High positive predictive value 22q11.2 microdeletion screening by prenatal cell-free DNA testing that incorporates fetal fraction amplification

OBJECTIVE

22q11.2 deletion syndrome (DS) is a serious condition with a range of features. The small microdeletion causing 22q11.2DS makes it technically challenging to detect using standard prenatal cfDNA screening. Here, we assess 22q11.2 microdeletion clinical performance by a prenatal cfDNA screen that incorporates fetal fraction (FF) amplification.

METHODS

The study cohort consisted of patients who received Prequel (Myriad Genetics, Inc.), a prenatal cfDNA screening that incorporates FF amplification, and met additional eligibility criteria. Pregnancy outcomes were obtained via a routine process for continuous quality improvement. Samples with diagnostic testing results were used to calculate positive predictive value (PPV).

RESULTS

379,428 patients met study eligibility criteria, 76 of whom were screen-positive for a de novo 22q11.2 microdeletion. 22 (29.7%) had diagnostic testing results available, and all 22 cases were confirmed as true positives, for a PPV of 100% (95% CI 84.6%-100%). This performance was based on cases that ranged broadly across FF (5.9%-41.1%, mean 23.0%), body mass index (22.3-44.8, mean 29.9), and gestational age at testing (10.0w-34.6w, median 12.7w). Ultrasound findings in screen-positive pregnancies were consistent with those known to be associated with 22q11.2DS.

CONCLUSION

22q11.2 microdeletion screening that incorporates FF amplification demonstrated high PPV across both general and high-risk population cohorts.

Characterization of Influenza-Like Illness Burden Using Commercial Wearable Sensor Data and Patient-Reported Outcomes: Mixed Methods Cohort Study

BACKGROUND

The burden of influenza-like illness (ILI) is typically estimated via hospitalizations and deaths. However, ILI-associated morbidity that does not require hospitalization remains poorly characterized.

OBJECTIVE

The main objective of this study was to characterize ILI burden using commercial wearable sensor data and investigate the extent to which these data correlate with self-reported illness severity and duration. Furthermore, we aimed to determine whether ILI-associated changes in wearable sensor data differed between care-seeking and non-care-seeking populations as well as between those with confirmed influenza infection and those with ILI symptoms only.

METHODS

This study comprised participants enrolled in either the FluStudy2020 or the Home Testing of Respiratory Illness (HTRI) study; both studies were similar in design and conducted between December 2019 and October 2020 in the United States. The participants self-reported ILI-related symptoms and health care-seeking behaviors via daily, biweekly, and monthly surveys. Wearable sensor data were recorded for 120 and 150 days for FluStudy2020 and HTRI, respectively. The following features were assessed: total daily steps, active time (time spent with >50 steps per minute), sleep duration, sleep efficiency, and resting heart rate. ILI-related changes in wearable sensor data were compared between the participants who sought health care and those who did not and between the participants who tested positive for influenza and those with symptoms only. Correlative analyses were performed between wearable sensor data and patient-reported outcomes.

RESULTS

After combining the FluStudy2020 and HTRI data sets, the final ILI population comprised 2435 participants. Compared with healthy days (baseline), the participants with ILI exhibited significantly reduced total daily steps, active time, and sleep efficiency as well as increased sleep duration and resting heart rate. Deviations from baseline typically began before symptom onset and were greater in the participants who sought health care than in those who did not and greater in the participants who tested positive for influenza than in those with symptoms only. During an ILI event, changes in wearable sensor data consistently varied with those in patient-reported outcomes.

CONCLUSIONS

Our results underscore the potential of wearable sensors to discriminate not only between individuals with and without influenza infections but also between care-seeking and non-care-seeking populations, which may have future application in health care resource planning.

TRIAL REGISTRATION

Clinicaltrials.gov NCT04245800; https://clinicaltrials.gov/ct2/show/NCT04245800.

Predictors of Seeking Care for Influenza-Like Illness in a Novel Digital Study

Background

Previous research has estimated that >50% of individuals experiencing influenza-like illness (ILI) do not seek health care. Understanding factors influencing care-seeking behavior for viral respiratory infections may help inform policies to improve access to care and protect public health. We used person-generated health data (PGHD) to identify factors associated with seeking care for ILI.

Methods

Two observational studies (FluStudy2020, ISP) were conducted during the United States 2019-2020 influenza season. Participants self-reported ILI symptoms using the online Evidation platform. A log-binomial regression model was used to identify factors associated with seeking care.

Results

Of 1667 participants in FluStudy2020 and 47 480 participants in ISP eligible for analysis, 518 (31.1%) and 11 426 (24.1%), respectively, sought health care. Participants were mostly female (92.2% FluStudy2020, 80.6% ISP) and aged 18-49 years (89.6% FluStudy2020, 89.8% ISP). In FluStudy2020, factors associated with seeking care included having health insurance (risk ratio [RR], 2.14; 95% CI, 1.30-3.54), more severe respiratory symptoms (RR, 1.53; 95% CI, 1.37-1.71), and comorbidities (RR, 1.37; 95% CI, 1.20-1.58). In ISP, the strongest predictor of seeking care was high symptom number (RR for 6/7 symptoms, 2.14; 95% CI, 1.93-2.38).

Conclusions

Using PGHD, we confirmed low rates of health care-seeking behavior for ILI and show that having health insurance, comorbidities, and a high symptom burden were associated with seeking health care. Reducing barriers in access to care for viral respiratory infections may lead to better disease management and contribute to protecting public health.

1471. Treatment of Influenza with Baloxavir was Associated with Reduced Absenteeism Compared with Oseltamivir in a Patient-Generated Health Data Study

Background

Lost productivity from workplace absenteeism is a significant component of the economic burden of influenza [1]. Antiviral treatment together with influenza vaccination may help reduce work time lost from influenza illness [2]. In clinical trials, baloxavir, an oral single dose treatment for influenza, demonstrated comparable symptom resolution to oseltamivir taken twice daily for 5 days [3]. We examined baloxavir real-world outcomes using patient generated health data (PGHD) to investigate the association between antiviral use and workplace absenteeism.

Methods

Using data from a participatory influenza-like illness (ILI) surveillance program (ISP), we identified participants who self-reported ILI using the online Evidation platform during the 2019-2020 influenza season in the United States. Participants who self-reported treatment with baloxavir or oseltamivir were included. We conducted an ordinal logistic regression to estimate the odds of missing work due to ILI, while adjusting for use of over-the-counter (OTC) medication, age, number of symptoms, US region, and comorbidities.

Results

Of 3658 participants eligible for inclusion in the analysis, 3285 (89.8%) were prescribed oseltamivir and 373 (10.2%) were prescribed baloxavir. A majority of participants (81.7%) reported missing at least one day of work. In the ordinal logistic regression, use of baloxavir was associated with lower odds of absenteeism, compared to oseltamivir (odds ratio [OR]: 0.748, 95% confidence interval [CI]: 0.616, 0.907). In addition, a higher number of symptoms (OR 2.922, 95% CI: 2.454, 3.481), older age (OR: 1.425, 95% CI: 1.162, 1.747), and use of OTC medication (OR: 1.242, 95% CI: 1.086, 1.420) were associated with higher odds of absenteeism. Due to a high rate of missing data on the timing of antiviral use (24.5% missing), its association with absenteeism could not be adequately assessed.

Conclusion

Treatment of patients with ILI with single dose baloxavir was associated with reduced workplace absenteeism compared to oseltamivir after adjusting for measured confounders. This study provides useful insight into factors associated with ILI-related workplace absenteeism and the potential real-world utility of baloxavir.

Disclosures

Hao Xu, MSc, Hoffmann-La Roche Limited: Employee Vincent Ukachukwu, n/a, Roche Products Ltd: Employee Devika Chawla, PhD, Genentech: Employee.

