A time-course prediction model of global COVID-19 mortality

Introduction

The COVID-19 pandemic has caused over 6 million deaths worldwide and is a significant cause of mortality. Mortality dynamics vary significantly by country due to pathogen, host, social and environmental factors, in addition to vaccination and treatments. However, there is limited data on the relative contribution of different explanatory variables, which may explain changes in mortality over time. We, therefore, created a predictive model using orthogonal machine learning techniques to attempt to quantify the contribution of static and dynamic variables over time.

Methods

A model was created using Partial Least Squares Regression trained on data from 2020 to rank order the significance and effect size of static variables on mortality per country. This model enables the prediction of mortality levels for countries based on demographics alone. Partial Least Squares Regression was then used to quantify how dynamic variables, including weather and non-pharmaceutical interventions, contributed to the overall mortality in 2020. Finally, mortality levels for the first 60 days of 2021 were predicted using rolling-window Elastic Net regression.

Results

This model allowed prediction of deaths per day and quantification of the degree of influence of included variables, accounting for timing of occurrence or implementation. We found that the most parsimonious model could be reduced to six variables; three policy-related variables - COVID-19 testing policy, canceled public events policy, workplace closing policy; in addition to three environmental variables - maximum temperature per day, minimum temperature per day, and the dewpoint temperature per day.

Conclusion

Country and population-level static and dynamic variables can be used to predict COVID-19 mortality, providing an example of how broad temporal data can inform a preparation and mitigation strategy for both COVID-19 and future pandemics and assist decision-makers by identifying population-level contributors, including interventions, that have the greatest influence in mitigating mortality, and optimizing the health and safety of populations.

Outcomes of coronavirus disease 2019 (COVID-19) and risk factors associated with severe COVID-19 in patients with mature B-cell non-Hodgkin lymphomas: A US electronic health record cohort study

OBJECTIVES

The objectives of this study were to assess the risk of severe coronavirus disease 2019 (COVID-19) outcomes in patients with mature B-cell non-Hodgkin lymphoma (mature B-cell NHL) compared with other cancers and to identify risk factors associated with severe COVID-19.

METHODS

This study used Optum's electronic health record database. Risk factors were evaluated using multivariable logistic regression.

RESULTS

Patients with mature B-cell NHL were more likely to be hospitalized or die from COVID-19 (age- and sex-standardized risk: 15.6%, 2.1%, respectively) than those without cancer (9.5%, 1.2%), or with solid tumors (9.7%, 1.3%). In patients with mature B-cell NHL, factors associated with severe COVID-19 outcomes included: greater age (75-84 years, adjusted odds ratio, 1.6 [95% CI, 1.3-2.0]; ≥85, 2.6 [2.0-3.4]), male sex (1.4 [1.2-1.6]), chronic kidney disease (1.4 [1.1-1.7]), chronic obstructive pulmonary disease (1.3 [1.0-1.6]), type 2 diabetes (1.3 [1.1-1.5]), and receiving treatment for NHL (1.5 [1.1-2.1]).

CONCLUSIONS

These data suggest that patients with mature B-cell NHL are at a higher risk of severe COVID-19 than patients with solid tumors or without cancer and that risk factors are largely consistent with those in the general population.

Predictors of cinacalcet discontinuation and reinitiation in hemodialysis patients: results from 7 European countries

Background

The putative benefits of cinacalcet therapy for management of secondary hyperparathyroidism (SHPT) are thought to be most manifested when patients are taking it consistently and as prescribed. Real-world descriptions of cinacalcet prescription discontinuation and reinitiation in European hemodialysis patients are lacking. To address this knowledge gap, we used Dialysis Outcomes and Practice Patterns Study (DOPPS) data, based on dialysis facility medical records, from seven European countries to estimate rates and predictors of cinacalcet prescription discontinuation and reinitiation in hemodialysis patients and to describe the trajectories of CKD-MBD laboratory values after discontinuation.

Methods

Cox regression analyses were used to predict (1) cinacalcet discontinuation among 613 patients with ≥3 consecutive months without cinacalcet prescription immediately prior to a new cinacalcet prescription and (2) cinacalcet reinitiation among 415 patients with a newly discontinued cinacalcet prescription immediately after ≥3 consecutive months of prescribed use.

Results

Cinacalcet was discontinued in 21 and 35% of new users after 6 and 12 months, respectively. Cinacalcet was reinitiated in 38 and 49% of newly-discontinued users after 6 and 12 months, respectively. Predictors of discontinuation included lower parathyroid hormone (PTH) in the previous month (< 150 pg/ml vs. 150–299, HR = 2.57 [95% CI: 1.52–4.33]) and lower serum calcium in the previous month (< 8.4 mg/dl vs. 8.4–10.19, HR = 1.67 [95% CI: 1.08–2.59]). Predictors of reinitiation included higher PTH in the previous month (300–599 pg/ml vs. 150–299, HR = 1.88 [95% CI = 1.19–2.97]; 600+ pg/ml, HR = 3.02 [95% CI = 1.92–4.76]). After cinacalcet discontinuation, mean serum PTH increased from 408 to 510 pg/ml, mean serum calcium briefly rose from 9.12 to 9.22 mg/dl before declining to 9.06 mg/dl, and mean serum phosphorus showed little change.

Conclusions

Nephrologist discontinuation of cinacalcet therapy is common in European countries. Additional research is needed to identify optimal cinacalcet treatment strategies for SHPT management, including comparisons of intermittent cinacalcet therapy versus sustained treatment with reduced dose or frequency.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1355-5) contains supplementary material, which is available to authorized users.

Tunable Photon Statistics Exploiting the Fano Effect in a Waveguide

A strong optical nonlinearity arises when coherent light is scattered by a semiconductor quantum dot coupled to a nanophotonic waveguide. We exploit the Fano effect in such a waveguide to control the phase of the quantum interference underpinning the nonlinearity, experimentally demonstrating a tunable quantum optical filter which converts a coherent input state into either a bunched or an antibunched nonclassical output state. We show theoretically that the generation of nonclassical light is predicated on the formation of a two-photon bound state due to the interaction of the input coherent state with the quantum dot. Our model demonstrates that the tunable photon statistics arise from the dependence of the sign of two-photon interference (either constructive or destructive) on the detuning of the input relative to the Fano resonance.

