Alcohol Prevention in Urgent and Emergency Care (APUEC): Development and Evaluation of Workforce Digital Training on Screening, Brief Intervention, and Referral for Treatment.

Excessive alcohol consumption carries a significant health, social and economic burden. Screening, brief intervention and referral to treatment (SBIRT) is one approach to identifying patients with excessive alcohol consumption and providing interventions to help them reduce their drinking. However, healthcare workers in urgent and emergency care settings do not routinely integrate SBIRT into clinical practice and raise a lack of training as a barrier to SBIRT delivery. Therefore, "Alcohol Prevention in Urgent and Emergency Care" (APUEC) training was developed, delivered, and evaluated. APUEC is a brief, stand-alone, multimedia, interactive digital training package for healthcare workers. The aim of APUEC is to increase positive attitudes, knowledge, confidence and skills related to SBIRT through the provision of (a) education on the impact of alcohol and the role of urgent and emergency care in alcohol prevention, and (b) practical guidance on patient assessment, delivery of brief advice and making referral decisions. Development involved collaborative-participatory design approaches and a rigorous six-step ASPIRE methodology (involving n = 28 contributors). APUEC was delivered to healthcare workers who completed an online survey (n = 18) and then participated in individual qualitative interviews (n = 15). Analysis of data was aligned with Levels 1-3 of the Kirkpatrick Model of Training Evaluation. Survey data showed that all participants (100%) found the training useful and would recommend it to others. Insights from the qualitative data showed that APUEC digital training increases healthcare workers' perceived knowledge, confidence and skills related to alcohol prevention in urgent and emergency care settings. Participants viewed APUEC to be engaging and relevant to urgent and emergency care workers. This digital training was perceived to be useful for workforce skills development and supporting the implementation of SBIRT in clinical practice. While the impact of APUEC on clinician behaviour and patient outcomes is yet to be tested, APUEC digital training could easily be embedded within education and continuing professional development programmes for healthcare workers and healthcare trainees of any discipline. Ultimately, this may facilitate the integration of SBIRT into routine care and contribute to population health improvement.

Blind spots on western blots: Assessment of common problems in western blot figures and methods reporting with recommendations to improve them.

Western blotting is a standard laboratory method used to detect proteins and assess their expression levels. Unfortunately, poor western blot image display practices and a lack of detailed methods reporting can limit a reader's ability to evaluate or reproduce western blot results. While several groups have studied the prevalence of image manipulation or provided recommendations for improving western blotting, data on the prevalence of common publication practices are scarce. We systematically examined 551 articles published in the top 25% of journals in neurosciences (n = 151) and cell biology (n = 400) that contained western blot images, focusing on practices that may omit important information. Our data show that most published western blots are cropped and blot source data are not made available to readers in the supplement. Publishing blots with visible molecular weight markers is rare, and many blots additionally lack molecular weight labels. Western blot methods sections often lack information on the amount of protein loaded on the gel, blocking steps, and antibody labeling protocol. Important antibody identifiers like company or supplier, catalog number, or RRID were omitted frequently for primary antibodies and regularly for secondary antibodies. We present detailed descriptions and visual examples to help scientists, peer reviewers, and editors to publish more informative western blot figures and methods. Additional resources include a toolbox to help scientists produce more reproducible western blot data, teaching slides in English and Spanish, and an antibody reporting template.

Disruptive technologies in health care disenchanted: a systematic review of concepts and examples.

OBJECTIVES: To clarify the concept of disruptive technologies in health care, provide examples and consider implications of potentially disruptive technologies for health technology assessment (HTA). METHODS: We conducted a systematic review of conceptual and empirical papers on healthcare technologies that are described as "disruptive." We searched MEDLINE and Embase from 2013 to April 2019 (updated in December 2021). Data extraction was done in duplicate by pairs of reviewers utilizing a data extraction form. A qualitative data analysis was undertaken based on an analytic framework for analysis of the concept and examples. Key arguments and a number of potential predictors of disruptive technologies were derived and implications for HTA organizations were discussed. RESULTS: Of 4,107 records, 28 were included in the review. Most of the papers included conceptual discussions and business models for disruptive technologies; only few papers presented empirical evidence. The majority of the evidence is related to the US healthcare system. Key arguments for describing a technology as disruptive include improvement of outcomes for patients, improved access to health care, reduction of costs and better affordability, shift in responsibilities between providers, and change in the organization of health care. A number of possible predictors for disruption were identified to distinguish these from "sustaining" innovations. CONCLUSIONS: Since truly disruptive technologies could radically change technology uptake and may modify provision of care patterns or treatment paths, they require a thorough evaluation of the consequences of using these technologies, including economic and organizational impact assessment and careful monitoring.

