.

CLINICAL TRIAL REGISTRATION NUMBER

ISRCTN55685305.

Co-suppression of AtMIPS demonstrates cooperation of MIPS1, MIPS2 and MIPS3 in maintaining myo-inositol synthesis

Co-suppressed MIPS2 transgenic lines allow bypass of the embryo lethal phenotype of the previously published triple knock-out and demonstrate the effects of MIPS on later stages of development. Regulation of inositol production is of interest broadly for its effects on plant growth and development. The enzyme L-myo-inositol 1-phosphate synthase (MIPS, also known as IPS) isomerizes D-glucose-6-P to D-inositol 3-P, and this is the rate-limiting step in inositol production. In Arabidopsis thaliana, the MIPS enzyme is encoded by three different genes, (AtMIPS1, AtMIPS2 and AtMIPS3), each of which has been shown to produce proteins with biochemically similar properties but differential expression patterns. Here, we report phenotypic and biochemical effects of MIPS co-suppression. We show that some plants engineered to overexpress MIPS2 in fact show reduced expression of AtMIPS1, AtMIPS2 and AtMIPS3, and show altered vegetative phenotype, reduced size and root length, and delayed flowering. Additionally, these plants show reduced inositol, increased glucose levels, and alteration of other metabolites. Our results suggest that the three AtMIPS genes work together to impact the overall synthesis of myo-inositol and overall inositol homeostasis.

The curious incident of groaning in the night-time

Catathrenia (from the Greek kata, meaning “below”, and threnia, meaning “to lament”) is a rare sleep disorder with very few cases reported in children [1]. The principal feature of catathrenia is a monotonic expiratory groaning noise that may or may not be associated with an altered respiratory pattern. It is now classified amongst the sleep-related breathing disorders [2].

The first report of catathrenia in a child who has been symptomatic from birthhttp://ow.ly/XcY830bevOH

Obstructive sleep apnoea/hypopnoea syndrome in adults with Down syndrome

Key points

Educational aims

Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is characterised by repeated cycles of upper airway obstruction during sleep, leading to diurnal symptoms. Individuals with Down syndrome are predisposed to OSAHS due to overlap between the Down syndrome phenotype and OSAHS risk factors. Recent large studies using subjective and objective measures estimate that OSAHS affects around 40% of adults with Down syndrome, in contrast to 2–4% of the general adult population. The “double-hit” of comorbid Down syndrome and OSAHS may accelerate cognitive decline in adults with Down syndrome. However, with the appropriate care and support, OSAHS can be treated effectively in this group using continuous positive airway pressure (CPAP) therapy, improving daytime function and behaviour. Symptoms of OSAHS should be routinely monitored in this population, with testing and treatment available to all adults with Down syndrome; however, this is not currently commonplace, and health inequalities are evident.

Obstructive sleep apnoea/hypopnoea syndrome affects ∼40% of adults with Down syndrome cut can be treated effectivelyhttp://ow.ly/Jdco3062xP5

Comparison of antibody titers in donor specimens and associated AS-1 leukoreduced donor units

BACKGROUND

Donor units with unexpected antibodies to red blood cell (RBC) antigens have transfusion restrictions and are often discarded by collection facilities. This study examined the antibody titer reduction in AS-1 leukoreduced RBC (LR-RBC) units and potential acceptability of these units for unrestricted transfusions.

STUDY DESIGN AND METHODS

Donor specimens and AS-1 LR-RBC segment samples from donors with positive antibody screens and group O donors were analyzed. Antibody identifications were performed, and titer results from the matched serum samples and segment supernatants were compared.

RESULTS

During the 5-month study, 39 donor samples with positive antibody screens, five random group O donor samples, and the associated LR-RBC unit segments were assessed. The median donor sample and segment supernatant titers were 4 and 1, respectively. Alloantibodies were undetectable in 28% of the donor segment supernatants. The median anti-A and anti-B titers in the group O donor samples were 128 and were reduced to 32 in the donor segment supernatants. All ABO and other antibodies were diluted by the AS-1 to a titer of not more than 32.

