Safety and efficacy of tenecteplase in patients with wake-up stroke assessed by non-contrast CT (TWIST): a multicentre, open-label, randomised controlled trial

BACKGROUND

Current evidence supports the use of intravenous thrombolysis with alteplase in patients with wake-up stroke selected with MRI or perfusion imaging and is recommended in clinical guidelines. However, access to advanced imaging techniques is often scarce. We aimed to determine whether thrombolytic treatment with intravenous tenecteplase given within 4·5 h of awakening improves functional outcome in patients with ischaemic wake-up stroke selected using non-contrast CT.

METHODS

TWIST was an investigator-initiated, multicentre, open-label, randomised controlled trial with blinded endpoint assessment, conducted at 77 hospitals in ten countries. We included patients aged 18 years or older with acute ischaemic stroke symptoms upon awakening, limb weakness, a National Institutes of Health Stroke Scale (NIHSS) score of 3 or higher or aphasia, a non-contrast CT examination of the head, and the ability to receive tenecteplase within 4·5 h of awakening. Patients were randomly assigned (1:1) to either a single intravenous bolus of tenecteplase 0·25 mg per kg of bodyweight (maximum 25 mg) or control (no thrombolysis) using a central, web-based, computer-generated randomisation schedule. Trained research personnel, who conducted telephone interviews at 90 days (follow-up), were masked to treatment allocation. Clinical assessments were performed on day 1 (at baseline) and day 7 of hospital admission (or at discharge, whichever occurred first). The primary outcome was functional outcome assessed by the modified Rankin Scale (mRS) at 90 days and analysed using ordinal logistic regression in the intention-to-treat population. This trial is registered with EudraCT (2014-000096-80), ClinicalTrials.gov (NCT03181360), and ISRCTN (10601890).

FINDINGS

From June 12, 2017, to Sept 30, 2021, 578 of the required 600 patients were enrolled (288 randomly assigned to the tenecteplase group and 290 to the control group [intention-to-treat population]). The median age of participants was 73·7 years (IQR 65·9-81·1). 332 (57%) of 578 participants were male and 246 (43%) were female. Treatment with tenecteplase was not associated with better functional outcome, according to mRS score at 90 days (adjusted OR 1·18, 95% CI 0·88-1·58; p=0·27). Mortality at 90 days did not significantly differ between treatment groups (28 [10%] patients in the tenecteplase group and 23 [8%] in the control group; adjusted HR 1·29, 95% CI 0·74-2·26; p=0·37). Symptomatic intracranial haemorrhage occurred in six (2%) patients in the tenecteplase group versus three (1%) in the control group (adjusted OR 2·17, 95% CI 0·53-8·87; p=0·28), whereas any intracranial haemorrhage occurred in 33 (11%) versus 30 (10%) patients (adjusted OR 1·14, 0·67-1·94; p=0·64).

INTERPRETATION

In patients with wake-up stroke selected with non-contrast CT, treatment with tenecteplase was not associated with better functional outcome at 90 days. The number of symptomatic haemorrhages and any intracranial haemorrhages in both treatment groups was similar to findings from previous trials of wake-up stroke patients selected using advanced imaging. Current evidence does not support treatment with tenecteplase in patients selected with non-contrast CT.

FUNDING

Norwegian Clinical Research Therapy in the Specialist Health Services Programme, the Swiss Heart Foundation, the British Heart Foundation, and the Norwegian National Association for Public Health.

Electrophysiologic Correlates of Attention versus Stimulus Competition in Young Male and Female Listeners

The effects of attention and stimulus competition on the late auditory-evoked potential (LAEP) were compared in 10 young males and 10 young females. Listeners attended to discrim- inably different oddball tonal sequences presented binaurally or monaurally. Peak amplitudes in response to the frequent tones were measured for Np P2, and early and late N2 (N2e and N2I) components of the LAEP. Whereas N, amplitudes increased, the amplitudes of P2 decreased when listeners attended to, rather than ignored, the tones. Competition effects for both N, and P2 resulted in reduced amplitudes in the presence of contralateral competition. Although findings with N2e and N2I suggested possible attention and competition effects, as well as gender differences, the data were inconsistent and will need further experimental verification. The present findings with the N1 and P2 components provide evidence that different neural processes underlie the attention and competition effects in the human brain.