Diet or medication in primary care patients with IBS: the DOMINO study - a randomised trial supported by the Belgian Health Care Knowledge Centre (KCE Trials Programme) and the Rome Foundation Research Institute.

BACKGROUND: In Europe, IBS is commonly treated with musculotropic spasmolytics (eg, otilonium bromide, OB). In tertiary care, a low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet provides significant improvement. Yet, dietary treatment remains to be explored in primary care. We evaluated the effect of a smartphone FODMAP-lowering diet application versus OB on symptoms in primary care IBS. METHODS: IBS patients, recruited by primary care physicians, were randomised to 8 weeks of OB (40 mg three times a day) or diet and followed for 24 weeks. We compared IBS Symptom Severity Score and the proportion of responders (improvement ≥50 points) in all patients and the subgroup fulfilling Rome IV criteria (Rome+). We also evaluated treatment efficacy, quality of life, anxiety, depression, somatic symptom severity (Patient Health Questionnaire (PHQ15, PHQ9)) and treatment adherence and analysed predictors of response. RESULTS: 459 primary care IBS patients (41±15 years, 76% female, 70% Rome+) were randomised. The responder rate after 8 weeks was significantly higher with diet compared with OB (71% (155/218) vs 61% (133/217), p=0.03) and more pronounced in Rome+ (77% (118/153) vs 62% (98/158), p=0.004). Patients allocated to diet (199/212) were 94% adherent compared with 73% with OB (148/202) (p<0.001). The significantly higher response rate with diet was already observed after 4 weeks (62% (132/213) vs 51% (110/215), p=0.02) and a high symptom response persisted during follow-up. Predictors of response were female gender (OR=2.08, p=0.04) for diet and PHQ15 (OR=1.10, p=0.02) for OB. CONCLUSION: In primary care IBS patients, a FODMAP-lowering diet application was superior to a spasmolytic agent in improving IBS symptoms. A FODMAP-lowering diet should be considered the first-line treatment for IBS in primary care. TRIAL REGISTRATION NUMBER: NCT04270487.

A nonhuman primate model of blue light-induced progressive outer retina degeneration showing brimonidine drug delivery system-mediated cyto- and neuroprotection.

Geographic atrophy (GA) is an advanced form of age-related macular degeneration (AMD) characterized by atrophy of the retinal pigment epithelium (RPE), loss of photoreceptors, and disruption of choriocapillaris. Excessive light exposure is toxic to the retina and is a known risk factor for AMD. We first investigated the effects of blue light-induced phototoxicity on RPE and photoreceptors in nonhuman primates (NHPs, a model of progressive retinal degeneration) and then evaluated the potential cyto- and neuroprotective effects of the brimonidine drug delivery system (Brimo DDS). In the first set of experiments related to model development, parafoveal lesions of varying severity were induced using blue light irradiation of the retina of cynomolgus monkeys to evaluate the level of phototoxicity in the RPE and photoreceptors. RPE damage was assessed using fundus autofluorescence imaging to quantify areas of hypofluorescence, while thinning of the outer nuclear layer (ONL, photoreceptor nuclei) was quantified using optical coherence tomography (OCT). Photoreceptor function was assessed using multifocal electroretinography (mfERG). RPE damage progressively increased across all lesion severities from 2 to 12 weeks, as did the extent of ONL thinning. Lesions of high severity continued to show reduction in mfERG amplitude, reaching a statistically significant maximum reduction at 12 weeks. Collectively, the first set of experiments showed that blue light irradiation of the NHP eye resulted in progressive retinal degeneration identified by damage to RPE, ONL thinning, and disrupted photoreceptor function - hallmarks of GA in humans. We then used the model to evaluate the cyto- and neuroprotective effects of Brimo DDS, administered as a therapeutic after allowing the lesions to develop for 5 weeks. Placebo DDS or Brimo DDS were administered intravitreally and a set of untreated animals were used as an additional control. In the placebo DDS group, hypofluorescence area continued to increase from baseline, indicating progressive RPE damage, while progression was significantly slowed in eyes receiving Brimo DDS. Likewise, ONL thinning continued to progress over time in eyes that received the placebo DDS, but was reduced in Brimo DDS-treated eyes. Pharmacologically relevant brimonidine concentrations were sustained in the retina for up to 26 weeks following Brimo DDS administration. In summary, Brimo DDS demonstrated cyto- and neuroprotective effects in a novel NHP GA model of progressive retinal degeneration.