CONCLUSION

Antibody titers in AS-1 LR-RBC units were significantly decreased compared to donor specimens and were lower than anti-A and -B titers in group O AS-1 LR-RBC units, which are frequently transfused to non-group O recipients. If a "clinically significant" titer for donor alloantibodies was established, blood centers could determine eligibility of units for unrestricted transfusions. This would decrease unnecessary RBC wastage and increase units available for transfusion.

Diagnostic delay in REM sleep behavior disorder (RBD)

STUDY OBJECTIVES

REM sleep behavior disorder (RBD) is a parasomnia in which normal muscle atonia of REM sleep is lost. The aim of this study was to confirm if diagnostic delay exists in RBD and identify any contributing factors.

METHODS

A database was compiled of 49 patients with RBD seen at a tertiary referral center from 2005 to 2011 by retrospective review of referral letters and polysomnographic (PSG) reports. Patients with comorbid narcolepsy were excluded. A questionnaire was sent to investigate diagnostic delay, management, and comorbidities.

RESULTS

Mean diagnostic delay was 8.7 ± 11 (median 4.5, IQR 1.75-11.75) years in 30 questionnaire responders. Common reasons for diagnostic delay included belief that symptoms were not serious enough to consult a doctor (59%), mild or infrequent occurrence of sleep behavior (56%), belief that symptoms may resolve (47%), and lack of knowledge of treatment options (47%). The bed partner was an important influence, with the decision to seek medical attention being made jointly by the patient and partner in 47%.

CONCLUSIONS

This study has demonstrated the existence of significant diagnostic delay in RBD, mainly due to lack of understanding of the disorder and its treatment by patients and members of the medical profession.

Oxygen-dependent autoaggregation in Shewanella oneidensis MR-1

In aerobic chemostat cultures maintained at 50% dissolved O(2) tension (3.5 mg l(-1) dissolved O(2)), Shewanella oneidensis strain MR-1 rapidly aggregated upon addition of 0.68 mM CaCl(2) and retained this multicellular phenotype at high dilution rates. Confocal microscopy analysis of the extracellular matrix material contributing to the stability of the aggregate structures revealed the presence of extracellular DNA, protein and glycoconjugates. Upon onset of O(2)-limited growth (dissolved O(2) below detection) however, the Ca(2+)-supplemented chemostat cultures of strain MR-1 rapidly disaggregated and grew as motile dispersed cells. Global transcriptome analysis comparing aerobic aggregated to O(2)-limited unaggregated cells identified genes encoding cell-to-cell and cell-to-surface adhesion factors whose transcription increased upon exposure to increased O(2) concentrations. The aerobic aggregated cells also revealed increased expression of putative anaerobic electron transfer and homologues of metal reduction genes, including mtrD (SO1782), mtrE (SO1781) and mtrF (SO1780). Our data indicate that mechanisms involved in autoaggregation of MR-1 are dependent on the function of pilD gene which encodes a putative prepilin peptidase. Mutants of S. oneidensis strain MR-1 deficient in PilD and associated pathways, including type IV and Msh pili biogenesis, displayed a moderate increase in sensitivity to H(2)O(2). Taken together, our evidence indicates that aggregate formation in S. oneidensis MR-1 may serve as an alternative or an addition to biochemical detoxification to reduce the oxidative stress associated with production of reactive oxygen species during aerobic metabolism while facilitating the development of hypoxic conditions within the aggregate interior.

Incidence and morbidity of hospital-presenting corneal infiltrative events associated with contact lens wear

AIM

To determine the incidence and morbidity (visual loss) of hospital-presenting corneal infiltrative events (CIEs) associated with the wearing of current generation contact lenses.