International survey of androgen deprivation therapy (ADT) for non-metastatic prostate cancer in 19 countries

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Background: ADT is commonly used for non-metastatic (M0) prostate cancer (PC) patients as primary therapy for high risk disease, adjuvant therapy together with radiation, or for recurrence after initial local therapy. Intermittent androgen deprivation (IAD) is a more recently developed alternative strategy for providing ADT that is thought to potentially reduce adverse effects, but little is known about practice patterns relating to it. We aimed to describe factors related to physicians' ADT use and modality for M0 PC patients. Methods: A 45-minute online survey was completed by urologists and oncologists from 19 countries with high or increasing prevalence of M0 PC. Respondents were responsible for treatment decisions for M0 PC, and had ≥10 patients on ADT. ADT comprises gonadotropin agonist (GnRH) treatment or bilateral orchiectomy. Results: 441 physicians completed the survey representing 98,689 PC patients under their care, of which 76,386 (77%) had M0 PC. Of M0-PC patients, 38% received ADT (37% GnRH, 2% orchiectomy); among patients on GnRH, 48% received continuous ADT (≥6 months [mos]), 25% IAD, and 26% <6 mos (table). Highest rates of ADT were reported among oncologists (62%) and in Eastern Europe (68%). PSA levels (65%), Gleason score (52%), and treatment guidelines (48%) were the most common reasons for continuous ADT whereas PSA levels (54%), patient request (48%), and patient age (38%) were cited most frequently as the reason for IAD. Conclusions: This international comparison showed that ADT modalities are commonly used in the treatment of M0 PC patients, and that the decision to use ADT is influenced by high risk criteria (PSA and Gleason) and treatment guidelines. IAD use is prevalent and often driven by patient choice and PSA levels. [Table: see text]

Comparing influenza vaccine efficacy against mismatched and matched strains: a systematic review and meta-analysis

BACKGROUND

Influenza vaccines are most effective when the antigens in the vaccine match those of circulating strains. However, antigens contained in the vaccines do not always match circulating strains. In the present work we aimed to examine the vaccine efficacy (VE) afforded by influenza vaccines when they are not well matched to circulating strains.

METHODS

We identified randomized clinical trials (RCTs) through MEDLINE, EMBASE, the Cochrane Library, and references of included RCTs. RCTs reporting laboratory-confirmed influenza among healthy participants vaccinated with antigens of matching and non-matching influenza strains were included. Two independent reviewers screened citations/full-text articles, abstracted data, and appraised risk of bias. Conflicts were resolved by discussion. A random effects meta-analysis was conducted. VE was calculated using the following formula: (1 - relative risk × 100%).

RESULTS

We included 34 RCTs, providing data on 47 influenza seasons and 94,821 participants. The live-attenuated influenza vaccine (LAIV) showed significant protection against mismatched (six RCTs, VE 54%, 95% confidence interval (CI) 28% to 71%) and matched (seven RCTs, VE 83%, 95% CI 75% to 88%) influenza strains among children aged 6 to 36 months. Differences were observed between the point estimates for mismatched influenza A (five RCTs, VE 75%, 95% CI 41% to 90%) and mismatched influenza B (five RCTs, VE 42%, 95% CI 22% to 56%) estimates among children aged 6 to 36 months. The trivalent inactivated vaccine (TIV) also afforded significant protection against mismatched (nine RCTs, VE 52%, 95% CI 37% to 63%) and matched (eight RCTs, VE 65%, 95% CI 54% to 73%) influenza strains among adults. Numerical differences were observed between the point estimates for mismatched influenza A (five RCTs, VE 64%, 95% CI 23% to 82%) and mismatched influenza B (eight RCTs, VE 52%, 95% CI 19% to 72%) estimates among adults. Statistical heterogeneity was low (I2 <50%) across all meta-analyses, except for the LAIV meta-analyses among children (I2 = 79%).

CONCLUSIONS

The TIV and LAIV vaccines can provide cross protection against non-matching circulating strains. The point estimates for VE were different for matching versus non-matching strains, with overlapping CIs.

Errors Associated with IV Infusions in Critical Care

BACKGROUND

All medication errors are serious, but those associated with the IV route of administration often result in the most severe outcomes. According to the literature, IV medications are associated with 54% of potential adverse events, and 56% of medication errors.

OBJECTIVES

To determine the type and frequency of errors associated with prescribing, documenting, and administering IV infusions, and to also determine if a correlation exists between the incidence of errors and either the time of day (day versus night) or the day of the week (weekday versus weekend) in an academic medicosurgical intensive care unit without computerized order entry or documentation.

METHODS

As part of a quality improvement initiative, a prospective, observational audit was conducted for all IV infusions administered to critically ill patients during 40 randomly selected shifts over a 7-month period in 2007. For each IV infusion, data were collected from 3 sources: direct observation of administration of the medication to the patient, the medication administration record, and the patient's medical chart. The primary outcome was the occurrence of any infusion-related errors, defined as any errors of omission or commission in the context of IV medication therapy that harmed or could have harmed the patient.

RESULTS

It was determined that up to 21 separate errors might occur in association with a single dose of an IV medication. In total, 1882 IV infusions were evaluated, and 5641 errors were identified. Omissions or discrepancies related to documentation accounted for 92.7% of all errors. The most common errors identified via each of the 3 data sources were incomplete labelling of IV tubing (1779 or 31.5% of all errors), omission of infusion diluent from the medication administration record (474 or 8.4% of all errors), and discrepancy between the medication order as recorded in the patient's chart and the IV medication that was being infused (105 or 1.9% of all errors).

CONCLUSIONS

Strict definitions of errors and direct observation methods allowed identification of errors at every step of the medication administration process that was evaluated. Documentation discrepancies were the most prevalent type of errors in this paper-based system.

Effect of influenza vaccines against mismatched strains: a systematic review protocol

BACKGROUND

Influenza vaccines are most effective when the antigens in the vaccine match those of circulating influenza strains. The extent to which the vaccine is protective when circulating strains differ from vaccine antigens, or are mismatched, is uncertain. We propose to systematically review the cross-protection offered by influenza vaccines against circulating influenza A or B viruses that are not antigenically well-matched to vaccine strains.