A Remarkable Remission: Treating HMA Refractory Transforming MDS with Single-Agent Low-Dose Cytarabine Leading to an Ongoing Six-Year OS.

Hypomethylating agents (HMA) are the standard of care for patients ≥65 years with intermediate-high risk myelodysplastic syndrome (MDS) unsuitable for intensive therapy or stem cell transplant (SCT). However, many patients will develop relapse/refractory disease, at which point limited treatment options remain. There has been a lot of research into investigational agents following HMA failure, especially now into targeted therapy, but there is no final consensus or convincing data to guide clinicians. Low-dose cytarabine (LDAC) has been in the armamentarium for some time, but the value of LDAC is judged differently by various guidelines. Nevertheless, in a subgroup of patients who fail on a HMA and wish to continue treatment, LDAC may still have the potential to improve overall survival (OS). In this case report, we present an 85-year-old gentleman with HMA refractory high-risk/transforming MDS (with a noncomplex karyotype) achieving an ongoing six-year OS with single-agent second-line LDAC. LDAC may therefore still be considered by clinicians as a therapeutic option, but when available, patients should be enrolled on a clinical trial.

Parents' views and experiences of talking about autism with their children.

The way an autism diagnosis is disclosed to parents has been found to play a crucial role in their acceptance of, and the way they cope with, their child's diagnosis. Yet, research into parents' subsequent experiences of disclosing a diagnosis to their children, and talking to their families about autism more generally, is limited. Using an online survey, the current study examined 558 parents' experiences of talking about autism with their autistic and non-autistic children. Results demonstrated that most parents (n = 379, 67.9%) had told their autistic children about their diagnosis. Despite few parents (n = 163, 20.4%) receiving advice or support regarding the disclosure of the diagnosis, those that had disclosed felt satisfied with the process (n = 319, 84.2%) and felt confident in talking about autism with their children (n = 339, 92.4%). Those who had not told their autistic children about the diagnosis largely planned to discuss this with their child in the future (n = 100, 73.5%), felt confident in doing so (n = 95, 70.9%) and were satisfied with their decision (n = 95, 70.4%). Analysis of open-ended data, using thematic analysis, highlighted the importance of openness and the need to tailor explanations to individual children's needs, while acknowledging that disclosure could often be challenging for parents.

Controls on iron(II) fluxes into waterways impacted by acid mine drainage: A Damköhler analysis of groundwater seepage and iron kinetics.

When acidic groundwater flows into an aquatic system the sediment water interface (SWI) acts as a transition zone between the groundwater and lake water, and often exhibits strong physical and biogeochemical gradients. The fate of groundwater-borne solutes, such as Fe(II), is determined by the balance between the exposure time during transport across the SWI and the reaction time within the SWI, however the relative role of groundwater seepage rates and iron kinetics on acidity generation in lakes is unknown. Porewater seepage velocities, porewater chemical profiles, and limnological data were collected across multiple field campaigns over the last two decades, in acid Mine Lake 77, in Lusatia, Germany. This rare data set was analyzed using a Damköhler approach that compares exposure and reactions timescales, to determine that Fe(II) would typically be transported with little reaction across the SWI, spatially separating it from sediment-processes that produce alkalinity and providing a source of acidity to the lake. This Damköhler analysis further showed that remediation should be focused on reducing groundwater seepage velocities and enhancing exposure times. Strategic planting of submerged benthic macroalgae would slow groundwater inflows, as well as oxygenating overlying waters and supplying organic matter to the sediments. A similar Damköhler analysis could be used to assess the fate of any groundwater-borne reactive chemicals (e.g. phosphorus) into lakes and streams.

STP Position Paper: Recommended Best Practices for Sampling, Processing, and Analysis of the Peripheral Nervous System (Nerves and Somatic and Autonomic Ganglia) during Nonclinical Toxicity Studies.