METHODS

All contact lens wearers presenting with any form of corneal infiltrate/ulcer to a hospital centre in Manchester, UK, were surveyed in this 12-month, prospective, hospital-based epidemiological study. A clinical severity matrix was used to quantify the overall severity of presenting signs and symptoms. The size of the hospital catchment population and the wearing modalities (daily wear [DW] or extended wear [EW]) and lens types used in that population were estimated from relevant demographic and market data to facilitate the calculation of incidence. We also attempted to ascertain, from their eye care practitioners, the visual acuity (VA) of patients suffering from CIEs prior to and at about six months following attendance at the hospital.

RESULTS

During the survey period, 118 patients presented with CIEs of varying severity. The annual incidence (cases per 10,000 wearers) for all wearing modalities and lens types is 21.3 (95 per cent confidence interval 17.8 to 25.5). The incidence of CIEs for each wearing modality and lens type is: DW rigid, 8.6 (3.9 to 18.7); DW hydrogel daily disposable, 14.0 (9.3 to 21.0); DW hydrogel (excluding daily disposable), 20.4 (15.9 to 26.2); DW silicone hydrogel, 55.9 (9.9 to 309.6); EW rigid, zero (0.0 to 1758.8); EW hydrogel, 144.6 (66.4 to 311.8) and EW silicone hydrogel, 118.6 (75.2 to 186.7). The risk of developing a CIE with EW lenses was 8.1 (5.3 to 12.5) times greater than that with DW lenses (p < 0.0001). Although there was no difference between EW hydrogel and EW silicone hydrogel lenses with respect to the risk of developing CIEs, the clinical severity of CIEs was greater with EW hydrogel lenses (p = 0.04). Results of VA for pre- and post-hospital attendance were obtained from 38 patients, none of whom lost more than one line of VA. For the study population, zero patients (95 per cent CI: 0 to 9.2 per cent) suffered a significant loss of VA as a result of developing a CIE.

CONCLUSIONS

Overall, there is an eight times higher incidence of CIEs in wearers who sleep in contact lenses compared with wearers who use lenses only during the waking hours. For those who choose to routinely or intermittently sleep in soft contact lenses, silicone hydrogels are the lens of first choice because CIEs are less clinically severe with this lens type compared with hydrogel lenses. The rate of significant visual loss as a result of developing a CIE is low.

The size, location, and clinical severity of corneal infiltrative events associated with contact lens wear

PURPOSE

The purpose of this study is to determine the relationship between the size, location, and clinical severity of corneal infiltrative events (CIEs) associated with contact lens wear.

METHODS

We examined a series of contact lens wearers, presenting consecutively to a large hospital clinic, who had any form of CIE. The severity of the CIE was quantified using a clinical severity matrix based on scores attributed to each of 10 signs and symptoms. The infiltrate was accurately drawn on a schematic diagram of the ocular surface, and from this, we determined its size (i.e., largest dimension) and distance from the limbus. Cartograms were constructed to illustrate the size and location of the corneal infiltrates according to wearing modality and lens type.

RESULTS

Useable data pertaining to 111 patients were analyzed. A significant positive correlation was found between the distance of the infiltrate from the limbus versus clinical severity (p = 0.002), but not between the distance of the infiltrate from the limbus versus infiltrate size (p = 0.97). The cartograms revealed a tendency for infiltrates to occur in the superior cornea of patients wearing extended wear silicone hydrogel lenses (p = 0.0002) in the central cornea of patients wearing daily wear hydrogel daily disposable lenses (p = 0.007) and in the peripheral cornea of patients wearing daily wear hydrogel (excluding daily disposable) lenses (p = 0.0006).

CONCLUSIONS

These data statistically validate the previously held anecdotal notion that CIEs which occur in the peripheral cornea are less clinically severe than those which occur in the central cornea. Consideration of the distribution of CIEs may facilitate a better understanding of the etiology of these events and can serve to alert practitioners as to their likely clinical presentation.

