Screening over Speech in Unselected Populations for Clinical Trials in AD (PROSPECT-AD): Study Design and Protocol

BACKGROUND

Speech impairments are an early feature of Alzheimer's disease (AD) and consequently, analysing speech performance is a promising new digital biomarker for AD screening. Future clinical AD trials on disease modifying drugs will require a shift to very early identification of individuals at risk of dementia. Hence, digital markers of language and speech may offer a method for screening of at-risk populations that are at the earliest stages of AD, eventually in combination with advanced machine learning. To this end, we developed a screening battery consisting of speech-based neurocognitive tests. The automated test performs a remote primary screening using a simple telephone.

OBJECTIVES

PROSPECT-AD aims to validate speech biomarkers for identification of individuals with early signs of AD and monitor their longitudinal course through access to well-phenotyped cohorts.

DESIGN

PROSPECT-AD leverages ongoing cohorts such as EPAD (UK), DESCRIBE and DELCODE (Germany), and BioFINDER Primary Care (Sweden) and Beta-AARC (Spain) by adding a collection of speech data over the telephone to existing longitudinal follow-ups. Participants at risk of dementia are recruited from existing parent cohorts across Europe to form an AD 'probability-spectrum', i.e., individuals with a low risk to high risk of developing AD dementia. The characterization of cognition, biomarker and risk factor (genetic and environmental) status of each research participants over time combined with audio recordings of speech samples will provide a well-phenotyped population for comparing novel speech markers with current gold standard biomarkers and cognitive scores.

PARTICIPANTS

N= 1000 participants aged 50 or older will be included in total, with a clinical dementia rating scale (CDR) score of 0 or 0.5. The study protocol is planned to run according to sites between 12 and 18 months.

MEASUREMENTS

The speech protocol includes the following neurocognitive tests which will be administered remotely: Word List [Memory Function], Verbal Fluency [Executive Functions] and spontaneous free speech [Psychological and/ or behavioral symptoms]. Speech features on the linguistic and paralinguistic level will be extracted from the recordings and compared to data from CSF and blood biomarkers, neuroimaging, neuropsychological evaluations, genetic profiles, and family history. Primary candidate marker from speech will be a combination of most significant features in comparison to biomarkers as reference measure. Machine learning and computational techniques will be employed to identify the most significant speech biomarkers that could represent an early indicator of AD pathology. Furthermore, based on the analysis of speech performances, models will be trained to predict cognitive decline and disease progression across the AD continuum.

CONCLUSION

The outcome of PROSPECT-AD may support AD drug development research as well as primary or tertiary prevention of dementia by providing a validated tool using a remote approach for identifying individuals at risk of dementia and monitoring individuals over time, either in a screening context or in clinical trials.

Association between Longitudinal Cerebrospinal Fluid Alzheimer's Biomarkers and the Lifestyle for Brain Health (LIBRA) Index: Findings from the European Prevention of Alzheimer's Dementia Cohort Study (EPAD LCS)

BACKGROUND

In the absence of preventative pharmacological interventions for Alzheimer's Disease dementia, there is a growing interest in modifiable risk factors associated with AD. Such risk factors are thought to contribute up to 40% of the risk of dementia. The Lifestyle for Brain Health (LIBRA) index, a dementia risk score which focuses exclusively on modifiable factors, has been found to be associated with increased risk of dementia and cognitive decline. It is currently unclear how the LIBRA index relates to cerebrospinal fluid (CSF) biomarkers of Alzheimer's Disease.

OBJECTIVES

To examine the association between LIBRA index scores and trajectories of phospho-tau 181 and total tau in the European Prevention of Alzheimer's Dementia Longitudinal Cohort Study (EPAD LCS), and to examine whether these trajectories differ between participants with high and low CSF amyloid-beta 1-42 (Aβ42).

DESIGN

Analysis of CSF biomarker and LIBRA index scores from the European Prevention of Alzheimer's Dementia Longitudinal Cohort Study.

SETTING

The European Prevention of Alzheimer's Dementia Longitudinal Cohort Study is a multi-centre, pan-European study.

MEASUREMENTS

Cerebrospinal fluid samples were taken by lumbar puncture and analysed using electrochemiluminescence. LIBRA index scores were calculated from self-reported variables, questionnaires, and physiological measurements.

