Field-Based Planetary Protection Operations for Melt Probes: Validation of Clean Access into the Blood Falls, Antarctica, Englacial Ecosystem

Subglacial environments on Earth offer important analogs to Ocean World targets in our solar system. These unique microbial ecosystems remain understudied due to the challenges of access through thick glacial ice (tens to hundreds of meters). Additionally, sub-ice collections must be conducted in a clean manner to ensure sample integrity for downstream microbiological and geochemical analyses. We describe the field-based cleaning of a melt probe that was used to collect brine samples from within a glacier conduit at Blood Falls, Antarctica, for geomicrobiological studies. We used a thermoelectric melting probe called the IceMole that was designed to be minimally invasive in that the logistical requirements in support of drilling operations were small and the probe could be cleaned, even in a remote field setting, so as to minimize potential contamination. In our study, the exterior bioburden on the IceMole was reduced to levels measured in most clean rooms, and below that of the ice surrounding our sampling target. Potential microbial contaminants were identified during the cleaning process; however, very few were detected in the final englacial sample collected with the IceMole and were present in extremely low abundances (∼0.063% of 16S rRNA gene amplicon sequences). This cleaning protocol can help minimize contamination when working in remote field locations, support microbiological sampling of terrestrial subglacial environments using melting probes, and help inform planetary protection challenges for Ocean World analog mission concepts.

12 The incidence, clinical features, and management of essential infantile esotropia in the United Kingdom. A British Ophthalmology Surveillance Unit (BOSU) study - Final Report

Studies from the UK have reported declining rates of surgery for childhood esotropia. It is not known if this equates to a reduced incidence of essential infantile esotropia (EIE). A national study was undertaken through the British ophthalmology surveillance unit (BOSU) to determine the incidence presenting features and management of EIE in the UKData from a prospective national observational cohort of newly diagnosed EIE presenting to clinicians in the United Kingdom over a 12-month period was collected. Cases with a confirmed diagnosis by a clinician of a constant, non-accommodative esotropia ≥ 20 prism dioptres (PD), presenting at ≤ 12months, with no neurological or ocular abnormalities were identified through BOSU. Follow up data was collected at 12 months. Data was collected on the age, gender, ethnicity, birth history, age at diagnosis, age at intervention, angle of esotropia, refraction, associated features of amblyopia, overelevation in adduction (OEIA), latent nystagmus and dissociated vertical deviation (DVD), method of management and outcomes.During the period of observation between October 2017 to October 2018 a total of 57 cases were reported giving an incidence of EIE of 1 in 12,828 live births with a corrected incidence of 1 in 9027 live births allowing for estimated under reporting. The mean age of diagnosis and intervention were 7.05± 2.6 months (range 2 to 12 months) and 14.7± 4.9 (range 6.5-28.1 months) respectively. The majority were Caucasians 86.5% and 52.7% were female. Management was surgical in 59.6%, and botulinum toxin alone in 22.8%, 17.5% were observed. There was no significant difference in the age of presentation (P=0.6), gender (P=0.8), prematurity (P=0.5), deprivation indices (P=0.68), refraction (P=0.7), OEIA (P=0.6), DVD (P=0.7) or follow up (P=0.3) between the three groups. The preoperative angle of esotropia was smaller in the observation group (P=0.04). The post-operative angle of esotropia was not statistically significant between botulinum toxin or surgery (P=0.3) though the age of intervention was earlier in the botulinum group (P=0.007). Early intervention did not influence the motor post intervention outcomes between 0-10 prism dioptres of esotropia (P=0.78). Amblyopia (P=0.02) and latent nystagmus (P=0.009) was more common in the observation group.The incidence of EIE in the UK is considerably lower than reported in other population-based studies. The preferred method of treatment was surgical with earlier intervention in those treated with botulinum toxin. An early age of intervention did not influence motor outcomes. Parental choice and amblyopia treatment were reasons cited for conservative management in the observational group.

