Mediation of the Relationship Between Endovascular Therapy and Functional Outcome by Follow-up Infarct Volume in Patients With Acute Ischemic Stroke

Importance

The positive treatment effect of endovascular therapy (EVT) is assumed to be caused by the preservation of brain tissue. It remains unclear to what extent the treatment-related reduction in follow-up infarct volume (FIV) explains the improved functional outcome after EVT in patients with acute ischemic stroke.

Objective

To study whether FIV mediates the relationship between EVT and functional outcome in patients with acute ischemic stroke.

Design, Setting, and Participants

Patient data from 7 randomized multicenter trials were pooled. These trials were conducted between December 2010 and April 2015 and included 1764 patients randomly assigned to receive either EVT or standard care (control). Follow-up infarct volume was assessed on computed tomography or magnetic resonance imaging after stroke onset. Mediation analysis was performed to examine the potential causal chain in which FIV may mediate the relationship between EVT and functional outcome. A total of 1690 patients met the inclusion criteria. Twenty-five additional patients were excluded, resulting in a total of 1665 patients, including 821 (49.3%) in the EVT group and 844 (50.7%) in the control group. Data were analyzed from January to June 2017.

Main Outcome and Measure

The 90-day functional outcome via the modified Rankin Scale (mRS).

Results

Among 1665 patients, the median (interquartile range [IQR]) age was 68 (57-76) years, and 781 (46.9%) were female. The median (IQR) time to FIV measurement was 30 (24-237) hours. The median (IQR) FIV was 41 (14-120) mL. Patients in the EVT group had significantly smaller FIVs compared with patients in the control group (median [IQR] FIV, 33 [11-99] vs 51 [18-134] mL; P = .007) and lower mRS scores at 90 days (median [IQR] score, 3 [1-4] vs 4 [2-5]). Follow-up infarct volume was a predictor of functional outcome (adjusted common odds ratio, 0.46; 95% CI, 0.39-0.54; P < .001). Follow-up infarct volume partially mediated the relationship between treatment type with mRS score, as EVT was still significantly associated with functional outcome after adjustment for FIV (adjusted common odds ratio, 2.22; 95% CI, 1.52-3.21; P < .001). Treatment-reduced FIV explained 12% (95% CI, 1-19) of the relationship between EVT and functional outcome.

Conclusions and Relevance

In this analysis, follow-up infarct volume predicted functional outcome; however, a reduced infarct volume after treatment with EVT only explained 12% of the treatment benefit. Follow-up infarct volume as measured on computed tomography and magnetic resonance imaging is not a valid proxy for estimating treatment effect in phase II and III trials of acute ischemic stroke.

Inhomogeneous spatial distribution of the magnetic transition in an iron-rhodium thin film

Monitoring a magnetic state using thermal or electrical activation is mandatory for the development of new magnetic devices, for instance in heat or electrically assisted magnetic recording or room-temperature memory resistor. Compounds such as FeRh, which undergoes a magnetic transition from an antiferromagnetic state to a ferromagnetic state around 100 °C, are thus highly desirable. However, the mechanisms involved in the transition are still under debate. Here we use in situ heating and cooling electron holography to quantitatively map at the nanometre scale the magnetization of a cross-sectional FeRh thin film through the antiferromagnetic–ferromagnetic transition. Our results provide a direct observation of an inhomogeneous spatial distribution of the transition temperature along the growth direction. Most interestingly, a regular spacing of the ferromagnetic domains nucleated upon monitoring of the transition is also observed. Beyond these findings on the fundamental transition mechanisms, our work also brings insights for in operando analysis of magnetic devices.

Films of iron-rhodium alloy undergo a magnetic transition at 100°C, and so are attractive for applications, but a detailed understanding of the transition mechanism has not been achieved. Here, the authors use electron holography to quantitatively map the transition's progress through the film depth.

