Intima-Media Thickness and Pulsatility Index of Common Carotid Arteries in Acute Ischaemic Stroke Patients with Diabetes Mellitus

Ultrasonographic parameters such as the common carotid artery (CCA) pulsatility index (PI) and CCA intima-media thickness (IMT) have been associated with an increased mortality and risk of recurrent stroke, respectively. We hypothesized that these ultrasonographic parameters may be useful for monitoring diabetic patients after an acute stroke. We analysed retrospective data of consecutive acute ischaemic stroke patients from the ASTRAL registry who underwent pre-cerebral ultrasonographic evaluation within 7 days of symptom onset. We compared clinical, demographic, radiological and ultrasonographic parameters in diabetic versus non-diabetic patients (univariable and multivariable analyses) and the association of these parameters with CCA PI and CCA IMT. We analysed 1507 carotid duplex ultrasound examinations from patients with a median age of 74 years. Cardiovascular co-morbidities, including hypertension, hypercholesterolemia, obstructive sleep apnoea syndrome, higher body-mass index (BMI) and peripheral artery disease, were associated with diabetes mellitus (DM). Diabetics were more often under antiplatelet therapy and had atrial fibrillation at admission. Diabetic patients showed an increased CCA PI and IMT in line with more atherosclerotic changes on acute CTA compared to non-diabetic patients. Taking IMT as the dependent variable in a second analysis, DM, higher age, hypertension, smoking and CCA PI were associated with higher IMT. Taking CCA PI as the dependent variable in a third analysis, DM, higher age and higher NIHSS at admission were associated with higher CCA PI values. Increased IMT was also associated with higher PI. We show that CCA PI and IMT are higher in diabetic patients in the first week after an initial stroke.

Distance Neurological Supervision Using Telestroke Does Not Increase Door-to-Needle Time in Acute Ischemic Stroke Management: The Experience of Two Regional Stroke Units

Background and Aims: Timely administration of recombinant tissue plasminogen activator (r-tPA) improves clinical outcomes in acute ischemic stroke patients. This study aims to explore the influence of the systematic presence on site of a neurologist compared with telestroke management on door-to-needle time in acute ischemic stroke outside of working hours (OWH).

Methods: This retrospective cohort study included all r-tPA-treated patients in the emergency rooms of two Swiss stroke units, Nyon Hospital [Groupement Hospitalier de l'Ouest Lémanique (GHOL)] and Fribourg Hospital [Hôpital de Fribourg (HFR)], between February 2014 and September 2018. Door-to-needle time was analyzed for patients admitted during working hours (WH' weekdays 08:00–18:00) and OWH (weekdays 18:00–08:00, weekends, and public holidays). The latter was compared between centers; OWH, every patient was evaluated prior to thrombolysis by a neurologist on site in GHOL, while HFR adopted distance neurological supervision with teleradiology, performed by telephone evaluation of relevant clinical information with online real-time access to brain imaging.

Results: Data were analyzed for 157 patients in HFR and 101 patients in GHOL. No statistically significant differences in baseline characteristics were found for the 258 r-tPA-treated acute ischemic stroke patients, in terms of age, gender, cardiovascular risk factors (hypertension, diabetes, and atrial fibrillation), and pre-Modified Rankin Scale (pre-mRs) between centers, with the exception of smoking and anticoagulation status. Patients in HFR presented with more severe strokes {median National Institutes of Health Stroke Scale (NIHSS) [6 (SD 6.88) (GHOL), 8 (SD 6.98) (HFR), p = 0.005]}. No significant differences in baseline characteristics were found as per admission time independently of the center. Door-to-needle time was significantly longer in the HFR cohort when compared with GHOL, irrespective of admission time. Both centers demonstrated significantly longer median door-to-needle time OWH. However, analysis of the door-to-needle time differences between WH and OWH showed no significant interaction using robust ANCOVA WRS2 analysis (p = 0.952) and a Bayesian model (BF01 = 3.97).