METHODS/DESIGN

This is a protocol for a systematic review and meta-analysis. Placebo-controlled randomized clinical trials (RCTs) reporting laboratory-confirmed influenza among healthy participants vaccinated with antigens of influenza strains that differed from those circulating will be included. The primary outcome is the incidence of laboratory-confirmed influenza (polymerase chain reaction (PCR) or viral culture). The secondary outcome is the incidence of laboratory-confirmed influenza through antibody assay (a less sensitive test than PCR or viral culture) alone or combined with PCR, and/ or viral culture. The review will be limited to RCTs written in English.We will search MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, previous influenza reviews, and the reference lists of included studies to identify potentially relevant RCTs. Two independent reviewers will conduct all levels of screening, data abstraction, and quality appraisal (using the Cochrane risk of bias tool).If appropriate, random effects meta-analysis of vaccine efficacy will be conducted in SAS (version 9.2) by calculating the relative risk. Vaccine efficacy will be calculated using the following formula: (1 - relative risk × 100). The results will be analyzed by type of vaccine (live attenuated, trivalent inactivated, or other). Subgroup analysis will include the effects of age (children, adults, older participants), and influenza A versus influenza B on the results. For influenza B we will also consider variable degrees of antigenic mismatch (lineage and drift mismatch).

DISCUSSION

Our results can be used by researchers and policy-makers to help predict the efficacy of influenza vaccines during mismatched influenza seasons. Furthermore, the review will be of interest to patients and clinicians to determine whether to get immunized or support immunization for a particular influenza season.

Use of intravenous immune globulin in the ICU: a retrospective review of prescribing practices and patient outcomes

RATIONALE

Intravenous immune globulin (IVIG) is a pooled human blood product. Much of IVIG use in Canada is prescribed for 'unlabelled' or 'off-label' indications. Due to costs, risk of use and limited supply, knowledge about the use of IVIG is important. We collected data regarding the usage of IVIG and outcomes of patients receiving IVIG in the intensive care units (ICUs) of two community and three academic hospitals.

METHODS

We reviewed the charts of adult patients who received IVIG in the five ICUs over a 5-year period. Data collection included demographics, severity of illness, indication for and dose of IVIG, mortality and adverse effects. On the basis of a classification developed by Canadian Blood Services, the indications for IVIG were then classified as 'appropriate' or 'inappropriate'.

RESULTS

One hundred and forty-five patients received IVIG in the ICU. In all, 19% of IVIG prescriptions were for 'appropriate' indications and 7% were 'inappropriate'. The remaining 74% were prescribed for indications with some evidence to support their use. Three indications accounted for 50% of all IVIG prescribed: Guillain-Barre syndrome (GBS), necrotising fasciitis (NF) and toxic epidermal necrolysis (TEN). Both the community and academic centres prescribed IVIG for similar indications. Adverse effects associated with IVIG administration included deep vein thrombosis/pulmonary embolism, fever and renal failure, although direct causation related to IVIG could not be established. The overall mortality rate was 55%.

CONCLUSIONS

IVIG is used relatively infrequently in the critical care setting. The most common indications were GBS, TEN and NF. Mortality was high. There was no difference between community and academic ICUs.

Evaluation of standard and modified severity of illness scores in the obstetric patient

PURPOSE

To test discrimination and calibration of APACHE-II and SAPS-II risk prediction scores in a cohort of obstetric patients, and to evaluate the effect of modifying these scores for the physiological changes in pregnancy.

MATERIALS AND METHODS

A retrospective review of obstetric patients, 12 weeks gestation to 48 hours postpartum, admitted to the ICU for more than 24 hours. APACHE-II and SAPS-II, and versions modified for the physiological changes of pregnancy, were evaluated by receiver operating characteristic (ROC) curves and standardized mortality ratios (SMR). Multivariable analysis identified other parameters associated with mortality.

RESULTS

Data were obtained from 332 patients from 5 countries, with a mortality rate of 12%. Mean (± SD) APACHE-II score was 16.8 ± 6.1 and SAPS-II score 26.5 ± 15.8. Good discrimination was demonstrated with area under the ROC curves of 0.82 and 0.78 respectively, with no improvement after modification for altered maternal physiology. APACHE-II overestimated mortality, with an SMR of 0.43 (0.52 after including diagnostic weighting) compared with 0.89 for SAPS-II. Bilirubin, albumin and Glasgow Coma Scale were independently associated with mortality.

CONCLUSION

APACHE-II and SAPS-II are good discriminators of illness severity and may be valuable for comparing obstetric cohorts, but APACHE-II significantly over-estimates mortality.

Fragment-based discovery of BACE1 inhibitors using functional assays

Novel nonpeptidic inhibitors of beta-secretase (BACE1) have been discovered by employing a fragment-based biochemical screening approach. A diverse library of 20000 low-molecular weight compounds were screened and yielded 26 novel hits that were confirmed by biochemical and surface plasmon resonance secondary assays. We describe here fragment inhibitors cocrystallized with BACE1 in a flap open and flap closed conformation as determined by X-ray crystallography.

Regional citrate anticoagulation for PrismaFlex continuous renal replacement therapy

BACKGROUND

Since Mehta et al. reported the first successful use of regional citrate anticoagulation (RCA) for continuous renal replacement therapy (CRRT) in 1990, RCA is increasingly used for CRRT because it provides filter patency with minimal risk of bleeding. However, RCA has been associated with significant metabolic complications including hypocalcemia, hypernatremia, metabolic alkalosis, and citrate toxicity.

OBJECTIVE

To describe our experience with a newly implemented RCA protocol with acid citrate dextrose formula A (ACD-A) and intravenous calcium gluconate, for use with PrismaFlex CRRT in critically ill patients with acute kidney injury.

METHODS

A retrospective chart review was conducted from May 1, 2006, until May 1, 2007, in a 16-bed medical-surgical university-affiliated intensive care unit. Data collected included dialysis filter life, patient and circuit metabolic parameters, and units of packed red blood cells transfused.

RESULTS

Forty-eight patients received dialysis with citrate (n = 178 filters). Circuit clotting occurred in 24% of all filters. Mean +/- SD filter life was 38.4 +/- 25.9 hours, and filter survival at 48 hours was 38.2%. Persistent metabolic alkalosis while on CRRT was identified in 6 of 45 (13.3%) patients. Mild hypocalcemia (ionized calcium <3.6 mg/dL) occurred in 11 (23%) patients, but no patient had an ionized calcium level less than 2.8 mg/dL. Six patients, 3 with acute leukemia, required transfusion of 2 or more units of packed red blood cells in 24 hours.

CONCLUSIONS

We found that anticoagulation of PrismaFlex CRRT with ACD-A and intravenous calcium gluconate provided reasonable filter patency, but with minor metabolic complications. Close monitoring of electrolyte and acid-base balance is required to minimize metabolic derangements.