High-resolution imaging of remanent state and magnetization reversal of superdomain structures in high-density cobalt antidot arrays

Remanent state and magnetization reversal processes of a series of cobalt antidot arrays with a fixed hole diameter (d ≈ 55 nm) and an array periodicity (p) ranging between 95 and 524 nm were studied by in situ Lorentz microscopy (LM) as a function of the magnetic field. At remanence, defocused LM images showed the periodicity dependence of the magnetic states inside the lattice. A remarkable transition was observed in the type of domain structures as a function of p: for the large periodicities (p > 300 nm), conventional 90° and 180° domain walls were formed, whereas in small-period antidot arrays (p ≦ 160 nm) magnetic superdomain walls (SDWs) were nucleated to separate regions with different average magnetization direction, the so-called magnetic superdomains. In the SDW regime, a low-frequency Fourier filtering method was implemented to allow a quantitative analysis of the LM images by the transport of intensity equation method. In situ LM experiments under applied magnetic fields were performed to study the reversal magnetization process in a particular array (p = 160 nm), and clear differences were observed as a function of the magnetic field orientation. The switching process under magnetic fields parallel to the horizontal antidot rows occurs in two stages: the system first nucleates and propagates horizontal SDWs, parallel to the field. Then, at higher magnetic fields, vertical SDWs, perpendicular to the field, appear before saturation. When the magnetic field is applied at 45° with respect to the antidot rows, both horizontal and vertical SDWs are nucleated and propagated simultaneously. All the experiments were successfully correlated with micromagnetic simulations. The current study sheds new light on the magnetization reversal processes of antidot arrays and opens new possibilities of exploiting the potential of high-resolution in situ LM and new data analysis procedures to probe magnetization processes in nanomagnetism, particularly in periodic arrays of nanomagnets.

Improvement of domain wall conduit properties in cobalt nanowires by global gallium irradiation

Applications based on the movement of domain walls (DWs) in magnetic nanowires (NWs) require a good DW conduit behavior, i.e. a significant difference between DW nucleation and propagation fields. In this work, we have systematically studied how this property evolves in cobalt NWs grown by focused electron beam induced deposition (FEBID) as a function of global gallium irradiation, for irradiation doses up to 1.24 × 10(17) ions cm(-2). Whereas for high doses the DW conduit is lost, below 6.42 × 10(15) ions cm(-2) the difference between the two fields increases with irradiation, becoming up to ∼9 times larger than for non-irradiated wires, due to a strong increase in the nucleation field, while the propagation field remains approximately constant. This behavior stems from two effects. The first effect is a decrease in the magnetic volume of the parasitic halo around the NW, typically present in FEBID nanostructures, leading to the disappearance of weak nucleation centers. The second effect is the formation of a 20 nm outer shell with Co crystals about twice the size of those forming the NW core, causing a net increase of the local magnetocrystalline anisotropy. The results presented here are important for the potential use of magnetic NWs grown by FEBID in DW-based devices, and might also be of interest for magnetic NWs fabricated by other techniques.

Quantitative in situ magnetization reversal studies in Lorentz microscopy and electron holography

A generalized procedure for the in situ application of magnetic fields by means of the excitation of the objective lens for magnetic imaging experiments in Lorentz microscopy and electron holography is quantitatively described. A protocol for applying magnetic fields with arbitrary in-plane magnitude and orientation is presented, and a freeware script for Digital Micrograph(™) is provided to assist the operation of the microscope. Moreover, a method to accurately reconstruct hysteresis loops is detailed. We show that the out-of-plane component of the magnetic field cannot be always neglected when performing quantitative measurements of the local magnetization. Several examples are shown to demonstrate the accuracy and functionality of the methods.

A 45-kDa acetylcholinesterase protoxin of Aeromonas hydrophila: purification and immunogenicity in fish

A rabbit antiserum to the 15-kDa acetylcholinesterase toxin neutralised the lethal effect of the 15-kDa toxin of Aeromonas hydrophila when injected into trout. However, immunisation of fish with the 15-kDa toxoid failed to induce an antibody response, and a higher molecular mass form of this toxin was purified from the extracellular products with the aim of inducing an immune response in fish. The optimal conditions for production of extracellular products by A. hydrophila strain B32 were studied to increase the concentration of this protoxin. The extracellular products were fractionated by molecular exclusion chromatography to yield a purified protoxin with an estimated molecular mass of 45 kDa by SDS-PAGE and which gave a positive reaction in Western blotting with the rabbit anti-15-kDa toxin serum. Since the 45-kDa protoxin showed lower specific acetylcholinesterase activity than the active 15-kDa toxin, the behaviour of the active site was studied using specific inhibitors. This 45-kDa protoxin was 13.3-fold less toxic than the 15-kDa toxin and induced antibody production in fish.

