Ultrafast Double Pulse All-Optical Reswitching of a Ferrimagnet

All-optical reswitching has been investigated in the half-metallic Heusler ferrimagnet Mn_{2}Ru_{0.9}Ga, where Mn atoms occupy two inequivalent sites in the XA-type structure. The effect of a second 200 fs, 800 nm laser pulse that follows the first pump pulse, when both are above the threshold for switching, is studied as a function of t_{12}, the time between them. Aims were to determine the minimum time needed for reswitching and to identify the physical mechanisms involved. The time trajectory of the switching process on a plot of sublattice angular momentum, S^{4a} vs S^{4c}, is in three stages; when t<0.1  ps, the sublattice moments are rapidly disordered, but not destroyed, while conserving net angular momentum via optical spin-wave excitations. This leads to transient parallel alignment of the residual Mn spins in the first quadrant. The net angular momentum associated with the majority sublattice then flips after about 2 ps, and a fully reversed ferrimagnetic state is then established via the spin-lattice interaction, which allows reswitching provided t_{12}>10  ps.

Generation of squeezed light vacuum enabled by coherent population trapping

We demonstrate the possibility to generate squeezed vacuum states of light by four wave mixing (FWM) enabled coherent population trapping in a metastable helium cell at room temperature. Contrary to usual FWM far detuned schemes, we work at resonance with an atomic transition. We investigate the properties of such states and show that the noise variances of the squeezed and anti-squeezed quadratures cannot be explained by the simple presence of losses. A specific model allows us to demonstrate the role played by spontaneous emitted photons, which experience squeezing while propagation inside of the cell. This theoretical model, which takes into account both residual absorption and spontaneous emission, leads to an excellent agreement with the experimental data without any adjusted parameter.

Abstract P400: Racial Disparities in Subarachnoid Hemorrhage Outcomes-A Single Center Experience

Introduction: Subarachnoid hemorrhage (SAH) has high morbidity and mortality, and prior studies have reported outcome disparities between African American (AA) and Caucasian patients. We compared demographics, risk factors, and discharge outcomes among different ethnicities treated at our comprehensive stroke center.

Methods: We used data on all SAH patients admitted between July 2014 and March 2020 to our university hospital in the Southeast United States. Race was categorized into AA, Caucasian, and “other.” Pearson chi-square test and analysis of variance were used to compare these variables between the different groups.

Results: A total of 578 SAH patients were identified (39% AA patients, 54% Caucasian, and 7% other). Admission Glascow Coma Score (GCS) and Hunt & Hess scores were comparable between the 3 groups. AA patients were significantly younger (51 vs 59 in Caucasian group vs 56 years in Other, p-value <0.001) and had higher BP at admission (systolic BP 152 vs 144 vs 145, p=0.002, diastolic BP 86 vs 80 vs 81, p<0.001). AA patients were more likely to have a history of hypertension (p<0.001) and had higher BMI (30 vs 28.1 vs 26, p=0.003) and Hemoglobin A1c (5.8 vs 5.6 vs 6.1, p=0.013). Modified Rankin scale (mRS) at discharge, in-hospital mortality, and discharge destination were similar between the groups, but AA patients had a longer mean hospital length of stay (19 vs 14 vs 17 days, p=0.035).

Conclusion: In our cohort, AA SAH patients were significantly younger and had more comorbidities at admission. Although they had a higher length of stay, discharge outcomes were comparable to other races.

Single pulse all-optical toggle switching of magnetization without gadolinium in the ferrimagnet Mn2RuxGa

Energy-efficient control of magnetization without the help of a magnetic field is a key goal of spintronics. Purely heat-induced single-pulse all-optical toggle switching has been demonstrated, but so far only in Gd-based amorphous ferrimagnet films. In this work, we demonstrate toggle switching in films of the half-metallic ferrimagnetic Heusler alloys Mn2RuxGa, which have two crystallographically-inequivalent Mn sublattices. Moreover, we observe the switching at room temperature in samples that are immune to external magnetic fields in excess of 1 T, provided they exhibit a compensation point above room temperature. Observation of the effect in compensated ferrimagnets without Gd challenges our understanding of all-optical switching. The dynamic behavior indicates that Mn2RuxGa switches in 2 ps or less. Our findings widen the basis for fast optical switching of magnetization and break new ground for engineered materials that can be used for nonvolatile ultrafast switches using ultrashort pulses of light.

Transverse drag of slow light in moving atomic vapor

The Fresnel-Fizeau effect of transverse drag, in which the trajectory of a light beam changes due to the transverse motion of the optical medium, is usually extremely small and hard to detect. We observe transverse drag in a moving hot-vapor cell, utilizing slow light due to electromagnetically induced transparency (EIT). The drag effect is enhanced by a factor 3.6×10⁵, corresponding to the ratio between the light speed in vacuum and the group velocity under EIT conditions. We study the contribution of the thermal atomic motion, which is much faster than the mean medium velocity, and identify the regime where its effect on the transverse drag is negligible.

Simultaneous Bilateral Carotid Thrombectomies: A Technical Note

BACKGROUND

Although extremely rare, acute bilateral large vessel occlusion (LVO) is a morbid condition that requires prompt intervention.

OBJECTIVE

To report the technique used to achieve recanalization of bilateral internal carotid artery (ICA) terminus occlusions.

METHODS

This is a case of bilateral ICA terminus occlusions managed with simultaneous bilateral thrombectomies with poor collateral circulation.

RESULTS

Recanalization of bilateral ICA with thrombolysis in cerebral infarction (TICI) grade 0 to left TICI 2b flow with distal left A1 occlusion and right TICI 3 flow was achieved in 32 min with the use of simultaneous catheterization and aspiration thrombectomies.

CONCLUSION

The described technique offers an efficient and feasible means to reduce time to recanalization and radiation in cases of bilateral LVO.

Functional Outcomes of Intravenous Thrombolysis in Octogenarians and Nonagenarians Through Telestroke: Single-Center Experience

Background: Patients aged ≥80 years are often underrepresented in stroke trials. Observational studies have shown that older patients have worse outcomes compared with younger patients, but outcomes in patients aged ≥80 years treated with intravenous (IV)-alteplase specifically through telestroke (TS) have not been studied. Aim: To compare clinical and safety outcomes in stroke patients aged ≥80 and 60-79 years treated with IV-alteplase via TS. Methods: The Medical University of South Carolina TS database was analyzed to identify IV-alteplase-treated patients aged 60-79 and ≥80 years between January 2015 and March 2018. Baseline demographics and TS-specific variables were compared. Clinical outcomes were assessed using the 90-day modified Rankin Scale (mRS). Safety outcomes were evaluated by comparing symptomatic intracranial hemorrhage (sICH). Multivariate logistic regression analysis was performed to determine odds ratio (OR) for good outcome (mRS 0-2) in the older age group at 90 days. Results: IV-alteplase was used in 151 patients in ≥80 years age group and 273 patients in 60-79 years age group. The older age group had more women and a higher National Institutes of Health Stroke Scale. The mean "ED-door-to-TS-consultant-login" time was shorter (21.6 min vs. 25.6 min; p = 0.048), but "TS-consultant-login-to-alteplase" time was longer (22.1 min vs. 19.3 min; p = 0.01) in the older age group. No difference was noted in eventual "door-to-needle" time. The older age group had fewer good outcomes (39.1% vs. 74%; p = 0.001) and more deaths (38% vs. 14%; p = 0.001) at 90 days. The sICH rates were similar in the two groups. The OR for good outcome in ≥80 years age group was 0.20 (95% CI: 0.12-0.34) after controlling for baseline variables. Conclusions: Stroke patients aged ≥80 years treated via TS have similar post-thrombolysis hemorrhage rates but worse clinical outcomes compared with patients aged 60-79 years.