Peripheral nervous system (PNS) toxicity is surveyed inconsistently in nonclinical general toxicity studies. These Society of Toxicologic Pathology "best practice" recommendations are designed to ensure consistent, efficient, and effective sampling, processing, and evaluation of PNS tissues for four different situations encountered during nonclinical general toxicity (screening) and dedicated neurotoxicity studies. For toxicity studies where neurotoxicity is unknown or not anticipated (situation 1), PNS evaluation may be limited to one sensorimotor spinal nerve. If somatic PNS neurotoxicity is suspected (situation 2), analysis minimally should include three spinal nerves, multiple dorsal root ganglia, and a trigeminal ganglion. If autonomic PNS neuropathy is suspected (situation 3), parasympathetic and sympathetic ganglia should be assessed. For dedicated neurotoxicity studies where a neurotoxic effect is expected (situation 4), PNS sampling follows the strategy for situations 2 and/or 3, as dictated by functional or other compound/target-specific data. For all situations, bilateral sampling with unilateral processing is acceptable. For situations 1-3, PNS is processed conventionally (immersion in buffered formalin, paraffin embedding, and hematoxylin and eosin staining). For situation 4 (and situations 2 and 3 if resources and timing permit), perfusion fixation with methanol-free fixative is recommended. Where PNS neurotoxicity is suspected or likely, at least one (situations 2 and 3) or two (situation 4) nerve cross sections should be postfixed with glutaraldehyde and osmium before hard plastic resin embedding; soft plastic embedding is not a suitable substitute for hard plastic. Special methods may be used if warranted to further characterize PNS findings. Initial PNS analysis should be informed, not masked ("blinded"). Institutions may adapt these recommendations to fit their specific programmatic requirements but may need to explain in project documentation the rationale for their chosen PNS sampling, processing, and evaluation strategy.

C-MAC© videolaryngoscopy: The anaesthetic assistant's view.

Although videolaryngoscopy plays a major role in the 2015 Difficult Airway Society guidelines, the impact on anaesthetic assistant working practices and training has not previously been reported. We surveyed anaesthetic assistants in our hospital to document their experience with using the C-MAC© videolaryngoscope (48 practitioners, 100% response rate). Improvements in the following were reported: patient safety 100%; ability to see whether laryngoscopy is difficult 98%; ability to anticipate the 'next step' 98%; team-working and human factors 96%; ability to call a senior anaesthetist more quickly 94%; assessment or adjustment of cricoid force application 92%, understanding of laryngeal anatomy 92%; training in intubation 98%; training in cricoid force application 87%. Concerns were primarily about local issues such as decontamination and blade availability. Ninety percent reported that the clinical benefit outweighed any additional workload. In conclusion, the C-MAC© videolaryngoscope is judged by anaesthetic assistants to confer numerous advantages for their working practice and training.

Cervical Spine Aneurysmal Bone Cysts in the Pediatric Population: A Systematic Review of the Literature.

Cervical spine aneurysmal bone cysts (ABCs) in pediatric patients have not been thoroughly studied. Using PubMed and Google Scholar, a systematic review of the literature was conducted for publications that included patients aged ≤15 years with a confirmed diagnosis of ABC in the cervical spine. Thirty-five studies with a total of 71 patients met the inclusion criteria. Nearly 80% of patients presented with neck or shoulder pain. The axis was the level most frequently involved (34.28%), followed by C5 (24.28%). Posterior elements were most likely to be affected (88.46%) while exclusive involvement of the body was uncommon. To our knowledge, this is the first systematic review of the literature regarding ABCs of the cervical spine in a pediatric population. Spinal ABCs are rarely found in the cervical region, and their treatment remains challenging due to their location, vascularization, and a high overall recurrence rate even with surgical resection.

Improving Bisphosphonate Infusion Monitoring at Haematology Medical Day Unit.

This project was started after an incident of bisphosphonate-induced hypocalcaemia in September 2015. As part of management of lytic bone lesions in patients with multiple myeloma were given either Zoledronic Acid or Pamidronate Disodium at our Haematology Day Unit. According to the British National Formulary (BNF), it is necessary to correct disturbances of calcium metabolism (e.g. vitamin D deficiency, hypocalcaemia) and consider dental check-ups before starting bisphosphonate infusion due to the risk of osteonecrosis of the jaw. There was no formal checklist in place for all patients prior to starting bisphosphonate infusion. The aim of this quality improvement project was (1) to avoid preventable bisphosphonate induced adverse effects, (2) to improve safety of bisphosphonate prescribing and administration and (3) to increase patient's awareness of needing regular dental checks. Interventions were modified over multiple Plan-Do-Study-Act (PDSA) improvement cycles to improve bisphosphonate infusion monitoring and patient safety.There was an overall improvement in ensuring safety checks were done prior to administration of bisphosphonate infusion compared to baseline measurements. At baseline, 36% (n=9) of patients had a dental check within the last 6 months; after PDSA cycle 3, there was an improvement of up to 69% (n=11). All patients had renal function and bone profile checked prior to infusion from throughout the study. It was all recorded in the blood results section of the checklist with no missing data. We found that 32% (n=8) of patients had never had 25-OHD at baseline. After PDSA cycle 3, all patients had 25-OHD checked at some point.