Conclusions: On-site systematic evaluation by a neurologist did not appear to influence door-to-needle time OWH, suggesting distance supervision may be time-efficient in thrombolysis. This supports existing prospective studies in hyperacute telestroke management. The relevance lies in optimizing resource use considering the increasing demand for emergency neurological management.

Predictors of the pulsatility index in the middle cerebral artery of acute stroke patients

Cervical and transcranial Doppler (TCD) are widely used as non-invasive methods in the evaluation of acute ischemic stroke (AIS) patients. High-grade carotid artery stenosis induces haemodynamic changes such as collateral flow and a so-called post-stenotic flow pattern of the middle cerebral artery (MCA), which appears flattened, with a reduction of the velocity difference between systole and diastole. We studied the influence of carotid artery stenosis and other variables on the flow pattern in the MCA using the pulsatility index (PI), a quantitative TCD parameter reflecting the flow spectrum in a large of cohort AIS patients. We performed ultrasound examinations of 1825 AIS patients at the CHUV from October 2004 to December 2014. We extracted patient characteristics from the ASTRAL registry. Carotid stenosis severity was classified as < 50%, 50–70%, 70–90% and > 90%, or occlusion, according to Doppler velocity criteria. We first determined variables associated with stenosis grade. Then we performed a multivariate analysis after adjusting for baseline differences, using MCA PI as dependent variable. Carotid stenosis > 70% (− 0.07) and carotid stenosis > 90%, or occlusion (− 0.14) and left side (− 0.02) are associated with lower MCA PI values. Age (+0.006 PI units per decade), diabetes (+0.07), acute ischemic changes on initial CT (+0.03) and severe plaque morphology (+0.18) are associated with higher MCA PI values. We found a number of clinical and radiological conditions that significantly influence the PI of the MCA, including high-grade ipsilateral carotid stenosis in AIS patients. We provide for the first time a quantitative evaluation of the effect of these influencing factors from a large cohort of AIS patients.

Focal Hypoperfusion in Acute Ischemic Stroke Perfusion CT: Clinical and Radiologic Predictors and Accuracy for Infarct Prediction

BACKGROUND AND PURPOSE

Perfusion CT may improve the diagnostic performance of noncontrast CT in acute ischemic stroke. We assessed predictors of focal hypoperfusion in acute ischemic stroke and perfusion CT performance in predicting infarction on follow-up imaging.

MATERIALS AND METHODS

Patients from the Acute STroke Registry and Analysis of Lausanne data base with acute ischemic stroke and perfusion CT were included. Clinical and radiologic data were collected. We identified predictors of focal hypoperfusion using multivariate analyses.

RESULTS

From the 2216 patients with perfusion CT, 38.2% had an acute ischemic lesion on NCCT and 73.3% had focal hypoperfusion on perfusion CT. After we analyzed 104 covariates, high-admission NIHSS, visual field defect, aphasia, hemineglect, sensory deficits, and impaired consciousness were positively associated with focal hypoperfusion. Negative associations were pure posterior circulation, lacunar strokes, and anticoagulation. After integrating radiologic variables into the multivariate analyses, we found that visual field defect, sensory deficits, hemineglect, early ischemic changes on NCCT, anterior circulation, cardioembolic etiology, and arterial occlusion were positively associated with focal hypoperfusion, whereas increasing onset-to-CT delay, chronic vascular lesions, and lacunar etiology showed negative association. Sensitivity, specificity, and positive and negative predictive values of focal hypoperfusion on perfusion CT for infarct detection on follow-up MR imaging were 66.5%, 79.4%, 96.2%, and 22.8%, respectively, with an overall accuracy of 76.8%.

CONCLUSIONS

Compared with NCCT, perfusion CT doubles the sensitivity in detecting acute ischemic stroke. Focal hypoperfusion is independently predicted by stroke severity, cortical clinical deficits, nonlacunar supratentorial strokes, and shorter onset-to-imaging delays. A high proportion of patients with focal hypoperfusion developed infarction on subsequent imaging, as did some patients without focal hypoperfusion, indicating the complementarity of perfusion CT and MR imaging in acute ischemic stroke.