Abbreviations: EEG = electroencephalographic activity, ERP = event-related potential, LAEP = late auditory-evoked potential, PN = processing negativity, SOA = stimulus-onset asynchrony

Abstract P5-01-10: A panel of murine mammary tumor cell lines to study immune responses to epitopes created by different mutagens including human APOBEC3 enzymes

Background: Tumor mutation loads are a strong predictor of immunotherapy benefit. This is evidenced by studies on skin, lung, and colon cancer, where well-defined processes elicit high mutation burdens and checkpoint therapies often provoke strong anti-tumor immune responses. In comparison, only a small number of breast cancer patients have responded to checkpoint therapies such as anti-PD-L1 and anti-PD-1 monoclonal antibodies. Approximately one-fourth of primary breast cancer and one-third of metastatic tumors have a significant APOBEC mutation burden defined as C-to-T and C-to-G mutations in TCA or TCT trinucleotide motifs, and many tumors have >10,000 of these APOBEC signature single base substitution mutations. However, to our knowledge, systematic immunotherapy studies focusing on this unique, hypermutated subset of breast cancers have yet to be done. Methods: To address the potential relationship between different checkpoint therapies and APOBEC mutation burden, we created a panel of >30 mammary tumor cell lines derived from fully immune-proficient C57BL/6 animals. At least 6 of these cell lines are immortalized, readily engineered using standard molecular biology procedures, and capable of re-engraftment and tumor formation in immune proficient C57BL/6 animals. Two lines were engineered to inducibly express human APOBEC3A, subjected to 1- to 20-rounds of sublethal mutagenesis, and tested systematically for checkpoint therapy responsiveness. Results: Two cell lines were engineered to inducibly express APOBEC3A or a catalytic mutant (E72A). Clones were characterized for inducible APOBEC3A expression and associated DNA damage responses. After varying rounds of mutagenesis, clones were engrafted into the subcutaneous flank or mammary fat pad of C57BL/6 animals. Immunohistochemical and flow cytometry analysis revealed a robust intratumoral CD8 T cell population including a subset with PD-1 expression. Additionally, engrafted tumor cells expressed high levels PD-L1. Experiments are ongoing and immunotherapy responses will be presented. Conclusions: We have isolated a panel of C57BL/6 mammary tumor-derived cell lines and demonstrated re-engraftment into immunocompetent animals. These cell lines constitute a platform for studying the relationship between different mutagens including APOBEC and immunotherapy responses.

Citation Format: Jordan Naumann, Michael Carpenter, Prokopios Argyris, William Brown, Reuben Harris. A panel of murine mammary tumor cell lines to study immune responses to epitopes created by different mutagens including human APOBEC3 enzymes [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-01-10.

Development and characterization of SARS-CoV-2 variant-neutralizing monoclonal antibodies

Vaccination and administration of monoclonal antibody cocktails are effective tools to control the progression of infectious diseases and to terminate pandemics such as COVID-19. However, the emergence of SARS-CoV-2 mutants with enhanced transmissibility and altered antigenicity requires broad-spectrum therapies. Here we developed a panel of SARS-CoV-2 specific mouse monoclonal antibodies (mAbs), and characterized them based on ELISA, Western immunoblot, isotyping, and virus neutralization. Six neutralizing mAbs that exhibited high-affinity binding to SARS-CoV-2 spike protein were identified, and their amino acid sequences were determined by mass spectrometry. Functional assays confirmed that three mAbs, F461G11, F461G15, and F461G16 neutralized four variants of concern (VOC): B.1.1.7 (alpha), B.1.351 (beta), P.1 (gamma) and B.1.617.2 (delta) These mAbs are promising candidates for COVID-19 therapy, and understanding their interactions with virus spike protein should support further vaccine and antibody development.

Intersex human rights, sexual orientation, gender identity and the Yogyakarta Principles

Background

Intersex people are at risk of human rights abuses because their bodies do not fit medical and social norms for female or male bodies. The 2006 Yogyakarta Principles aim to promote good practices in protecting the rights of LGBT and intersex people by applying human rights law in relation to ‘sexual orientation' and ‘gender identity'. They were ineffective in protecting the rights of intersex people, including due to an inappropriate framing around sexual orientation and gender identity. In the same year, a group of clinicians published a ‘consensus statement' reframing intersex traits as ‘disorders of sex development', reinscribing medical authority over intersex bodies. In 2015 a first country (Malta) enacted protections of rights to bodily integrity and physical autonomy and freedom from discrimination, associated with a new attribute of ‘sex characteristics'.

Methods

In January 2017, the International Service for Human Rights and ARC International issued a call for submissions to supplement the Yogyakarta Principles, and brought together a drafting team. The Asia Pacific Forum of National Human Rights Institutions and United Nations Development Program also held a gender- and geopolitically-balanced conference to mark a decade of the original Principles and produce recommendations. An expert meeting was held in Geneva in September 2017 to agree the update.

Results

The ‘Yogyakarta Principles plus 10' elaborated a new attribute of sex characteristics and recognised rights to bodily integrity, truth and legal recognition. These directly respond to the human rights situation of intersex people, with relevance to intersex populations, healthcare workers, advocates, and policymakers.

Conclusions

Adoption of the new attribute and attention to the new Principles can help address the human rights of people with intersex variations within health, education, and other social policy settings.

Effects of oral anticoagulation for atrial fibrillation after spontaneous intracranial haemorrhage in the UK: a randomised, open-label, assessor-masked, pilot-phase, non-inferiority trial

BACKGROUND

Oral anticoagulation reduces the rate of systemic embolism for patients with atrial fibrillation by two-thirds, but its benefits for patients with previous intracranial haemorrhage are uncertain. In the Start or STop Anticoagulants Randomised Trial (SoSTART), we aimed to establish whether starting is non-inferior to avoiding oral anticoagulation for survivors of intracranial haemorrhage who have atrial fibrillation.