Abstract TP417: Advanced Cardiac Imaging in Patients With Ischemic Stroke: When to Scan?

Background: Advanced cardiac imaging(ACI) with cardiac CT (CCT) and cardiac MR (CMR) are valuable noninvasive investigative tools to assess cardiac structure in cryptogenic stroke assessment. In this study, we examine patient, electrocardiographic (EKG), and TTE variables associated with subsequent detection of intracardiac thrombus using CCT and CMR in patients with cryptogenic stroke.

Methods: The Medical University of South Carolina Comprehensive stroke center database was used to identify acute ischemic stroke patients who received inpatient CCT or CMR between January 2017 to May 2018. Patient demographics, past medical history, EKG, and TTE related variables were abstracted by 2 physicians. Univariate and multivariable logistic regression was used to identify factors associated with detection of intracardiac thrombus on CCT/CMR. Negative and positive predictive value (NPV and PPV) were calculated for TTE, with CCT/CMR considered as gold standard.

Results: 256 subjects received CCT/CMR after TTE during the study period; with 25 (9.7%) found to have an intracardiac thrombus [12 (4.7%) LV thrombus, 6 (2.3%) LA thrombus, 7 (2.8%) Others including myxoma,valve aortic arch thrombus]. The PPV and NPV of TTE were 57% and 93% respectively. Mild-Modertely Reduced (30-50% EF was associated with subsequent detection of intracardiac thrombus onCCT/CMR in univariate model, but did not reach significance after adjusting for other variables. Atrial fibrillation, P wave abnormality on EKG, ST changes on EKG, Left Ventricle wall motion akinesia on TTE were associated with intracardiac thrombus on CCT/CMR in both models.

Conclusion: Advanced cardiac imaging is a useful noninvasive tool to identify cardiac source of ischemic stroke. Although small sample size and inadequate power may limit generalizability, patients with atrial fibrillation, P wave and ST changes on EKG, and LV wall motion akinesis should be considered for advanced cardiac.

Abstract WP310: On versus Off-hour Intravenous Thrombolysis in Acute Ischemic Stroke Patients Treated via Telestroke: Impact on Long-term Functional Outcome

Introduction: Telestroke has expanded access to acute stroke care. Time of presentation to the emergency department affects the door to needle time (DTN) and may subsequently affect long-term outcome in acute ischemic stroke (AIS) patients assessed via telestroke. In this study, we assess whether DTN times and long-term functional outcome differ among AIS patients treated with IV tPA via telestroke during on-hours versus off-hours.

Methods: All patients who received IV tPA through the Medical University of South Carolina telestroke network between January 2016 and December 2017 were analyzed. Primary outcome was 90-day Modified Rankin Scale (mRS), with mRS ≤2 considered a good functional outcome. Independent variables included time of presentation, age, race, sex, admission NIHSS, symptom onset to needle, and door to needle time. On-hours were defined as 8am-5pm monday - friday, and off-hours were 5pm-8am Monday-Friday, weekends and holidays. Chi-square and t-tests were used to compare differences among categorical and continuous baseline variables, respectively. Multivariable logistic regression was used to examine the relationship between tPA delivery time and 90-day mRS, adjusting for patient baseline characteristics.

Results: During the study period, 223 (39%) AIS patients received IV tPA during on-hours and 349 (61%) during off-hours in our telestroke network. Baseline characteristics were similar, except that the off-hours group had more white patients (P=0.04), and longer tPA decision to administration time (P=0.006). On-hours mean DTN time was 57.3 minutes, as compared to 63.2 minutes during off-hours (P=0.017). Primary outcome was similar between the 2 groups (OR 1.088, 0.687-1.722).

Conclusion: AIS patients who presented during off-hours and received tPA had a longer DTN time, but comparable long-term outcome after IV thrombolysis in our telestroke network. The findings need validation in other telestroke cohorts, with the aim of providing consistent 24-hour telestroke care.

Abstract WP318: On Versus Off-Hour Intravenous Thrombolysis in Acute Ischemic Stroke Patients Treated via Telestroke- Impact on Long-Term Functional Outcome

Introduction: Time of presentation to the emergency department may affect the door to needle time (DTN) and could subsequently affect long-term outcome in acute ischemic stroke (AIS) patients assessed via telestroke. In this study, we evaluate whether DTN times and long-term functional outcome differ among AIS patients treated with IV tPA via telestroke during on-hours versus off-hours.

Methods: All patients who received IV tPA through the Medical University of South Carolina telestroke network between January 2016 and December 2017 were analyzed. Primary outcome was 90-day Modified Rankin Scale (mRS), with mRS ≤2 considered a good functional outcome. Independent variables included time of presentation, age, race, sex, admission NIHSS, symptom onset to needle, and door to needle time. On-hours were defined as 8am-5pm Monday-Friday, and off-hours were 5pm-8am Monday-Friday, weekends and holidays. Chi-square and t-tests were used to compare differences among categorical and continuous baseline variables, respectively. Multivariable logistic regression was used to examine the relationship between tPA delivery time and 90-day mRS, adjusting for patient baseline characteristics.

Results: During the study period, 223 (39%) AIS patients received IV tPA during on-hours and 349 (61%) during off-hours in our telestroke network. Baseline characteristics were similar, except that the off-hours group had more white patients (P=0.04), and longer tPA decision to administration time (P=0.006). On-hours mean DTN time was 57.3 minutes, as compared to 63.2 minutes during off-hours (P=0.017). Primary outcome was similar between the two groups (OR 1.088, 0.687-1.722).

Conclusions: AIS patients who presented during off-hours and received tPA had a longer DTN time, but comparable long-term outcome after IV thrombolysis in our telestroke network. The findings need validation in other telestroke cohorts, with the aim of providing consistent 24-hour telestroke care.

Abstract WP230: Safety of Intravenous Thrombolysis in Telestroke and Impact of an Acute Stroke Training Curriculum

Background: Stroke telemedicine has the potential to improve access to intravenous thrombolysis nationwide among acute ischemic stroke (AIS) patients. No formal training or credentialing process has been established nationally for neurologists to provide telestroke care. Our academic Remote Evaluation of Acute Ischemic Stroke (REACH) program has been delivering telestroke care for almost 10 years. Every telestroke provider neurologist undergoes a training curriculum prior to providing telestroke care.

Aim: 1. To demonstrate safety of IV tPA in AIS patients treated via telestroke. 2. To assess impact of acute stroke training curriculum by comparing safety outcomes in patients treated by fellowship trained stroke neurologists (FTSN) versus other neurologists (ON).