Baloxavir vs oseltamivir: reduced utilization and costs in influenza

OBJECTIVES

To determine whether baloxavir use is associated with lower health care resource utilization (HCRU) and costs for secondary influenza complications post treatment compared with oseltamivir.

STUDY DESIGN

Retrospective cohort study.

METHODS

Patients filling a prescription for baloxavir or oseltamivir within 48 hours following an influenza-related outpatient visit were identified in the 2018-2019 influenza season from the US Truven MarketScan Research Databases and propensity matched 1:2 (baloxavir:oseltamivir). Outcomes were assessed 15 and 30 days after antiviral treatment and included all-cause, all respiratory-related, and select respiratory-related (influenza, asthma, chronic obstructive pulmonary disease, or infection) HCRU and costs.

RESULTS

The study included 5080 baloxavir-treated and 10,160 matched oseltamivir-treated patients. All-cause emergency department (ED) visits and inpatient hospitalizations were lower in baloxavir-treated patients, with a statistically significant difference in the percentage hospitalized at 30 days (0.3% vs 0.5%; P = .04). ED visits for all or select respiratory-related conditions were significantly reduced with baloxavir (P < .01 for all comparisons). Mean per-patient cost savings at day 30 for all-cause, all respiratory-related, and select respiratory-related conditions were $79, $50, and $51, respectively, despite slightly higher prescription costs for baloxavir. In high-risk patients (baloxavir: n = 1958; oseltamivir: n = 3949), the incidence of ED visits was significantly lower for all respiratory-related and select respiratory-related conditions (P < .01); cost savings with baloxavir in the high-risk cohort were substantially greater than in the overall cohort.

CONCLUSIONS

Treatment of patients with influenza with single-dose baloxavir was generally associated with lower HCRU and costs post treatment compared with oseltamivir, particularly in high-risk patients.

Severity of COVID-19 and adverse long-term outcomes: a retrospective cohort study based on a US electronic health record database

OBJECTIVE

To identify potential risk factors for adverse long-term outcomes (LTOs) associated with COVID-19, using a large electronic health record (EHR) database.

DESIGN

Retrospective cohort study. Patients with COVID-19 were assigned into subcohorts according to most intensive treatment setting experienced. Newly diagnosed conditions were classified as respiratory, cardiovascular or mental health LTOs at >30-≤90 or >90-≤180 days after COVID-19 diagnosis or hospital discharge. Multivariate regression analysis was performed to identify any association of treatment setting (as a proxy for disease severity) with LTO incidence.

SETTING

Optum deidentified COVID-19 EHR dataset drawn from hospitals and clinics across the USA.

PARTICIPANTS

Individuals diagnosed with COVID-19 (N=57 748) from 20 February to 4 July 2020.

MAIN OUTCOMES

Incidence of new clinical conditions after COVID-19 diagnosis or hospital discharge and the association of treatment setting (as a proxy for disease severity) with their risk of occurrence.

RESULTS

Patients were assigned into one of six subcohorts: outpatient (n=22 788), emergency room (ER) with same-day COVID-19 diagnosis (n=11 633), ER with COVID-19 diagnosis≤21 days before ER visit (n=2877), hospitalisation without intensive care unit (ICU; n=16 653), ICU without ventilation (n=1837) and ICU with ventilation (n=1960). Respiratory LTOs were more common than cardiovascular or mental health LTOs across subcohorts and LTO incidence was higher in hospitalised versus non-hospitalised subcohorts. Patients with the most severe disease were at increased risk of respiratory (risk ratio (RR) 1.86, 95% CI 1.56 to 2.21), cardiovascular (RR 2.65, 95% CI 1.49 to 4.43) and mental health outcomes (RR 1.52, 95% CI 1.20 to 1.91) up to 6 months after hospital discharge compared with outpatients.

CONCLUSIONS

Patients with severe COVID-19 had increased risk of new clinical conditions up to 6 months after hospital discharge. The extent that treatment setting (eg, ICU) contributed to these conditions is unknown, but strategies to prevent COVID-19 progression may nonetheless minimise their occurrence.

515. Evolution of Treatment Patterns for Patients Hospitalized with COVID-19 in the United States

Background

COVID-19 remains a threat to public health, with over 30 million cases in the US alone. As understanding of optimal patient care has improved, treatment guidelines have continued to evolve. This study characterized real-world trends in treatment for US patients hospitalized with COVID-19, stratified by whether patients required invasive ventilation.

Methods

US patients diagnosed and hospitalized with COVID-19 between March 23 and December 31, 2020, in the Optum de-identified COVID-19 electronic health record (EHR) data set were identified. Both drug and procedure codes were used to ascertain medications, and both procedure and diagnostic codes were used to detect invasive ventilation during hospitalization. Medication trends were estimated by computing proportions of hospitalized patients receiving each drug weekly during the study period.

Results

In this cohort of 71,366 hospitalized patients, the largest observed change in care was related to chloroquine/hydroxychloroquine (HCQ) (Figure). HCQ usage peaked at 87% of patients receiving invasive ventilation (54% without ventilation) in the first week of this study (March 23-29), but declined to < 5% of patients, regardless of ventilation status, by the end of May. In contrast, dexamethasone usage was 10% at baseline in patients receiving ventilation (1% without ventilation) and increased to a steady state of >85% of patients receiving ventilation ( >50% without ventilation) by the end of June. Similarly, remdesivir usage increased sharply from a baseline of 2% of patients and continued to rise to a peak of 79% of patients receiving invasive ventilation (44% without ventilation) in November before declining.

Conclusion

Meaningful shifts in treatments for US patients hospitalized with COVID-19 were observed from March through December 2020. A dramatic decline was observed for HCQ use, likely owing to safety concerns, while usage of dexamethasone and remdesivir increased as evidence of their efficacy mounted. Across medications, usage was substantially more prevalent among patients requiring invasive ventilation compared with patients with less severe cases.

Disclosures

Kelly Zalocusky, PhD, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee) Shemra Rizzo, PhD, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee) Devika Chawla, PhD MSPH, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee) Yifeng Chia, PhD, F. Hoffmann-La Roche Ltd (Shareholder)Genentech, Inc. (Employee) Tripthi Kamath, PhD, F. Hoffmann-La Roche Ltd (Shareholder)Genentech, Inc. (Employee) Larry Tsai, MD, F. Hoffmann-La Roche Ltd (Shareholder)Genentech, Inc. (Employee)

26. Risk of Post–COVID-19 Dyspnea and Interstitial Lung Disease (ILD) in a Real-World Cohort of Patients Hospitalized with COVID-19 in the United States

Background

While COVID-19 carries substantial morbidity and mortality, the extent of long-term complications remains unclear. Reports suggest that acute lung damage associated with severe COVID-19 can result in chronic respiratory dysfunction. This study: (1) estimated the incidence of dyspnea and ILD after COVID-19 hospitalization, and (2) assessed risk factors for developing dyspnea and ILD in a real-world cohort of patients hospitalized with COVID-19 using US electronic health records (EHR).

Methods

Patients in the Optum de-identified COVID-19 EHR database who were hospitalized for COVID-19 (lab confirmed or diagnosis code) between February 20 and July 2020 and had at least 6 months of follow-up were eligible for analysis. Dyspnea and ILD were identified using diagnosis codes. The effects of baseline characteristics and hospitalization factors on the risk of incident dyspnea or ILD 3 to 6 months’ post discharge were evaluated.