METHODS

SoSTART was a prospective, randomised, open-label, assessor-masked, parallel-group, pilot phase trial done at 67 hospitals in the UK. We recruited adults (aged ≥18 years) who had survived at least 24 h after symptomatic spontaneous intracranial haemorrhage, had atrial fibrillation, and had a CHA2DS2-VASc score of at least 2. Web-based computerised randomisation incorporating a minimisation algorithm allocated participants (1:1) to start or avoid long-term (≥1 year) full treatment dose open-label oral anticoagulation. The participants assigned to start oral anticoagulation received either a direct oral anticoagulant or vitamin K antagonist, and the group assigned to avoid oral anticoagulation received standard clinical practice (antiplatelet agent or no antithrombotic agent). The primary outcome was recurrent symptomatic spontaneous intracranial haemorrhage, and was adjudicated by an individual masked to treatment allocation. All outcomes were ascertained for at least 1 year after randomisation and assessed in the intention-to-treat population of all randomly assigned participants, using Cox proportional hazards regression adjusted for minimisation covariates. We planned a sample size of 190 participants (one-sided p=0·025, power 90%, allowing for non-adherence) based on a non-inferiority margin of 12% (or adjusted hazard ratio [HR] of 3·2). This trial is registered with ClinicalTrials.gov (NCT03153150) and is complete.

FINDINGS

Between March 29, 2018, and Feb 27, 2020, consent was obtained at 61 sites for 218 participants, of whom 203 were randomly assigned at a median of 115 days (IQR 49-265) after intracranial haemorrhage onset. 101 were assigned to start and 102 to avoid oral anticoagulation. Participants were followed up for median of 1·2 years (IQR 0·97-1·95; completeness 97·2%). Starting oral anticoagulation was not non-inferior to avoiding oral anticoagulation: eight (8%) of 101 in the start group versus four (4%) of 102 in the avoid group had intracranial haemorrhage recurrences (adjusted HR 2·42 [95% CI 0·72-8·09]; p=0·152). Serious adverse events occurred in 17 (17%) participants in the start group and 15 (15%) in the avoid group. 22 (22%) patients in the start group and 11 (11%) patients in the avoid group died during the study.

INTERPRETATION

Whether starting oral anticoagulation was non-inferior to avoiding it for people with atrial fibrillation after intracranial haemorrhage was inconclusive, although rates of recurrent intracranial haemorrhage were lower than expected. In view of weak evidence from analyses of three composite secondary outcomes, the possibility that oral anticoagulation might be superior for preventing symptomatic major vascular events should be investigated in adequately powered randomised trials.

FUNDING

British Heart Foundation, Medical Research Council, Chest Heart & Stroke Scotland.

Snowflake porous multi-metal oxide nanocatalysts from metallocene@metal organic framework precursors

Snowflake metallocene@MOF-derived ammonia catalyst.

MOF-derived nanostructured catalysts for low-temperature ammonia synthesis

Nanostructured catalysts for low-temperature ammonia synthesis have been developed via thermal treatment under nitrogen of Ru-containing MOFs.

The interaction between the Nipah virus nucleocapsid protein and phosphoprotein regulates virus replication

Continued outbreaks of Henipaviruses in South Asia and Australia cause severe and lethal disease in both humans and animals. Together, with evidence of human to human transmission for Nipah virus and the lack of preventative or therapeutic measures, its threat to cause a widespread outbreak and its potential for weaponization has increased. In this study we demonstrate how overexpression of the Nipah virus nucleocapsid protein regulates viral polymerase activity and viral RNA production. By overexpressing the Nipah virus nucleocapsid protein in trans viral transcription was inhibited; however, an increase in viral genome synthesis was observed. Together, the bias of polymerase activity towards genome production led to the severe inhibition of viral progeny. We identified two domains within the nucleocapsid protein, which were each independently capable of binding the viral phosphoprotein. Evident by our data, we propose that the nucleocapsid protein’s ability to interact with the phosphoprotein of the polymerase complex causes a change in polymerase activity and subsequent deficiency in viral replication. This study not only provides insights into the dynamics of Henipavirus RNA synthesis and replication, but also provides insight into potential targets for antiviral drug development.

The role of inflammation in the association between gestational diabetes and obstructive sleep apnea: A pilot study

Background

Obstructive sleep apnea is associated with pregnancy complications including gestational diabetes. Mechanisms underlying the association between obstructive sleep apnea and gestational diabetes remain to be elucidated.

Methods

Twenty-three participants with gestational diabetes underwent home sleep apnea testing. Obstructive sleep apnea was defined as an apnea hypopnea index > 5. Fasting morning blood samples were measured using multianalyte profiling (xMAP) multiplexed bead array immunoassay for Interleukin 6, tumor necrosis factor-alpha, and Interleukin 8.