Methods: All REACH consults from May 2008 to July 2017 were included in our analysis. Patients were classified based on whether remote evaluation was performed by FTSN or ON. Symptomatic ICH (sICH), asymptomatic ICH (aICH), and any ICH rates were determined overall, and in the 2 groups. Fisher’s exact test and Wilcoxon rank-sum test were used to compare categorical variables and continuous variables respectively.

Results: Total number of telestroke consults performed were 10,904 (7644 by 12 FTSN and 3260 by 13 ON respectively). IV tPA was given to 1446 (18.91%) patients in FTSN and 569 (17.45%) patients in ON group respectively (p=0.07). Symptomatic ICH occurred in 59 (2.92%) patients overall, and was comparable between the two groups [42 (2.90%) vs 17 (2.98%), p-value 0.88]. Asymptomatic ICH occurred in 121 (6%) patients, 77 (5.32%) of whom were in FTSN group and 44 (7.73%) patients in ON group (p-value 0.04). Any ICH occurred in 180 patients, 119 (8.22%) and 61 patients (10.72%), p-value 0.08 respectively.

Discussion: Our study demonstrates safety of IV tPA delivery via telestroke in AIS patients. There were no differences in IV tPA administration, sICH and any ICH rates between FTSN and ON providers, but the aICH rate was higher among ON. The comparable safety outcomes between ON and FTSN in our study are likely attributed to an AIS training curriculum at credentialing. National standardized credentialing training curricula for telestroke providers may help improve outcomes in AIS patients.

Abstract TP240: Determinants of Functional Outcomes in Patients Treated With Intravenous Tissue Plasminogen Activator in Telestroke

Background: Intravenous thrombolysis in acute ischemic stroke patients (AIS) via telestroke (TS) is safe and effective, with comparable functional outcomes to patients treated at academic stroke centers. However, the association between demographic, clinical and TS logistic factors and functional outcome at 3 months in TS patients has not been studied. Identification of TS specific predictors of good outcome may guide future strategies of care delivery.

Aim: To determine demographic, clinical, and TS logistic variables associated with 90-day functional outcome in AIS patients treated with IV tPA via TS.

Methods: We retrospectively analyzed all TS consults treated with IV tPA between January 2016-July 2017 in our state-wide telestroke network. Patients who underwent endovascular intervention were excluded. Fisher exact and χ 2 test for categorical and Student t test for continuous variables with a significance level of <0.05 were used. Stepwise logistic regression model was used to identify predictors for favorable outcome (mRS 0-2) at 3 months

Results: tPA was given to 400 AIS patients via TS. Functional outcome at 90 days was obtained in 94.3% patients. Mean age was 66.8 years and 62% patients were Caucasian. Median NIHSS on presentation was 7. Medical history included hypertension (72%), diabetes (36%), hyperlipidemia (25%), atrial fibrillation (AF) (11%), and CHF (5%). Mean “onset to needle” time was 138.4 minutes(min) and mean “door to needle time” was 61.4 min. Mean “door to login” time was 26.2 min, and mean “login to tPA” time was 19.7 min. Symptomatic ICH and asymptomatic ICH occurred in 15 (5.98%) and 28(11.3%) respectively. Younger age, lower NIHSS at presentation, lower door to login time, and absence of AF and CHF were associated with higher odds of good functional outcome at 90 days in univariate analyses. In multivariate logistic regression, age (OR 0.75, 95% CI 0.67-0.84) and NIHSS at presentation (OR 0.85, 95% CI 0.82-0.89) remained independent predictors.

Discussion: Younger patients and patients with low NIHSS at presentation are more likely to have good outcome post IV tPA treatment via TS. Larger studies powered to measure the impact of TS delivery variables on functional outcome are needed.

Pneumocephalus following Dorsal Laminectomy: An Unusual Complication

A 16-year-old male presented at Bangur Institute of Neurosciences Neurosurgery Outpatient Department with history of gradually progressive paraparesis for 5 months associated with stiffness, urinary hesitancy, and urge incontinence for last 2 months. Magnetic resonance imaging spine was done which showed cystic intradural extramedullary space occupying lesion at D4/D5 to D9. Patient had 2 episodes of generalized tonic–clonic seizure on the day 4. Computed tomography scan showed pneumocephalus. Histopathological examination report was that of nonspecific inflammatory cyst.

Large Artery Atherosclerosis: Extracranial and Intracranial

Large vessel atherosclerotic disease (affecting both intracranial and extracranial arteries) is a highly prevalent cause of stroke. In this review, the authors describe the epidemiology, evaluation, diagnosis, and therapeutic aspects of large-vessel atherosclerotic disease. Endarterectomy and stenting have proven to be effective methods for carotid artery revascularization and stroke prevention, although some of the clinical trials demonstrating this benefit predated the advances in modern medical therapy. Randomized clinical trials comparing aggressive management with surgical and endovascular stenting plus aggressive medical management have shown medical management alone to be safer and more effective for preventing stroke in intracranial and vertebrobasilar stenosis.

Stroke Caused by Atherosclerosis of the Major Intracranial Arteries

Our goal in this review is to discuss the pathophysiology, diagnosis, and treatment of stroke caused by atherosclerosis of the major intracranial arteries. References for the review were identified by searching PubMed for related studies published from 1955 to June 2016 using search terms intracranial stenosis and intracranial atherosclerosis. Reference sections of published randomized clinical trials and previously published reviews were searched for additional references. Intracranial atherosclerotic disease is a highly prevalent cause of stroke that is associated with a high risk of recurrent stroke. It is more prevalent among blacks, Hispanics, and Asians compared with whites. Diabetes mellitus, hypertension, metabolic syndrome, smoking, hyperlipidemia, and a sedentary lifestyle are the major modifiable risk factors associated with intracranial atherosclerotic disease. Randomized clinical trials comparing aggressive management (dual antiplatelet treatment for 90 days followed by aspirin monotherapy and intensive management of vascular risk factors) with intracranial stenting plus aggressive medical management have shown medical management alone to be safer and more effective for preventing stroke. As such, aggressive medical management has become the standard of care for symptomatic patients with intracranial atherosclerotic disease. Nevertheless, there are subgroups of patients who are still at high risk of stroke despite being treated with aggressive medical management. Future research should aim to establish clinical, serological, and imaging biomarkers to identify high-risk patients, and clinical trials evaluating novel therapies should be focused on these patients.

Abstract 2: Tolerability and Medication Requirements of Aggressive Medical Management in SAMMPRIS

Introduction: SAMMPRIS was the first secondary stroke prevention trial to employ multi-modal protocol-driven aggressive medical management (AMM). Achievement of target SBP, LDL and physical activity were predictors of lower vascular event rates. We sought to determine the tolerability and medication requirements related to AMM.

Methods: Medications and adverse events (AEs) in all 451 SAMMPRIS patients were recorded by sites at baseline, 30 days, 4 monthly visits, and closeout. Start and stop dates were recorded for each medication and AE, with AEs classified by the site as possibly, probably, definitely, or unrelated to risk factor treatment. AEs were adjudicated centrally by consensus of 3 neurologists after the trial ended. Standard descriptive statistics were used.