Artefactual 25-OH vitamin D concentration in multiple myeloma.

The most commonly used techniques to measure vitamin D are automated immunoassays which are known to be affected by interferences, especially from immunoglobulins present in the patient's serum. We present a case of a patient with myeloma in whom interference with the vitamin D assay was identified. An 83-year-old female, known to have IgG myeloma, was found to have a high concentration of 25-OH vitamin D on a routine test without any signs of vitamin D toxicity. She was not taking vitamin D supplements or any other multivitamin preparation and had minimal sun exposure. The initial and subsequent samples run by the ARCHITECT 25-OH vitamin D assay (chemiluminescent microparticle immunoassay technology, Abbott Laboratories, Abbott Park, IL) showed a high concentration of 25-OH vitamin D of 281 nmol/L and 327 nmol/L, respectively. Further fresh samples taken for 25-OH vitamin D and analysed by liquid chromatography-mass spectrometry (LC-MS/MS) and ARCHITECT analysis showed results of 49 nmol/L and 289 nmol/L, respectively. Our patient had high concentrations of circulating IgG paraproteins and had a long history of rheumatoid arthritis; paraproteins and rheumatoid factor may interfere in the assay. In conclusion, we report a case of a patient with IgG myeloma and rheumatoid arthritis with high concentrations of 25-OH vitamin D detected by the Abbott ARCHITECT, but not by a reference method (LC-MS/MS). The most likely cause of the discordant results is interference in the immunoassay by the paraprotein but interference from rheumatoid factor remains a possibility.

The Source and Impact of Specific Parameters that Enhance Well-Being in Daily Life.

The purpose of this study was to review four parameters (forgiveness, gratitude, hope and empathy) frequently noted when evaluating well-being. We reviewed clinical studies from 1966 to present. We included 63 articles. All four of the parameters were shown to generally improve an individual's well-being. These parameters demonstrated a positive influence within more specific societal issues including improvement in social relationships, delinquent behavior and physical health. These parameters were generally derived from training and religion. This study suggests that these parameters may improve either one of general well-being, pro-social and positive relational behavior and demonstrate positive health effects.

Experiences of receiving a diagnosis of autism spectrum disorder: a survey of adults in the United kingdom.

A total of 128 adults with high-functioning autism spectrum disorders were surveyed concerning the process they went through to obtain their diagnosis and the subsequent support they received. Results suggested that routes to diagnosis were quite heterogeneous and overall levels of satisfaction with the diagnostic process were mixed; 40 % of respondents were 'very/quite' dissatisfied, whilst 47 % were 'very/quite' satisfied. The extent of delays, number of professionals seen, quality of information given at diagnosis and levels of post-diagnostic support predicted overall satisfaction with the diagnostic process. Important areas and suggestions for improvement were noted for all stages of the diagnostic pathway. Respondents also displayed above average levels of depressed mood and anxiety, with greater support being requested in this area.

STP position paper: Recommended practices for sampling and processing the nervous system (brain, spinal cord, nerve, and eye) during nonclinical general toxicity studies.

The Society of Toxicologic Pathology charged a Nervous System Sampling Working Group with devising recommended practices to routinely screen the central nervous system (CNS) and peripheral nervous system (PNS) in Good Laboratory Practice-type nonclinical general toxicity studies. Brains should be weighed and trimmed similarly for all animals in a study. Certain structures should be sampled regularly: caudate/putamen, cerebellum, cerebral cortex, choroid plexus, eye (with optic nerve), hippocampus, hypothalamus, medulla oblongata, midbrain, nerve, olfactory bulb (rodents only), pons, spinal cord, and thalamus. Brain regions may be sampled bilaterally in rodents using 6 to 7 coronal sections, and unilaterally in nonrodents with 6 to 7 coronal hemisections. Spinal cord and nerves should be examined in transverse and longitudinal (or oblique) orientations. Most Working Group members considered immersion fixation in formalin (for CNS or PNS) or a solution containing acetic acid (for eye), paraffin embedding, and initial evaluation limited to hematoxylin and eosin (H&E)-stained sections to be acceptable for routine microscopic evaluation during general toxicity studies; other neurohistological methods may be undertaken if needed to better characterize H&E findings. Initial microscopic analyses should be qualitative and done with foreknowledge of treatments and doses (i.e., "unblinded"). The pathology report should clearly communicate structures that were assessed and methodological details. Since neuropathologic assessment is only one aspect of general toxicity studies, institutions should retain flexibility in customizing their sampling, processing, analytical, and reporting procedures as long as major neural targets are evaluated systematically.