An uncommon complication of Listeria monocytogenes infection: Polyradiculoneuritis following Listeria meningoencephalitis

Listeria monocytogenes, primarily a foodborne pathogen, is commonly responsible for disorders affecting the central nervous system and cranial nerves. We hereby present the first case to our knowledge of listeriosis linked to a peripheral neurological disorder causing acute upper limb weakness.

Intravenous thrombolysis and platelet count

OBJECTIVE

To study the effect of platelet count (PC) on bleeding risk and outcome in stroke patients treated with IV thrombolysis (IVT) and to explore whether withholding IVT in PC < 100 × 10⁹/L is supported.

METHODS

In this prospective multicenter, IVT register-based study, we compared PC with symptomatic intracranial hemorrhage (sICH; Second European-Australasian Acute Stroke Study [ECASS II] criteria), poor outcome (modified Rankin Scale score 3-6), and mortality at 3 months. PC was used as a continuous and categorical variable distinguishing thrombocytopenia (<150 × 10⁹/L), thrombocytosis (>450 × 10⁹/L), and normal PC (150-450 × 10⁹/L [reference group]). Moreover, PC < 100 × 10⁹/L was compared to PC ≥ 100 × 10⁹/L. Unadjusted and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) from the logistic regression models were calculated.

RESULTS

Among 7,533 IVT-treated stroke patients, 6,830 (90.7%) had normal PC, 595 (7.9%) had thrombocytopenia, and 108 (1.4%) had thrombocytosis. Decreasing PC (every 10 × 10⁹/L) was associated with increasing risk of sICH (OR_adjusted 1.03, 95% CI 1.02-1.05) but decreasing risk of poor outcome (OR_adjusted 0.99, 95% CI 0.98-0.99) and mortality (OR_adjusted 0.98, 95% CI 0.98-0.99). The risk of sICH was higher in patients with thrombocytopenic than in patients with normal PC (OR_adjusted 1.73, 95% CI 1.24-2.43). However, the risk of poor outcome (OR_adjusted 0.89, 95% CI 0.39-1.97) and mortality (OR_adjusted 1.09, 95% CI 0.83-1.44) did not differ significantly. Thrombocytosis was associated with mortality (OR_adjusted 2.02, 95% CI 1.21-3.37). Forty-four (0.3%) patients had PC < 100 × 10⁹/L. Their risks of sICH (OR_unadjusted 1.56, 95% CI 0.48-5.07), poor outcome (OR_adjusted 1.63, 95% CI 0.82-3.24), and mortality (OR_adjusted 1.38, 95% CI 0.64-2.98) did not differ significantly from those of patients with PC ≥ 100 × 10⁹/L.

CONCLUSION

Lower PC was associated with increased risk of sICH, while higher PC indicated increased mortality. Our data suggest that PC modifies outcome and complications in individual patients, while withholding IVT in all patients with PC < 100 × 10⁹/L is challenged.

[Creating a stroke unit in a community hospital improves the management of stroke patients]

Dramatic advances in recent years have changed the care of stroke patients. Creation of stroke hubs with centers and units achieved a significant reduction in mortality and morbidity. The indications for acute therapies such as intravenous thrombolysis and endovascular treatment target an increasing proportion of stroke patients. Early rehabilitation and multidisciplinary approaches have become part of the gold standard in stroke care. The creation of additional stroke units and strengthening local synergies should continue in order to propose the best medical treatments for all stroke patients.

Sex Differences and Functional Outcome After Intravenous Thrombolysis

Background and Purpose—

Women have a worse outcome after stroke compared with men, although in intravenous thrombolysis (IVT)–treated patients, women seem to benefit more. Besides sex differences, age has also a possible effect on functional outcome. The interaction of sex on the functional outcome in IVT-treated patients in relation to age remains complex. The purpose of this study was to compare outcome after IVT between women and men with regard to age in a large multicenter European cohort reflecting daily clinical practice of acute stroke care.

Methods—

Data were obtained from IVT registries of 12 European tertiary hospitals. The primary outcome was poor functional outcome, defined as a modified Rankin scale score of 3 to 6 at 3 months. We stratified outcome by age in decades. Safety measures were symptomatic intracranial hemorrhage and mortality at 3 months.