Results: As Table 1 shows, most subjects were on statins and BP medications at baseline. The use of rosuvastatin, which was donated for the trial, increased during follow-up. ACE inhibitors were the most commonly used BP medication. AEs related to BP medications (e.g. standing BP drop > 15mm Hg or postural hypotension) occurred in 240 (53.2%) patients at any point in the trial (including baseline), of which 123 (27.3%) were symptomatic. Syncope occurred in 11 patients, with 3 considered probably or definitely related to study treatment. AEs related to lipid lowering medications occurred in 18.8% patients, 16.6% of which were myopathy symptoms and 1.3% were AST/ALT > 3 times normal, and there were no reported cases of rhabdomyolysis. AEs related to other risk factor treatments occurred in 17.5% patients (e.g. hypoglycemia secondary to glipizide).

Conclusion: In the SAMMPRIS trial, AMM required the use of multiple risk factor medications and was well tolerated by most patients, with AE rates similar to SPS3 and SPARCL.

Phase-sensitive amplification via coherent population oscillations in metastable helium at room temperature

In this Letter, we report our experimental results on phase-sensitive amplification (PSA) in a nondegenerate signal-idler configuration using ultranarrow coherent population oscillations in metastable helium at room temperature. We achieved a high PSA gain of nearly 7 with a bandwidth of 200 kHz by using the system at resonance in a single-pass scheme. Further, the measured minimum gain is close to the ideal value, showing that we have a nearly pure PSA. This is also confirmed from our phase-to-phase transfer curves measurements, illustrating that we have a nearly perfect squeezer, which is interesting for a variety of applications.

Mechanical Thrombectomy in Cerebral Venous Thrombosis

Background and Purpose—

Cerebral venous thrombosis is generally treated with anticoagulation. However, some patients do not respond to medical therapy and these might benefit from mechanical thrombectomy. The aim of this study was to gain a better understanding of the efficacy and safety of mechanical thrombectomy in patients with cerebral venous thrombosis, by performing a systematic review of the literature.

Methods—

We identified studies published between January 1995 and February 2014 from PubMed and Ovid. We included all cases of cerebral venous thrombosis in whom mechanical thrombectomy was performed with or without intrasinus thrombolysis. Good outcome was defined as normal or mild neurological deficits at discharge (modified Rankin Scale, 0–2). Secondary outcome variables included periprocedural complications and recanalization rates.

Results—

Our study included 42 studies (185 patients). Sixty percent of patient had a pretreatment intracerebral hemorrhage and 47% were stuporous or comatose. AngioJet was the most commonly used device (40%). Intrasinus thrombolysis was used in 131 patients (71%). Overall, 156 (84%) patients had a good outcome and 22 (12%) died. Nine (5%) patients had no recanalization, 38 (21%) had partial, and 137 (74%) had near to complete recanalization. The major periprocedural complication was new or increased intracerebral hemorrhage (10%). The use of AngioJet was associated with lower rate of complete recanalization (odds ratio, 0.2; 95% confidence interval, 0.09–0.4) and lower chance of good outcome (odds ratio, 0.5; 95% confidence interval, 0.2–1.0).

Conclusions—

Our systematic review suggests that mechanical thrombectomy is reasonably safe but controlled studies are required to provide a definitive answer on its efficacy and safety in patients with cerebral venous thrombosis.

Mechanical thrombectomy versus intrasinus thrombolysis for cerebral venous sinus thrombosis: a non-randomized comparison

Small retrospective studies have shown the benefit of endovascular treatment with intrasinus thrombolysis (IST) or mechanical thrombectomy (MT) with/without IST (MT ± IST) in cases of multifocal cerebral venous thrombosis (CVT). Our study compares the mortality, functional outcome and periprocedural complications among patients treated with MT ± IST versus IST alone. We reviewed clinical and angiographic findings of 63 patients with CVT who received endovascular treatment at three tertiary care centers. Primary outcome variables were discharge mortality and neurological dysfunction, and intermediate (three months) and long-term (>six months) morbidity. The modified Rankin scale (mRS) was used to assess morbidity. mRS ≤ 1 was considered a good recovery. Neurological dysfunction was rated as neuroscore: 0, normal; 1, mild (ambulatory, communicative); 2, moderate (non-ambulatory, communicative); and 3, severe (non-ambulatory, non-communicative/comatose). In patients who received IST alone, presenting neurological deficits were comparatively minor (p<0.001). When the two groups were adjusted for admission neuroscore, there was no statistical significance between discharge mortality [7(21%) versus 4(14%), p=0.228], neurological dysfunction (p=0.442), intermediate (p=0.336) and long-term morbidity (p=0.988). Patients who received MT ± IST had a higher percentage of periprocedural complications without reaching statistical significance. Compared to IST, MT was performed in severe cases with extensive sinus involvement. When adjusted for admission neurological dysfunction, both groups had similar mortality and discharge neurological dysfunction and similar intermediate and long-term morbidity.

Abstract T MP81: Combination Therapy of Intravenous Glycoprotein IIb-IIIa Inhibitors and Low Dose Tissue Plasminogen Activator for Acute Ischemic Stroke

Introduction: Glycoprotein IIb/IIIa (Gp IIb/IIIa) inhibitors block platelet aggregation following fibrinolysis. No phase III randomized clinical trial has assessed efficacy of combination therapy [Gp IIb/IIIa + IV tissue plasminogen activator (tPA)] to standard of care in acute ischemic stroke.

Aim: To conduct a retrospective pooled analysis of data from published prospective studies and randomized phase 1 and 2 trials, to assess efficacy and safety profile of IV combination therapy (Gp IIb/IIIa inhibitors and tPA) in management of acute ischemic stroke.

Methods: We searched the Cochrane Central Register of Controlled Trials, MEDLINE, PubMed and EMBASE databases, and 3 reviewers independently selected studies reporting safety endpoints and outcome measures in acute ischemic stroke patients treated with low dose tPA + eptifibatide. Demographic/ clinical variables: sex, age, NIH stroke scale (NIHSS) at presentation and Time-to-treatment, Safety endpoint: symptomatic intracranial hemorrhage (sICH), as well as outcome measures: Death at 90 days and modified Rankin score (mRS) 0-1 were consolidated into the two groups. tPA arm of the NINDS tPA trial was included in the tPA only group. Weighted means and proportions were calculated for numeric and categorical variables respectively. Bivariate analysis to compare baseline descriptors, safety endpoints and outcome measures consisted of Fisher’s exact test.

Results: 188 patients comprised the combination therapy arm, whereas the IV tPA arm had 218 patients. Mean NIHSS in the two groups were 12.8 and 14.6 respectively. Mean time-to-treatment was 2.3 hours in combination therapy arm and 2.55 hours in the tPA arm. Treatment with combination therapy was associated with a better functional outcome (mRS 0-1) (OR 1.79, 95% CI 1.15 - 2.80, p <0.01) at 90 days. There was also a significant reduction in the rate of sICH (OR 0.26, 95% CI 0.07 - 0.83) in the combination therapy group. Death at 90 days was not significantly different in the 2 groups (OR 1.26, 95% CI 0.73 - 2.18).