Resectability of bilobar liver tumours after simultaneous portal and hepatic vein embolization versus portal vein embolization alone: meta-analysis

BACKGROUND

Many patients with bi-lobar liver tumours are not eligible for liver resection due to an insufficient future liver remnant (FLR). To reduce the risk of posthepatectomy liver failure and the primary cause of death, regenerative procedures intent to increase the FLR before surgery. The aim of this systematic review is to provide an overview of the available literature and outcomes on the effectiveness of simultaneous portal and hepatic vein embolization (PVE/HVE) versus portal vein embolization (PVE) alone.

METHODS

A systematic literature search was conducted in PubMed, Web of Science, and Embase up to September 2022. The primary outcome was resectability and the secondary outcome was the FLR volume increase.

RESULTS

Eight studies comparing PVE/HVE with PVE and six retrospective PVE/HVE case series were included. Pooled resectability within the comparative studies was 75 per cent in the PVE group (n = 252) versus 87 per cent in the PVE/HVE group (n = 166, OR 1.92 (95% c.i., 1.13-3.25)) favouring PVE/HVE (P = 0.015). After PVE, FLR hypertrophy between 12 per cent and 48 per cent (after a median of 21-30 days) was observed, whereas growth between 36 per cent and 67 per cent was reported after PVE/HVE (after a median of 17-31 days). In the comparative studies, 90-day primary cause of death was similar between groups (2.5 per cent after PVE versus 2.2 per cent after PVE/HVE), but a higher 90-day primary cause of death was reported in single-arm PVE/HVE cohort studies (6.9 per cent, 12 of 175 patients).

CONCLUSION

Based on moderate/weak evidence, PVE/HVE seems to increase resectability of bi-lobar liver tumours with a comparable safety profile. Additionally, PVE/HVE resulted in faster and more pronounced hypertrophy compared with PVE alone.

Human versus machine: does artificial intelligence add value to identification of hypertrophic cardiomyopathy in pediatric patients?

Introduction

An abnormal increase in left ventricular thickness is a hallmark of hypertrophic cardiomyopathy (HCM). Although standard measures of left ventricular voltage abnormalities on electrocardiograms (ECGs) have high false positive rates and poor correlation to left ventricular thickness, ECGs continue to be part of most screening programs. We developed a machine learning model for HCM classification from ECG in a pediatric cohort and compared its efficacy to that of clinician specialists.

Purpose

To compare clinician-based predictions of HCM to a machine learning model trained to classify pediatric patients with HCM utilizing 12-lead ECG.

Methods

ECGs from patients <19 years with HCM, including those with HCM gene mutations, were compared to those from age- and sex-matched controls with normal heart structure and function on echocardiogram. Patients with a known history of primary causes of left ventricular hypertrophy such as aortic stenosis or glycogen storage disease were excluded. A cascaded convolutional neural network was developed combining a residual neural network with a 2-layer dense neural network with 10-fold cross validation. The performance of the machine learning based HCM classification was compared to that of two independent clinicians.

Results

Analytic sample included data from 82 patients with clinical HCM compared to 91 healthy control subjects. The machine model AUC was 0.89 (0.84–0.94). Clinician inter-rater reliability was 0.8. The clinicians had a higher specificity (97% vs 82%) but lower sensitivity (50% vs 78%) than the machine learning model. Compared to clinician-classification, the positive predictive value was lower in the machine model (82% vs 93%).

Conclusion

In this preliminary study, machine learning classification of HCM utilizing 12-lead ECG had greater sensitivity than that of clinician interpretation. Machine learning may play a role in screening and diagnosis, including in subjects with normal-appearing ECG. Evaluation of its utility in a larger cohort is needed.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Le Bonheur Children's Hospital

Dragon 1 Protocol Manuscript: Training, Accreditation, Implementation and Safety Evaluation of Portal and Hepatic Vein Embolization (PVE/HVE) to Accelerate Future Liver Remnant (FLR) Hypertrophy

STUDY PURPOSE

The DRAGON 1 trial aims to assess training, implementation, safety and feasibility of combined portal- and hepatic-vein embolization (PVE/HVE) to accelerate future liver remnant (FLR) hypertrophy in patients with borderline resectable colorectal cancer liver metastases.