The acetylcholinesterase ichthyotoxin is a common component in the extracellular products of Vibrionaceae strains

In previous work, it was reported that a strain of Aeromonas hydrophila (B32) produces the most potent lethal toxin with neurotoxic activity described so far for fish. In the present study, the presence and distribution of this acetylcholinesterase toxin lethal for fish were determined in extracellular products (ECP) of 42 Vibrionaceae strains using both immunological and colorimetric methods. This neurotoxin was shown to be present in the majority of the ECP from the Aeromonas and Vibrio strains tested and is responsible for the specific acetylcholinesterase activity. Also, although the Western blot and Ouchterlony techniques are valid as qualitative methods for the detection of this toxin, the Western blot procedure was 100-fold more sensitive than the Ouchterlony technique.

Lipid-lowering drugs and risk of myopathy: a population-based follow-up study

We conducted a population-based cohort study to estimate the risk of myopathy associated with use of lipid-lowering drugs. Using data from general practices in the United Kingdom in 1991 through 1997, we identified three cohorts of individuals 40 to 74 years of age. One cohort comprised 17,219 persons who had received at least one prescription for lipid-lowering drugs in the period; a second cohort consisted of patients with a hyperlipidemia diagnosis who had not been prescribed lipid-lowering drugs (N = 28,974); and a third cohort comprised 50,000 individuals from the general population with no diagnosis of hyperlipidemia. The incidence rate of myopathy in the cohort of users of lipid-lowering drugs was 2.3 per 10,000 person-years [95% confidence interval (95% CI) = 1.2-4.4], which exceeded the incidence rates observed in the nontreated hyperlipidemia cohort [0 per 10,000 person-years (95% CI = 0.0-0.4)] and the general population [0.2 per 10,000 person-years (95% CI = 0.1-0.4)]. The relative risks of myopathy in current users of fibrates and statins compared with nonusers were 42.4 (95% CI = 11.6-170.5) and 7.6 (95% CI = 1.4-41.3), respectively. Potential risk factors other than drug use could not explain our findings in the nested case-control analysis. We conclude that use of lipid-lowering drugs is associated with a substantially greater risk of myopathy, which is most pronounced for fibrates. The absolute risk of myopathy in users of lipid-lowering drugs is, however, small.

Steroids and risk of upper gastrointestinal complications

Most antiinflammatory drugs have been associated with an increase in upper gastrointestinal complications. However, the literature on steroids is more limited than that on nonsteroidal antiinflammatory drugs (NSAIDs). To estimate the risk of upper gastrointestinal complications associated with use of steroids alone and in combination, a nested case-control analysis was conducted on the General Practice Research Database from the United KINGDOM: The authors identified 2,105 cases of upper gastrointestinal complications and 11,500 controls between 1993 and 1998. The adjusted odds ratios associated with current use of oral steroids were 1.8 (95% confidence interval (CI): 1.3, 2.4) for upper gastrointestinal complications overall and 2.4 (95% CI: 1.7, 3.4) for gastric and 1.2 (95% CI: 0.8, 1.9) for duodenal damage. Steroids were similarly associated with bleeding (odds ratio (OR) = 1.8; 95% CI: 1.3, 2.4) and perforations (OR = 1.6; 95% CI: 0.9, 3.1). Simultaneous use of steroids with low-medium and high NSAID doses, respectively, produced odds ratios of 4.0 (95% CI: 1.3, 12.0) and 12.7 (95% CI: 6.2, 26.1), compared with users of none. Whenever possible, antiinflammatory drugs should be given in monotherapy and at the lowest effective dose in order to reduce the risk of upper gastrointestinal complications.

Association between nonsteroidal anti-inflammatory drugs and upper gastrointestinal tract bleeding/perforation: an overview of epidemiologic studies published in the 1990s

BACKGROUND

In the last decades, studies have estimated the upper gastrointestinal tract bleeding/perforation (UGIB) risk associated with individual nonsteroidal anti-inflammatory drugs (NSAIDs). Later analyses have also included the effect of patterns of NSAID use, risk factors for UGIB, and modifiers of NSAID effect.