Survey of information technology in Intensive Care Units in Ontario, Canada

Background

The Intensive Care Unit (ICU) is a data-rich environment where information technology (IT) may enhance patient care. We surveyed ICUs in the province of Ontario, Canada, to determine the availability, implementation and variability of information systems.

Methods

A self-administered internet-based survey was completed by ICU directors between May and October 2006. We measured the spectrum of ICU clinical data accessible electronically, the availability of decision support tools, the availability of electronic imaging systems for radiology, the use of electronic order entry and medication administration systems, and the availability of hardware and wireless or mobile systems. We used Fisher's Exact tests to compare IT availability and Classification and Regression Trees (CART) to estimate the optimal cut-point for the number of computers per ICU bed.

Results

We obtained responses from 50 hospitals (68.5% of institutions with level 3 ICUs), of which 21 (42%) were university-affiliated. The majority electronically accessed laboratory data and imaging reports (92%) and used picture archiving and communication systems (PACS) (76%). Other computing functions were less prevalent (medication administration records 46%, physician or nursing notes 26%; medication order entry 22%). No association was noted between IT availability and ICU size or university affiliation. Sites used clinical information systems from15 different vendors and 8 different PACS systems were in use. Half of the respondents described the number of computers available as insufficient. Wireless networks and mobile computing systems were used in 23 ICUs (46%).

Conclusion

Ontario ICUs demontrate a high prevalence of the use of basic information technology systems. However, implementation of the more complex and potentially more beneficial applications is low. The wide variation in vendors utilized may impair information exchange, interoperability and uniform data collection.

A multicenter survey of Ontario intensive care unit nurses regarding the use of sedatives and analgesics for adults receiving mechanical ventilation

BACKGROUND

Nursing-directed sedation protocols have been shown to reduce the duration of mechanical ventilation and shorten the length of intensive care unit (ICU) stay among critically ill adult patients.

METHODS

We designed a self-administered questionnaire to understand nurses' satisfaction with current sedation and analgesia practices as well as drug therapies in the ICU setting and the perceived relevance of sedation protocols to patient care and nursing autonomy. We surveyed nurses from 3 academic medical-surgical ICUs that were not using a sedation protocol or a sedation scale. Responses were based on a 5-point Likert scale and on text responses to open-ended questions.

RESULTS

Of the 88 respondents, only 52.7% were satisfied (score, > or =4) overall with their local ICU's approach to sedation and analgesia. Nurses favored the use of morphine (85.0%), midazolam (71.2%), and fentanyl (59.6%) over that of lorazepam (38.6%) and haloperidol (15.4%). Some nurses (39.3%) were satisfied with the subjective methods used in their ICU to evaluate sedation adequacy. Almost all respondents believed that a nursing-directed sedation protocol combined with a sedation/agitation scoring system would be valuable to patient care (84.3%) as well as professional nursing practice (85.3%) and that a standardized approach by nurses and physicians was important (81.6%).

CONCLUSIONS

In this survey of ICU nurses, we identified a perceived need for improvement in sedation and analgesia practices. Most respondents believed that the use of a nursing-directed sedation protocol in combination with a sedation scoring system would provide greater practice consistency among nurses and physicians and thus improve the care of critically ill patients.

OVERDIAGNOSIS OF ASTHMA AND ITS RELATIONSHIP TO BODY MASS INDEX

STUDY OBJECTIVES

To describe the clinical features and outcome of patients with invasive group A streptococcal (GAS) infections admitted to the ICU.

DESIGN

Prospective, population-based surveillance for invasive GAS infections was conducted in Ontario from January 1992 until June 2002. All 62 patients meeting clinical and/or histopathologic criteria for invasive GAS who were admitted to the ICUs of four university-affiliated hospitals in Toronto, Canada were included. Demographic and clinical information were obtained retrospectively by chart review. ICU morbidity data included the occurrence of organ dysfunction (renal, hepatic, coagulation, ARDS), treatment, and interventions such as hemodialysis and mechanical ventilation.

MEASUREMENTS AND RESULTS

ARDS developed in 34%, renal dysfunction developed in 55%, hepatic dysfunction developed in 64%, and coagulopathy developed in 69% of patients. A total of 56% of patients were treated with IV polyspecific IgG (IVIG), 81% were intubated and placed on mechanical ventilation, and 21% required renal replacement therapy. The median durations of ICU and hospital stay were 5.3 days and 15.0 days, respectively. The overall mortality was 40%. Mortality correlated directly with acute physiology and chronic health evaluation II score and the number of dysfunctional organs. Survivors were younger, had lower severity of illness scores, fewer dysfunctional organs, and were less likely to have shock or to receive treatment with vasopressors, mechanical ventilation, or pulmonary artery catheters. There was no association between the use of IVIG, surgical intervention, or clindamycin, and survival. Variables independently associated with mortality on multivariable analysis were the presence of coagulopathy (p = 0.0005) and liver dysfunction (p = 0.0123).

CONCLUSIONS

Patients with invasive GAS infection admitted to the ICU have a high mortality rate. In this group of patients, coagulopathy and liver failure were independently associated with mortality. We did not observe any association between the use of IVIG, surgical intervention, or clindamycin, and survival.

Evidence for a significant role of alpha 3-containing GABAA receptors in mediating the anxiolytic effects of benzodiazepines

The GABA(A) receptor subtypes responsible for the anxiolytic effects of nonselective benzodiazepines (BZs) such as chlordiazepoxide (CDP) and diazepam remain controversial. Hence, molecular genetic data suggest that alpha2-rather than alpha3-containing GABA(A) receptors are responsible for the anxiolytic effects of diazepam, whereas the anxiogenic effects of an alpha3-selective inverse agonist suggest that an agonist selective for this subtype should be anxiolytic. We have extended this latter pharmacological approach to identify a compound, 4,2'-difluoro-5'-[8-fluoro-7-(1-hydroxy-1-methylethyl)imidazo[1,2-á]pyridin-3-yl]biphenyl-2-carbonitrile (TP003), that is an alpha3 subtype selective agonist that produced a robust anxiolytic-like effect in both rodent and non-human primate behavioral models of anxiety. Moreover, in mice containing a point mutation that renders alpha2-containing receptors BZ insensitive (alpha2H101R mice), TP003 as well as the nonselective agonist CDP retained efficacy in a stress-induced hyperthermia model. Together, these data show that potentiation of alpha3-containing GABA(A) receptors is sufficient to produce the anxiolytic effects of BZs and that alpha2 potentiation may not be necessary.