METHODS

The DRAGON 1 trial is a worldwide multicenter prospective single arm trial. The primary endpoint is a composite of the safety of PVE/HVE, 90-day mortality, and one year accrual monitoring of each participating center. Secondary endpoints include: feasibility of resection, the used PVE and HVE techniques, FLR-hypertrophy, liver function (subset of centers), overall survival, and disease-free survival. All complications after the PVE/HVE procedure are documented. Liver volumes will be measured at week 1 and if applicable at week 3 and 6 after PVE/HVE and follow-up visits will be held at 1, 3, 6, and 12 months after the resection.

RESULTS

Not applicable.

CONCLUSION

DRAGON 1 is a prospective trial to assess the safety and feasibility of PVE/HVE. Participating study centers will be trained, and procedures standardized using Work Instructions (WI) to prepare for the DRAGON 2 randomized controlled trial. Outcomes should reveal the accrual potential of centers, safety profile of combined PVE/HVE and the effect of FLR-hypertrophy induction by PVE/HVE in patients with CRLM and a small FLR.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT04272931 (February 17, 2020). Toestingonline.nl: NL71535.068.19 (September 20, 2019).

Tuberous Sclerosis: A Rare Disease with an Orphan Complex

Introduction In the Republic of Ireland, there are no tuberous sclerosis complex (TSC) specialist clinics. Methods A clinical audit was carried out to assess the care received by patients attending two specialist adult epilepsy specialist centres, measuring their care against the UK guidelines. Results Although many baseline investigations are carried out, only one-third of patients had diagnostic genetic testing results available. Neuropsychiatry is largely neglected, and the completion of neuropsychiatric assessments checklists is inadequate. Discussions concerning SUDEP are not happening and access to treatment is limited. Reporting of radiological findings in TSC is inconsistent and the number of adults with TSC accessing specialist epilepsy services appear to be low. Discussion TSC care in the Republic of Ireland is fragmented, difficult to navigate and wasteful of resources due to the complex nature of the disease and no formal clinical setting to manage it. The service gaps echo the demand for an improved care system including consistent radiological reporting of TSC pathology. The absence of a specialist TSC clinic compounds the complexity of navigating care for individuals with TSC, families and healthcare professionals. Extending this audit nationally will give a more complete picture and highlight the resources required to bring care of these patients in line with recommended guidelines.

Machine learning can identify hypertrophic cardiomyopathy in pediatric patients using electrocardiogram

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): Le Bonheur Children’s Hospital

Background

Hypertrophic cardiomyopathy (HCM) is the most common genetic based heart disease and is associated with sudden cardiac death, particularly in young athletes. Standard measures of voltage abnormalities on electrocardiograms (ECGs) have demonstrated high false positive rates and poor correlation of LV thickness. Despite poor testing characteristics, ECGs continue to be part of most adolescent and family screening programs. While recent studies suggest that machine learning based analysis of ECGs may have utility in the identification of HCM in adult patients, there are limited data regarding its effectiveness in the pediatric population.

Purpose

The purpose of this study was to develop a deep learning model utilizing raw digital ECG data to accurately distinguish healthy pediatric patients from those with HCM.

Methods

ECGs from patients < 19 years with HCM were compared to ECGs from age- and sex-matched patients that underwent evaluation with ECG and echocardiogram for chest pain, sports clearance, syncope, or abnormal ECG between January 2011 and March 2021. Patients with a known clinical history of primary causes of left ventricular hypertrophy such as aortic stenosis, systemic hypertension, and glycogen storage disease were excluded from the study. Unsupervised signal processing tools including descriptive statistics and wavelet transformation were used to extract features from 12-lead ECG signals. A cascaded convolutional neural network was developed combining a residual neural network to extract features from waveform 12-lead ECG signals with a 2-layer dense neural network to embed features from signal processing tools. Model performance was evaluated by 10-fold stratified cross validation.

Results

The analytic sample included 181 patients (72% male; 63% Caucasian). Mean age was 12.3 ± 5.8 years. A cascaded deep learning model classified patients into healthy or HCM categories with a cross validation sensitivity of 77.7% and specificity of 81.6%. The positive predictive value was 82% and AUC of 0.89 (0.84-0.94).

Conclusion

This CNN trained with a relatively small number of images was able to accurately identify HCM in pediatric patients from standard 12-lead ECG. Evaluation of its potential utility in larger populations is needed.