Results

Among eligible patients (n=26,339), 1705 (6.5%) had dyspnea and 220 (0.8%) had ILD 3 to 6 months after discharge. Among patients without prior dyspnea or ILD (n=22,613), 110 (0.5%) had incident ILD (Table 1) and 1036 (4.6%) had incident dyspnea (Table 2) 3 to 6 months after discharge. In multivariate analyses, median (IQR) length of stay (LOS; 5.0 [3.0, 9.0] days in patients who did not develop ILD vs 14.5 [6.0, 26.0] days in patients who developed ILD; RR: 1.12, 95% CI: 1.08, 1.15; P=4.34 x 10^-10) and age (RR: 1.02, 95% CI: 1.01, 1.03; P=4.63 x 10^-3) were significantly associated with ILD. Median (IQR) LOS (5.0 [3.0, 9.0] days in patients who did not develop dyspnea vs 7 [4.0, 14.0] days in patients who developed dyspnea; RR: 1.04, 95% CI: 1.02, 1.06; P=8.52 x 10^-4), number of high-risk comorbidities (RR: 1.18, 95% CI: 1.12, 1.24; P=3.85 x 10^-9), and obesity (RR: 1.52, 95% CI: 1.25, 1.86; P=2.59 x 10^-4) were significantly associated with dyspnea.

Table 1. Selected Baseline Risk Factors for Incident ILD

Table 2. Selected Baseline Risk Factors for Incident Dyspnea

Conclusion

In a real-world cohort, 4.6% and 0.5% of patients developed dyspnea and ILD, respectively, after COVID-19 hospitalization. Multivariate analyses suggested that LOS, age, obesity, and comorbidity burden may be risk factors for post-COVID-19 respiratory complications. Limitations included sensitivity of diagnosis codes, availability of labs, and care-seeking bias.

Disclosures

Kelly Zalocusky, PhD, F. Hoffmann-La Roche Ltd (Shareholder)Genentech, Inc. (Employee) Devika Chawla, PhD MSPH, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee) Margaret Neighbors, PhD, F. Hoffmann-La Roche Ltd (Shareholder)Genentech, Inc. (Employee) Shemra Rizzo, PhD, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee) Larry Tsai, MD, F. Hoffmann-La Roche Ltd (Shareholder)Genentech, Inc. (Employee)

322. Risk Factors for COVID-19 Disease Severity Using Electronic-Health Records in a Real-World Cohort in the United States

Background

Over 32 million cases of COVID-19 have been reported in the US. Outcomes range from mild upper respiratory infection to hospitalization, acute respiratory failure, and death. We assessed risk factors associated with severe disease, defined as hospitalization within 21 days of diagnosis or death, using US electronic health records (EHR).

Methods

Patients in the Optum de-identified COVID-19 EHR database who were diagnosed with COVID-19 in 2020 were included in the analysis. Regularized multivariable logistic regression was used to identify risk factors for severe disease. Covariates included demographics, comorbidities, history of influenza vaccination, and calendar time.

Results

Of the 193,454 eligible patients, 36,043 (18.6%) were hospitalized within 21 days of COVID-19 diagnosis, and 6,397 (3.3%) died. Calendar time followed an inverse J-shaped relationship where severe disease rates rapidly declined in the first 25 weeks of the pandemic. BMI followed an asymmetric V-shaped relationship with highest rates of disease severity observed at the extremes. In the multivariable model, older age had the strongest association with disease severity (odds ratios and 95% confidence intervals of significant associations in Figure). Other risk factors were male sex, uninsured status, underweight and obese BMI, higher Charlson Comorbidity Index, and individual comorbidities including hypertension. Asthma and overweight BMI were not associated with disease severity. Blacks, Hispanics, and Asians experienced higher odds of disease severity compared to Whites.

Figure. Significant associations (odds ratio and 95% confidence intervals) with COVID-19 severity (hospitalization or death), adjusted for geographical division.

Reference and abbreviation categories: Charlson comorbidity index (CCI) = 0; Age = 18-30; Sex = Female; Race/Ethnicity = White; Insurance = Commercial; Body mass index (BMI) = 18.5-25; Calendar time = 0-25 weeks; Chronic obstructive pulmonary disease (COPD).

Conclusion

Odds of hospitalization or death have decreased since the start of the pandemic, with the steepest decline observed up to mid-August, possibly reflecting changes in both testing and treatment. Older age is the most important predictor of severe COVID-19. Obese and underweight, but not overweight, BMI were associated with increased odds of disease severity when compared to normal weight. Hypertension, despite not being included in many guidelines for vaccine prioritization, is a significant risk factor. Pronounced health disparities remain across race and ethnicity after accounting for comorbidities, with minorities experiencing higher disease severity.

Disclosures

Shemra Rizzo, PhD, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee) Ryan Gan, PhD, F. Hoffmann-La Roche Ltd (Shareholder)Genentech, Inc. (Employee) Devika Chawla, PhD MSPH, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee) Kelly Zalocusky, PhD, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee) Xin Chen, PhD, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee) Yifeng Chia, PhD, F. Hoffmann-La Roche Ltd (Shareholder)Genentech, Inc. (Employee)

281. Prevalence of Influenza Co-infection in a Real-world Cohort of COVID-19 Patients in the U.S

Background

Over 29 million people have been infected with COVID-19 in the U.S. alone. While COVID-19 carries serious morbidity and mortality, potential for co-infection with other respiratory infections remains unclear. We aimed to: (1) estimate co-infection prevalence of COVID-19 and influenza, and (2) compare demographics and clinical outcomes of co-infected patients to those of COVID-19 singly-infected patients using U.S. electronic health records (EHR).

Methods

Patients in the Optum De-identified COVID-19 EHR database diagnosed with COVID-19 (lab-confirmed or ICD code) between February 2020 and January 2021 were eligible. Influenza co-infection was defined as an influenza diagnosis (lab-confirmed or ICD code) within ±10 days of COVID-19 diagnosis. We report co-infection prevalence for all COVID-19 patients and for a subset of hospitalized COVID-19 patients.

Results

Among all COVID-19 patients (N = 549,532), 1,794 (0.3%) were co-infected with influenza. Among the hospitalized subset (N = 80,192), 242 (0.3%) were co-infected with influenza. In sensitivity analyses restricting to lab-confirmed influenza, co-infection prevalence was 0.1% overall and 0.2% among hospitalized patients. No meaningful differences were observed in baseline demographics between co-infected and singly-infected patients. Among hospitalized patients, univariate analysis suggested higher likelihood of invasive ventilation (12.8% vs. 9.8%; p=0.14), respiratory failure (56.2% vs. 46.6%, p< 0.01), and ICU stay (27.3% vs. 23.1%, p=0.13), but no meaningful difference in mortality (13.3% vs. 13.0%, p=0.97), for co-infected as compared to singly-infected COVID-19 patients.

Conclusion

In a real-world cohort, we observed a low proportion (0.3%) of COVID-19 patients co-infected with influenza. Co-infected patients had similar baseline characteristics but higher likelihood of hospitalization severity as compared to singly-infected COVID-19 patients. Limitations include low prevalence of circulating influenza and potential missing data bias.

Disclosures

Devika Chawla, PhD MSPH, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee) Xin Chen, PhD, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee) Klaus Kuhlbusch, PhD MD, F. Hoffmann-La Roche Ltd. (Employee) Kelly Zalocusky, PhD, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee) Shemra Rizzo, PhD, F. Hoffmann-La Roche Ltd. (Shareholder)Genentech, Inc. (Employee)

1518. Real-World Comparative Effectiveness of Baloxavir Marboxil versus Oseltamivir on Influenza-Related Complication and Resource Utilization

Background

In the 2018-19 season, there were an estimated 490,500 hospitalizations and 24,000 deaths from influenza in the US. Understanding how antiviral use affects rates and severity of complications is crucial to inform clinical practice. The objective of this study was to compare the frequency and costs of complications in influenza patients treated with baloxavir compared with oseltamivir-treated patients. This is one of the first analyses to examine comparative effectiveness of baloxavir in a real-world setting.

Methods

This retrospective cohort study used IBM MarketScan US administrative claims data from the 2018–19 influenza season. Patients were required to have an outpatient visit for influenza followed by a prescription for baloxavir or oseltamivir within 2 days. Baloxavir- and oseltamivir-treated patients were propensity score matched based on key baseline clinical and demographic characteristics. All-cause, all respiratory-related, and select respiratory-related (infection, asthma, and COPD) HRU in the 15 and 30 days following prescription fill were assessed using chi-square and Fisher’s exact tests for categorical measures and Wilcoxon signed-rank tests for counts and costs.