Conclusion: Combination of low dose IV tPA with Gp IIb/IIIa inhibitor is associated with a better functional outcome at 90 days, as well as a reduction in sICH rates in patients with acute ischemic stroke, as compared to 0.9g/kg IV tPA.

Up, Up and Away! The Economics of Vertical Farming

With rising population and purchasing power, demand for food and changing consumer preferences are building pressure on our resources. Vertical Farming, which means growing food in skyscrapers, might help to solve many of these problems. The purpose of this study was to construct a Vertical Farm and thereof investigate the economic feasibility of it. In a concurrent Engineering Study initiated by DLR Bremen, a farm, 37 floors high, was designed and simulated in Berlin to estimate the cost of production and market potential of this technology. It yields about 3,500 tons of fruits and vegetables and ca. 140 tons of tilapia fillets, 516 times more than expected from a footprint area of 0.25 ha due to stacking and multiple harvests. The investment costs add up to € 200 million, and it requires 80 million litres of water and 3.5 GWh of power per year. The produced food costs between € 3.50 and € 4.00 per kilogram. In view of its feasibility, we estimate a market for about 50 farms in the short term and almost 3000 farms in the long term. To tap the economic, environmental and social benefits of this technology, extensive research is required to optimise the production process.

Adjuvant chemotherapy with six cycles of AC regimen versus three cycles of AC regimen followed by three cycles of Paclitaxel in node-positive breast cancer

CONTEXT

Antracycline-Cyclophosphamide (AC) along with Paclitaxel/Docetaxel, either in combination or sequential regimens, is showing superior results than Anthracycline-containing regimens.

AIMS

This study was designed to determine whether adding Paclitaxel to a standard adjuvant chemotherapy regimen AC for breast cancer patients would prolong the time to recurrence and survival.

SETTINGS AND DESIGN

Randomized, prospective, open-labeled, single-institutional study.

MATERIALS AND METHODS

Fifty stage II breast cancer patients accruing 25 patients in each arm, treated between July 2007 and January 2010, were included in the study. Initial surgical treatment was Modified Radical Mastectomy. Systemic therapy was to have begun within 4-6 weeks of the patient's surgery. In the control arm, all the patients were treated with six cycles of adjuvant chemotherapy with AC regimen repeated at an interval of 3 weeks. For the study arm, the patients received adjuvant chemotherapy with three cycles of AC regimen followed by three cycles of Paclitaxel, repeated at an interval of 3 weeks. All the patients of both the arms received locoregional external beam radiotherapy (EBRT) after the entire course of chemotherapy. All the hormone receptor-positive patients received Tamoxifen.

STATISTICAL ANALYSIS USED

Statistical analysis was performed using the chi-square test and the Kaplan Meier survival analysis with the log-rank (Mantel-Cox) test.

RESULTS

Adding Paclitaxel to AC resulted in a statistically significant disease-free survival. The overall survival was also improved significantly. The toxicity profile in both the arms was comparable.

CONCLUSIONS

In early and node-positive breast cancer, the addition of three cycles of Paclitaxel after completion of three cycles of AC improves the disease-free and overall survival.

Clinical Reasoning: a woman with recurrent aphasia and visual field defects

A 73-year-old woman with a history of hypertension and a recent stroke presented with recurrent nonsensical speech and visual problems. One month prior, she had been diagnosed with a stroke, after sudden-onset speech and visual difficulties that resolved after a few hours. Thirteen days before, she had had a second episode of similar symptoms. She was seen in our institution after a few hours of sudden-onset unintelligible speech. Her vital signs were within normal limits. She was not in distress, but appeared frustrated. Her general physical examination was unremarkable. She had no carotid, ophthalmic, or cranial bruits. Her neurologic examination was notable for fluent aphasia, with paraphasic errors and inability to name, read, or write. She also had right homonymous hemianopia, right-sided sensory loss, and generalized brisk deep tendon reflexes. The rest of her neurologic examination showed no abnormalities.

Duration of diabetes and risk of ischemic stroke: the Northern Manhattan Study

BACKGROUND AND PURPOSE

Diabetes increases stroke risk, but whether diabetes status immediately before stroke improves prediction and whether duration is important are less clear. We hypothesized that diabetes duration independently predicts ischemic stroke.

METHODS

Among 3298 stroke-free participants in the Northern Manhattan Study, baseline diabetes and age at diagnosis were determined. Incident diabetes was assessed annually (median, 9 years). Cox proportional hazard models were used to estimate hazard ratios (HR) and 95% CI for incident ischemic stroke using baseline diabetes, diabetes as a time-dependent covariate, and duration of diabetes as a time-varying covariate; models were adjusted for demographic and cardiovascular risk factors.

RESULTS

Mean age was 69 ± 10 years (52% Hispanic, 21% white, and 24% black); 22% had diabetes at baseline and 10% had development of diabetes. There were 244 ischemic strokes, and both baseline diabetes (HR, 2.5; 95% CI, 1.9-3.3) and diabetes considered as a time-dependent covariate (HR, 2.4; 95% CI, 1.8-3.2) were similarly associated with stroke risk. Duration of diabetes was associated with ischemic stroke (adjusted HR, 1.03 per year with diabetes; 95% CI, 1.02-1.04). Compared to nondiabetic participants, those with diabetes for 0 to 5 years (adjusted HR, 1.7; 95% CI, 1.1-2.7), 5 to 10 years (adjusted HR, 1.8; 95% CI, 1.1-3.0), and ≥ 10 years (adjusted HR, 3.2; 95% CI, 2.4-4.5) were at increased risk.

CONCLUSIONS

Duration of diabetes is independently associated with ischemic stroke risk adjusting for risk factors. The risk increases 3% each year, and triples with diabetes ≥ 10 years.

Eclampsia-scenario in a hospital--a ten years study

This cross sectional record based institutional study was conducted in the Department of Obstetrics & Gynaecology, Burdwan Medical College, Burdwan over ten years (1999-2008) aiming analysis of eclamptic mothers for evaluation of maternal and perinatal outcome with different anticonvulsant medications. Total 5991 pregnant mothers with eclampsia admitted in the inpatient department of the tertiary care teaching hospital were recruited for the study, irrespective of their previous antenatal check up history. Subjects with known seizure disorders were excluded from the study. The subjects were managed according to standard regimens (Menon, Ph-sodium, diazepam & magnesium sulphate) and results were documented in standardised format. Case fatality rate, mean induction delivery time & birth-weight, perinatal mortality rates were recorded. Study reveals that the incidence of eclampsia <20 years was 6.97% and majority (5.41%) came from rural areas. Eclampsia was noted primarily in primigravida (7.43%) and unbooked (6.41%) mothers. Ante partum eclampsia predominated (64%) and incidence of caesarean section was 22.25%.The overall case fatality rate was 6.05% and eclampsia contributed 27.85% of all maternal deaths during the last two years of the study period. The overall incidence of low birth weight baby was 26.96% and perinatal mortality was 30.33% (1411/4651).The incidence of perinatal mortality and low birth weight babies are lower in the last 4 years when compared to earlier studies. Proper socio-demographic assessment of pregnancy with eclampsia, planned delivery, shorter induction delivery interval, good control of convulsion by magnesium sulphate, intensive intranatal monitoring causes less maternal and perinatal morbidity and mortality.