Results

Age, body mass index, and gestational age at enrollment were 31 + 4.4 years, 35.7 + 7.4 kg/m², and 28 ± 4 weeks, respectively. Participants were 52% Caucasian and 16% had obstructive sleep apnea. We observed positive correlations between apnea hypopnea index and Interleukin 6 (r = 0.62, p = 0.005), Interleukin 8 (r = 0.56, p = .56), and tumor necrosis factor-alpha (r = .58, p = .009). Women with obstructive sleep apnea had higher levels of Interleukin 6 (F = 5.01, p = .037) and Interleukin 8 (F = 6.33, p = .021) vs. women without obstructive sleep apnea.

Conclusion

These preliminary results indicate that in women with gestational diabetes, apnea hypopnea index is associated with an elevated inflammatory profile.

Nuclear shapes: Quest for triaxiality in 86Ge and the shape of 98Zr

The region of neutron-rich nuclei above the N = 50 magic neutron shell closure encompasses a rich variety of nuclear structure, especially shapeevolutionary phenomena. This can be attributed to the complexity of sub-shell closures, their appearance and disappearance in the region, such as the N = 56 sub shell or Z = 40 for protons. Structural effects reach from a shape phase transition in the Zr isotopes, over shape coexistence between spherical, prolate, and oblate shapes, to possibly rigid triaxial deformation. Recent experiments in this region and their main physics viewpoints are summarized.

Reasons for non-recruitment of eligible patients to a randomised controlled trial of secondary prevention after intracerebral haemorrhage: observational study

Background

Recruitment to randomised prevention trials is challenging, not least for intracerebral haemorrhage (ICH) associated with antithrombotic drug use. We investigated reasons for not recruiting apparently eligible patients at hospital sites that keep screening logs in the ongoing REstart or STop Antithrombotics Randomised Trial (RESTART), which seeks to determine whether to start antiplatelet drugs after ICH.

Method

By the end of May 2015, 158 participants had been recruited at 108 active sites in RESTART. The trial coordinating centre invited all sites that kept screening logs to submit screening log data, followed by one reminder. We checked the integrity of data, focused on the completeness of data about potentially eligible patients and categorised the reasons they were not randomised.

Results

Of 108 active sites, 39 (36%) provided usable screening log data over a median of ten (interquartile range = 5–13) months of recruitment per site. During this time, sites screened 633 potentially eligible patients and randomised 53 (8%) of them. The main reasons why 580 patients were not randomised were: 43 (7%) patients started anticoagulation, 51 (9%) patients declined, 148 (26%) patients’ stroke physicians were not uncertain about using antiplatelet drugs, 162 (28%) patients were too unwell and 176 (30%) patients were not randomised due to other reasons.

Conclusion

RESTART recruited ~8% of eligible patients. If more physicians were uncertain about the therapeutic dilemma that RESTART is addressing, RESTART could have recruited up to four times as many participants. The trial coordinating centre continues to engage with physicians about their uncertainty.

Trial registration

EU Clinical Trials, EudraCT 2012-003190-26. Registered on 3 July 2012.

Milestone assessment of minimally invasive surgery in Pediatric Urology fellowship programs

INTRODUCTION

Minimally invasive surgery has become an important aspect of Pediatric Urology fellowship training. In 2014, the Accreditation Council for Graduate Medical Education published the Pediatric Urology Milestone Project as a metric of fellow proficiency in multiple facets of training, including laparoscopic/robotic procedures.

OBJECTIVE

The present study assessed trends in minimally invasive surgery training and utilization of the Milestones among recent Pediatric Urology fellows.

STUDY DESIGN

Using an electronic survey instrument, Pediatric Urology fellowship program directors and fellows who completed their clinical year in 2015 were surveyed. Participants were queried regarding familiarity with the Milestone Project, utilization of the Milestones, robotic/laparoscopic case volume and training experience, and perceived competency with robotic/laparoscopic surgery at the start and end of the fellowship clinical year according to Milestone criteria. Responses were accepted between August and November 2015.

RESULTS

Surveys were distributed via e-mail to 35 fellows and 30 program directors. Sixteen fellows (46%) and 14 (47%) program directors responded. All fellows reported some robotic experience prior to fellowship, and 69% performed >50 robotic/laparoscopic surgeries during residency. Fellow robotic/laparoscopic case volume varied: three had 1-10 cases (19%), four had 11-20 cases (25%), and nine had >20 cases (56%). Supplementary or robotic training modalities included simulation (9), animal models (6), surgical videos (7), and courses (2). Comparison of beginning and end of fellowship robotic/laparoscopic Milestone assessment (Summary Fig.) revealed scores of <3 in (10) 62% of fellow self-assessments and 10 (75%) of program director assessments. End of training Milestone scores >4 were seen in 12 (75%) of fellow self-assessment and eight (57%) of program director assessments.

DISCUSSION

An improvement in robotic/laparoscopic Milestone scores by both fellow self-assessment and program director assessment was observed during the course of training; however, 43% of program directors rated their fellow below the graduation target of a Milestone score of 4.