METHODS

Systematic review of case-control and cohort studies on serious gastrointestinal tract complications and nonaspirin NSAIDs published between 1990 and 1999 using MEDLINE. Eighteen original studies were selected according to predefined criteria. Two researchers extracted the data independently. Pooled relative risk estimates were calculated according to subject and exposure characteristics. Heterogeneity of effects was tested and reasons for heterogeneity were considered.

RESULTS

Advanced age, history of peptic ulcer disease, and being male were risk factors for UGIB. Nonsteroidal anti-inflammatory drug users with advanced age or a history of peptic ulcer had the highest absolute risks. The pooled relative risk of UGIB after exposure to NSAIDs was 3.8 (95% confidence interval, 3.6-4.1). The increased risk was maintained during treatment and returned to baseline once treatment was stopped. A clear dose response was observed. There was some variation in risk between individual NSAIDs, though these differences were markedly attenuated when comparable daily doses were considered.

CONCLUSIONS

The elderly and patients with a history of peptic ulcer could benefit the most from a reduction in NSAID gastrotoxicity. Whenever possible, physicians may wish to recommend lower doses to reduce the UGIB risk associated with all individual NSAIDs, especially in the subgroup of patients with the greatest background risk.

The risk of acute pancreatitis associated with acid-suppressing drugs

AIMS

To assess the risk of acute pancreatitis associated with use of acid-suppressing drugs.

METHODS

We conducted a retrospective cohort study with a nested case-control design within the General Practice Research Database (GPRD) in the United Kingdom. The cohort included 180 178 persons aged 20-74 years, who had received at least one prescription of cimetidine, famotidine, nizatidine, ranitidine, lansoprazole, or omeprazole from January 1992 to September 1997 and who did not have major risk factors for pancreatic diseases. Patients with a computerized medical history compatible with idiopathic acute pancreatitis were validated through review of medical records. For the nested case-control analysis 1000 controls were randomly selected from the study population.

RESULTS

We identified 88 potential cases of idiopathic acute pancreatitis. Medical records were available for 86. After review of these records 36 cases of acute pancreatitis were confirmed. Seven cases occurred during nonuse, corresponding to a background incidence rate (IR) of 4.4/100 000 person-years (PY). Six cases occurred during current use of ranitidine (IR 10.5/100 000 PY), five patients were current users of cimetidine (IR 13.9/100 000 PY), and three were current users of omeprazole (IR 7.8/100 000 PY). There were no cases among current users of famotidine, lansoprazole, or nizatidine. Relative risk (RR) compared with nonuse and corrected for age, gender, calendar year and use of medication known to be associated with acute pancreatitis was 1.3 (95% CI: 0.4,4.1) for ranitidine, 2.1 (95% CI: 0.6,7.2) for cimetidine, and 1.1 (95% CI: 0.3,4.6) for omeprazole.

CONCLUSIONS

The results of this study do not support an association between acute pancreatitis and the use of acid-suppressing drugs, although a substantial increase in risk cannot be excluded with confidence.

Identification of motile Aeromonas strains with the MicroScan WalkAway system in conjunction with the combo negative type 1S panels

This study was performed to compare the MicroScan WalkAway automated identification system in conjunction with the new MicroScan Combo Negative type 1S panels with conventional biochemical methods for identifying 85 environmental, clinical, and reference strains of eight Aeromonas species.

Identification of environmental Serratia plymuthica strains with the new combo panels type 1S

Automated systems are required when numerous samples need to be processed, offering both high through put and test of a multiple simultaneously. This study was performed to compare the MicroScan WalkAway automated identification system in conjunction with the new MicroScan Combo Neg Panels Type 1S with conventional biochemical methods for identifying ten environmental Serratia plymuthica strains. High correlation between both methods were observed for all the 21 tests evaluated, and the MicroScan system was found capable of correctly identifying all S. plymuthica strains tested. In all tests, the percentage of correlation was 100%, except in raffinose test (91%).

Identification of Hafnia alvei with the MicroScan WalkAway system

Hafnia alvei is a gram-negative facultatively anaerobic bacillus that belongs to the family Enterobacteriaceae. This organism is a causative agent of intestinal disorders and is found in different environments. H. alvei has received increased clinical attention as a cause of different infections in humans. This study was performed to compare the MicroScan WalkAway automated identification system in conjunction with the new MicroScan Combo Negative type 1S panels with conventional biochemical methods for identification of 21 H. alvei strains. The MicroScan WalkAway system was found capable of correctly identifying 20 of the 21 strains tested.