Comparative study between omentopexy and omental plugging in treatment of giant peptic perforation

Giant peptic perforation is a life threatening surgical emergency with high mortality.. This study aims to compare the success rate between omental plugging and standard omentopexy in the emergency management of giant perforations. A prospective non-randomized study of 23 patients with giant peptic perforation (≥2 cm in diameter) was carried out over a period of 18 months. The highest incidence was seen in the age group of 41-50 years. Intestinal fistula occurred in 23.08% of the omentopexy group compared to none in the omental plugging group. The mean hospital stay was slightly higher in the omentopexy group. Three patients died in the omentopexy group post operatively after 24 h compared to none in the omental plugging group and this was statistically significant (p < 0.05). Omental plugging is associated with lesser morbidity and mortality compared to omentopexy in the management of giant peptic perforations.

Research on software security awareness

People attack software deliberately to steal highly sensitive as well as personal information with the sole intention of carrying out well-funded, destructive and unethical goals that could harm individuals, nations or the whole world. Available technological controls could be implemented to tighten access and minimize persistent threats but the complete solution of secure software could only be provided by changing the behavior of the people involved. This can be achieved through effective security awareness techniques implemented by individuals because they are, in most cases, the first target for gaining access into the system. This paper highlights the utility of security awareness with the help of recent published work for building more secure software . In addition, areas that need further investigations are identified in the paper.

A Comparative Analysis of Immunorestoration and Recovery with Conventional and Immunotherapeutic Protocols in Canine Generalized Demodicosis: A Newer Insight of Immunotherapeutic Efficacy of T11TS

Demodex canis is a natural inhabiting mite of canine skin. Immunological disorder or genetic disorder induces the Demodex population to proliferate vigorously resulting in generalized demodicosis with consequent chronic immunosuppression. Signs of generalized demodicosis include alopecia, crysting, erythema, secondary pyoderma etc. Amitraz, an acaricide, is used conventionally for the treatment of generalized demodicosis. In many instances, the disease relapses due to the residual immunosuppression. The need of an immunorestorative therapy has been urged in generalized demodicosis. Two immunorestorative drugs, namely, Immuplus, a herbal drug, and T11TS, a sheep erythrocyte surface glycoprotein, has been used in two separate groups of dogs having generalized demodicosis and receiving Amitraz treatment. It was observed that though Amitraz treated group responded to the therapy showing increased E-rosettes and nonspecific cytotoxic efficacy of T-lymphocytes and decrease in phagocytic potential of macrophages, the groups treated with the immunotherapeutics like Immuplus and T11TS, responded better. However, the group treated with T11TS showed best recovery. These results emphasize the need for an immunorestorative therapy in generalized demodicosis and provide data in favor of T11TS as a better immunomodulator in comparison to Immuplus.

A sequential scanning of the immune efficiency in astrocytoma (Grade I to Grade Iii), meningioma and secondary glioma patients with and without therapeutic scheduling

PURPOSE

Glioma induces immune suppression. However, data revealing the immune status in glioma patients with sequential therapeutic interventions is missing. Thus, the study aims at evaluating the sequential immune status of glioma bearing patients (Astrocytoma Grade I to Grade III) receiving conventional therapeutic measures. The results were compared with the immune status of metastatic secondary glioma and meningioma patients where there is minimal immune suppression and the effect of therapeutic intervention on the above score.

METHODS

Functional immune parameters of peripheral blood lymphocytes were assayed by CD2 receptors enumeration through E-rosetting and lymphocyte cytotoxicity assay and assessing the generation of reactive oxygen species by NBT assay of peripheral blood macrophages in patient groups bearing Astrocytoma (Grade I to Grade III), meningioma and secondary glioma.

RESULTS

Patients bearing Astrocytoma (all 3 grades) showed maximum immune suppression as compared to the normal subjects, diseased meningioma controls, and secondary glioma. Therapeutic interventions viz. radiotherapy, surgery and radiotherapy after surgery and chemotherapy could not recover the suppressed activity of the CD2 bearing lymphocytes and that of peripheral blood macrophages. However, therapeutic scheduling could recover the functional activity of the CD8 bearing lymphocytes and the CD56 NK cells from that of tumor bearing patients.

CONCLUSION

Astrocytoma and not meningioma is capable of causing immunesuppression. As the tumor progresses from Grade I to Grade III, a linear reduction in the functional efficacy of immunocytes is seen to occur. Radiotherapy, surgery, and chemotherapy also induces an inhibitory effect towards the host immune system. The inhibitory effect of tumor as well as of therapy were mainly directed towards the CD2 bearing lymphocyte population and the peripheral blood macrophage population.

The cAMP-binding proteins of Leishmania are not the regulatory subunits of cAMP-dependent protein kinase

The most commonly used method to determine the cAMP binding activity in cytosolic extracts of promastigotes of Leishmania spp. underestimated by approximately 11.5-fold the total amount of [(3)H]cAMP bound, when compared with results obtained by the modified Millipore filter technique. Three cAMP-binding proteins (BPI, BPII and BPIII) were partially purified and characterized. The native molecular masses of BPI, BPII and BPIII were estimated to be 105, 155 and 145 kDa, respectively. The binding of [(3)H]cAMP to these proteins was affected to different extents by several cAMP analogues. Antibodies directed against the types I and II regulatory subunits of PKA did not cross-react with the leishmanial extract. Photoaffinity labeling of the cytosolic extracts with 8-N(3)-[(32)P]cAMP specifically labeled a band of M(r) 116000 and a band of M(r) 80000 partially saturable by cAMP. From these results, it is concluded that the leishmanial cAMP-binding proteins appear to belong to a different class distinct from the regulatory subunits of cAMP-dependent protein kinases.

Differential regulation of the two principal Runx2/Cbfa1 n-terminal isoforms in response to bone morphogenetic protein-2 during development of the osteoblast phenotype

Cbfa1/Runx2 is a transcription factor essential for bone formation and osteoblast differentiation. Two major N-terminal isoforms of Cbfa1, designated type I/p56 (PEBP2aA1, starting with the sequence MRIPV) and type II/p57 (til-1, starting with the sequence MASNS), each regulated by distinct promoters, are known. Here, we show that the type I transcript is constitutively expressed in nonosseous mesenchymal tissues and in osteoblast progenitor cells. Cbfa1 type I isoform expression does not change with the differentiation status of the cells. In contrast, the type II transcript is increased during differentiation of primary osteoblasts and is induced in osteoprogenitors and in premyoblast C2C12 cells in response to bone morphogenetic protein-2. The functional equivalence of the two isoforms in activation and repression of bone-specific genes indicates overlapping functional roles. The presence of the ubiquitous type I isoform in nonosseous cells and before bone morphogenetic protein-2 induced expression of the type II isoform suggests a regulatory role for Cbfa1 type I in early stages of mesenchymal cell development, whereas type II is necessary for osteogenesis and maintenance of the osteoblast phenotype. Our data indicate that Cbfa1 function is regulated by transcription, cellular protein levels, and DNA binding activity during osteoblast differentiation. Taken together, our studies suggest that developmental timing and cell type- specific expression of type I and type II Cbfa isoforms, and not necessarily molecular properties or sequences that reside in the N-terminus of Cbfa1, are the principal determinants of the osteogenic activity of Cbfa1.