Inefficacy of Aspheric Soft Contact Lenses for the Correction of Low Levels of Astigmatism

PURPOSE

The purpose of this article is to compare the visual performance of a toric soft (TS) contact lens (SofLens 66 Toric; Bausch & Lomb, Rochester, NY), an aspheric soft (AS) contact lens (Frequency Aspheric; CooperVision, Fairport, NY) and a spectacle correction (SC) in subjects with low levels of astigmatism.

METHODS

One eye of 30 subjects with refractive astigmatism of -0.75 DC or -1.00 DC was tested. After pupil dilation, each subject was fitted with all three forms of correction in random order. Subjects were masked from the contact lens type. High-contrast visual acuity (HCVA) and low-contrast visual acuity (LCVA) were recorded for each correction using 2-mm, 4-mm, and 6-mm artificial pupils.

RESULTS

With a 2-mm pupil, HCVA was similar for the TS lens and the SC (p = 0.13); better HCVA was demonstrated with the TS lens than with the AS lens (p = 0.001). With 4-mm and 6-mm pupils, HCVA was poorer with the AS lens than with the SC (p < 0.002) and TS lenses (p < 0.0001). The difference in HCVA between the TS and AS lenses was two letters, three letters, and one line with pupil sizes of 2 mm, 4 mm, and 6 mm, respectively. LCVA was similar for the three refractive conditions with the 2-mm pupil size. With 4-mm and 6-mm pupils, LCVA was similar for the TS lens and SC, but better than the AS lens by approximately one line in each case (all p < 0.0001).

CONCLUSIONS

For small pupil sizes, there is little difference in HCVA and LCVA between various refractive corrections. However, for larger pupils, HCVA and LCVA are superior with TS contact lenses and SC versus AS contact lenses by approximately a half-line or more, which is considered to be clinically significant. Superior vision can be achieved for low astigmatic contact lens wearers using TS rather than AS contact lenses.

Risk Factors for the Development of Corneal Infiltrative Events Associated with Contact Lens Wear

PURPOSE

To identify risk factors for the development of corneal infiltrative events (CIEs) associated with contact lens wear, and to report other relevant clinical characteristics.

METHODS

A series of symptomatic contact lens wearers presenting consecutively to a large hospital clinic over a 1-year period were examined. The clinical severity of any CIE was determined with a scoring system, and general and lens-specific information was captured with a questionnaire. Logistic regression analyses were performed to investigate the association between a range of risk factors and the occurrence of any CIE and the subset of cases categorized as severe keratitis. Three quasi-independent control groups were used for this analysis: hospital, lens-matched, and population. The relationship between clinical severity and the delay in attending the hospital was investigated. The prevalence of symptoms and initial actions taken by patients are reported.

RESULTS

Factors identified as being associated with an increased risk of development of a CIE include: wearing modality/lens type (greatest risk for extended-wear hydrogel lenses of 7.1 vs. daily wear hydrogel lenses), male gender (relative risk 1.4), smoking (1.4), the absence of relevant ocular (1.8) and general health (2.4) problems, and the late winter months (greatest risk in March of 3.6 vs. July). The overall predictive value of these risk factors for a given individual was low. Shorter time delays in hospital attendance were associated with increasing severity of keratitis. Eye soreness was the most common initial symptom (prevalence 69%), and the most frequent initial course of action taken by the patient was lens removal (prevalence 50%).

CONCLUSIONS

Risk factors for the development of contact lens keratitis were identified that, although being of limited predictive value for individual patients, highlight general associations that may assist in the management of contact lens wearers. Such risk factors may also assist in the development of a more complete understanding of the etiology of contact-lens-associated CEIs.

Incidence of keratitis of varying severity among contact lens wearers

AIM

To determine the incidence of non-severe keratitis (NSK) and severe keratitis (SK) among wearers of current generation contact lenses.