Association between selective serotonin reuptake inhibitors and upper gastrointestinal bleeding: population based case-control study

OBJECTIVE

To examine the association between selective serotonin reuptake inhibitors and risk of upper gastrointestinal bleeding.

DESIGN

Population based case-control study.

SETTING

General practices included in the UK general practice research database.

SUBJECTS

1651 incident cases of upper gastrointestinal bleeding and 248 cases of ulcer perforation among patients aged 40 to 79 years between April 1993 and September 1997, and 10 000 controls matched for age, sex, and year that the case was identified.

INTERVENTIONS

Review of computer profiles for all potential cases, and an internal validation study to confirm the accuracy of the diagnosis on the basis of the computerised information.

MAIN OUTCOME MEASURES

Current use of selective serotonin reuptake inhibitors or other antidepressants within 30 days before the index date.

RESULTS

Current exposure to selective serotonin reuptake inhibitors was identified in 3.1% (52 of 1651) of patients with upper gastrointestinal bleeding but only 1.0% (95 of 10 000) of controls, giving an adjusted rate ratio of 3.0 (95% confidence interval 2.1 to 4.4). This effect measure was not modified by sex, age, dose, or treatment duration. A crude incidence of 1 case per 8000 prescriptions was estimated. A small association was found with non-selective serotonin reuptake inhibitors (relative risk 1.4, 1.1 to 1.9) but not with antidepressants lacking this inhibitory effect. None of the groups of antidepressants was associated with ulcer perforation. The concurrent use of selective serotonin reuptake inhibitors with non-steroidal anti-inflammatory drugs increased the risk of upper gastrointestinal bleeding beyond the sum of their independent effects (15.6, 6.6 to 36.6). A smaller interaction was also found between selective serotonin reuptake inhibitors and low dose aspirin (7.2, 3.1 to 17.1).

CONCLUSIONS

Selective serotonin reuptake inhibitors increase the risk of upper gastrointestinal bleeding. The absolute effect is, however, moderate and about equivalent to low dose ibuprofen. The concurrent use of non-steroidal anti-inflammatory drugs or aspirin with selective serotonin reuptake inhibitors greatly increases the risk of upper gastrointestinal bleeding.

Risk of ventricular arrhythmias associated with nonsedating antihistamine drugs

AIMS

To quantify and compare the incidence of ventricular arrhythniias associated with the use of five nonsedating antihistamines: acrivastine, astemizole, cetirizine, loratadine and terfenadine. The effects of age, sex, dose, duration of treatment, and the interaction with P450 inhibitor drugs were also examined.

METHODS

We carried out a cohort study with a nested case-control analysis using the UK-based General Practice Research database (GPRD). The study cohort included persons aged less than 80 years old who received their first prescription for any of the five study drugs between January 1, 1992 and September 30, 1996. We estimated relative risks and 95% confidence intervals of idiopathic ventricular arrhythmias with current use of antihistamines as compared with non use.

RESULTS

The study cohort included 197425 persons who received 513012 prescriptions. Over the study period 18 valid cases of idiopathic ventricular arrhythmias were detected. Nine occurred during the current use of any antihistamine, resulting in a crude incidence of 1.9 per 10000 person-years (95%CI: 1.0-3.6) and a relative risk of 4.2 (95%CI: 1.5-11.8) as compared with non use. Astemizole presented the highest relative risk (RR= 19.0; 95%CI: 4.8-76.0) of all study drugs, while terfenadine (RR=2.1; 95%CI:0.5-8.5) was in the range of other nonsedating antihistamines. Older age was associated with a greater risk of ventricular arrhythmias (RR=7.4; 95%CI: 2.6-21.4) and seemed to increase the effect of antihistamines (RR=6.4; 95%CI: 1.7-24.8). The proportions of high dose terfenadine and the concomitant use with P450 inhibitors among current users of terfenadine were 2.7% and 3.4%, respectively over the study period with no single case of ventricular arrhythmias occurring in the presence of these two risk factors.