Results

We included 5,080 baloxavir-treated patients and 10,160 matched oseltamivir-treated patients in the analysis. Statistically significantly lower HRU was associated with baloxavir compared with oseltamivir therapy (15-day: respiratory-related ED visits, select respiratory-related ED visits and outpatient visits; 30-day: all-cause hospitalization, respiratory-related ED visits, select respiratory-related ED visits and outpatient visits (Table 1). Similarly, associated costs were generally lower in the baloxavir-treated group. Baloxavir-treated patients had lower mean per-patient all-cause 15-day costs (ED visits: $30 [95% CI: $21–$39] vs $42 [95% CI: $32–$51]; hospitalizations: $31 [95% CI: $6–$55] vs $74 [95% CI: $43–$104]) and 30-day costs (ED visits: $46 [95% CI: $35–$57] vs $67 [95% CI: $55–$79]; hospitalizations: $47 [95% CI: $15–$80] vs $119 [95% CI: $78–$161]).

Table 1. Proportion of patients with at least one event

Conclusion

These findings suggest that treatment of influenza with baloxavir may improve outcomes and lower HRU costs compared with oseltamivir treatment.

Disclosures

Eddie Neuberger, PharmD, Genentech, Inc. (Employee) Chris Wallick, PharmD, MS, Genentech, Inc. (Employee) Devika Chawla, PhD MSPH, Genentech, Inc. (Employee) Rita de Cassia Castro, MD, Genentech, Inc. (Employee)

Diagnostic yield of sputum induction in patients with pleural tuberculosis at a tertiary care hospital in Karachi

OBJECTIVE: To evaluate the diagnostic yield of acid-fast bacilli (AFB) smear, culture for Mycobacterium tuberculosis and Xpert® MTB/RIF assay in induced sputum (IS) specimens in patients with pleural tuberculosis (TB).DESIGN: A total of 156 patients were evaluated at Jinnah Postgraduate Medical Centre, Karachi, Pakistan, from April 2016 to December 2017. Patients with exudative lymphocytic pleural effusions with normal lung parenchyma on chest radiography were included in the study: 102 were due to tuberculous and 54 due to non-tuberculous infections as diagnosed using thoracoscopic pleural biopsy. IS samples were sent for acid-fast bacilli (AFB) smear, AFB culture and Xpert assay.RESULT: In patients with a clinical diagnosis of TB, mycobacteria were detected in IS AFB smear in 7.8%, AFB culture in 21.6% and Xpert assay in 34.3% of cases. All sputum samples collected from patients with non-tuberculous aetiology were negative.CONCLUSION: Testing IS samples for M. tuberculosis provides another approach to diagnosing pleural TB, especially in settings in which invasive procedures are less accessible. Our study also emphasises the contagiousness of pleural TB, and the need to screen the household contacts of these patients and possible isolation of patients with pleural TB admitted to hospital.

2647. Influenza Treatment Rates in UK Primary Care Settings: Real-World Data Analysis of the CPRD, 2003–2018

Background

Influenza remains a significant public health burden, resulting in serious morbidity and mortality globally. The National Institute for Health and Care Excellence (NICE) recommends treatment with antivirals for a broad range of high-risk influenza cases; however, anecdotal reports suggest treatment rates in the United Kingdom remain low. Real-world evidence on influenza treatment patterns in this region is limited. We therefore sought to investigate the proportion of influenza cases presenting to UK primary care facilities that receive antiviral treatment.

Methods

Data were obtained from the Clinical Practice Research Datalink (CPRD), a database of medical records from 674 primary care facilities in the UK. Cases were eligible for study inclusion if a diagnosis code for influenza or influenza-like illness (ILI) occurred between 1 January 2003 and 31 December 2018, and the medical record had sufficient data quality. Treatment was defined as prescription of an antiviral (oseltamivir, zanamivir, peramivir, or amantadine) within ±10 days of diagnosis. We examined (1) treatment rates, overall and by study year to understand time trends, (2) distribution of antiviral types prescribed, and (3) patient characteristics across treatment status.

Results

Of the 116,923 cases of influenza that met study inclusion criteria, 10,923 (9.3%) were treated with an antiviral. Treatment rates varied by study year, ranging from <1.0% in 2004 to 24.0% in 2009. The most recent study year (2018) had a treatment rate of 11.2%. Oseltamivir was the most frequent antiviral prescribed, followed by zanamivir. Treated cases of influenza were younger and more likely to be female compared with untreated cases.

Conclusion

We evaluated real-world estimates of influenza treatment rates over a 16-year period in UK primary care settings, where anecdotal reports suggested low treatment rates. Consistent with these reports, we observed low treatment rates, likely due in part to inclusion criteria and clinical guidelines specifying treatment only for high-risk cases. Subsequent analyses will investigate treatment patterns and patient characteristics in high-risk vs. low-risk cases to provide additional context for observed treatment rates.

Disclosures

All authors: No reported disclosures.

P5658Incorporation of severity of left atrial enlargement in clinical risk factors improves identification of patients at risk for development of atrial fibrillation

Background

Early identification of patients at risk for atrial fibrillation (AF) is desirable to prevent its development and complications. Clinical predictors have been recognized but need refinement to improve predictability. We evaluated whether severity of left atrial enlargement (LAE) added to a scoring system (CHA2DS2VASC) in an unselected non-AF population improves risk stratification for incident AF.

Purpose

To assess the incremental benefit of LAE severity added to CHA2DS2VASc in predicting future AF in non-AF patients.

Methods

From 2012–2017, consecutive adult patients with an echocardiogram and no prior AF were identified. CHA2DS2VASc was used to define baseline AF risk, and the incremental risk of AF with addition of LAE was assessed through increased LA volume index (LAVI; moderate 42–48 ml/m2, severe >48 ml/m2). To quantify improvement in risk prediction, logistic regression model was fitted and odds ratios (OR) and ROC curves obtained.

Results

Out of 155,597 patients with no prior AF, 13.8% developed AF over 1.5±1.3 years. OR for AF with CHA2DS2VASc was 1.68 (95% CI 1.66–1.69). With addition of moderately or severely increased LAVI to the model, OR for AF increased to 2.3 (2.2–2.5) and 3.8 (3.6–4.0), respectively. ROC analysis showed c-statistics of 0.66 with CHA2DS2VASc, 0.63 with LAVI, and 0.71 with incorporation of both (Fig).

AF CHAD score

Conclusion(s)

In non-AF patients, predictability for future AF can be improved by using clinical factors (CHA2DS2VASc) and increased LAVI. This information may guide closer monitoring and initiation of therapies to prevent progression to AF or stroke.

Acknowledgement/Funding

None

Zika and travel in the news: a content analysis of US news stories during the outbreak in 2016-2017

OBJECTIVES

This study aimed to understand what information the US media communicated about Zika virus (ZIKV) and travel in 2016 and 2017.

STUDY DESIGN

We conducted a content analysis of news coverage about ZIKV and travel from April 5, 2016 to March 31, 2017.

METHODS

We obtained a stratified, random sample of English language, US print newspaper and television news coverage about ZIKV and travel. We developed a coding scheme to assess key messages in the news, including how ZIKV is transmitted, the symptoms and outcomes of ZIKV infection, and recommended prevention behaviors.

RESULTS

Almost all news stories mentioned mosquito-borne transmission (96.8%) and just over half mentioned sexual transmission (55.3%). News stories were more likely to talk about ZIKV outcomes (78.8%) than ZIKV symptoms (40.6%). However, outcomes affecting babies were mentioned more frequently than outcomes affecting adults. Recommendations included a wide array of protective behaviors, such as delaying or avoiding travel (77.6%) and using mosquito repellent (41.0%). However, few studies (10.9%) mentioned barriers to practicing ZIKV prevention behaviors.