Classical Alzheimer features and cholinergic dysfunction: towards a unifying hypothesis?

OBJECTIVE

Our autopsy studies show possible links between classical Alzheimer pathology and decreased expression of nicotinic acetylcholine receptors. For further elucidation we are now using in vitro models. We report preliminary evidence for the impact of beta-amyloid on nicotinic receptor expression in hippocampal dissociation culture.

METHODS

Cultures (E18 rats) were grown in a serum-free medium and incubated at 8 days in vitro for 3 days with 1 microM Abeta1-42. Expression of alpha4, alpha7, and beta2 nicotinic receptor subunit protein was assessed immunohistochemically and rated semiquantitatively.

RESULTS

Abeta1-42 incubation resulted in a massive reduction of alpha4 protein-expressing neurons, this effect was less pronounced for the alpha7 and beta2 subunit protein.

CONCLUSION

These findings provide first evidence for a direct impact of classical Alzheimer pathology features on nicotinic receptor expression in vitro. Our model will be useful for testing the potential of drugs to stop or reverse these effects.

Expression and regulation of Runx2/Cbfa1 and osteoblast phenotypic markers during the growth and differentiation of human osteoblasts

The runt family transcription factor (AML-3/PEBP2alphaA1/Cbfa1/RUNX2) plays a crucial role in formation of the mineralized skeleton during embryogenesis and regulates maturation of the osteoblast phenotype. Because steroid hormones and growth factors significantly influence growth and differentiation properties of osteoblasts, we addressed Cbfa1 as a target gene for regulation by dexamethasone (Dex), 1,25(OH)D(3) (vitamin D(3)), 17beta-estradiol, and transforming growth factor-beta1 (TGF-beta1). The representation of functional protein levels by Western blot analyses and gel mobility shift assays was examined during the growth and mineralization of several conditionally immortalized human osteoblast cell lines HOB 04-T8, 03-CE6, and 03-CE10, each representing different stages of maturation. In situ immunofluorescence demonstrates Cbfa1 is associated with nuclear matrix in punctate domains, some of which are transcriptionally active, colocalizing with phosphorylated RNA polymerase II. Although each of the cell lines exhibited different responses to the steroid hormones and to TGF-beta1, all cell lines showed a similar increase in Cbfa1 protein and DNA binding activity induced only by Dex. On the other hand, Cbfa1 mRNA levels were not altered by Dex treatment. This regulation of Cbfa1 by steroid hormones in human osteoblasts contrasts to modifications in Cbfa1 expression in primary rat calvarial osteoblasts and the mouse MC3T3-E1 osteoblast cell line. Thus, these results reveal multiple levels of regulation of Cbfa1 expression and activity in osteoblasts. Moreover, the data suggest that in committed human osteoblasts, constitutive expression of Cbfa1 may be required to sustain the osteoblast phenotype.

Cellular expression of alpha7 nicotinic acetylcholine receptor protein in the temporal cortex in Alzheimer's and Parkinson's disease--a stereological approach

Cognitive deficits in Alzheimer's and Parkinson's disease are closely related to disturbed cholinergic transmission. The decrease of nicotinic acetylcholine receptor protein has been assessed by Western blotting and immunohistochemistry. Stereology, however, has not been used to assess numbers of receptor-expressing human cerebrocortical neurons. Our approach applies a combination of alpha7 subunit-immunohistochemistry with a stereological technique using defined stretches of pial surface as reference standard. The number of alpha7 subunit protein-expressing neurons in the Alzheimer temporal cortices amounted to approximately half of that of controls while numbers in Parkinson patients lay in between. No differences in the total number of neurons were seen. These results corroborate nonstereological studies on Alzheimer cortices and for the first time show a similar decrease in receptor expression in Parkinson's disease. They provide evidence that not only Alzheimer dementia but also cognitive deficits in Parkinson's disease may be related to decreased nicotinic receptor expression.

Ca2+ and calmodulin-dependent protein phosphatase from Leishmania donovani

A protein phosphatase exclusively dependent upon micromolar amounts of Ca2+ and calmodulin has been identified and partially purified from Leishmania spp. Complete obliteration of its activity is observed in the presence of calmodulin antagonists such as trifluoperazine, fluphenazine and calmidazolium. Relative insensitivity to okadaic acid and lack of activation in the absence of Ca2+ and calmodulin distinguishes this enzyme from PP1, PP2A and PP2C-type protein phosphatases. Cross-reactivity of the enzyme was observed with antibodies that recognize both the A and B chains of calcineurin, a PP2B type Ca2+ and calmodulin-dependent phosphatase from brain. FK506, an immunosuppresive drug that inhibits the enzyme from other sources inhibited the enzyme only in the presence of exogenous FK binding protein, whereas Cyclosporin A inhibited the enzyme in crude preparations. Taken together these results reveal the presence of a Ca2+ and calmodulin-dependent phosphatase from Leishmania. This is the first report of the presence of a PP2B-type protein phosphatase from a pathogenic protozoa.

Runt homology domain proteins in osteoblast differentiation: AML3/CBFA1 is a major component of a bone-specific complex

The AML/CBFA family of runt homology domain (rhd) transcription factors regulates expression of mammalian genes of the hematopoietic lineage. AML1, AML2 and AML3 are the three AML genes identified to date which influence myeloid cell growth and differentiation. Recently AML-related proteins were identified in an osteoblast-specific promoter binding complex that functionally modulates bone-restricted transcription of the osteocalcin gene. In the present study we demonstrate that in primary rat osteoblasts AML-3 is the AML family member present in the osteoblast-specific complex. Antibody specific for AML-3 completely supershifts this complex, in contrast to antibodies with specificity for AML-1 or AML-2, AML-3 is present as a single 5.4 kb transcript in bone tissues. To establish the functional involvement of AML factors in osteoblast differentiation, we pursued antisense strategies to alter expression of rhd genes. Treatment of osteoblast cultures with rhd antisense oligonucleotides significantly decreased three parameters which are linked to differentiation of normal diploid osteoblasts: the representation of alkaline phosphatase-positive cells, osteocalcin production, and the formation of mineralized nodules. Our findings indicate that AML-3 is a key transcription factor in bone cells and that the activity of rhd proteins is required for completion of osteoblast differentiation.

Multiple irrigation, debridement, and retention of components in infected total knee arthroplasty

The results of 24 infected total knee arthroplasties (22 patients) that were treated by irrigation, debridement, and retention of the prosthetic components were prospectively studied. Strict criteria were used for the selection of this method of treatment. Patients had to be less than 30 days after index arthroplasty (postsurgical group) or had to have less than 30 days of knee symptoms (hematogenous group). In addition, there had to be no radiographic signs of osteitis or evidence of a loose prosthetic component. Patients had one to three irrigation and debridement procedures depending on systemic signs, knee symptoms, or the results of knee aspirations. All of the immediate postsurgical infections (10 knees) and 10 of the 14 (71%) late hematogenously infected knees retained the prosthesis without further evidence of infection at the final follow-up visit at 48 months (range, 24-140 months). This study shows that in selected circumstances, irrigation, debridement, and retention of the components can result in low morbidity with high success rates.