CONCLUSION

The best ways to teach minimally invasive surgery in fellowship training must be critically considered.

The α-β phase transition in volcanic cristobalite

Cristobalite is a common mineral in volcanic ash produced from dome-forming eruptions. Assessment of the respiratory hazard posed by volcanic ash requires understanding the nature of the cristobalite it contains. Volcanic cristobalite contains coupled substitutions of Al3+ and Na+ for Si4+; similar co-substitutions in synthetic cristobalite are known to modify the crystal structure, affecting the stability of the α and β forms and the observed transition between them. Here, for the first time, the dynamics and energy changes associated with the α-β phase transition in volcanic cristobalite are investigated using X-ray powder diffraction with simultaneous in situ heating and differential scanning calorimetry. At ambient temperature, volcanic cristobalite exists in the α form and has a larger cell volume than synthetic α-cristobalite; as a result, its diffraction pattern sits between ICDD α- and β-cristobalite library patterns, which could cause ambiguity in phase identification. On heating from ambient temperature, volcanic cristobalite exhibits a lower degree of thermal expansion than synthetic cristobalite, and it also has a lower α-β transition temperature (∼473 K) compared with synthetic cristobalite (upwards of 543 K); these observations are discussed in relation to the presence of Al3+ and Na+ defects. The transition shows a stable and reproducible hysteresis loop with α and β phases coexisting through the transition, suggesting that discrete crystals in the sample have different transition temperatures.

Identification of differentially expressed proteins in the cervical mucosa of HIV-1-resistant sex workers

Novel tools are necessary to understand mechanisms of altered susceptibility to HIV-1 infection in women of the Pumwani Sex Worker cohort, Kenya. In this cohort, more than 140 of the 2000 participants have been characterized to be relatively resistant to HIV-1 infection. Given that sexual transmission of HIV-1 occurs through mucosal surfaces such as that in the cervicovaginal environment, our hypothesis is that innate immune factors in the genital tract may play a role in HIV-1 infection resistance. Understanding this mechanism may help develop microbicides and/or vaccines against HIV-1. A quantitative proteomics technique (2D-DIGE: two-dimensional difference in-gel electrophoresis) was used to examine cervical mucosa of HIV-1 resistant women ( n = 10) for biomarkers of HIV-1 resistance. Over 15 proteins were found to be differentially expressed between HIV-1-resistant women and control groups ( n = 29), some which show a greater than 8-fold change. HIV-1-resistant women overexpressed several antiproteases, including those from the serpin B family, and also cystatin A, a known anti-HIV-1 factor. Immunoblotting for a selection of the identified proteins confirmed the DIGE volume differences. Validation of these results on a larger sample of individuals will provide further evidence these biomarkers are associated with HIV-1 resistance and could help aid in the development of effective microbicides against HIV-1.

High molecular mass multimer complexes and vascular expression contribute to high adiponectin in the fetus

CONTEXT

High plasma adiponectin concentrations in human fetuses and neonates are unique features of early developmental stages. Yet, the origins of the high adiponectin concentrations in the perinatal period remain elusive.

OBJECTIVE

This study was undertaken to identify the sources and functional properties of adiponectin in utero.

DESIGN AND METHODS

Tissue specimens were obtained at autopsy from 21- to 39-wk-old stillborn human fetuses. Adipose tissue and placenta were obtained at term elective cesarean section. Adiponectin complexes and expression were measured by immunodetection and real-time PCR.

RESULTS

Adiponectin mRNA transcripts were detected in fetal sc and omental adipose depots at lower concentrations than in maternal adipose tissue. Immunoreactive adiponectin was also observed in vascular endothelial cells of fetal organs, including skeletal muscle, kidney, and brain. The absence of adiponectin in all placental cell types and lack of correlation between maternal and umbilical adiponectin indicate that umbilical adiponectin reflects its exclusive production by fetal tissues. The most prominent forms of adiponectin in fetal plasma were high and low molecular mass (HMW and LMW) multimers of 340 and 160 kDa, respectively. The proportion of the HMW complexes was 5-fold (P < 0.001) higher in umbilical plasma than in adult. The high HMW and total adiponectin levels were associated with lower insulin concentration and lower homeostasis model of assessment of insulin resistance indices in umbilical plasma, reflecting higher insulin sensitivity of the fetus compared with adult.

CONCLUSIONS

The abundance of HMW adiponectin and its vascular expression are characteristics of human fetal adiponectin. Combined with high insulin sensitivity, fetal adiponectin may be a critical determinant of in utero growth.

Virtual pulmonary arterioscopy in pulmonary embolic disease

16 slice multidetector CT provides virtual endoscopic views of the inside of arteries, or any other hollow structures. This is performed non-invasively using post-processing of three-dimensional isotropic image data sets, acquired during standard CT examinations. These virtual endoscopic views are simultaneously correlated with the standard multiplanar reconstructions, with the ability to navigate a virtual camera through the hollow structure under study. Normal and abnormal volume rendered images of the pulmonary arteries are presented in correlation with the multiplanar reformats. The abnormal images show the volume rendered appearances of acute and chronic pulmonary embolic disease. It is also postulated that this technique has a problem solving role in the differential diagnosis of chronic mural emboli from extravascular structures such as adjacent lymph nodes or bronchiolar impaction. This technique may also have a role in medical education, providing clinicians and medical students with interactive three-dimensional representations of disease processes.