CONCLUSIONS

The use of nonsedating antihistamines increases the risk of ventricular arrhythmias by a factor of four in the general population. Yet, the absolute effect is quite low requiring 57000 prescriptions, or 5300 person-years of use for one case to occur. The risk associated with terfenadine was no different from that with other nonsedating antihistamines.

Puerto Rican youth in drug treatment facilities: who volunteers for HIV testing?

This paper examines the characteristics of youngsters in drug treatment who volunteer for AIDS testing in comparison to those who do not. HIV Antibodies testing was offered on a voluntary basis to a sample of 250 Puerto Rican youngsters enrolled in three ambulatory drug treatment centers in 1991. Sixty-six percent of the youngsters agreed to take the test. Male adolescents who volunteered reported fewer years of education and were more likely to have dropped-out of school. Consistent with research findings among adults, those adolescents at greater risk of HIV infection as measured by drug use and sexual behaviors were more likely to volunteer for on-site testing for HIV infection. Higher rates of alcohol use and marijuana use differentiated volunteers from those who did not. Among the sexual behaviors investigated, number of partners, engaging in less risk reduction practices, having a sexual partner who had used illicit drugs and using condoms to avoid STD's were found to be significantly higher in volunteers.

Surface phenotypic characteristics and virulence of Spanish isolates of Aeromonas salmonicida after passage through fish

Eleven strains of Aeromonas salmonicida were passaged twice by intraperitoneal injection through rainbow trout and reisolated from the kidney of moribund fish. The surface characteristics and virulence of the strains changed following passage through fish. None of the in vitro tests used could effectively predict the in vivo virulence.

HIV risk factors among Puerto Rican youth in drug treatment

A cross-section of 250 youngsters enrolled in drug treatment programs in Puerto Rico were surveyed in 1991. Even though the surveyed youngsters are not intravenous drug users it was found that they have a high prevalence of behaviors considered by the Centers for Diseases Control as increasing the risk of HIV infection in youth. These behaviors include frequent experimentation with non-IV drugs, early onset of sexual behaviors (mean = 13.5 years) and drug use (mean = 13.8 years), and a high number of sexual partners (mean = 3.13) reported for the year preceding the interview. Infrequent use of contraceptives and condoms and ineffective practices to prevent STD/HIV were also reported. This subgroup of youngsters in drug treatment centers can be defined as a high risk group in need of HIV infection prevention services.

Prenatal and postnatal corticosteroid therapy to prevent neonatal necrotizing enterocolitis: a controlled trial

To determine whether prenatal corticosteroid therapy would reduce the incidence of neonatal necrotizing enterocolitis (NEC), we assigned a total of 466 women admitted in premature labor either to receive placebo (group A, n = 256), if delivery was expected to occur within 24 hours of admission, or to receive betamethasone (group B, n = 210) if delivery was expected to take place more than 24 hours after admission. All women were free of severe medical complications or drug therapy; cases of intrauterine growth retardation or premature rupture of the membranes were excluded. Their newborn infants, excluding malformed, congenitally infected, and growth-retarded infants, were enrolled in the study unless they had died before the age of 10 postnatal days. Babies born to group A mothers (n = 248) were further assigned to a treatment group (group A1, n = 130) receiving dexamethasone, 2 mg/kg/day by intravenous injection during the first 7 days of life, or to a control group (group A2, n = 118) receiving 10% dextrose solution placebo. Group B infants (prenatal betamethasone, n = 205) received neither treatment nor placebo. The incidence of NEC in group A1 was 6.9% (9/130), and in group A2 it was 14.4% (17/118) (p less than 0.05). In group B the incidence was 3.4% (7/205); this was much lower than in group A2 (p less than 0.01) and lower than in group A combined (10.4%) (p less than 0.01). There was no death from NEC and no surgical intervention among group B patients. The mortality rate for group A1 (11%) was lower than for group A2 (56%) (p less than 0.02). There were fewer indications for surgical intervention for NEC in group A1 than in group A2. Histologic studies confirmed bowel ischemia in all specimens analyzed. These data support the hypothesis that the incidence of NEC is significantly reduced after prenatal steroid treatment. Although postnatal therapy with steroids does not decrease the incidence as effectively as prenatal therapy, it improves clinical outcome of NEC.