Canadian survey of the use of sedatives, analgesics, and neuromuscular blocking agents in critically ill patients

OBJECTIVES

To characterize the perceived utilization of sedative, analgesic, and neuromuscular blocking agents, the use of sedation scales, algorithms, and daily sedative interruption in mechanically ventilated adults, and to define clinical factors that influence these practices.

DESIGN

Cross-sectional mail survey.

PARTICIPANTS

Canadian critical care practitioners.

MEASUREMENTS AND MAIN RESULTS

A total of 273 of 448 eligible physicians (60%) responded. Respondents were well distributed with regard to age, years of practice, specialist certification, size of intensive care unit and hospital, and location of practice. Twenty-nine percent responded that a protocol/care pathway/guideline for the use of sedatives or analgesics is currently in use in their intensive care unit. Daily interruption of continuous infusions of sedatives or analgesics is practiced by 40% of intensivists. A sedation scoring system is used by 49% of respondents. Of these, 67% use the Ramsay scale, 10% use the Sedation-Agitation Scale, 9% use the Glasgow Coma Scale, and 8% use the Motor Activity Assessment Scale. Only 3.7% of intensivists use a delirium scoring system in their intensive care units. Only 22% of respondents currently have a protocol for the use of neuromuscular blocking agents in their intensive care unit, and 84% of respondents use peripheral nerve stimulation for monitoring. In patients receiving neuromuscular blocking agents for >24 hrs, 63.7% of respondents discontinue the neuromuscular blocking agent daily. Intensivists working in university-affiliated hospitals are more likely to employ a sedation protocol and scale (p < .0001), as are intensivists working in larger intensive care units (>or=15 beds, p < .01). Intensivists with anesthesiology training (and no formal critical care training) are more likely to use a protocol and sedation scale, and critical care-trained intensivists are more likely to use daily interruption. Younger physicians (<40 yrs) are more likely to practice daily interruption (p = .0092).

CONCLUSIONS

There is significant variation in critical care sedation, analgesia, and neuromuscular blockade practice. Given the potential effect of practices regarding these medications on patient outcome, future research and educational efforts related to evidence-based protocols for the use of these agents in mechanically ventilated patients might be worthwhile.

8-Fluoroimidazo[1,2-a]pyridine: synthesis, physicochemical properties and evaluation as a bioisosteric replacement for imidazo[1,2-a]pyrimidine in an allosteric modulator ligand of the GABA A receptor

8-Fluoroimidazo[1,2-a]pyridine has been established as a physicochemical mimic of imidazo[1,2-a]pyrimidine, using both in silico and traditional techniques. Furthermore, a novel synthesis of a 3,7-disubstituted-8-fluoroimidazopyridine 3 has been developed and the utility of the physicochemical mimicry has been demonstrated in an in vitro system. Here, the 8-fluoroimidazopyridine ring contained in ligand 3 acts as a bioisosteric replacement for imidazopyrimidine in the GABA(A) receptor modulator 2.

Unsafe driving in North American automobile commercials

BACKGROUND

Motor-vehicle crashes (MVCs) are a leading cause of death of young Americans and Canadians. Aggressive driving and driving at high speed are frequently cited as contributing to crashes. Consumer and safety associations have raised concern that driving behaviour portrayed in automobile commercials may influence consumer-driving behaviour. However, the prevalence of aggressive driving in automobile commercials has not been systematically evaluated.

OBJECTIVES

To identify the prevalence and types of unsafe driving that are portrayed in United States and Canadian televised automobile commercials as well as the use of safety promotion and disclaimers.

DESIGN

All English language automobile and truck commercials (>or=30 seconds in length), airing nationally on major broadcast and cable networks in either the United States or Canada during January or July between 1998 and 2002 were assessed by three independent raters for the presence and type of unsafe driving activity, presence of safety promotion and the use of written disclaimers in each commercial.

RESULTS

Of 250 total commercials, 113 (45 per cent) contained an unsafe driving sequence as determined by at least two of three raters. Unanimous agreement as to the presence of an unsafe driving sequence was found in 63 (25 per cent) commercials. Aggressive driving accounted for 85 per cent of the unsafe driving sequences, including 56 per cent with speed violations. Safety promotion was present in 30 (12 per cent) commercials. Of 141 commercials in which the gender /sex of the driver was shown, 115 (81 per cent) displayed a male driver.

CONCLUSION

Unsafe driving is prevalent in North American automobile commercials. Given the extent to which MVCs are a public health and economic concern, this finding seems in conflict with responsible advertising. The degree to which the portrayal of driving in automobile commercials affects consumer-driving behaviour should be an area of further investigation.

Prospective evaluation of an internet-linked handheld computer critical care knowledge access system

Introduction

Critical care physicians may benefit from immediate access to medical reference material. We evaluated the feasibility and potential benefits of a handheld computer based knowledge access system linking a central academic intensive care unit (ICU) to multiple community-based ICUs.

Methods

Four community hospital ICUs with 17 physicians participated in this prospective interventional study. Following training in the use of an internet-linked, updateable handheld computer knowledge access system, the physicians used the handheld devices in their clinical environment for a 12-month intervention period. Feasibility of the system was evaluated by tracking use of the handheld computer and by conducting surveys and focus group discussions. Before and after the intervention period, participants underwent simulated patient care scenarios designed to evaluate the information sources they accessed, as well as the speed and quality of their decision making. Participants generated admission orders during each scenario, which were scored by blinded evaluators.

Results

Ten physicians (59%) used the system regularly, predominantly for nonmedical applications (median 32.8/month, interquartile range [IQR] 28.3–126.8), with medical software accessed less often (median 9/month, IQR 3.7–13.7). Eight out of 13 physicians (62%) who completed the final scenarios chose to use the handheld computer for information access. The median time to access information on the handheld handheld computer was 19 s (IQR 15–40 s). This group exhibited a significant improvement in admission order score as compared with those who used other resources (P = 0.018). Benefits and barriers to use of this technology were identified.

Conclusion

An updateable handheld computer system is feasible as a means of point-of-care access to medical reference material and may improve clinical decision making. However, during the study, acceptance of the system was variable. Improved training and new technology may overcome some of the barriers we identified.