CONCLUSIONS

Public health organizations and professionals can use these findings to help improve communication about future outbreaks of mosquito-borne illnesses. We also recommend conducting real-time monitoring of news media and frequent content analysis of news stories to ensure coverage provides the information the public needs.

Past-month cannabis use among U.S. individuals from 2002-2015: An age-period-cohort analysis

BACKGROUND

Cannabis is the most commonly used illicit drug among U.S. adolescents and adults, but little is known about factors that drive trends in cannabis use prevalence. To better understand drivers of these trends, we aimed to estimate age, period, and cohort effects on past-month cannabis use among U.S. individuals age 12 and older from 2002 to 2015.

METHODS

We conducted an age-period-cohort analysis on past-month cannabis use among participants ages 12 and older using the National Survey on Drug Use and Health (NSDUH), an annual cross-sectional nationally-representative survey of drug use. Additionally, we examined how age, period, and cohort effects differed across gender. Participants (n = 779,799) self-reported cannabis patterns using a computer-assisted telephone interview (CATI).

RESULTS

Past-month cannabis use in this population increased from 6.0% in 2002 to 8.1% in 2015. Distinct age, period, and cohort effects were observed. Compared to participants ages 12-13, participants ages 18-21 (PR: 16.8, 95% CI: 15.6, 18.1) and 22-25 (PR: 13.2, 95% CI: 12.2, 14.4) had dramatically higher prevalence of past-month cannabis use. Compared to participants in 2002, participants in 2014 (PR: 1.2, 95% CI: 1.1, 1.4) and 2014 (PR: 1.2, 95% CI: 1.1, 1.4) had slightly higher prevalence of past-month cannabis use. Compared to the 1940s birth cohort, the 1950s birth cohort (PR: 1.8, 95% CI: 1.5, 2.2) had a higher prevalence of past-month cannabis use.

CONCLUSIONS

Past-month cannabis use is prevalent and increasing among U.S. adults. Distinct age, period, and cohort effects are at play, though age effects are strongest.

An epidemiological, developmental and clinical overview of cannabis use during pregnancy

The objective of the current narrative literature review is to provide an epidemiological, developmental and clinical overview on cannabis use during pregnancy. Cannabis use in pregnancy poses major health concerns for pregnant mothers and their developing children. Although studies on the short- and long-term consequences of prenatal cannabis exposure are increasing, findings have been inconsistent or difficult to interpret due to methodological issues. Thus, consolidating these findings into clinical recommendations based on the mixed studies in the literature remains a challenge. Synthesizing the available observational studies is also difficult, because some of the published studies have substantial methodological weaknesses. Improving observational studies will be an important step toward understanding the extent to which prenatal exposure to cannabis influences neurodevelopment in the offspring. Therefore, further research on prenatal cannabis exposure and the long-term consequences to offspring health in representative samples are needed to guide and improve clinical care for pregnant women and their children. Future research should also investigate the role of policies on prenatal cannabis use.

Broader autism phenotype in parents of children with autism: a systematic review of percentage estimates

The broader autism phenotype (BAP) is a collection of sub-diagnostic autistic traits more common in families of individuals with autism spectrum disorder (ASD) than in the general population. BAP is a latent construct that can be defined using different domains, measured using multiple instruments, and reported using different techniques. Therefore, estimates of BAP may vary greatly across studies. Our objective was to systematically review studies that reported occurrence of BAP in parents of children with ASD in order to quantify and describe heterogeneity in estimates. We systematically searched PubMed and Scopus using PRISMA guidelines for studies quantifying percentage of parents of children with ASD who had BAP We identified 41 studies that measured BAP in parents of children with ASD. These studies used eight different instruments, four different forms of data collection, and had a wide range of sample sizes (N=4 to N=3299). Percentage with BAP ranged from 2.6% to 80%. BAP was more prevalent in fathers than mothers. Parental BAP may be an important tool for parsing heterogeneity in ASD etiology and for developing parent-mediated ASD interventions. However, the variety in measurement instruments and variability in study samples limits our ability to synthesize estimates. To improve measurement of BAP and increase consistency across studies, universal methods should be accepted and adopted across studies. A more consistent approach to BAP measurement may enable efficient etiologic research that can be meta-analyzed and may allow for a larger evidence base that can be used to account for BAP when developing parent-mediated interventions.

Effect of maternal oxygen inhalation on foetal free radical activity: a prospective, randomized trial

BACKGROUND

Maternal inhalation of 35-40% oxygen concentration has no significant effect on foetal partial pressure of oxygen, and 60-100% produced maternal and foetal hyperoxia with increased free radical activity. The benefit of 50% maternal oxygen inhalation on foetal oxygenation, oxidant stress and total antioxidant status (TAS) during Caesarean section (CS) has not been simultaneously evaluated.

METHODS

In this prospective, randomized, controlled trial 120 ASA physical status I-II, term pregnant women were recruited to elective CS (n = 60) and emergency CS (n = 60) and received either 50% oxygen or air inhalation following subarachnoid block (SAB). Patients and investigators were blinded to the inhaled oxygen concentration. The primary outcome of the study was foetal umbilical artery (UA) malondialdehyde (MDA) at birth.

RESULTS

In both elective and emergency CS, there was no difference in foetal oxidative stress and TAS in spite of increase in maternal PaO2. In elective CS, maternal MDA was higher at delivery in mothers breathing 50% oxygen as compared to their own baseline values (P = 0.04). In emergency CS, maternal TAS at 10 min was lower in mothers inhaling 50% oxygen as compared to air (P = 0.01). The average duration of maternal oxygen supplementation was ~10.3 min in elective and ~7.4 min in emergency CS. Neonatal outcome, episodes of maternal hypotension and oxygen desaturation were similar in both the groups.

CONCLUSION

Brief duration of 50% oxygen maternal inhalation during elective or emergency CS did not significantly affect foetal MDA and TAS under SAB.

Early prenatal vitamin D concentrations and social-emotional development in infants

BACKGROUND

Many pregnant women in the United States have suboptimal vitamin D, but the impact on infant development is unclear. Moreover, no pregnancy-specific vitamin D recommendations have been widely accepted.

AIMS

Given the ubiquitous expression of vitamin D receptors in the brain, we investigated the association between early prenatal plasma 25-hydroxyvitamin D (25(OH)D) concentrations and children's social and emotional development in the Newborn Epigenetic Study, a prospective study of pregnancies from 2009 to 2011 in Durham, North Carolina.

METHODS

We measured 25(OH)D concentrations in first or second trimester plasma samples and categorized 25(OH)D concentrations into quartiles. Covariates were derived from maternal questionnaires. Mothers completed the Infant Toddler Social-Emotional Development Assessment when children were 12-24 months of age. We used multivariable linear regression to evaluate associations between 25(OH)D and specific behavior scores, adjusted for season of blood draw, maternal age, education, parity, smoking, marital status, prepregnancy BMI, and infant gender. We investigated effect-measure modification by race/ethnicity.

RESULTS

Of the 218 mother-infant pairs with complete data, Black mothers had much lower 25(OH)D concentrations as compared to White and Hispanic mothers. After adjustment, lower prenatal 25(OH)D was associated with slightly higher (less favorable) Internalizing scores among White children, but lower (more favorable) Internalizing scores among Black and Hispanic children. Lower prenatal 25(OH)D also appears to be associated with higher (less favorable) dysregulation scores, though only among White and Hispanic children.

CONCLUSIONS

Though imprecise, preliminary results warrant further investigation regarding a role for prenatal vitamin D on children's early social and emotional development.

Tele-education vs classroom training of neonatal resuscitation: a randomized trial

OBJECTIVE

To compare gain in knowledge and skills of neonatal resuscitation using tele-education instruction vs conventional classroom teaching.