Developmental expression and activities of specific fos and jun proteins are functionally related to osteoblast maturation: role of Fra-2 and Jun D during differentiation

Developmental studies of oncogene expression implicate the Fos and Jun family of transcription factors in the regulation of bone growth and differentiation. Promoters of many developmentally regulated genes, including osteocalcin, a marker of osteoblast differentiation, contain AP-1 sites that bind Fos/Jun dimers. Here, we demonstrate that the selective expression of fos- and jun-related genes is functionally related to the stage of osteoblast growth and differentiation in vitro. During osteoblast proliferation, nuclear protein levels of all seven activating protein-1 (AP-1) members are maximal. Subsequently, during the period of extracellular matrix maturation, levels decline. In fully differentiated osteoblasts, Fra-2 and (to a lesser extent) Jun D are the principal AP-1 members detectable by Western blot analysis. AP-1 complex composition and binding activity also exhibit developmental changes. All Fos and Jun family members are involved in AP-1 complex formation in proliferating cells, whereas Fra-2 and Jun D predominate in AP-1 complexes in differentiated osteoblasts. Overexpression of Fos and Jun family members in ROS 17/2.8 cells markedly affects the expression of an osteocalcin promoter-chloramphenicol acetyltransferase construct. Coexpression of only one AP-1 pair, Fra-2 and Jun D, stimulated reporter expression, whereas coexpression of other AP-1 pairs down-regulated expression (i.e. c-jun and any Fos family member) or had no effect (i.e. Fra-1 and Jun B). Promoter deletion analyses indicate that these effects are site specific. Consequential effects of Fra-2 on osteoblast differentiation are further demonstrated by antisense studies in which osteoblast differentiation and the development of a bone tissue-like organization were suppressed. Consistent with recent findings suggesting that AP-1 complex composition can selectively regulate gene transcription, our findings demonstrate that differential expression of Fos and Jun family members could play a role in the developmental regulation of bone-specific gene expression and, as a result, may be functionally significant for osteoblast differentiation.

An AML-1 consensus sequence binds an osteoblast-specific complex and transcriptionally activates the osteocalcin gene

Tissue and cell-type specific expression of the rat osteocalcin (rOC) gene involves the interplay of multiple transcriptional regulatory factors. In this report we demonstrate that AML-1 (acute myeloid leukemia-1), a DNA-binding protein whose genes are disrupted by chromosomal translocations in several human leukemias, interacts with a sequence essential for enhancing tissue-restricted expression of the rOC gene. Deletion analysis of rOC promoter-chloramphenicol acetyltransferase constructs demonstrates that an AML-1-binding sequence within the proximal promoter (-138 to -130 nt) contributes to 75% of the level of osteocalcin gene expression. The activation potential of the AML-1-binding sequence has been established by overexpressing AML-1 in osteoblastic as well as in nonosseous cell lines. Overexpression not only enhances rOC promoter activity in osteoblasts but also mediates OC promoter activity in a nonosseous human fibroblastic cell line. A probe containing this site forms a sequence specific protein-DNA complex with nuclear extracts from osteoblastic cells but not from nonosseous cells. Antisera supershift experiments indicate the presence of AML-1 and its partner protein core-binding factor beta in this osteoblast-restricted complex. Mutations of the critical AML-1-binding nucleotides abrogate formation of the complex and strongly diminish promoter activity. These results indicate that an AML-1 related protein is functional in cells of the osteoblastic lineage and that the AML-1-binding site is a regulatory element important for osteoblast-specific transcriptional activation of the rOC gene.

Bone tissue-specific transcription of the osteocalcin gene: role of an activator osteoblast-specific complex and suppressor hox proteins that bind the OC box

Bone-specific expression of the osteocalcin gene is transcriptionally controlled. Deletion analysis of osteocalcin promoter sequences by transient transfection of osseous (ROS 17/2.8) and nonosseous (R2 fibroblast) cells revealed that the most proximal 108 nucleotides are sufficient to confer tissue-specific expression. By gel mobility shift assays with wild-type and mutated oligonucleotides and nuclear extracts from several different cell lines we identified a novel transcription factor complex which exhibits sequence-specific interactions with the primary transcriptional element, the OC box (nt -99 to -76). This OC box binding protein (OCBP) is present only in osteoblast-like cells. Methylation interference demonstrated association of the factor with OC box sequences overlapping the Msx homeodomain consensus binding site. By assaying several mutations of the OC box, both in gel shift and transient transfection studies using ROS 17/2.8, we show the following. First, binding of OCBP correlates with osteocalcin promoter activity in ROS 17/2.8 cells. Increased binding leads to a 2-3-fold increase in transcription, while decreased binding results in transcription 30-40% of control. Second, homeodomain protein binding suppresses transcription. However, Msx expression is critical for full development of the bone phenotype as determined by antisense studies. Last, we show that one of the mutations of the OC box permits expression of osteocalcin in non-osseous cell lines. In summary, we demonstrate association of at least two classes of tissue-restricted transcription factors with the OC box element, the OCBP and Msx proteins, supporting the concept that these sequences contribute to defining tissue specificity.

Transforming growth factor-beta 1 responsiveness of the rat osteocalcin gene is mediated by an activator protein-1 binding site

Osteocalcin (OC), a bone specific protein expressed during differentiation and mineralization of the bone extracellular matrix, is down-regulated upon treatment with transforming growth factor (TGF)-beta 1. To address the potential role of OC gene expression in relation to TGF-beta 1 regulation of bone formation and resorption, we examined the transcriptional activity of the rat OC promoter after TGF-beta 1 treatment. 5' deletion analysis of rat OC promoter-chloramphenicol acetyltransferase constructs demonstrated that TGF-beta 1 treatment repressed chloramphenicol acetyltransferase activity by 2.4-fold in transient transfections of ROS 17/2.8 cells. A 29-bp region between -162 and -134 identified as the TGF-beta 1 response domain, conferred TGF-beta 1 responsiveness to the -108 to +24 rat OC basal promoter in an orientation dependent manner. Mutation of an activator protein-1/cAMP-response element-like motif (- 146 to -139) abolished TGF-beta 1 responsiveness of the construct. In vitro gel-mobility shift and competition assays using wild-type and mutated oligonucleotides and antibodies indicate that Fra-2, a Fos related transcription factor, binds to this motif. We show that Fra-2 is an activator of the OC promoter, and TGF-beta 1 inhibits this activation. Our results demonstrate that Fra-2 is hyperphosphorylated upon TGF-beta 1 treatment of ROS 17/2.8 cells. Additionally, treatment of cells with a staurosporine protein kinase C inhibitor abrogates TGF-beta 1 mediated down-regulation of the OC promoter activity. Together, these results demonstrate that TGF-beta 1 responsiveness of the rat osteocalcin gene in ROS 17/2.8 cells is mediated through an activator protein-1 like cis-acting element that interacts with Fra-2. Furthermore, our results are consistent with a critical role for TGF-beta 1 induced phosphorylation of Fra-2 in the repression of OC gene transcription.