Sequence-dependent enhancement of hydrolytic deamination of cytosines in DNA by the restriction enzyme PspGI

Hydrolytic deamination of cytosines in DNA creates uracil and, if unrepaired, these lesions result in C to T mutations. We have suggested previously that a possible way in which cells may prevent or reduce this chemical reaction is through the binding of proteins to DNA. We use a genetic reversion assay to show that a restriction enzyme, PspGI, protects cytosines within its cognate site, 5'-CCWGG (W is A or T), against deamination under conditions where no DNA cleavage can occur. It decreases the rate of cytosine deamination to uracil by 7-fold. However, the same protein dramatically increases the rate of deaminations within the site 5'-CCSGG (S is C or G) by approximately 15-fold. Furthermore, a similar increase in cytosine deaminations is also seen with a catalytically inactive mutant of the enzyme showing that endonucleolytic ability of the protein is dispensable for its mutagenic action. The sequences of the mutants generated in the presence of PspGI show that only one of the cytosines in CCSGG is predominantly converted to thymine. Our results are consistent with PspGI 'sensitizing' the cytosine in the central base pair in CCSGG for deamination. Remarkably, PspGI sensitizes this base for damage despite its inability to form stable complexes at CCSGG sites. These results can be explained if the enzyme has a transient interaction with this sequence during which it flips the central cytosine out of the helix. This prediction was validated by modeling the structure of PspGI-DNA complex based on the structure of the related enzyme Ecl18kI which is known to cause base-flipping.

Inhalation delivery of manganese superoxide dismutase-plasmid/liposomes protects the murine lung from irradiation damage

Intratracheal injection of manganese superoxide dismutase-plasmid/liposome (MnSOD-PL) complexes has been demonstrated to delay the onset and reduce the extent of ionizing irradiation-induced murine pulmonary organizing alveolitis/fibrosis. To facilitate translation of this modality to clinical fractionated radiotherapy, inhalation delivery of MnSOD-PL was developed using an ultrasonic nebulizer. Transgene product was quantitated by immunohistochemical quantitation and pulmonary tissue levels of MnSOD biochemical activity. C57BL/6NHsd female mice demonstrated a plasmid dose-dependent increased expression of MnSOD transgene product over the range of 250 microg-2.5 mg of MnSOD-PL administered over a constant 5 min interval. Delivery of a constant concentration of 500 microg of MnSOD-PL with varying times of administration ranging from 0.5 to 10 min demonstrated optimal MnSOD expression at 5 min. Mice pretreated by inhalation delivery of MnSOD-PL demonstrated significantly improved survival after 20 Gy single fraction irradiation to both lungs compared to LacZ-PL inhalation-treated or irradiated control mice. Mice receiving 10 fractions of 3.5 cGy demonstrated increased pulmonary MnSOD transgene product activity by a protocol of every Monday-Wednesday or daily inhalation of MnSOD-PL. Thus, inhalation radioprotective gene therapy using MnSOD-PL provides a practical and effective method for delivery of lung-specific radioprotection during fractionated radiotherapy protocols in a mouse model.

Molecular analysis of collagen XVIII reveals novel mutations, presence of a third isoform, and possible genetic heterogeneity in Knobloch syndrome

Knobloch syndrome (KS) is a rare disease characterized by severe ocular alterations, including vitreoretinal degeneration associated with retinal detachment and occipital scalp defect. The responsible gene, COL18A1, has been mapped to 21q22.3, and, on the basis of the analysis of one family, we have demonstrated that a mutation affecting only one of the three COL18A1 isoforms causes this phenotype. We report here the results of the screening of both the entire coding region and the exon-intron boundaries of the COL18A1 gene (which includes 43 exons), in eight unrelated patients with KS. Besides 20 polymorphic changes, we identified 6 different pathogenic changes in both alleles of five unrelated patients with KS (three compound heterozygotes and two homozygotes). All are truncating mutations leading to deficiency of one or all collagen XVIII isoforms and endostatin. We have verified that, in exon 41, the deletion c3514-3515delCT, found in three unrelated alleles, is embedded in different haplotypes, suggesting that this mutation has occurred more than once. In addition, our results provide evidence of nonallelic genetic heterogeneity in KS. We also show that the longest human isoform (NC11-728) is expressed in several tissues (including the human eye) and that lack of either the short variant or all of the collagen XVIII isoforms causes similar phenotypes but that those patients who lack all forms present more-severe ocular alterations. Despite the small sample size, we found low endostatin plasma levels in those patients with mutations leading to deficiency of all isoforms; in addition, it seems that absence of all collagen XVIII isoforms causes predisposition to epilepsy.