Results—

In this cohort, 9495 patients were treated with IVT, and 4170 (43.9%) were women with a mean age of 71.9 years. After adjustments for baseline differences, female sex remained associated with poor functional outcome (odds ratio, 1.15; 95% confidence interval, 1.02–1.31). There was no association between sex and functional outcome when data were stratified by age. Symptomatic intracranial hemorrhage rate was similar in both sexes (adjusted odds ratio, 0.93; 95% confidence interval, 0.73–1.19), whereas mortality was lower among women (adjusted odds ratio, 0.83; 95% confidence interval, 0.70–0.99).

Conclusions—

In this large cohort of IVT-treated patients, women more often had poor functional outcome compared with men. This difference was not dependent on age.

Applying openEHR's Guideline Definition Language to the SITS international stroke treatment registry: a European retrospective observational study

Background

Interoperability standards intend to standardise health information, clinical practice guidelines intend to standardise care procedures, and patient data registries are vital for monitoring quality of care and for clinical research. This study combines all three: it uses interoperability specifications to model guideline knowledge and applies the result to registry data.

Methods

We applied the openEHR Guideline Definition Language (GDL) to data from 18,400 European patients in the Safe Implementation of Treatments in Stroke (SITS) registry to retrospectively check their compliance with European recommendations for acute stroke treatment.

Results

Comparing compliance rates obtained with GDL to those obtained by conventional statistical data analysis yielded a complete match, suggesting that GDL technology is reliable for guideline compliance checking.

Conclusions

The successful application of a standard guideline formalism to a large patient registry dataset is an important step toward widespread implementation of computer-interpretable guidelines in clinical practice and registry-based research. Application of the methodology gave important results on the evolution of stroke care in Europe, important both for quality of care monitoring and clinical research.

Electronic supplementary material

The online version of this article (doi:10.1186/s12911-016-0401-5) contains supplementary material, which is available to authorized users.

Added value of multimodal computed tomography imaging: analysis of 1994 acute ischaemic strokes

BACKGROUND AND PURPOSE

Multimodal computed tomography (CT) based imaging (MCTI) is widely used in acute ischaemic stroke. It was postulated that the use of MCTI is associated with improved patient outcome without causing harm.

METHODS

All patients with an acute ischaemic stroke and CT-based imaging within 24 h from the ASTRAL (Acute Stroke Registry and Analysis of Lausanne) registry were included. Preceding demographic, clinical, biological, radiological and follow-up data were collected. Significant predictors of MCTI use were identified retrospectively to go on to fit a multivariable analysis. Then, patients undergoing additional CT angiography (CTA) or CTA and perfusion CT (CTP) were compared with non-contrast CT only patients with regard to 3-month favourable outcome (modified Rankin Scale score ≤2), 12-month mortality, stroke mechanism, short-term renal failure, use of ancillary diagnostic tests, duration of hospitalization and 12-month stroke recurrence.

RESULTS

Of the 1994 included patients, 273 had only non-contrast CT, 411 had both non-contrast CT and CTA and 1310 had all three examinations. Factors independently associated with MCTI were younger age, low pre-stroke modified Rankin Scale score, low creatinine value, known stroke onset, anterior circulation stroke, anticoagulation or antihypertensive therapy (CTA only) and higher National Institutes of Health Stroke Scale scores (CTP only). After adjustment, MCTI was associated with a 50% reduction of 12-month mortality and a lower likelihood of unknown stroke mechanism. No association was found between MCTI and 3-month outcome, contrast-induced nephropathy, hospitalization duration, number of ancillary diagnostic tests or with stroke recurrence.

CONCLUSION

Our study shows an association of MCTI use with lower adjusted 12-month mortality, better identification of the stroke mechanism and no signs of harm.

