Multi-laboratory evaluation of the reproducibility of polymer biodegradation assessments applying standardized and modified respirometry methods.

This research evaluated the intra- and interlaboratory variability when applying OECD 301F and OECD 301B Ready Biodegradation respirometric test methods to quantify polymer biodegradation as well as the impact of method modifications including test duration, inoculum level and test substance concentration on results. This assessment synthesizes results of mineralization studies on 5 polymers of varying structural components, molecular weight, charge, and solubility, evaluated at 8 different laboratories in 4 different countries, providing significant geographic variation in inoculum source as well as lab to lab variations in test setup. Across all laboratories, intralaboratory variability was low (≤18 % absolute difference) indicating the reproducibility of results between replicates and uniformity of test setup in each laboratory. Interlaboratory variation was also low for all 5 polymers with extent of mineralization being comparable in all OECD 301F and 301B studies even when test methods were modified. Across all studies mean mineralization was 89 ± 5.5 % for polyethylene glycol 35,000, 85 ± 7.4 % for polyvinyl alcohol 18-88, 44 ± 13 % for carboxymethyl cellulose (DS 0.6), 48 ± 4.1 % for a modified guar gum, and 88 ± 6.2 % for microcrystalline cellulose (MCC) at study completion. Due to the lack of polymeric reference materials, MCC was evaluated and found to be a suitable reference material for polymers that biodegrade rapidly in screening studies. An additional respirometric study was conducted quantifying mineralization of the 5 polymers in river water to evaluate the relationship with OECD 301 results using activated sludge as the inoculum. A similar extent of mineralization was observed for all 5 polymers in the OECD 301 and river water studies but time to reach the maximum extent of mineralization was longer using river water as the inoculum source likely due to the lower microbial counts (106 CFU/L) in the test system.

Does Diffusion Restriction Pattern on MRI Predict Stroke Etiology in a Cancer Patient?

BACKGROUND: Stroke and cancer are two of the most common health problems. Moreover, stroke is more common in patients with cancer than in the normal population, due to coagulation problems. Knowing the etiology of stroke is important for determining treatment options. This study aimed to determine the relationship between ischemic lesion topographies using diffusion-weighted magnetic resonance imaging (MRI) and the etiology of stroke in patients with cancer. PATIENTS AND METHODS: All patients with ischemic stroke in the Bezmialem Stroke Registry over a 4- year period were retrospectively analyzed in this study. Patients with acute ischemic stroke and additional diagnoses of solid and active malignancy (excluding hematologic malignancies) were included in the analysis. We investigated whether there was a relationship between the etiology of patients with cancer-related stroke according to the stroke etiologic classification and the diffusion restriction patterns on MRI. RESULTS: In this registry, 32 of 1472 patients were diagnosed as having active cancer. Fourteen patients were evaluated as having definite cardioembolism, eight patients as probable cardioembolism, and four patients had inadequate examinations. Only one patient was classified as having an atherothrombotic stroke. Isolated acute infarction was seen in 15 of 32 patients. In patients with multiple acute infarct areas (n=17), acute lesions characterized by micro embolisms in a single vessel area were detected in four patients, and acute lesions characterized by bilateral (anterior and/or posterior system) micro embolisms in more than one vessel area in 13 patients. CONCLUSION: The most common etiology of stroke in patients with cancer was found to be embolic/ cardioembolic. This is important for the treatment plans for ischemic stroke in patients with cancer.

Safety and Outcomes of Intravenous Thrombolysis in Posterior Versus Anterior Circulation Stroke: Results From the Safe Implementation of Treatments in Stroke Registry and Meta-Analysis.