RESULT

In the total sample (n = 1715; mean age = 66.0, 56.4% female), there were no significant associations between LIBRA scores (mean = 0.73 points) and rate of change in cerebrospinal fluid biomarkers. In participants with high Aβ, reflecting less deposition in the brain, (n = 1134), LIBRA scores were significantly associated with the rate of change in total tau, where higher LIBRA scores (denoting higher dementia risk) were associated with increases in t-tau. There were no significant associations between LIBRA scores and change in cerebrospinal biomarkers in participants with low Aβ.

CONCLUSION

We found an association between modifiable risk factors and total tau accumulation in participants without dementia and without Aβ accumulation. This suggests that increasing levels of total tau may be driven by factors other than Aβ accumulation and highlights the need for developing and examining tau-targeting drugs in Alzheimer's Disease development.

The Effect of Hemodialysis on Whole Blood, Plasma and Erythrocyte Viscosity

The effect of hemodialysis (HD) on blood viscosity has not been adequately investigated. We studied blood viscosity during HD employing coneplate viscometry. Ten patients with end-stage renal disease were studied before and immediately after HD. To dissect the possible effects of HD on plasma and red blood cell (RBC) determinants, we measured whole blood, plasma, and reconstituted erythrocyte viscosities. The latter consisted of RBC's suspended in a buffered saline solution (pH = 7.4 units). In addition, serum, electrolytes and hematocrit (HCT) were measured. The results revealed a significant rise in whole blood viscosity after dialysis. Likewise, plasma viscosity rose considerably with dialysis. However, when the RBC's were reconstituted to a constant HCT, no significant difference was noted before and after HD. As expected, body weight, blood urea nitrogen (BUN) and creatinine concentrations fell while HCT and protein concentration rose with HD. A significant correlation was found between the observed rise in HCT, and dialysis-induced rise in whole blood viscosity. Likewise, the observed rises in plasma viscosity after dialysis significantly correlated with the rise in protein concentration. In addition, the change in whole blood and plasma viscosity values correlated with the degree of ultrafiltration (weight loss). In conclusion, whole blood and plasma viscosity rises with hemodialysis. The observed rise in viscosity is primarily due to hemoconcentration.

Microwave-assisted synthesis of organically functionalized hexa-molybdovanadates

The microwave-assisted reaction of (TBA)₄[β-Mo₈O₂₄] and (TBA)₃[H₃V₁₀O₂₈] with pentaerythritol or tris(hydroxymethyl)aminomethane yields polyanions with the general formula (TBA)₂[V₃Mo₃O₁₆(O₃–R)] (R: C₅H₈OH – 1; R: C₄H₆NH₂ – 3). Post-synthetic esterification of 1 yields the acylated derivative 2, with all compounds being characterized in the solid and solution state.

PRECISION MEDICINE - The Golden Gate for Detection, Treatment and Prevention of Alzheimer's Disease

During this decade, breakthrough conceptual shifts have commenced to emerge in the field of Alzheimer's disease (AD) recognizing risk factors and the non-linear dynamic continuum of complex pathophysiologies amongst a wide dimensional spectrum of multi-factorial brain proteinopathies/neurodegenerative diseases. As is the case in most fields of medicine, substantial advancements in detecting, treating and preventing AD will likely evolve from the generation and implementation of a systematic precision medicine strategy. This approach will likely be based on the success found from more advanced research fields, such as oncology. Precision medicine will require integration and transfertilization across fragmented specialities of medicine and direct reintegration of Neuroscience, Neurology and Psychiatry into a continuum of medical sciences away from the silo approach. Precision medicine is biomarker-guided medicine on systems-levels that takes into account methodological advancements and discoveries of the comprehensive pathophysiological profiles of complex multi-factorial neurodegenerative diseases, such as late-onset sporadic AD. This will allow identifying and characterizing the disease processes at the asymptomatic preclinical stage, where pathophysiological and topographical abnormalities precede overt clinical symptoms by many years to decades. In this respect, the uncharted territory of the AD preclinical stage has become a major research challenge as the field postulates that early biomarker guided customized interventions may offer the best chance of therapeutic success. Clarification and practical operationalization is needed for comprehensive dissection and classification of interacting and converging disease mechanisms, description of genomic and epigenetic drivers, natural history trajectories through space and time, surrogate biomarkers and indicators of risk and progression, as well as considerations about the regulatory, ethical, political and societal consequences of early detection at asymptomatic stages. In this scenario, the integrated roles of genome sequencing, investigations of comprehensive fluid-based biomarkers and multimodal neuroimaging will be of key importance for the identification of distinct molecular mechanisms and signaling pathways in subsets of asymptomatic people at greatest risk for progression to clinical milestones due to those specific pathways. The precision medicine strategy facilitates a paradigm shift in Neuroscience and AD research and development away from the classical "one-size-fits-all" approach in drug discovery towards biomarker guided "molecularly" tailored therapy for truly effective treatment and prevention options. After the long and winding decade of failed therapy trials progress towards the holistic systems-based strategy of precision medicine may finally turn into the new age of scientific and medical success curbing the global AD epidemic.