Anti-TNF alpha medications and neuropathy

We studied the clinical, electrophysiological, and pathological features, outcome, and frequency of anti-tumor necrosis factor alpha (a-TNF) medications-induced neuropathies (ATIN) in patients with inflammatory disorders. Of 2,017 patients treated with a-TNF medication, 12 patients met our inclusion criteria for a prevalence of 0.60% and an incidence of 0.4 cases per 1,000 person-years. The median time from a-TNF medication treatment to ATIN was 16.8 months (range 2-60 months). Six patients had focal or multifocal peripheral neuropathies. The other six had generalized neuropathies. For all, a-TNF medication was stopped. Seven patients received immunoglobulin infusions. ATIN outcome was favorable in all but one patient. ATINs are rare and heterogeneous neuropathies. In 10 patients, the neuropathy was "inflammatory", suggesting that it could be due to systemic pro-inflammatory effects of a-TNF agents.

Intravenous Thrombolysis in Patients Dependent on the Daily Help of Others Before Stroke

Background and Purpose—

We compared outcome and complications in patients with stroke treated with intravenous thrombolysis (IVT) who could not live alone without help of another person before stroke (dependent patients) versus independent ones.

Methods—

In a multicenter IVT-register–based cohort study, we compared previously dependent (prestroke modified Rankin Scale score, 3–5) versus independent (prestroke modified Rankin Scale score, 0–2) patients. Outcome measures were poor 3-month outcome (not reaching at least prestroke modified Rankin Scale [dependent patients]; modified Rankin Scale score of 3–6 [independent patients]), death, and symptomatic intracranial hemorrhage. Unadjusted and adjusted odds ratios (ORs) with 95% confidence intervals (OR [95% confidence interval]) were calculated.

Results—

Among 7430 IVT-treated patients, 489 (6.6%) were dependent and 6941 (93.4%) were independent. Previous stroke, dementia, heart, and bone diseases were the most common causes of preexisting dependency. Dependent patients were more likely to die (OR unadjusted , 4.55 [3.74–5.53]; OR adjusted , 2.19 [1.70–2.84]). Symptomatic intracranial hemorrhage occurred equally frequent (4.8% versus 4.5%). Poor outcome was more frequent in dependent (60.5%) than in independent (39.6%) patients, but the adjusted ORs were similar (OR adjusted , 0.95 [0.75–1.21]). Among survivors, the proportion of patients with poor outcome did not differ (35.7% versus 31.3%). After adjustment for age and stroke severity, the odds of poor outcome were lower in dependent patients (OR adjusted , 0.64 [0.49–0.84]).

Conclusions—

IVT-treated stroke patients who were dependent on the daily help of others before stroke carry a higher mortality risk than previously independent patients. The risk of symptomatic intracranial hemorrhage and the likelihood of poor outcome were not independently influenced by previous dependency. Among survivors, poor outcome was avoided at least as effectively in previously dependent patients. Thus, withholding IVT in previously dependent patients might not be justified.

Implementability of stroke guidelines: a pragmatic comparison between US and European recommendations using eGLIA

Due to the prevalence and severity of stroke, and the emergency of its management, the need of reaching a consensus towards its treatment is of prime importance. This paper's aim is to compare two stroke guidelines by using eGLIA in order to evaluate their implementability. Methods included a systematic assessment of the European (ESO) and American (AHA/ASA) guidelines with eGLIA and a review of literature and analysis of each recommendation with the program. The ESO performs better in Executability and Decidability, as 91.5% and 34.8% of recommendations show no barriers, compared to 81.0% and 14.0% in the AHA/ASA guidelines. On the other hand, AHA/ASA guideline have more recommendations with positive assessments in the Validity and Effect on the Process of Care (91.4% vs 83.0% and 58.1% vs 25%). Results show that ESO guidelines address a wider patient view and that the AHA/ASA guidelines are stricter, only publishing recommendations with a high level of evidence; AHA/ASA guidelines are updated with more frequency and have a clearer sequence of action. Both guidelines show some contradictions, but of minor importance. The strength of this study is the fact that the whole guidelines were read and analysed, and, although we would suggest an improvement of the tool by adding an automatic statistics chart and clarifying some questions, it showed that eGLIA should be used whenever such a text is published.