STUDY DESIGN

This randomized controlled trial was conducted in the tele-education facility of a tertiary care center. In-service staff nurses were randomized to receive training by tele-education instruction (TI, n=26) or classroom teaching (CT, n=22) method from two neonatology instructors using a standardized teaching module on neonatal resuscitation. Gain in knowledge and skill scores of neonatal resuscitation were measured using objective assessment methods.

RESULT

Age, educational qualification and professional experience of the participants in two groups were comparable. Pre-training mean knowledge scores were higher in TI group (8.3±1.7 vs 6.6±1.4, P=0.004). However, skill scores were comparable in the two groups (11.7±3 vs 10.3±2.9, P=0.13). Training resulted in a significant and comparable gain in knowledge scores (4.2±2.2 vs 5.3±1.7; P=0.06) and skills scores (4.5±3.3 vs 5.0±3.1, P=0.62) in both the groups. The post-training knowledge scores (TI: 12.5±1.7 vs CT: 12.0±1.7, P=0.37) and the post-training skill scores (TI: 16.0±0.5 vs CT: 15.6±2.5, P=0.55) were comparable in the two groups. However, the post-training scores, adjusted for baseline knowledge scores, were statistically higher in the in-person group compared with the telemedicine group (knowledge: 12.46±0.03 vs 12.16±0.01, P=0.00; skills: 15.6±2.5 vs 16.0±2.8, P=0.00). The quantum of lower scores in the telemedicine group was only 2% for knowledge and 6% for skills. This difference was felt to be of only marginal importance. Satisfaction scores among trainees and instructors were comparable in the two groups.

CONCLUSION

Tele-education offers a feasible and effective alternative to conventional training in neonatal resuscitation among health-care providers.

Transcutaneous bilirubinometry reduces the need for blood sampling in neonates with visible jaundice

OBJECTIVES

We determined usefulness of transcutaneous bilirubinometry to decrease the need for blood sampling to assay serum total bilirubin (STB) in the management of jaundiced healthy Indian neonates.

METHODS

Newborns, > or =35 weeks' gestation, with clinical evidence of jaundice were enrolled in an institutional approved randomized clinical trial. The severity of hyperbilirubinaemia was determined by two non-invasive methods: i) protocol-based visual assessment of bilirubin (VaB) and ii) transcutaneous bilirubin (TcB) determination (BiliCheck). By a random allocation, either method was used to decide the need for blood sampling, which was defined to be present if assessed STB by allocated method exceeded 80% of hour-specific threshold values for phototherapy (2004 AAP Guidelines).

RESULTS

A total of 617 neonates were randomized to either TcB (n = 314) or VaB (n = 303) groups with comparable gestation, birth weight and postnatal age. Need for blood sampling to assay STB was 34% lower (95% CI: 10% to 51%) in the TcB group compared with VaB group (17.5% vs 26.4% assessments; risk difference: -8.9%, 95% CI: -2.4% to -15.4%; p = 0.008).

CONCLUSION

Routine use of transcutaneous bilirubinometry compared with systematic visual assessment of bilirubin significantly reduced the need for blood sampling to assay STB in jaundiced term and late-preterm neonates. (ClinicalTrials.gov number, NCT00653874).

Limb splinting for intravenous cannulae in neonates: a randomised controlled trial

OBJECTIVE

To evaluate the efficacy of peripheral intravenous (IV) cannula site joint immobilisation by splint application on functional duration of peripheral IV cannula in neonates.

DESIGN

Randomised controlled trial.

SETTING

Neonatal intensive care unit of a tertiary care hospital.

PARTICIPANTS

Neonates requiring continuous IV infusion for an expected duration of more than or equal to 72 hours.

INTERVENTION

Eligible cannulations were randomised to either "splint" or "no-splint" group. In the splint group, a cardboard splint was used to immobilise the joint at peripheral IV cannula site. No attempt was made to immobilise the limb in the no-splint group.

OUTCOME MEASURE

Functional duration of a peripheral IV cannula measured as interval from time of insertion to the development of predefined sign of removal (extravasation, blockage, inflammation).

RESULTS

A total of 69 peripheral IV cannulations in 54 neonates were randomised to either the splint (n = 33) or no-splint group (n = 36). Both groups were comparable in birth weight, gestation, site of cannulation and nature of fluids administered. Mean functional duration of cannula was lesser in the splint group compared to the no-splint group (h; 23.5 (SD15.9) vs 26.9 (SD15.5), mean difference: -3.3 h, 95% CI -11.02 to 4.3 h) although the difference was not statistically significant (p = 0.38). Extravasation at cannula site was found be the commonest indication for cannula removal in both the groups (84% vs 76.5%).

CONCLUSION

Joint immobilisation with splint at cannula site did not improve the functional duration of peripheral IV cannula.

Efficacy of two dose regimes of intravenous immunoglobulin in Rh hemolytic disease of newborn--a randomized controlled trial

OBJECTIVE

To compare the effect of two dose regimes of IVIg (0.5 g/kg vs. 1g/kg given soon after birth) on duration of phototherapy in Rh-isoimmunized neonates 32 week and above gestation.

DESIGN

Randomized controlled trial.

SETTING

Tertiary care hospital.

SUBJECTS

Rh positive blood group neonates of gestation 32 weeks and above born to Rh negative mothers having positive Direct Coombs test and without any major malformation.

INTERVENTION

Intravenous immunoglobulin (IVIg) infusion over 2 h either 0.5 g/kg (low dose group, n=19) or 1.0 g/kg (high dose group, n=19).

PRIMARY OUTCOME VARIABLE

Duration of phototherapy.

RESULTS

The mean duration of phototherapy was 77.3+/-57.2 h in low dose group versus 55.4+/-49 h in high dose group (mean difference=21.9; 95% CI-13.1 to 56.9). There was no difference in need for exchange transfusion (21% in both the groups) and requirement of packed red blood cells transfusion (12 transfusions in both groups). The duration of hospital stay was similar [8.4+/-6.9 and 13.6+/-14.8 days, respectively (mean difference=-5.1; 95% CI-12.8 to 2.5)]. No adverse effects of IVIg administration were noted.

CONCLUSION

Two regimens of IVIg (0.5 g/Kg or 1 g/Kg) had comparable effect on duration of phototherapy, duration of hospital stay and exchange transfusion requirement, in Rh isoimmunized neonates of gestation 32 weeks and above.

Vitamin K1 versus vitamin K3 for prevention of subclinical vitamin deficiency: a randomized controlled trial

OBJECTIVE

To compare efficacy of intramuscular phytomenadione (fat soluble vitamin K or vitamin K1) with menadione (water soluble vitamin K or vitamin K3) in prevention of subclinical vitamin K deficiency.

DESIGN

A doubleblind randomized controlled trial.

SETTINGS

Tertiary care hospital.

METHODS

Healthy term neonates were randomized to receive 1 mg of either phytomenadione (Group I, n = 85) or menadione (Group II, n = 85) intramuscularly within 2 hours of birth. PIVKA-II, a sensitive and specific marker of vitamin K deficiency was measured by ELISA method (Diagnostica Stago, France). Plasma level > 2 ng/mL was labeled as detectable PIVKA-II.

RESULTS

Birth weight (2914 +/- 318 vs 2958 +/- 312 g), gestation (38.4 +/- 1.2 vs 38.4 +/- 1.0 wk) and other baseline variables were comparable between the two groups. 48.2% (41/85) neonates in Group I and 44.7%(38/85) neonates in Group II had detectable PIVKAII levels ([Relative Risk (95% confidence interval): 1.1 (0.8-1.5); P = 0.76]). Median PIVKA-II levels in Group I and Group II were 1.99 ng/mL and 1.97 ng/mL respectively (P = 0.26). At 72 +/- 12 h of age, mean packed cell volume and mean serum bilirubin levels were comparable in the two groups.