Hospital outbreak of New Delhi metallo-β-lactamase type-1 (NDM-1) in Salmonella enterica with inter-species plasmid transmission

New Delhi metallo-β-lactamase (NDM) gene confers high-level resistance to an array of β-lactams including carbapenems. Short- and long-read sequencing was used to investigate outbreaks of NDM-positive Enterobacterales including a potential horizontal gene transfer (HGT) event of an NDM-positive plasmid between Salmonella enterica and Klebsiella pneumoniae. Genomic analysis demonstrated a high degree of similarity between NDM-carrying plasmids from patient 1 in K. pneumoniae and patient 2 with S. enterica, K. pneumoniae and Klebsiella oxytoca, confirming an inter-species HGT event. The utility of whole-genome sequencing was demonstrated for in-hospital outbreaks, previously undetected using traditional infection-control surveillance.

Reference Protocol to Assess Analytical Performance of Higher Order Structural Analysis Measurements: Results from an Interlaboratory Comparison

Measurements of protein higher order structure (HOS) provide important information on stability, potency, efficacy, immunogenicity, and biosimilarity of biopharmaceuticals, with a significant number of techniques and methods available to perform these measurements. The comparison of the analytical performance of HOS methods and the standardization of the results is, however, not a trivial task, due to the lack of reference protocols and reference measurement procedures. Here, we developed a protocol to structurally alter and compare samples of somatropin, a recombinant biotherapeutic, and describe the results obtained by using a number of techniques, methods and in different laboratories. This, with the final aim to provide tools and generate a pool of data to compare and benchmark analytical platforms and define method sensitivity to structural changes. Changes in somatropin HOS, induced by the presence of zinc at increasing concentrations, were observed, both globally and at more localized resolution, across many of the methods utilized in this study and with different sensitivities, suggesting the suitability of the protocol to improve understanding of inter- and cross-platform measurement comparability and assess analytical performance as appropriate.

A role for cardiopulmonary exercise testing in detecting physiological changes underlying health status in Idiopathic pulmonary fibrosis: a feasibility study

Introduction

There is limited data available on the use of CPET as a predictive tool for disease outcomes in the setting of IPF. We investigated the feasibility of undertaking CPET and the relationship between CPET and quality of life measurements in a well-defined population of mild and moderate IPF patients.

Methods

A prospective, single-centre observational study.

Results

Thirty-two IPF patients (mild n = 23, moderate n = 9) participated in the study, n = 13 mild patients attended for repeat CPET testing at 12 months. At baseline, total K-BILD scores and total IPF-PROM scores significantly correlated with 6MWT distance, but not with baseline FVC % predicted, TLco % predicted, baseline or minimum SpO₂. VO₂ peak/kg at AT positively correlated with total scores, breathlessness/activity and chest domains of the K-BILD questionnaire (p < 0.05). VO₂ peak significantly correlated with total IPF PROM scores and wellbeing domains (p < 0.05), with a trend towards statistical significance for total IPF-PROM and VO₂ peak/kg at anaerobic threshold (p = 0.06).

There was a statistically significant reduction in FVC% predicted at 12 months follow up, although the mean absolute decline was < 10% (p < 0.05). During this period VO₂ peak significantly reduced (21.6 ml/kg/min ± 2.9 vs 19.1 ± 2.8; p = 0.017), with corresponding reductions in total K-BILD and breathlessness/activity domains that exceeded the MCID for responsiveness. Lower baseline VO₂ peak/kg at anaerobic threshold correlated with greater declines in total K-BILD scores (r =  − 0.62, 0.024) at 12 months. Whilst baseline FVC% predicted or TLco % predicted did not predict change in health status,

Conclusion

We have shown that it is feasible to undertake CPET in patients with mild to moderate IPF.

CPET measures of VO₂ peak correlated with both baseline and change in K-BILD measurements at 1 year, despite relatively stable standard lung function (declines of < 10% in FVC), suggesting its potential sensitivity to detect physiological changes underlying health status.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01520-8.