Severe stroke: patient profile and predictors of favorable outcome

BACKGROUND

Severe stroke carries high rates of mortality and morbidity. The aims of this study were to determine the characteristics of patients who initially presented with severe ischemic stroke, and to identify acute and subacute predictors of favorable clinical outcome in these patients.

METHODS

An observational cohort study, Acute Stroke Registry and Analysis of Lausanne (ASTRAL), was analyzed, and all patients presenting with severe stroke - defined as a National Institute of Health Stroke Scale score of ≥ 20 on admission - were compared with all other patients. In a multivariate analysis, associations with demographic, clinical, pathophysiologic, metabolic and neuroimaging factors were determined. Furthermore, we analyzed predictors of favorable outcome (modified Rankin scale score of ≤ 3 at 3 months) in the subgroup of severe stroke patients.

RESULTS

  Of 1915 consecutive patients, 243 (12.7%) presented with severe stroke. This was significantly associated with cardio-embolic stroke mechanism (odds ratio [OR] 1.74, 95% confidence interval [CI] 1.19-2.54), unknown stroke onset (OR 2.35, 95% CI 1.14-4.83), more neuroimaging signs of early ischemia (mostly computed tomography; OR 2.65, 95% CI 1.79-3.92), arterial occlusions on acute imaging (OR 27.01, 95% CI 11.5-62.9), fewer chronic radiologic infarcts (OR 0.43, 95% CI 0.26-0.72), lower hemoglobin concentration (OR 0.97, 95% CI 0.96-0.99), and higher white cell count (OR 1.05, 95% CI 1.00-1.11). In the 68 (28%) patients with favorable outcomes despite presenting with severe stroke, this was predicted by lower age (OR 0.94, 95% CI 0.92-0.97), preceding cerebrovascular events (OR 3.00, 95% CI 1.01-8.97), hypolipemic pretreatment (OR 3.82, 95% CI 1.34-10.90), lower acute temperature (OR 0.43, 95% CI 0.23-0.78), lower subacute glucose concentration (OR 0.74, 95% CI 0.56-0.97), and spontaneous or treatment-induced recanalization (OR 4.51, 95% CI 1.96-10.41).

CONCLUSIONS

Severe stroke presentation is predicted by multiple clinical, radiologic and metabolic variables, several of which are modifiable. Predictors in the 28% of patients with favorable outcome despite presenting with severe stroke include hypolipemic pretreatment, lower acute temperature, lower glucose levels at 24 h, and arterial recanalization.

Abstract 3329: Multimodal Predictors of Massive Ischemic Stroke Presentation and Favourable Outcome

Background: Severe stroke carries a high case fatality and disability rate. The aims of this study are to determine the characteristics of patients with initially severe (“massive”) ischemic stroke, and to identify acute and subacute predictors of favourable clinical outcome in such patients.

Methodology: Using the Acute STroke Registry and Analysis of Lausanne (ASTRAL), we compared all patients with massive stroke defined as a NIHSS ≥ 20 on admission with all the other patients. In a multivariate analysis, associations with a demographic, clinical, pathophysiological, metabolic and neuroimaging factors and were determined. Furthermore, we analyzed predictors in the subgroup of massive stroke patients with favourable outcome (mRS ≤3 at three months).

Results: Among 1’915 consecutive patients, 243 (12.7%) had massive stroke. It was significantly associated with cardio-embolic stroke mechanism (OR=1.74 / 95% CI 1.193 - 2.548), unknown stroke onset (OR=2.35 / 95% CI 1.143 - 4.831), more early ischemic findings on neuroimaging (mostly CT, OR=2.65 / 95% CI 1.795 - 3.924), arterial occlusions on acute imaging (OR=0.03 / 95% CI 0.0158 - 0.0862), less chronic radiological infarcts (OR=0.43 / 95% 0.258 - 0.719), lower haemoglobin concentration per g/l (OR=0.97 / 95% CI 0.965 - 0.987), and higher white cell count per 1000 cells/l (OR=1.05 / 95%CI 1.001 - 1.109). In the 68 (28%) patients with favourable outcome, this was predicted by lower age (OR=0.943 / 95% CI 0.917 - 0.971), previous cerebrovascular events (OR=3.00 / 95% CI 1.009 - 8.964), hypolipemic pre-treatement (OR= 3.82 / 95% CI 1.341 - 10.895), lower acute temperature (OR=0.427 / 95% CI 0.232 - 0.785), lower subacute glucose concentration (OR=0.739 / 95% CI 0.565 - 0.966), and spontaneous or treatment-induced recanalisation at 24 hours (OR= 4.51 / 95%CI 1.957 - 10.407).