CONCLUSION

Comparable PIVKAII detection rate and PIVKAII levels in neonates receiving phytomenadione or menadione indicate their similar efficacy in prevention of vitamin K deficiency. However, high PIVKAII detection rate observed with both preparations indicates recent vitamin K deficiency and may be due to either inadequate dose of vitamin K or persistence of PIVKAII of fetal origin.

Zero-lag synchronous dynamics in triplets of interconnected cortical areas

Oscillatory and synchronized activities involving widespread populations of neurons in neocortex are associated with the execution of complex sensorimotor tasks and have been proposed to participate in the 'binding' of sensory attributes during perceptual synthesis. How the brain constructs these coherent firing patterns remains largely unknown. Several mechanisms of intracortical synchronization have been considered, in particular mutual inhibition and reciprocal excitation. These mechanisms fail to account for the zero-lag correlations observed among areas located at different levels in the visual hierarchy because the asymmetric laminar organization of ascending and descending connections in this hierarchy would predict systematic inter-areal phase lags. Here we show through detailed computer simulations that, when triplets rather than pairs of reciprocally connected areas in a cortical hierarchy are considered, zero-lag synchronization emerges naturally from their three-way interactions. These simulations were motivated by the observation that most areas in the cat and macaque monkey visual cortex are organized in such triplets. Our results suggest that patterns of anatomical connections in the mammalian neocortex provide a structural basis for the multi-level synchronization of neuronal activity.

Relating macroscopic measures of brain activity to fast, dynamic neuronal interactions

In this article we used biologically plausible simulations of coupled neuronal populations to address the relationship between phasic and fast coherent neuronal interactions and macroscopic measures of activity that are integrated over time, such as the BOLD response in functional magnetic resonance imaging. Event-related, dynamic correlations were assessed using joint peristimulus time histograms and, in particular, the mutual information between stimulus-induced transients in two populations. This mutual information can be considered as an index of functional connectivity. Our simulations showed that functional connectivity or dynamic integration between two populations increases with mean background activity and stimulus-related rate modulation. Furthermore, as the background activity increases, the populations become increasingly sensitive to the intensity of the stimulus in terms of a predisposition to transient phase locking. This reflects an interaction between background activity and stimulus intensity in producing dynamic correlations, in that background activity augments stimulus-induced coherence modulation. This is interesting from a computational perspective because background activity establishes a context that may have a profound effect on event-related interactions or functional connectivity between neuronal populations. Finally, total firing rates, which subsume both background activity and stimulus-related rate modulation, were almost linearly related to the expression of dynamic correlations over large ranges of activities. These observations show that under the assumptions implicit in our model, rate-specific metrics based on rate or coherence modulation may be different perspectives on the same underlying dynamics. This suggests that activity (averaged over all peristimulus times), as measured in neuroimaging, may be tightly coupled to the expression of dynamic correlations.

Nonlinear PCA: characterizing interactions between modes of brain activity

This paper presents a nonlinear principal component analysis (PCA) that identifies underlying sources causing the expression of spatial modes or patterns of activity in neuroimaging time-series. The critical aspect of this technique is that, in relation to conventional PCA, the sources can interact to produce (second-order) spatial modes that represent the modulation of one (first-order) spatial mode by another. This nonlinear PCA uses a simple neural network architecture that embodies a specific form for the nonlinear mixing of sources that cause observed data. This form is motivated by a second-order approximation to any general nonlinear mixing and emphasizes interactions among pairs of sources. By introducing these nonlinearities principal components obtain with a unique rotation and scaling that does not depend on the biologically implausible constraints adopted by conventional PCA. The technique is illustrated by application to functional (positron emission tomography and functional magnetic resonance imaging) imaging data where the ensuing first- and second-order modes can be interpreted in terms of distributed brain systems. The interactions among sources render the expression of any one mode context-sensitive, where that context is established by the expression of other modes. The examples considered include interactions between cognitive states and time (i.e. adaptation or plasticity in PET data) and among functionally specialized brain systems (using a fMRI study of colour and motion processing).

Revealing interactions among brain systems with nonlinear PCA

In this work, we present a nonlinear principal component analysis (PCA) that identifies underlying sources causing the expression of spatial modes or patterns of activity in neuroimaging time series where these sources can interact to produce second-order modes. This nonlinear PCA uses a neural network architecture that embodies a specific form for the mixing of sources that is based on a second-order approximation to any general nonlinear mixing. The modes obtained have a unique rotation and scaling that does not depend on the biologically implausible constraints adopted by conventional PCA. Interactions among sources render the expression of any mode or brain system sensitive to the expression of others. The example considers interactions among functionally specialized brain systems (using a fMRI study of colour and motion processing).

The relationship between synchronization among neuronal populations and their mean activity levels

In the past decade the importance of synchronized dynamics in the brain has emerged from both empirical and theoretical perspectives. Fast dynamic synchronous interactions of an oscillatory or nonoscillatory nature may constitute a form of temporal coding that underlies feature binding and perceptual synthesis. The relationship between synchronization among neuronal populations and the population firing rates addresses two important issues: the distinction between rate coding and synchronization coding models of neuronal interactions and the degree to which empirical measurements of population activity, such as those employed by neuroimaging, are sensitive to changes in synchronization. We examined the relationship between mean population activity and synchronization using biologically plausible simulations. In this article, we focus on continuous stationary dynamics. (In a companion article, Chawla (forthcoming), we address the same issue using stimulus-evoked transients.) By manipulation parameters such as extrinsic input, intrinsic noise, synaptic efficacy, density of extrinsic connections, the voltage-sensitive nature of postsynaptic mechanisms, the number of neurons, and the laminar structure within the populations, we were able to introduce variations in both mean activity and synchronization under a variety of simulated neuronal architectures. Analyses of the simulated spike trains and local field potentials showed that in nearly every domain of the model's parameter space, mean activity and synchronization were tightly coupled. This coupling appears to be mediated by an increase in synchronous gain when effective membrane time constants are lowered by increased activity. These observations show that under the assumptions implicit in our models, rate coding and synchrony coding in neural systems with reciprocal interconnections are two perspectives on the same underlying dynamic. This suggests that in the absence of specific mechanisms decoupling changes in synchronization from firing levels, indexes of brain activity that are based purely on synaptic activity (e.g., functional magnetic resonance imaging) may also be sensitive to changes in synchronous coupling.

The physiological basis of attentional modulation in extrastriate visual areas

Selective attention to color or motion enhances activity in specialized areas of extrastriate cortex, but mechanisms of attentional modulation remain unclear. By dissociating modulation of visually evoked transient activity from the baseline for a particular attentional set, human functional neuroimaging was used to investigate the physiological basis of such effects. Baseline activity in motion- and color-sensitive areas of extrastriate cortex was enhanced by selective attention to these attributes, even without moving or colored stimuli. Further, visually evoked responses increased along with baseline activity. These results are consistent with the hypothesis that attention modulates sensitivity of neuronal populations to inputs by changing background activity.

Speed-dependent responses in V5: A replication study

In a previous paper, we used fMRI to examine motion-sensitive responses in human area V5 as a function of stimulus speed. As predicted by electrophysiological findings, we observed optimal responses at intermediate speeds of around 7 to 30 degrees /s. These results revealed a nonlinear (inverted "U") dependency on speed that was also evident in V3a. In this paper we repeated the experiment using an improved stimulus and a larger range of speeds. We replicated our previous findings and extended our characterization of speed-dependent responses: Optimal responses were seen in V5 at speeds of 4 and 8 degrees /s and in V3a at speeds of 4 to 16 degrees /s. We were also able to show an interaction between speed (fast vs slow) and contrast (color > luminance) in V5. This interaction was anticipated on the basis of the different properties of the geniculate and extrageniculate inputs to V5. Finally, we were also able to demonstrate an interaction between motion (moving vs stationary) and contrast (color > luminance) in V4. This suggests that for V4, color-specific responses are augmented in the context of motion; or equivalently, that color contrast enhances any motion-sensitive responses in V4.