Enumeration of Total Aerobic Microorganisms in Foods by SimPlate® Total Plate Count–Color Indicator Methods and Conventional Culture Methods: Collaborative Study

The relative efficacy of the SimPlate® Total Plate Count–Color Indicator (TPC–CI) method (SimPlate 35°C) was compared with the AOAC Official Method 966.23 (AOAC 35°C) for enumeration of total aerobic microorganisms in foods. The SimPlate TPC–CI method, incubated at 30°C (SimPlate 30°C), was also compared with the International Organization for Standardization (ISO) 4833 method (ISO 30°C). Six food types were analyzed: ground black pepper, flour, nut meats, frozen hamburger patties, frozen fruits, and fresh vegetables. All foods tested were naturally contaminated. Nineteen laboratories throughout North America and Europe participated in the study. Three method comparisons were conducted. In general, there was &lt;0.3 mean log count difference in recovery among the SimPlate methods and their corresponding reference methods. Mean log counts between the 2 reference methods were also very similar. Repeatability (sr) and reproducibility (sR) standard deviations were similar among the 3 method comparisons. The SimPlate method (35°C) and the AOAC method were comparable for enumerating total aerobic microorganisms in foods. Similarly, the SimPlate method (30°C) was comparable to the ISO method when samples were prepared and incubated according to the ISO method.

The role of anatomic pelvic dissection in the successful closure of bladder exstrophy: an aid to success

INTRODUCTION

Classic bladder exstrophy is one of the rarest congenital anomalies compatible with life. Surgical treatment of bladder exstrophy has progressed, but the goal of surgery remains a successful primary bladder closure. Several factors have been identified to decrease the risk of failed closure, including appropriate use of osteotomy and adequate postoperative immobilization and analgesia. However, the role of the radical anatomic pelvic dissection, including dissection of the urogenital diaphragm fibers, in a successful closure has not yet been extensively explored.

OBJECTIVE

The objective of this study was go examine the role of radical anatomic pelvic dissection, including dissection of the urogenital diaphragm fibers, in patients with classic bladder exstrophy.

STUDY DESIGN

This was a retrospective study based on an institutional database.

METHODS

A retrospective review from an institutional approved database of more than 1,300 patients with epispadias-exstrophy complex was performed. The inclusion criteria included patients with classic bladder exstrophy with at least one failed bladder closure and a reclosure at the authors' institution with a single senior surgeon. Data collection included demographics, clinical variables, and status of urogenital diaphragm fibers. Magnetic resonance imaging (MRI) scans, if available, were reviewed with a pediatric radiologist to identify urogenital diaphragm fibers.

RESULTS

From the database, 93 patients met inclusion criteria. Of these patients, 74 had urogenital diaphragm fibers completely intact at the time of repeat closure, whereas 19 patients did not. There was no association with age or gender and status of urogenital diaphragm fibers. There was no association with osteotomy, the type of primary bladder closure, surgeon subspecialty, and the status of the urogenital fibers. Fourteen patients had at least two prior closures; surprisingly, 11 of these repeat closure patients still had intact urogenital fibers even after two prior closures.

DISCUSSION

The recent development and application of 3D MRI-guided pelvic dissection in a large group of patients led the authors to investigate whether adequate pelvic floor dissection had been accomplished at primary or secondary closure. Several patients had MRI scans performed before repeat closure in which the urogenital diaphragm fibers were identified to be intact on imaging; this was corroborated with surgical findings. Approximately 80% of patients had their urogenital diaphragm fibers completely intact and, therefore, did not have an adequate pelvic dissection during their primary or secondary bladder closure, putting the success of their previous closures at risk.

CONCLUSION

Inadequate pelvic diaphragm dissection, defined as intact urogenital diaphragm fibers, demonstrated in a large group of patients with failed exstrophy closure, may be a decisive factor in bladder closure failure. The use of 3D intra-operative image guidance may aid in a safer and more successful pelvic dissection.

Differences in health outcomes associated with initial adherence to oral antidiabetes medications among veterans with uncomplicated Type 2 diabetes: a 5-year survival analysis

AIM

To determine the association of adherence to oral antidiabetes medication with macrovascular and microvascular complications, time to insulin therapy, revascularization, admissions, and death among veterans with uncomplicated diabetes.