Conclusion: Massive stroke presentation is predicted by multiple clinical, radiological and metabolic variables, several of which are modifiable. Predictors in the 28% of patients with favourable outcome despite massive stroke include hypolipemic pretreatment, lower acute temperature, lower glucose levels at 24 hours and arterial recanalisation. Massive ischemic stroke is a serious, preventable and treatable condition.

IL-2 mRNA levels and degradation rates change with mode of stimulation and phorbol ester treatment of lymphocytes

Transient expression of interleukin 2 (IL-2) in activated T lymphocytes may be due to transcriptional and post-transcriptional regulation. As incubation of lymphocytes with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) prior to mitogenic stimulation results in decreased levels of IL-2 mRNA, we asked if IL-2 mRNA stability was affected. We found that in TPA-treated cells, IL-2 mRNA was degraded more rapidly than in untreated ones whether the mitogenic stimulus was Concanavalin A (Con A), Con A plus TPA, or TPA plus ionomycin. The degradation was blocked if the TPA pre-incubation included cycloheximide. In contrast, when TPA was included as a co-mitogen, i.e. added at the same time as the mitogen, the IL-2 mRNA levels and stability significantly increased. Compared to the levels found in Con A stimulated cells, TPA plus Con A increased IL-2 mRNA levels by as much as 20-fold and the half-life by 5-fold. TPA plus ionomycin increased the message levels at least 100-fold and half-life by nearly 10-fold. These effects on IL-2 mRNA were not general because IL-2 receptor mRNA stability was not changed even though it also is transiently expressed during the course of lymphocyte activation.

Evidence for ecto-protein kinase activity that phosphorylates Kemptide in a cyclic AMP-dependent mode

The heptapeptide Leu-Arg-Arg-Ala-Ser-Leu-Gly (Kemptide) is a synthetic construct of a substrate for cAMP-dependent protein kinase (PK). In this work we show that Kemptide has all the properties of a cytophilic substrate, i.e. it is a molecule preserving cell membrane intactness when added to cultured cells. Kemptide thus satisfies the prerequisites for employment in assays for cell surface-located ecto-PK activity. Different types of intact cells catalyze the phosphorylation of Kemptide in the presence of extracellular ATP and cAMP with Km values of 3-4 microM for Kemptide. Kemptide phosphorylation was influenced by PKI, the inhibitory protein specific for cAMP-PK. The results of comparative experiments with intact cells and with cell extracts demonstrate the ectoenzyme nature of this cAMP-PK. Further, the possibility was ruled out of a transfer of enzyme activity from damaged cells to the surface of intact cells. The anchorage of the surface cAMP-PK activity to the plasma membrane appears to be relatively stable since (i) cell supernatants, obtained after preincubation of intact cells with cAMP or Kemptide, did not show Kemptide phosphorylation, and (ii) the cAMP-dependent PK activity remained with cells even after five consecutive washes with cAMP or Kemptide. This is in contrast to the ecto-cAMP-independent phosvitin/casein type PK (Kübler, D., Pyerin, W., Burow, E., and Kinzel, V. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 4021-4025) which is released from intact cells through the addition of substrate. Data are presented which show that both ectokinase activities are exhibited independently. In conjunction with published evidence for an active export of cAMP from cells as well as for the appearance of extracellular ATP the demonstration of an ecto-cAMP-PK further supports the potential of PK for intercellular regulation. The potential of ecto-cAMP-PK is demonstrated by its ability to phosphorylate biologically active forms of atrial natriuretic peptide, the atrial natriuretic peptide, which possesses the specific sequence for a cAMP-PK-catalyzed phosphorylation.