Electrophysiologic correlates of attention versus distraction in young and elderly listeners

This study examined the effects of selective attention versus stimulus competition on the late auditory evoked potential (LAEP) in 20 young and 20 elderly listeners. In a series of test runs, different oddball tonal sequences were presented to one or both ears, and listeners were instructed to attend to tones at a specific target ear. Peak amplitudes were recorded for the N1, P2, and the early and late N2 components of the LAEP. Significant attention effects were found for all four components. N1 amplitudes increased significantly when participants attended to the target stimuli, whereas the amplitudes of P2, N2e, and N21 decreased. For all LAEP components except N21, the attention effect did not differ between young and elderly listeners. Significant competition effects also were found for all four components. Amplitudes were significantly larger in monaural than binaural conditions for all components except N21. The magnitude of this competition effect also was significantly larger for the young listeners than the elderly for all components except N1. These results suggest that the ability to attend selectively to sounds may be more resistant to normal aging than are effects related to stimulus competition.

Re-examination of the role of the human acoustic stapedius reflex

The "rollover" seen in the word recognition performance scores of patients with Bell's palsy (facial nerve paralysis) has historically been taken as an indicator of the role of the stapedius reflex in the protection from upward spread of masking. Bell's palsy, however, may be a polyneuropathy, so it is not clear that the poor word recognition performance at high levels is necessarily attributable specifically to impaired facial nerve function. The present article reports two new experiments that probe whether an isolated impairment of the stapedius reflex can produce rollover in word recognition performance-intensity functions. In experiment 1, performance-intensity functions for monosyllabic speech materials were obtained from ten normal listeners under two listening conditions: normal and low-frequency augmented to offset the effects of the stapedius reflex on the transmission of low-frequency vibrations to the cochlea. There was no effect of the spectral augmentation on word recognition for stimulus levels up to 107 dB SPL. In experiment 2, six patients who had undergone stapedectomy were tested for rollover using performance-intensity functions. None of the patients showed rollover in their performance-intensity functions, even at stimulus levels in excess of 100 dB HL. These data suggest that if the stapedius reflex has a role in protection from upward spread of masking, then this role is inconsequential for word recognition in quiet.

A planned randomized clinical trial of treatment for mild gestational diabetes mellitus

OBJECTIVE

A planned study is described which will determine whether a benefit exists for the treatment of mild carbohydrate intolerance during pregnancy.

METHODS

A randomized clinical trial of women with mild gestational diabetes will compare perinatal outcomes in those receiving diet therapy and insulin as required versus those randomized to no specific treatment.

RESULTS

The primary outcome of this study will be a composite of neonatal morbidity in the treatment and control groups.

CONCLUSIONS

A randomized treatment trial of mild gestational diabetes mellitus will clarify whether identification and treatment of mild gestational diabetes mellitus reduces perinatal morbidity. This information will aid in selecting appropriate thresholds for the treatment of gestational diabetes mellitus.

Recipient cells form the intimal proliferative lesion in the rat aortic model of allograft arteriosclerosis

Chronic rejection is the leading cause of late graft loss following solid organ transplantation and is characterized by a vasculopathy referred to as allograft arteriosclerosis. While the etiology of allograft arteriosclerosis remains unknown, it has been hypothesized that migration of donor medial smooth muscle cells into the intimal compartment is responsible for the formation of the occlusive lesion (neointima). In this study we have used aortic interposition grafts between fully histoincompatible rat strains (Brown Norway and Lewis) to investigate the origin of the neointimal cells. Three transplant paradigms were used: BN to Lew, Lew to BN and BN to Lew with immunosuppression. Neointimal cells were isolated from aortic transplant tissue through an EDTA wash/mechanical stripping technique. We have developed polymerase chain reaction primers to the MHC1 allele that are specific to each rat strains' DNA. Polymerase chain reaction analysis, using the strain-specific primers and purified neointimal cell DNA from transplanted aortic tissue from all three experimental groups, demonstrated that the neointimal cells are of recipient, and not donor origin.

Electrophysiologic signs of attention versus distraction in a binaural listening task

Effects of active versus passive listening on the N1 and P2 components of the late auditory evoked potential were examined in 20 young adults following instructions to ignore and later to attend to different trains of frequent and deviant tones presented to one or both ears. To distinguish monaural from binaural neural refractory or recovery effects, monaural test runs were used to control for differences in stimulus-onset asynchronies (SOAs) between monaural and binaural runs. As expected, selective attention and monaural neuronal refractory effects were found. When attending the tones, listeners exhibited significantly larger P2, but not N1, amplitudes. During test runs with shorter monaural SOAs, listeners exhibited smaller N1 and P2 amplitudes than they did with longer SOAs. However, whether attending or nonattending, P2 amplitudes were smaller during binaural than monaural test runs, which suggests the possible existence of some form of "binaural" neuronal refractory or recovery effect. However, the absence of this binaural effect with the N1 component would suggest that binaural refractoriness, if it exists, involves different physiologic processes than monaural refractoriness.