METHODS

This was a retrospective cohort study using the Veterans Affairs Corporate Data Warehouse to examine 159 032 veterans diagnosed with uncomplicated diabetes during 2002-2014 and starting oral antidiabetes therapy for the first time. The first uncomplicated diabetes diagnosis was identified and confirmed by subsequent oral antidiabetes therapy initiation. Adherence was calculated from outpatient pharmacy records using the proportion of days covered over the first year of therapy. Health outcomes were observed up to 5 years beyond the first oral antidiabetes agent fill, and compared according to adherence status using Cox proportional hazards models adjusted for baseline demographic and clinical characteristics.

RESULTS

During the first 5 years of oral antidiabetes treatment, people initially non-adherent to oral antidiabetes therapy were more likely to experience myocardial infarction (hazard ratio 1.14, 95% CI 1.03-1.27) and ischaemic stroke (hazard ratio 1.22, 95% CI 1.05-0.1.42), or to die (hazard ratio 1.21; 95% CI 1.15-1.28). Veterans with <20% adherence to oral antidiabetes therapy in the first year had particularly high hazards for ischaemic stroke (hazard ratio 1.78, 95% CI 1.27-2.49) and all-cause death (hazard ratio 1.33, 95% CI 1.17-151). Adherent people were more likely to be diagnosed with a microvascular complication or chronic kidney disease.

CONCLUSIONS

People who are non-adherent to treatment were more likely to experience detrimental health outcomes within the first 5 years of antidiabetes therapy. Adherence is paramount to disease management and this should be stressed from the time at which treatment is initiated.

Solitary fibrous tumor of the ischioanal fossa-a multidisciplinary approach to management with radiologic-pathologic correlation

Solitary fibrous tumors are primary mesenchymal tumors, which may occur in any part of the body. Overall, these tumors are considered to have intermediate malignant potential with 5- and 10-year metastasis-free and overall disease-specific survival rates of 74% and 55%, and 89% and 73%, respectively (Demicco et al, 2012). Herein we present an unusual case of solitary fibrous tumors involving the ischioanal fossa in a 19-year-old woman with radiologic-pathologic correlation. This case was complicated by extensive tumor vascularity and was thus managed with preoperative embolization followed by en bloc surgical resection.

Choice Reaction Times and the Theory of Intermittency in Human Performance

One visual signal, drawn from two equi-probable alternatives, was followed at a variable interval by a similar signal, also drawn from two equi-probable alternatives. The relationship between reaction time to the second signal and the interval between signals was studied under the following conditions: (1) Subjects were trained from the beginning to regard the first signal as irrelevant. (2) Subjects were asked to report on the nature of the first signal after they had responded to the second. The interval between signals was one of the five values, 50, 100, 150, 200, 250 millisec. In the regular interval situation the same interval was used over a block of 20 trials. In the random interval situation the values of the interval were randomly arranged, with equal frequency within each block of 20 trials.

The results showed: (1) In the random interval situation there was a definite disturbing effect of the first signal on the reaction time to the second, despite the fact that subjects were trained to disregard the first signal. However, the delays in reaction time were significant only at the shortest interval, 50 millisec. (2) In the regular interval situation this disturbing effect was not evident. (3) The additional requirement of having to report on the nature of the first signal produced no consistent increase in reaction time to the second signal. Some implications of these results for the conception of the human operator as a channel of limited capacity are discussed.

The Human Operator as a Single Channel Information System

A further experiment is reported on reaction times to stimuli separated by short intervals. On this occasion an auditory stimulus was followed by a visual stimulus. Results indicate that the pattern of delays at short intervals is the same as the pattern of delays when the stimuli are presented in one modality only. This suggests a model of the human operator functioning as a single channel through which information from both sense modalities has to pass before appropriate responses are organized. An attempt is also made to reconcile data with the known facts about the peripheral and central components of reaction time and the possibility that delays are the result of occupation of the channel for a central time plus a central refractory time is suggested.