Analysis of CARD15 polymorphisms in Korean patients with ankylosing spondylitis reveals absence of common variants seen in western populations

OBJECTIVE

Substantial epidemiological and genetic evidence suggests that ankylosing spondylitis (AS) is likely due to an interplay of genetic and environmental factors. Recently, CARD15, located in chromosome 16q12, has been established as a disease susceptibility gene for Crohn's disease, Blau syndrome, and possibly psoriatic arthritis. Association studies in admixed populations from Northern European ancestry noted no such association between CARD15 mutations and AS. However, a homogenous population has yet to be studied. We investigated the prevalence of the 3 common CARD15 variants in a homogenous Korean population with AS.

METHODS

All subjects were native Koreans with AS satisfying the modified New York criteria. Korean controls were examined and confirmed to be unaffected by AS. Subjects with AS were genotyped for the R702W, G908R, and Leu1007fsinsC variants of CARD15 using mass array MALDI-TOF mass spectrometry.

RESULTS

A total of 205 AS subjects and 200 controls were genotyped. No subject with AS had any variants at the 702 and 1007 sites of CARD15. Only one subject was heterozygous for the 908 variant. The overall genotype frequency in AS for any CARD15 variant was 0.5%. No control had any of the 3 CARD15 variants.

CONCLUSION

Our findings indicate that the CARD15 gene is not a major contributor to AS susceptibility in the Korean population.

Temporal change, reproducibility, and interobserver variability in pressure-volume curves in adults with acute lung injury and acute respiratory distress syndrome

OBJECTIVES

To assess the reproducibility of the static pressure-volume curve of the respiratory system by using a "mini-syringe" technique; to assess the temporal change in upper (UIP) and lower inflection points (LIP) measured from pressure-volume curves of the respiratory system; to assess the inter- and intraobserver variability in detection of the UIP and LIP in patients with acute lung injury (ALI)/acute respiratory distress syndrome (ARDS); and to compare the syringe and multiple occlusion techniques for determining LIP and UIP.

DESIGN

Prospective observational study.

SETTING

Academic medical-surgical critical care unit.

PATIENTS

Consecutive patients with ALI or ARDS.

INTERVENTIONS

Static inspiratory pressure-volume curves of the respiratory system were determined twice on day 1 of diagnosis of ALI/ARDS and then once daily for up to 6 days by using the syringe technique. Pressure-volume curves were determined from zero positive end-expiratory pressure. At each time point, three separate measurements of the pressure-volume curve were made to determine reproducibility. A 100-mL graduated syringe was used to inflate patients' lungs with 50- to 100-mL increments up to an airway pressure of 45 cm H2O or a total volume of 2 L; each volume step was maintained for 2-3 secs until a plateau airway pressure was recorded. On day 1, the static pressure-volume curve also was determined by using the multiple occlusion technique. In a random and blinded sequence, the pressure-volume curves were examined visually by three critical care physicians on three different occasions, to determine the intra- and interobserver variability in visual detection of the LIP and UIP. Observers were given objective instructions to visually identify LIP and UIP.

MEASUREMENTS AND MAIN RESULTS

Eleven patients were enrolled, with a total of 134 pressure-volume curves generated. LIP and UIP could be detected in 90-94% and 61-68% of curves, respectively. When the three successive pressure-volume curves were compared, both the LIP and UIP were within 3 cm H2O in >65% of curves. The index of reliability (intraclass correlation coefficient) in LIP and UIP was 0.92 and 0.89 for interobserver variability and 0.90 and 0.88 for intraobserver variability. Daily variability was as high as 7 cm H2O for LIP and 5 cm H2O for UIP. When pressure-volume curves obtained by using the multiple occlusion and syringe techniques were compared, LIP was within 2 cm H2O, and UIP was within 4 cm H2O with the two techniques.

CONCLUSIONS

The static pressure-volume curve of the respiratory system is reasonably reproducible, thus avoiding the need for multiple measurements at a single time. We found excellent interobserver and intraobserver correlation in manual identification of the LIP and UIP. Both LIP and UIP show appreciable daily variability in patients with ALI/ARDS. The multiple occlusion and syringe techniques generate similar values for LIP and UIP.

Critically ill patients with severe acute respiratory syndrome

CONTEXT

Severe acute respiratory syndrome (SARS) is a newly recognized infectious disease capable of causing severe respiratory failure.

OBJECTIVE

To determine the epidemiological features, course, and outcomes of patients with SARS-related critical illness.

DESIGN, SETTING, AND PATIENTS

Retrospective case series of 38 adult patients with SARS-related critical illness admitted to 13 intensive care units (ICUs) in the Toronto area between the onset of the outbreak and April 15, 2003. Data were collected daily during the first 7 days in the ICUs, and patients were followed up for 28 days.

MAIN OUTCOME MEASURES

The primary outcome was mortality at 28 days after ICU admission. Secondary outcomes included rate of SARS-related critical illness, number of tertiary care ICUs and staff placed under quarantine, and number of health care workers (HCWs) contracting SARS secondary to ICU-acquired transmission.

RESULTS

Of 196 patients with SARS, 38 (19%) became critically ill, 7 (18%) of whom were HCWs. The median (interquartile range [IQR]) age of the 38 patients was 57.4 (39.0-69.6) years. The median (IQR) duration between initial symptoms and admission to the ICU was 8 (5-10) days. Twenty-nine (76%) required mechanical ventilation and 10 of these (34%) experienced barotrauma. Mortality at 28 days was 13 (34%) of 38 patients and for those requiring mechanical ventilation, mortality was 13 (45%) of 29. Six patients (16%) remained mechanically ventilated at 28 days. Two of these patients had died by 8 weeks' follow-up. Patients who died were more often older, had preexisting diabetes mellitus, and on admission to hospital were more likely to have bilateral radiographic infiltrates. Transmission of SARS in 6 study ICUs led to closure of 73 medical-surgical ICU beds. In 2 university ICUs, 164 HCWs were quarantined and 16 (10%) developed SARS.

CONCLUSIONS

Critical illness was common among patients with SARS. Affected patients had primarily single-organ respiratory failure, and half of mechanically ventilated patients died. The SARS outbreak greatly strained regional critical care resources.

Safety of pressure-volume curve measurement in acute lung injury and ARDS using a syringe technique

STUDY OBJECTIVES

To assess the safety of frequent pressure-volume (PV) curve measurement in patients with acute lung injury (ALI)/ARDS.

DESIGN

Prospective observational study.

SETTING

Academic medical-surgical critical care unit.

PATIENTS

Consecutive patients with ALI or ARDS.