METHODS

A 12 month, prospective, hospital based epidemiological study was conducted by examining all contact lens wearers presenting with a corneal infiltrate/ulcer to a hospital centre in Manchester. A clinical severity matrix was used to differentiate between NSK and SK, based on the severity of signs and symptoms. The size of the hospital catchment population and the wearing modalities (daily wear (DW) or extended wear (EW)) and lens types being used were estimated from relevant demographic and market data.

RESULTS

During the survey period, 80 and 38 patients presented with NSK and SK, respectively. The annual incidences (cases per 10,000 wearers) for each wearing modality and lens type were: DW rigid--NSK 5.7, SK 2.9; DW hydrogel daily disposable--NSK 9.1, SK 4.9; DW hydrogel (excluding daily disposable)--NSK 14.1, SK 6.4; DW silicone hydrogel--NSK 55.9, SK 0.0; EW rigid--NSK 0.0, SK 0.0; EW hydrogel--NSK 48.2, SK 96.4; EW silicone hydrogel--NSK 98.8, SK 19.8. The difference in SK between EW hydrogel and EW silicone hydrogel was significant (p = 0.04).

CONCLUSIONS

A clinical severity matrix has considerable utility in assessing contact lens related keratitis. There is a significantly higher incidence of SK in wearers who sleep in contact lenses compared with those who only use lenses during the waking hours. Those who choose to sleep in lenses should be advised to wear silicone hydrogel lenses, which carry a five times decreased risk of SK for extended wear compared with hydrogel lenses.

Metabolic response after intraarterial 90Y-glass microsphere treatment for colorectal liver metastases: comparison of quantitative and visual analyses by 18F-FDG PET

Our aim was to assess the feasibility of using PET for quantifying metabolic response after intraarterial (90)Y-glass microspheres for metastatic colorectal cancer to the liver by comparing visual estimates with hepatic standardized uptake values (SUVs).

METHODS

Twenty-seven patients (15 men, 12 women; age, 68 +/- 12 y [+/-SD]) with metastatic colorectal cancer to the liver, and tumor progression despite polychemotherapy, were included. All patients had baseline CT or MRI, (18)F-FDG PET, hepatic angiography, and intraarterial (99m)Tc-labeled macroaggregated albumin scanning. Patients were treated with (90)Y-glass microspheres and were monitored for 3 mo using PET and serum carcinoembryonic antigen. The average absorbed dose was 139 +/- 22 Gy. All treatments were performed on a lobar basis. For each case analyzed, regions of interest were drawn along the liver edge to measure SUVs on maximum-intensity-projection (MIP) and resliced axial images. Concomitantly, the visual estimate was graded as +1, 0, -1, -2, or -3 for progression, no change, and mild, moderate, and dramatic improvement at posttreatment PET.

RESULTS

Visual estimates placed 20 patients in the response category (-3 to -1) and 7 patients in the nonresponse category (0 to +1). There was a significant drop in the median SUV on the resliced axial images from 10,455 at baseline to 9,075 after treatment (P = 0.011) for the entire group. The percentage of metabolic response was significantly greater in the response group compared with that of the nonresponse group (-26% +/- 25% vs. +6% +/- 15%, P = 0.004). This correlated significantly with the respective visual estimates (r = 0.75, P < 0.0001). Furthermore, the direction of change agreed in 85% of patients using both methods. There was no significant correlation when the SUV from the simplified MIP images were used in the coronal or sagittal manner.

CONCLUSION

It is feasible to quantify reduction of hepatic tumor metabolism objectively after (90)Y treatment for unresectable metastatic disease to the liver. SUVs of the entire axial slices of liver agree well with subjective visual evaluations. Quantitative PET is a useful technique in the treatment response evaluation of patients after (90)Y-glass microspheres.