Helping students reflect: lessons from cognitive psychology.

The challenges of teaching students to reflect on experience and, thus, learn from it, are better understood with the application of constructs from cognitive psychology. The present paper focuses on two such constructs-self-schemas and scripts-to help educators better understand both the threats and opportunities associated with effective reflection. Emotion is presented as an important accompaniment to reflection. Suggestions are presented, using the notions of self-schemas and scripts, to help students manage the emotion associated with reflection and to enhance the value of that reflection.

Modern pathology methods for neural investigations.

This session at the 2010 joint symposium of the Society of Toxicologic Pathology (STP) and the International Federation of Societies of Toxicologic Pathologists (IFSTP) explored modern neuropathology methods for assessing the neurotoxicologic potential of xenobiotics. Conventional techniques to optimally prepare and evaluate the central and peripheral neural tissues while minimizing artifact were reviewed, and optimal schemes were set forth for evaluation of the nervous system during both routine (i.e., general toxicity) studies and enhanced (i.e., specialized neurotoxicity) studies. Stereology was introduced as the most appropriate means of examining the possible impact of toxicants on neural cell numbers. A focused discussion on brain sampling took place among a panel of expert neuroscientists (anatomists and pathologists) and the audience regarding the proper balance between sufficient sampling and cost- and time-effectiveness of the analysis. No consensus was reached on section orientation (coronal sections of both sides vs. a parasagittal longitudinal section with several unilateral hemisections from the contralateral side), but most panelists favored sampling at least 8 sections (or approximately double to triple the current complement) in routine toxicity studies.

Spontaneous aortic dissecting hematoma in two dogs.

This report describes 2 cases of spontaneous aortic dissecting hematoma in young Border Collie and Border Collie crossbred dogs. Histology was performed in one of the cases involving an unusual splitting of the elastin present within the wall of the aorta, consistent with elastin dysplasia as described in Marfan syndrome in humans. The first case involved a young purebred Border Collie that died suddenly and the second case involved a Border Collie crossbred dog that died after a 1-month history of seizures. Gross lesions included pericardial tamponade with dissection of the ascending aorta in the former case and thoracic cavity hemorrhage, mediastinal hematoma, and aortic dissection in the latter. Histologic lesions in the case of the Border Collie crossbred dog included a dissecting hematoma of the ascending aorta with elastin dysplasia and right axillary arterial intimal proliferation.

Preclinical safety and pharmacokinetics of recombinant human factor XIII.

Factor XIII (FXIII) is a thrombin-activated protransglutaminase responsible for fibrin clot stabilization and longevity. Deficiency in FXIII is associated with diffuse bleeding and wound-healing disorders in humans. This report summarizes results from several studies conducted in adult cynomolgus monkeys (M. fascicularis) to evaluate the safety and pharmacokinetics of recombinant human factor XIII A(2) dimer (rFXIII). Intravenous slow bolus injection of rFXIII resulted in the expected formation of the heterotetramer rA(2)cnB(2), prolonged circulating half-life (5-7 days), and increased plasma transglutaminase activity. Recombinant FXIII was well tolerated as a single dose up to 20 mg/kg rFXIII (2840 U/kg), as repeated daily doses up to 6 mg/kg (852 U/kg) for 14 days, and as 3 repeated doses of 8 mg/kg (1136 U/kg) separated by 14 days. Overt toxicity occurred after a single intravenous injection of = 22.5 mg/kg rFXIII (3150 U/kg), or with 2 doses of = 12.5 mg/kg (1775 U/kg) administered within 72 hours. The rFXIII-mediated toxicity was expressed as an acute systemic occlusive coagulopathy. Evaluation of plasma samples from dosed animals demonstrated formation of cross-linked fibrin/fibrinogen oligomers and higher-order protein aggregates, which are hypothesized to be responsible for the observed vessel occlusion and associated embolic sequelae. These results demonstrate that rFXIII-mediated toxicity results from exaggerated pharmacological activity of the molecule at supraphysiological concentrations. The absence of observed toxicological effect with repeated intravenous doses up to 8 mg/kg (1136 U/kg) was used to support an initial clinical dose range of 0.014 to 0.35 mg/kg (2-50 U/kg).