INTERVENTIONS

Static inspiratory PV curves of the respiratory system were determined twice on day 1, then once daily for up to 6 days using a syringe. At each time point, three separate measurements of the PV curve were made. A 100-mL graduated syringe was used to inflate patients' lungs with 50- to 100-mL increments up to an airway pressure of 45 cm H(2)O or a total volume of 2 L; each volume step was maintained for 2 to 3 s until a plateau airway pressure was recorded. Outcome measures were mean arterial BP, heart rate (HR), and oxyhemoglobin saturation (SpO(2)) prior to and immediately after PV curve measurement. There were a priori criteria for procedure discontinuation if poorly tolerated.

MEASUREMENTS AND RESULTS

Eleven patients were enrolled with a total of 134 PV curves generated. SpO(2) was 93 +/- 4% (mean +/- SD) before and fell to a nadir of 89 +/- 5% during PV curve measurement (p < 0.001), but increased to 97 +/- 4% immediately afterwards (p < 0.001, before vs after). HR rose from 106 +/- 22 to 108 +/- 22 beats/min immediately after the maneuver (p < 0.001). Mean arterial BP was 93 +/- 15 mm Hg before and 100 +/- 17 mm Hg immediately afterwards (p < 0.001). During PV curve measurement, systolic BP in one patient fell to 64 mm Hg from 113 mm Hg; in another patient, SpO(2) dropped to 79% from 89%. Both changes were transient. The study was discontinued in one patient because of inability to tolerate zero positive end-expiratory pressure; in another patient, the study was discontinued because of the development of subcutaneous emphysema.

CONCLUSIONS

PV curve measurement by syringe technique is well tolerated in most patients. Nonetheless, the maneuver may cause significant changes in oxygenation and/or hemodynamics, necessitating close monitoring.

Patient handling of a dry-powder inhaler in clinical practice

BACKGROUND

Multi-dose dry-powder inhalers are perceived as being easier for patients to use than conventional pressurized aerosol inhalers; however, no study has determined whether patients handle such devices adequately and whether there is a need for patient education in this area.

METHOD

We used trained observers to assess the handling of a specific multi-dose dry powder inhaler (Turbuhaler; AstraZeneca Canada; Mississauga, ON) by patients currently using the device for the management of their asthma. Fourteen discrete steps were scored independently by two observers simultaneously. Patients were divided into two groups for analysis: those who had received formal instruction in the use of the inhaler at The Asthma Centre and those who had received no formal instruction in the community.

RESULTS

There was no significant difference between the formally trained groups and control groups in the percentage of handling steps performed correctly (79% vs 78%, respectively; p > 0.05). Fewer than 50% of patients in both groups demonstrated optimal breath-holding when using the device.

CONCLUSION

Patient handling of Turbuhaler was generally good, with no evidence that a structured education intervention offered an advantage over the usual education incidental to the prescribing or dispensing process. The most common handling flaw, suboptimal breath-holding, is not specific to this device and is of uncertain clinical significance.

Handheld computers in critical care

BACKGROUND

Computing technology has the potential to improve health care management but is often underutilized. Handheld computers are versatile and relatively inexpensive, bringing the benefits of computers to the bedside. We evaluated the role of this technology for managing patient data and accessing medical reference information, in an academic intensive-care unit (ICU).

METHODS

Palm III series handheld devices were given to the ICU team, each installed with medical reference information, schedules, and contact numbers. Users underwent a 1-hour training session introducing the hardware and software. Various patient data management applications were assessed during the study period. Qualitative assessment of the benefits, drawbacks, and suggestions was performed by an independent company, using focus groups. An objective comparison between a paper and electronic handheld textbook was achieved using clinical scenario tests.

RESULTS

During the 6-month study period, the 20 physicians and 6 paramedical staff who used the handheld devices found them convenient and functional but suggested more comprehensive training and improved search facilities. Comparison of the handheld computer with the conventional paper text revealed equivalence. Access to computerized patient information improved communication, particularly with regard to long-stay patients, but changes to the software and the process were suggested.

CONCLUSIONS

The introduction of this technology was well received despite differences in users' familiarity with the devices. Handheld computers have potential in the ICU, but systems need to be developed specifically for the critical-care environment.

Early damage as measured by the SLICC/ACR damage index is a predictor of mortality in systemic lupus erythematosus

The aim of this study was to determine whether early damage accrued in SLE as measured by the SLICC/ACR Damage Index predicts mortality in an inception cohort of lupus patients that have been followed prospectively in a single centre. SLE patients from the University of Toronto Lupus Clinic presenting within 1 y of their diagnosis prior to 1988 were included. This enabled all patients to be potentially followed for at least 10 y. Yearly SLICC/ACR Damage Index scores were determined for each patient. Early damage was defined as a score > or = 1 and no damage as a score of 0 at the initial assessment. Log rank test was used to compare the survival experience between those with and without damage, with all patients being censored at 10 y. Two-hundred and sixty-three patients were identified in this inception cohort who were followed for 10 y. One-hundred and ninety patients (72%) had a SLICC/ACR Damage Index score of 0 (no damage) while 73 patients (28%) had at least one SLICC/ACR Damage Index item scored (early damage). Twenty-five percent of lupus patients who exhibited damage at their first SLICC/ACR Damage Index assessment died within 10 y of their illness as compared to only 7.3% who had no early damage (log rank P-value = 0.0002). SLE patients who died within 10 y were more likely to have renal damage (P = 0.013), and a trend toward more cardiovascular disease (P = 0.056), compared to patients who were alive. Early damage as reflected by the initial SLICC/ACR Damage Index is associated with a higher rate of mortality.

Vascular events in hypertensive patients with systemic lupus erythematosus

Our purpose was to examine prospectively the relationship between systemic hypertension and vascular events in patients with SLE. SLE patients followed in the University of Toronto Lupus Clinic presenting between 1980 and 1988 and within one year of their diagnosis of SLE were identified. Standard definitions were used for hypertension and for all vascular events (MI, angina, CVA, PVD). The presence of traditional CAD risk factors, along with disease- and therapy-related risk factors for the development of vascular disease, were compared in the hypertensive and normotensive group. A multivariate logistic regression was performed to determine the best predictor of a vascular event. One hundred and fifty patients were identified in our inception cohort [75 hypertensive (50%) and 75 (50%) normotensive]. Seventeen hypertensive patients (22.7%) had at least one vascular event as compared to six (8.0%) normotensive patients (p = 0.022). The vascular events included 7 with CAD, 5 with CVA, and 5 with PVD in the hypertensive group while in the normotensive group 3 patients developed CAD, 2 CVA and 1 PVD. Fifteen deaths were recorded in the hypertensive group as compared to eight deaths in the non-hypertensive groups (P = 0.09). The groups were comparable with respect to associated risk factors, except for higher frequency of hypercholesterolemia (P = 0.003), azotemia (P = 0.001) and corticosteroid use (P = 0.038) in the hypertension group. In a multivariate analysis the best predictor of a vascular event was hypercholesterolemia (OR 6.9, 95% CI 2.4-24.8, P < 0.001). We conclude that systemic hypertension is associated with an increased frequency of vascular events in SLE. This is best explained by its association with hypercholesterolemia.