Microwave assisted synthesis of a mono organoimido functionalized Anderson polyoxometalate

The synthesis of an aliphatic organoimido functionalized polyoxometalate has been achieved through a microwave assisted reaction protocol in the absence of any activating reagents.

Shared learning for oral health therapy and dental students: enhanced understanding of roles and responsibilities through interprofessional education

INTRODUCTION

To enhance interprofessional learning outcomes, The School of Dentistry at The University of Queensland redesigned first-year curricula. Courses for Bachelor of Oral Health (OHT) and Bachelor of Dental Science (DS) students were combined, and learning content created to support the development of skills, knowledge and attitudes required for the oral healthcare team to work effectively in providing the best possible care for patients.

METHODS

Over a 2-year period, all commencing OHT and DS students were invited to participate in this study. One cohort (n = 93) was enrolled into a traditional, discipline-specific programme (TRAD), whereas the other cohort (n = 93) experienced an integrated learning programme (INT) with combined courses for OHT and DS students. The Readiness for Interprofessional Learning Scale (RIPLS) and a modified dental and dental care professional roles and responsibilities (DRR) survey were completed to determine students' awareness of dental professionals' roles and responsibilities, and their attitudes to interprofessional education and teamwork.

RESULTS

Following completion of 1 year of learning, both INT and TRAD cohorts showed similar levels of readiness for shared learning. At the commencement of the second year of the study programme, however, there was a significantly better understanding of shared care amongst INT students.

CONCLUSIONS

This study provides initial support for the integrated learning approach adopted by this university. The INT cohort had significantly improved understandings of the roles and responsibilities of dentists and oral health therapists. The results of this study have been used to refine ongoing curriculum developments.

Abstract P2-12-14: Use of the MD Anderson Symptom Inventory to Screen for Depression in Breast Cancer

Background: The prevalence of depression among breast cancer patients is estimated to be twice that in the general population, is linked to diminished quality of life and impaired adherence to therapy. Depression is frequently underdiagnosed or misdiagnosed in this population. Efficient screening for depression is central to patient-centered care and enhanced clinical outcomes for breast cancer patients.

Purpose: To evaluate the use of a commonly utilized symptom assessment instrument as a screen to enhance identification of breast cancer patients experiencing depression.

Methods: Data from a longitudinal surveillance database in outpatient supportive and palliative care were utilized, 174 breast cancer patient contacts were evaluated. Patients completed both the MD Anderson Symptom Inventory (MDASI) and the 9-item Patient Health Questionnaire (PHQ-9) as components of a routinely collected patient-reported outcomes battery. Performance of the MDASI (using the 1–10 Depression question) in identifying cases of depression (defined as a score ≥ 15 on the PHQ-9) was determined using receiver operating characteristic (ROC) analysis.

Results: Data were available on 174 patient contacts. When scored as a continuous measure, the MDASI performed well with an area under the ROC curve of 0.87 (95% confidence interval [CI], 0.81–0.94). An MDASI cutoff score of >= 6 provided a sensitivity of 73% (95% CI, 58%–88%), a specificity of 80% (95% CI, 74%–87%), a positive predictive value (PPV) of 46%, and a negative predictive value (NPV) of 93%.

Conclusion: The “depression” component of the MDASI as a screening instrument for depression in breast cancer patients yields suboptimal sensitivity and specificity for use as a screening tool. Further efforts to evaluate subsequent iterations of the MDASI and combinations of elements in the MDASI that may enhance performance are indicated.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-12-14.