Speed-dependent motion-sensitive responses in V5: an fMRI study

This fMRI study examined motion-sensitive responses in human area V5 as a function of stimulus speed. Consistent with electrophysiological findings, we observed optimal responses at intermediate speeds of around 7 degrees/s to 30 degrees/s. The results are consistent with a nonlinear (inverted "U") dependency on speed that was also observed in V3a. V1 activation was observed to decrease linearly as speed increased. This is consistent with the fact that speed-sensitive cells in V1 have been shown to be tuned to much slower speeds than in V5.

Secretion of active human lecithin-cholesterol acyltransferase by insect cells infected with a recombinant baculovirus

Difficulties in purifying the plasma enzyme lecithin-cholesterol acyltransferase (LCAT) have hampered detailed studies of its (patho)physiological role in lipoprotein metabolism and of structure-function relationships. Potentially, baculovirus-driven expression systems offer a powerful means to produce significant amounts of LCAT. Accordingly, full-length LCAT cDNA was cloned into pVL 1392, a high-level expression derivative of Autographa californica nuclear polyhedrosis virus (AcNPV), and the resultant plasmid was co-transfected into Trichoplusia ni insect cells (High 5 line) with a linearized viral DNA using lipofectin. Such viral DNA had a lethal mutation and grew only when recombined with a pVL1392-type rescue plasmid; cells infected with recombinant Autographa californica LCAT virus changed from a fibroblast-like morphology to rounded, but lacked the polyhedrin occlusion bodies characteristic of wild-type AcNPV infections. Enzymically active recombinant LCAT (rLCAT), sensitive to sulphydryl reagents, was secreted in the late phase of infection (36-48 h) but was absent with wild-type infections. The secreted protein had an apparent molecular mass of 53 kDa by SDS/PAGE, lower than that of native plasma LCAT; it was susceptible to endoglycosidase H digestion and was bound by concanavalin A, suggesting that precursor high-mannose N-glycan chains had not undergone full maturation to complex types. Pretreatment of the cells with tunicamycin to inhibit the first step of N-glycosylation led to intracellular accumulation of immature rLCAT (approximately 46-48 kDa) and a marked reduction in enzyme secreted. We conclude that the baculovirus gene-expression system will permit production of biologically active normal and mutant forms of LCAT protein.

Bowringia mildbraedii agglutinin: polypeptide composition, primary structure and homologies with other legume lectins

The amino-acid sequences of the subunits of the lectin BMA from seeds of Bowringia mildbraedii have been determined. The data indicate that the lectin consists of a precursor polypeptide of approx. 29 kDa that is cleaved almost completely into two fragments of approx. 13.3 kDa (alpha subunit) and approx. 11.9 kDa (beta subunit), respectively. The beta subunit represents the N-terminal half of precursor polypeptides and is disulphide-linked in a beta beta dimer in the native (alpha beta)2 protein. BMA shows extensive amino-acid sequence homologies with known legume lectins. The site of post-translational proteolysis of the putative precursor occurs at a position similar to that identified in lectins obtained from other Sophoreae plants such as Sophora japonica and in Diocleae lectins such as Concanavalin A, but different from that of two chain lectins obtained from other tribes of the Papilionaceae.

Optimum needle length for DPT inoculation of Indian infants

Correct placement of the injected DPT vaccine into the deep muscular layers decreases the local reactions, including the sterile abscess formation. However, recommendations on size of the needle to be used and the angle of injection are not easily available, are not uniform and are based on case reports. The only study based on scientific data of ultrasonographic measurement of fat layer and muscle layer thickness of thigh of only 24 infants of 4 months age covers only American children. (Hick et al, Pediatrics 1989; 84: 136-37). In the present study, we have produced similar data on 215 Indian children belonging to all those age groups in which DPT vaccinations are given. Mean thickness of skin + fat layer in the middle one-third of the anterolateral aspect of thigh was 1.03 +/- 0.23 cm, 1.04 +/- 0.21 cm, 0.95 +/- 0.19 cm and 1.06 +/- 0.27 cm in the age groups of 6-12 weeks (Groups I), 13-18 weeks (Group II), 19-24 weeks (Groups III) and 18 +/- 1 month (Group IV) respectively. These age groups correspond to the timings of first 3 primary doses and the first booster dose of the DPT vaccine in our immunization clinic. Mean thickness of all the soft tissues together at the same site were 1.87 +/- 0.35, 2.17 +/- 0.38, 2.07 +/- 0.39 and 2.07 +/- 0.26 cm respectively for the groups I to IV.(ABSTRACT TRUNCATED AT 250 WORDS)

CT appearances in macronodular hepatosplenic tuberculosis: a review with five additional new cases

Pseudotumoral or macronodular hepatosplenic tuberculosis (HSTB) is rare. Only 31 cases have been documented in imaging literature so far. Presented is the clinico-imaging review with five additional new cases of this uncommon variety. Due to nonspecific wide spectrum of imaging appearances, biopsy is mandatory in almost all cases. Clinical recovery and resolution of lesions on imaging may not be directly proportional.

Interactions of Bowringia mildbraedii agglutinin with complex- and hybrid-type glycans

Affinity chromatography on Bowringia mildbraedii agglutinin (BMA) Sepharose of glycopeptides confirmed a previous report using oligosaccharides (Animashaun, T. and Hughes, R. C. (1989) J. Biol. Chem. 264,4657-4663) that high affinity binding requires the sequence Man alpha 1---2 Man alpha 1----6 Man alpha 1----6 Man beta 1----4. However, moderate binding was still exhibited by structures lacking this sequence provided the oligosaccharide core sequence Man alpha 1----3[Man alpha 1----6]Man beta 1----4GlcNAc was present. This moderate binding was not affected by substitution with N-acetylglucosamine at C2 and C4, respectively, of the Man alpha 1----3 and Man beta 1----4 residues and BMA Sepharose should prove to be a useful tool for the isolation of bisected or non-bisected hybrid-type glycans.

Effects of brefeldin A on oligosaccharide processing. Evidence for decreased branching of complex-type glycans and increased formation of hybrid-type glycans

Brefeldin A (BFA), a drug that induces redistribution of Golgi-apparatus proteins into the endoplasmic reticulum, was used to determine the role of subcellular compartmentalization in the processing of asparagine-linked oligosaccharides. Baby-hamster kidney cells were pulse-labelled with [3H]mannose for 30-60 min and chased for up to several hours in the presence or in the absence of BFA or labelled continuously for several hours with and without the drug. Cellular glycoproteins were digested to glycopeptides with Pronase and either fractionated into glycan classes by lectin affinity chromatography or digested further by endoglycosidase H and endoglycosidase D. Released oligosaccharides obtained in the latter procedure were then separated from each other and from endoglycosidase-resistant glycopeptides by paper chromatography. The results show that BFA induces a very fast processing of protein-linked Glc3Man9GlcNAc2 oligosaccharide down to man5GlcNAc2 and conversion into complex-type and hybrid-type glycans. The major difference between untreated and BFA-treated cells is a large increase in bi-antennary and hybrid-type glycans in the latter cells. These results indicate that galactosylation of a mono-antennary GlcNAcMan5GlcNAc2 hybrid blocks subsequent action by mannosidase II and N-acetylglucosaminyl transferase II, producing galactosylated hybrid-type glycans. Similarly, galactosylation of the product of N-acetylglucosaminyltransferases I and II, i.e. a Man3GlcNAc2 core substituted with GlcNAc beta 1----2 on both alpha 1----3- and alpha 1----6-linked mannose residues, blocks branching N-acetylglucosaminyltransferases IV and V, thereby causing an increase in bi-antennary glycans and a decrease in tri- and tetra-antennary glycans.