Background and Purpose- Posterior circulation stroke (PCS) accounts for 5% to 19% of patients with acute stroke receiving intravenous thrombolysis. We aimed to compare safety and outcomes following intravenous thrombolysis between patients with PCS and anterior circulation stroke (ACS) and incorporate the results in a meta-analysis. Methods- We included patients in the Safe Implementation of Treatments in Stroke Thrombolysis Registry 2013 to 2017 with computed tomography/magnetic resonance angiographic occlusion data. Outcomes were parenchymal hematoma, symptomatic intracerebral hemorrhage (SICH) per SITS-MOST (Safe Implementation of Thrombolysis in Stroke Monitoring Study), ECASS II (Second European Co-operative Stroke Study) and NINDS (Neurological Disorders and Stroke definition), 3-month modified Rankin Scale score, and death. Adjustment for SICH risk factors (age, sex, National Institutes of Health Stroke Scale, blood pressure, glucose, and atrial fibrillation) and center was done using inverse probability treatment weighting, after which an average treatment effect (ATE) was calculated. Meta-analysis of 13 studies comparing outcomes in PCS versus ACS after intravenous thrombolysis was conducted. Results- Of 5146 patients, 753 had PCS (14.6%). Patients with PCS had lower median National Institutes of Health Stroke Scale: 7 (interquartile range, 4-13) versus 13 (7-18), P<0.001 and fewer cerebrovascular risk factors. In patients with PCS versus ACS, parenchymal hematoma occurred in 3.2% versus 7.9%, ATE (95% CI): -4.7% (-6.3% to 3.0%); SICH SITS-MOST in 0.6% versus 1.9%, ATE: -1.4% (-2.2% to -0.7%); SICH NINDS in 3.1% versus 7.8%, ATE: -3.0% (-6.3% to 0.3%); SICH ECASS II in 1.8% versus 5.4%, ATE: -2.3% (-5.3% to 0.7%). In PCS versus ACS, 3-month outcomes (70% data availability) were death 18.5% versus 20.5%, ATE: 6.0% (0.7%-11.4%); modified Rankin Scale score 0-1, 45.2% versus 37.5%, ATE: 1.7% (-6.6% to 3.2%); modified Rankin Scale score 0-2, 61.3% versus 49.4%, ATE: 2.4% (3.1%-7.9%). Meta-analysis showed relative risk for SICH in PCS versus ACS being 0.49 (95% CI, 0.32-0.75). Conclusions- The risk of bleeding complications after intravenous thrombolysis in PCS was half that of ACS, with similar functional outcomes and higher risk of death, acknowledging limitations of the National Institutes of Health Stroke Scale for stroke severity or infarct size adjustment.

A case with CMTX1 disease showing transient ischemic-attack-like episodes.

Charcot-Marie-Tooth (CMT) disease is a hereditary neurologic disease which affects the sensorial and motor fibers of the peripheral nerves. CMTX1 is an X-linked dominantly inherited subtype of CMT and is caused by mutations in gap junction beta 1 gene (GJB1). A small proportion of GJB1 mutations are associated with recurrent central nervous system findings. We describe a 15-year-old male patient with CMTX1 who had stroke-like findings along with foot deformities and peripheral neuropathy. Strokes and stroke-like attacks are rarely seen in children and adolescents. Herein, neurological signs, MRI findings and genetic results of a CMTX1 case are presented and discussed.

Vascular Ischemia as a Cause of Transient Global Amnesia: A Patient Series.

INTRODUCTION: Epileptic, migrainous, and vascular pathologies may cause transient global amnesia (TGA); however, the mechanism of causation remains unclear. We investigated possible vascular causes of TGA. METHODS: We retrospectively evaluated the clinical and radiologic studies of 13 patients with TGA. On admission, patients underwent diffusion-weighted imaging (DWI) and intra- and extracranial magnetic resonance angiography (MRA); vascular risk factor profiles for diabetes, hypertension, and hyperlipidemia; electroencephalography; and neuropsychological tests. Seven patients underwent control DWIs 24 h after symptom onset. RESULTS: One patient had two punctiform acute infarcts in the left hippocampus, and one had a left pontine paramedian acute infarct. In the second patient, control DWI showed additional left hippocampal and right frontal acute infarcts. None of the patients had electroencephalographic evidence of epileptic activity. All patients except for one had at least one vascular risk factor. The second patient was shown to have paroxsysmal atrial fibrillation during follow-up. CONCLUSION: Minor posterior circulation ischemic stroke appears to cause TGA in some patients. Evaluations such as DWI and vascular risk factor assessment may be helpful in making the diagnosis.

Gender differences in acute stroke: Istanbul medical school stroke registry.

BACKGROUND: We aimed to investigate gender differences in Turkish stroke patients. MATERIAL AND METHODS: Demographics, risk factors, clinical and etiologic subtypes, laboratory findings, clinical course, and in-hospital prognosis of 1 522 patients with ischemic stroke (IS) and 320 patients with intracerebral hemorrhage prospectively registered in the Istanbul Medical School Stroke Registry (1994-2004) were analyzed separately. RESULTS: The mean age of IS patients was higher in females (n : 751) (P<0.0001). In males, smoking, ischemic heart disease, peripheral arterial disease, posterior circulation syndromes, and strokes due to large-artery atherosclerosis were more common (P<0.0001 for each). Prestroke disability, atrial fibrillation (P<0.0001), hypertension (P=0.041), modified Rankin Scale (mRS) 3-5 at admission (P<0.0001), total anterior circulation syndrome (P<0.0001), and cardioembolic stroke (P<0.0001) were more frequent in females. Female gender was an independent predictor of poor outcome (mRS 3-6). CONCLUSION: Gender differences were observed exclusively in patients with IS. Although our patients were younger than those reported, gender differences were similar.