Reliability and validity of physical fitness field tests for adults aged 55 to 70 years

The aim of this study was to examine the reliability and validity of field tests for assessing physical function in mid-aged and young-old people (55-70 y). Tests were selected that required minimal space and equipment and could be implemented in multiple field settings such as a general practitioner's office. Nineteen participants completed 2 field and 1 laboratory testing sessions. Intra-class correlations showed good reliability for the tests of upper body strength (lift and reach, R= .66), lower body strength (sit to stand, R = .80) and functional capacity (Canadian Step Test, R= .92), but not for leg power (single timed chair rise. R = .28). There was also good reliability for the balance test during 3 stances: parallel (94.7% agreement), semi-tandem (73.7%), and tandem (52.6%). Comparison of field test results with objective laboratory measures found good validity for the sit to stand (cf 1RM leg press, Pearson r= .68, p < .05), and for the step test (cf PWC140, r = -.60, p < .001), but not for the lift and reach (cf 1RM bench press, r = .43, p > .05), balance (r = -.13, -.18, .23) and rate of force development tests (r = -.28). It was concluded that the lower body strength and cardiovascular function tests were appropriate for use in field settings with mid-aged and young-old adults.

Apathy correlates with cognitive function but not CD4 status in patients with human immunodeficiency virus

Apathy is a prominent neuropsychiatric symptom associated with human immunodeficiency virus (HIV). The increased frequency of apathy in this population may reflect the direct involvement of the virus on the central nervous system (CNS), but the severity of apathy has not been shown to consistently relate to markers of disease activity or other neuropsychiatric complications of the virus. We examined the relationship between ratings of apathy and performance on measures of cognitive function and immune system status in a sample of HIV-infected patients. Apathy was significantly elevated among HIV-infected individuals compared to healthy comparison subjects. Apathy was significantly related to performance on measures of learning efficiency and a measure of cognitive flexibility. Ratings of apathy did not relate to CD4 cell count, but they were associated with disease duration. In addition, ratings of depression were independent of ratings of apathy. These findings suggest that apathy does not co-vary with a proxy measure of active disease status, but apathy does relate to several measures of cognitive dysfunction in patients with HIV. As such, the increased prevalence of apathy among HIV-infected adults may reflect HIV-associated neurologic dysfunction.

Strength of evidence linking oral conditions and systemic disease

Associations between dental diseases and systemic outcomes are potentially important because of the high occurrence of dental diseases. If this extremely common source of chronic infection (dental disease) leads to an increased morbidity and mortality rate, the public health impact of oral disease on millions of Americans would be substantial. Recent studies demonstrate an association between dental and systemic diseases, including systemic infections, cardiovascular disease, pregnancy outcomes, respiratory diseases, and increased all-cause mortality rate. Because there are several common risk factors for oral and systemic diseases, and limitations in published studies, a careful interpretation is needed. Confounding (shared risk factors for both systemic and dental disease) may explain part of the reported associations. It is also plausible that there may be a causal link. It is likely that if there is a causal link, several pathways and mediators coexist, linking oral and systemic disease. Bacteremia, bacterial endotoxins, cytokines, and other inflammatory mediators could conceivably be playing a direct or indirect role. Missing teeth are a surrogate marker for previous dental infection, and may also lead to altered dietary intake. Hence, diet may be an additional mediator for several of these outcomes. We caution clinicians not to recommend extracting infected teeth, based on the periodontal-systemic disease associations, if the teeth do not warrant extraction otherwise, because loss of teeth and edentulousness are associated with increased risk of systemic diseases. When assessed against causal-defined criteria, the evidence suggests possible causal associations between chronic periodontal disease and tooth loss with cardiovascular disease, bacterial endocarditis, pregnancy outcomes, and all-cause overall mortality. Further studies are needed to show consistency, to corroborate that the associations are independent of common risk factors for both systemic and dental disease, including healthy lifestyle factors, and to evaluate different biological pathways.

Clostridium perfringens type A enterotoxin forms mepacrine-sensitive pores in pure phospholipid bilayers in the absence of putative receptor proteins

Clostridium perfringens enterotoxin (CPE) is an important cause of food poisoning with no significant homology to other enterotoxins and its mechanism of action remains uncertain. Although CPE has recently been shown to complex with tight junction proteins, we have previously demonstrated that CPE increases ionic permeability in single Caco-2 cells using the whole-cell patch-clamp technique, thereby excluding any paracellular permeability. In this paper we demonstrate that CPE forms pores in synthetic phospholipid membranes in the absence of receptor proteins. The properties of the pores are consistent with CPE-induced permeability changes in Caco-2 cells suggesting that CPE has innate pore-forming ability.

Effects of the nicotinic antagonist mecamylamine on inspection time

RATIONALE

Several lines of evidence suggest that nicotinic acetylcholine receptors (nAchRs) are involved in speed of information processing, and inspection time appears to be particularly sensitive to nicotinic manipulation.