Accurately describing changes in disease activity in Systemic Lupus Erythematosus

OBJECTIVE

To determine whether Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores correlate with the clinician's impression of level of disease activity.

METHODS

In total, 230 patients with SLE followed at the University of Toronto Lupus Clinic who had 5 visits 3 months apart in 1992-93 were studied. At each visit a standard protocol was completed. A clinician who did not know the patients or their SLEDAI scores evaluated each patient record and assigned a clinical activity level. "Flare" was defined by new or increased therapy for active disease, an expression of concern, or use of the term "flare" in the physician's notes. The SLEDAI score was calculated from the database.

RESULTS

SLEDAI scores described a range of clinical activity as recognized by the clinician. Median SLEDAI scores ranged from 2 (inactive disease) to 8 (persistently active or flare). When the clinician assessed the patient to be improved, the median SLEDAI score decreased by 2. When the clinician assessed that the patient was experiencing a flare, the SLEDAI score increased by a median of 4.

CONCLUSION

Based on our data we propose the following outcomes for patients with SLE: flare, an increase in SLEDAI > 3; improvement is a reduction in SLEDAI of > 3; persistently active disease is change in SLEDAI +/- 3; and remission a SLEDAI of 0. These outcomes will allow a more complete description of a patient's response to therapeutic intervention in a responder index.

The cholesterol lowering effect of antimalarial drugs is enhanced in patients with lupus taking corticosteroid drugs

OBJECTIVE

To examine the relationship between antimalarial therapy and total cholesterol in patients with systemic lupus erythematosus (SLE) with or without steroid therapy.

METHODS

Retrospective study for the University of Toronto Lupus Clinic database between 1976 and 1997. The effects of antimalarials on random total cholesterol levels were assessed in the following situations: patients not receiving steroids (part I) that either initiated or discontinued antimalarials; patients receiving steroids (part II) that were either on a stable dose or initiating antimalarials; and patients initiating steroids with or without antimalarials (part III). Paired t test, Fisher's exact test, and 2 way analysis of variance were used when appropriate.

RESULTS

Initiation of antimalarials reduced the baseline total cholesterol by 4.1 % at 3 months in 53 patients (p = 0.020) and by 0.6% at 6 months in 30 patients (p = NS), while the cessation of antimalarials increased the total cholesterol by 3.6% at 3 months in 38 patients (p = NS) and 5.4% at 6 months in 22 patients (p = NS). In 181 patients taking steroids and antimalarials, the mean total cholesterol was 11% less than for 201 patients receiving a comparable dose of steroids alone (p = 0.0023). Initiation of antimalarials on a stable dose of steroids reduced the total cholesterol by 11.3% at 3 months in 29 patients (p = 0.0002) and 9.4% at 6 months in 20 patients (p = 0.004). For patients initiating steroids, the percentage increase in cholesterol was lower in those taking antimalarials compared to patients without antimalarial therapy (p = 0.0149).

CONCLUSION

Antimalarials lower total cholesterol in patients receiving steroids and may minimize steroid induced hypercholesterolemia.

Synthesis of hemoglobin Aic and related minor hemoglobin by erythrocytes. In vitro study of regulation

Factors that influence hemoglobin (Hb)A(Ic) synthesis by intact erythrocytes were studied in vitro. After incubation cells were lysed, and hemoglobins were separated by isoelectric focusing on polyacrylamide slab gels and quantitated by microdensitometry. HbA(Ic) increased with time, glucose concentrations (5-500 mM), and incubation temperature (4 degrees -37 degrees C). Low temperatures allowed prolonged incubations with minimal hemolysis. At 4 degrees C HbA(Ic) increased linearly with time for 6 wk; after incubation at the highest glucose concentration, HbA(Ic) comprised 50% of total hemoglobin. Insulin (1 and 0.1 mU/ml) did not affect HbA(Ic) synthesis in vitro. In addition to glucose, galactose and mannose, but not fructose, served as precursors to HbA(Ic). A good substrate for hexokinase (2-deoxyglucose) and a poor hexokinase substrate (3-O-methylglucose), were better precursors for HbA(Ic) synthesis than glucose, suggesting that enzymatic phosphorylation of glucose is not required for HbA(Ic) synthesis. Autoradiography after erythrocyte incubation with (32)P-phosphate showed incorporation of radioactivity into HbA(Ia1) and A(Ia2), but not HbA(Ib), A(Ic), or A. Acetylated HbA, generated during incubation with acetylsalicylate, migrated anodal to HbA(Ic) and clearly separated from it. Erythrocytes from patients with insulinopenic diabetes mellitus synthesized HbA(Ic) at the same rate as controls when incubated with identical glucose concentrations. Likewise, the rate of HbA(Ic) synthesis by erythrocytes from patients with cystic fibrosis and congenital spherocytosis paralleled controls. When erythrocytes from cord blood and from HbC and sickle cell anemia patients were incubated with elevated concentrations of glucose, fetal Hb, HbC, and sickle Hb decreased, whereas hemoglobins focusing at isoelectric points near those expected for the corresponding glycosylated derivatives appeared in proportionately increased amounts.

Analysis of in vitro transcription products of intracellular vesicular stomatitis virus RNA polymerase

The intracellular transcriptase complex of vesicular stomatitis virus-infected L cells synthesized RNA complementary to the entire infectious virus genome at either 37 degrees C or 28 degrees C in vitro. Not all sequences were present at the same frequency, however; copies of that segment of the genome common to the LT defective particles were present at 20 to 100 times higher frequently than copies of the genome segment common to the ST defective particle. The less frequent region was transcribed somewhat more effectively at 28 degrees C than at 37 degrees C. The results suggest that transcriptional regulation rather than selective degradation is responsible for the differential accumulation of RNA.