Using the picture exchange communication system (PECS) with children with autism: assessment of PECS acquisition, speech, social-communicative behavior, and problem behavior

The picture exchange communication system (PECS) is an augmentative communication system frequently used with children with autism (Bondy & Frost, 1994; Siegel, 2000; Yamall, 2000). Despite its common clinical use, no well-controlled empirical investigations have been conducted to test the effectiveness of PECS. Using a multiple baseline design, the present study examined the acquisition of PECS with 3 children with autism. In addition, the study examined the effects of PECS training on the emergence of speech in play and academic settings. Ancillary measures of social-communicative behaviors and problem behaviors were recorded. Results indicated that all 3 children met the learning criterion for PECS and showed concomitant increases in verbal speech. Ancillary gains were associated with increases in social-communicative behaviors and decreases in problem behaviors. The results are discussed in terms of the provision of empirical support for PECS as well as the concomitant positive side effects of its use.

Understanding of others' intentions in children with autism

Many studies have shown that children with autism have difficulty understanding the thoughts and beliefs of other people. However, little research has been conducted on what these children understand about simpler mental states such as intentions. The current study tested the understanding of others' intentions in 2 1/2- to 5-year-old children with autism and a control group of children with other developmental delays. We used Meltzoff's (1995) test of understanding of others' unfulfilled intentions in an imitation context, with an additional "End State" condition. We found no significant between-group differences on any measure involving the understanding of others' intentions. Although within-group patterns suggested that children with autism may have a slightly less complex understanding of others' intentions than do other children, it was clear that any deficits these children showed in this area were not as marked as those they typically show on traditional theory of mind tasks.

Why we should eliminate the due date: a truth in jest

We currently use flawed calculations to set a woman's due date based on menstrual periods to determine gestational age. We use the estimated gestational age to make management decisions based on our patients' individual needs. This principle is in contrast to our patients' use of dating to set an estimated date of confinement. This date is seen as a very specific point in time. Patients and their families plan on that date and become distressed when the expected date is not met. Given that many patients are induced electively, that many will have their delivery dates changed, and that many will have delivery dates adjusted for medical reasons, and most importantly given that dating is inaccurate and unreliable, we propose eliminating the due date. We propose giving patients a calculated assigned week of delivery at 32 weeks. An assigned week of delivery allows for individualization of obstetric care based on the needs of our patients, their support systems, and hospital staffing. We believe an assigned week of delivery will improve obstetric practice and patient satisfaction.

Mortality experience among employees at a hydrometallurgical nickel refinery and fertiliser complex in Fort Saskatchewan, Alberta (1954-95)

OBJECTIVE

To study the mortality experience of workers at a hydrometallurgical nickel refinery and fertiliser complex in Fort Saskatchewan, Alberta, Canada.

METHODS

A total of 1649 male employees of Sherritt International who worked for at least 12 continuous months during the years 1954 to 1978 at the Fort Saskatchewan, Alberta hydrometallurgical nickel refinery and fertiliser complex were followed up for an additional 17 years. Mortality was ascertained from the Canadian mortality data base maintained by Statistics Canada and covered the years 1954-95. Statistics were analysed with Monson's computer program.

RESULTS

Total mortality, when compared with the Canadian population, was significantly below expectation. Fewer deaths were found for circulatory disease, ischaemic heart disease, respiratory disease, neoplasms, digestive cancer, and accidents, poisonings, and violence. Among the 718 men in the group exposed to nickel, there were no deaths due to nasal cavity or paranasal sinus cancer. Fewer deaths were found for all causes, circulatory disease, ischaemic heart disease, neoplasms and digestive cancer. Lower death rates were observed than expected for respiratory malignancies and cancer of the bronchus and lung.

CONCLUSION

No association was found in this study between exposure to nickel concentrate or metallic nickel in the hydrometallurgical refining process and the subsequent development of respiratory cancer.

Possible neuronal refractory or recovery artifacts associated with recording the mismatch negativity response

The mismatch negativity (MMN) is an event-related potential that involves a negative voltage shift of baseline electroencephalographic (EEG) activity in the approximate latency window of the N1 and P2 cortical potentials in response to new or novel sounds. The MMN is present at birth and has been hypothesized to serve as an automatic preconscious detector of changes in the auditory environment. Research paradigms used to extract the MMN response from EEG activity have a potential problem related to neuronal refractoriness or recovery. Both N1 and P2 are known to increase in amplitude with longer interstimulus intervals (ISIs). The MMN extraction procedures involve mathematical subtraction of waveforms elicited by standard sounds (with short ISIs) from those recorded to rare deviant sounds (with longer ISIs). Any ISI-dependent amplitude changes in N1 and/or P2 could therefore alter the morphology of the resulting difference wave and lead to misinterpretation of the nature of the underlying MMN generators. We tested 12 young females and found that the MMN can be influenced by ISI-dependent refractory effects that may modify the waveform morphology. This has important clinical implications since the MMN is being investigated as an assessment tool.