Imitative Responses and the Rate of Gain of Information

A series of experiments is described on audio-verbal reaction times. In the first experiment the signals were letters or digits recorded on magnetic tape and presented through earphones. In the second experiment the signals were nonsense syllables drawn from vocabularies of different size. The subjects responded by repeating what they heard as soon as it was presented and reaction times were recorded. It is shown that the size of the group from which the signal is drawn has little effect on the reaction time to that signal. A distinction is drawn between situations in which the rate of gain of information may be expected to apply and situations in which it may not apply. It is suggested that many highly practiced skills fall into the latter category.

The Role of “Attention” in the Psychological Refractory Period

A set of experiments is described in which two consecutive signals, separated by a variable time interval, were presented to the subjects. Manual reaction times to these signals were recorded and the delays in the reactions to the second of the two signals were compared in situations where the subject was required to respond to both signals and where he was not required to respond to the first signal.

The magnitude of the delays found at any particular interval were the same in both situations, and there was not much difference between cases where the two signals were in the same sense modality (visual) or in different modalities (visual, followed by auditory). These results confirm the suggestion of the writer in a previous paper that there may be a common analysing and classifying system for auditory and visual information and also illustrate a new point. It is paying attention to a signal rather than performing any overt response to it which gives rise to delays in subsequent responses.

The Combination of Information from Different Sources

In this experiment subjects were presented with visual information from two different sources and were required to combine it in order to make the correct response. The time interval between the two signals was varied in two different ways (a) regularly and (b) randomly. Reaction times were measured from the moment of occurrence of the second signal. By this means the time course of the decision procedure involved in combining the information from the two sources was analysed.

Results indicate that subjects may deal with the situation in two ways (i) by means of a “perceptual” classification in which the individual elements are not analysed separately, or (ii) by means of an “intellectual” classification in which each signal is analysed sequentially. These two methods correspond to the experimental conditions of (a) regular intervals and (b) random intervals.

It is argued that when subjects use the latter strategy the results are consistent with the conception of the human operator as an intermittent analysing system.

The Limits of the “Psychological Refractory Period”

Previous evidence on the psychological refractory period is shown to be inadequate on the crucial issue of whether delays, which cannot be overcome by practice, occur in responding to the second of two signals, when the interval between them is less than 0·5 seconds. For simple key pressing responses it is shown that when the interval between signals is less than the reaction time to the first signal, delays in the reaction time to the second signal occur in a predictable manner. When the interval is greater than the first reaction time, however, no such delays are found. Possible reasons for the discrepancy between these and earlier findings are suggested.

Novel C-Terminal Heat Shock Protein 90 Inhibitors (KU711 and Ku757) Are Effective in Targeting Head and Neck Squamous Cell Carcinoma Cancer Stem cells

Advanced head and neck squamous cell carcinoma (HNSCC) remains a therapeutic challenge due to the development of therapy resistance. Several studies have implicated the development of cancer stem cells as a possible mechanism for therapy resistance in HNSCC. Heat shock protein 90's (Hsp90's) molecular chaperone function is implicated in pathways of resistance in HNSCC. Therefore, in the present study, we investigated the efficacy of novel C-terminal Hsp90 inhibitors (KU711 and KU757) in targeting HNSCC cancer stem cells (CSCs). Treatment of HNSCC human cell lines MDA1986, UMSCC 22B, and UMSCC 22B cisplatin-resistant cells with the KU compounds indicated complete blockage of self-renewal for the resistant and parent cell lines starting from 20 μM KU711 and 1 μM KU757. Dose-dependent decrease in the cancer stem cell markers CD44, ALDH, and CD44/ALDH double-positive cells was observed for all cell lines after treatment with KU711 and KU757. When cells were treated with either drug, migration and invasion were downregulated greater than 90% even at the lowest concentrations of 20 μM KU711 and 1 μM KU757. Western blot showed >90% reduction in client protein "stemness" marker BMI-1 and mesenchymal marker vimentin, as well as increase in epithelial marker E-cadherin for both cell lines, indicating epithelial to mesenchymal transition quiescence. Several CSC-mediated miRNAs that play a critical role in HNSCC therapy resistance were also downregulated with KU treatment. In vivo, KU compounds were effective in decreasing tumor growth with no observed toxicity. Taken together, these results indicate that KU compounds are effective therapeutics for targeting HNSCC CSCs.