Assessment of static isolator cages with automatic watering when used with conventional husbandry techniques as a factor in the transmission of mouse hepatitis virus

This study evaluated protection against mouse hepatitis virus (MHV) afforded by static filter-top caging when automatic watering was used with conventional husbandry techniques as a labor-saving option. We fitted one side of a double-sided 72-cage rack with valves external to each cage; cages on the other side were fitted with shielded internal valves. More than 50% of the mice were breeding mice, and 30% were genetically altered. One cage of mice on each shelf on both sides of the rack was infected with MHV-A59. Each row of cages also contained one standard cage (no filter top) of uninoculated mice at various distances from the infected cage. At 2, 4, and 6 weeks after infection of the mice in the test cages, uninoculated mice in 22 cages were tested by serology, and at 8 weeks the uninoculated mice in 54 cages were tested by serology and those in 24 cages were tested by polymerase chain reaction (PCR) amplification of fecal samples to assess transmission of infection. At 8 weeks post-infection, mice in one uninoculated cage (which had a filter top and an internal valve and was adjacent to a cage of inoculated mice) was seropositive. Examination of feces by PCR revealed MHV shedding in mice in nine uninoculated cages (three lacking filter tops but with internal valve cages; two with filter tops and internal valve cages and adjacent to non-filter top cages; two non-filter-top cages with external valves; and two filter-top cages with external valves, of which one was adjacent to a non-filter-top cage). Routine husbandry using either automatic water valve system prevented (with one exception) transmission among filter-top cages for at least 6 weeks. The 10 cages where transmission occurred were non-filter-top cages (n = 5) and filter-top cages adjacent to non-filter top, infected, or sentinel cages (n = 5). These results suggest that the use of filter top-caging with automatic watering may limit MHV transmission for 6 weeks, during which immunocompetent mice would be expected to clear the virus. Our findings also suggest that long-term use of automatic watering in static filter-top cages handled using conventional husbandry techniques may not prevent transmission in the vicinity of high virus concentrations or open caging.

Dosage uniformity in hydrocortisone ointment B.P

The content uniformity of hydrocortisone in seven commercially available brands of hydrocortisone ointment B.P. 1% has been investigated. Fifty 5 mg samples were assayed by high pressure liquid chromatography and the results indicated that for 95% confidence levels only two of the ointments exhibited no positive skewness, one exhibited a significant degree of positive skewness and four exhibited a highly significant degree of positive skewness. The extent of the skewed distributions is discussed in relation to previously published particle/agglomerate distributions for these ointments. The content uniformity in terms of the coefficient of variation CE calculated from the h.p.l.c. data is compared with the coefficient of variation CP that can be predicted from mixing theory on the basis of the particle/agglomerate distribution of the hydrocortisone. The departure from normality in drug content uniformity in the ointment is attributed to the hydrocortisone particles not being individually available for randomization, a large number being in an agglomerated form. That is, the manufacturing process is failing to achieve the full potential of the formulation by dispersing all of the agglomerates. Theoretical and experimental models predict that percutaneous absorption of drug may be enhanced over areas, where agglomerates are located, possibly not only resulting in localized toxicity but increased systemic availability. Drug content variability in small samples (5 mg) of topical steroid formulations could also effect the degree of skin blanching response in Mackenzie-Stoughton type tests since 5 mg portions containing in excess of twice the labelled strength were found. Regulatory control of content uniformity should be considered for certain topical steroids if unintentional over-dosage on small discrete areas is to be avoided.

Identification of strains of herpes simplex virus by comparison of the density of their DNA using the preparative ultracentrifuge

The buoyant densities of the DNA of herpes simplex virus type 1, type 2 and Pseudorabies virus, as determined in the analytical ultracentrifuge, are 1.725, 1.727 and 1.731 correlating with G+C contents of 67, 69 and 73 per cent respectively. The density differences for the DNA's of type 1 and type 2 herpes simplex viruses have been confirmed in experiments with isotopically labelled DNA from four type 1 and six type 2 strains by preparative CsCl gradient ultracentrifugation. The DNA of all the type 2 strains was denser than that of any of the type 1 strains examined. Despite these differences in DNA base composition of type 1 and type 2 strains, nearest neighbour analysis of their DNA's disclosed no obvious differences in doublet pattern or general design.