OBJECTIVE

The present study sought to examine the effects of the nAchR antagonist mecamylamine on inspection time. Furthermore, the extent to which the anticholinesterase donepezil would reverse the effects of mecamylamine on inspection time was also examined.

METHODS

A double-blind, repeated measures design was employed. Subjects (n = 6) received placebo, mecamylamine (20 mg PO) or mecamylamine (20 mg PO) and donepezil (5 mg PO). Inspection time and physiological measures were then assessed.

RESULTS

The mecamylamine condition and the mecamylamine and donepezil condition were associated with an increase in heart rate, when compared to the placebo condition. There was a significant slowing of inspection time in the mecamylamine condition; compared to placebo, which was partly reversed by donepezil.

CONCLUSIONS

The slowing of inspection time following mecamylamine is consistent with the role of nAchRs in speed of information processing, and add to the evidence that IT may in part index nAchR system integrity.

Splenectomy during partial remission in thrombotic thrombocytopenic purpura with prolonged plasma exchange dependency

Some patients with thrombotic thrombocytopenic purpura (TTP) remain plasma-exchange-dependent for prolonged periods of time. This exposes patients to risk, uses substantial resources, and requires prolonged hospitalization. We have splenectomized 7 such patients following 25-42 plasma exchanges while patients were in partial remission only and were clinically stable. In 6 patients, including 1 with TTP secondary to mitomycin C, thrombocytopenia promptly resolved. Relapse has not occurred during 18 or more months of observation. The seventh patient did not respond. We conclude that splenectomy should be considered as an alternative to continued plasma-exchange therapy in such patients.

Application of red cell distribution width to screening for coeliac disease in insulin-dependent diabetes mellitus

Coeliac disease has been reported to occur in 2-5 per cent of insulin-dependent diabetic patients (IDDM). Suitable non-invasive screening tests would allow identification of these patients. The aim of this study was to determine the value of the red cell distribution width (RDW) in detecting unrecognised coeliac disease in insulin-dependent diabetic patients (IDDM). All patients (n = 208) attending the Diabetic out-patient clinics at 2 adjacent centres who had a full blood picture and RDW carried out in the past 18 months were included. IDDM patients with an elevated RDW were identified and their charts were reviewed to determine if they had symptoms or laboratory abnormalities compatible with coeliac disease. They were invited to attend for serological screening. Ninety-five of 208 patients had an elevated RDW of whom 66 had non-insulin dependent diabetes mellitus and 29 had IDDM. Two of the 29 IDDM patients had died in the interim period. Six of the remaining 27 IDDM patients had previously been tested for serological markers associated with coeliac disease, of whom 1 had a positive antigliadin antibody titre (IgA-AGA 199 EU) and normal duodenal biopsy. Eighteen of the remaining 21 patients with IDDM consented to serological testing of whom only 1 had a positive titre of antiendomysial antibody (IgA-EMA) and villous atrophy. Although the RDW is known from previous studies to be a sensitive predictor for coeliac disease, this study has demonstrated its poor specificity in predicting IDDM patients who may have coeliac disease. The RDW is not recommended as a screening test for coeliac disease in patients with IDDM.

A Patient Who Changed my Practice

The patient in this paper illustrated the importance of the psychological manifestations of physical illness and a doctor's need to treat these within a medical model. She also highlighted the shortcomings of medical teaching to the undergraduate and career advice to postgraduate.

Papillary endothelial hyperplasia in a TEC coronary atherectomy specimen

Angiography in a 37 year old female with a three week history of typical crescendo angina found an 80% stenosis of the proximal left anterior descending (LAD) artery. The patient underwent percutaneous transluminal coronary angioplasty involving TEC artherectomy of the LAD artery. The specimen removed by atherectomy was found to have the appearance of papillary endothelial hyperplasia. This is an unusual histological diagnosis that occurs in association with thrombus. It is rarely found within arterial vessels and has not been reported in a coronary artery. Papillary endothelial hyperplasia is now thought to be a form of organising thrombus, probably dependent on the production of basic fibroblast growth factor by the endothelium.

Evidence of a correlation of estrogen receptor level and avian osteoclast estrogen responsiveness

Isolated osteoclasts from 5-week-old chickens respond to estradiol treatment in vitro with decreased resorption activity, increased nuclear proto-oncogene expression, and decreased lysosomal enzyme secretion. This study examines osteoclasts from embryonic chickens and egg-laying hens for evidence of estrogen responsiveness. Although osteoclasts from both of these sources express estrogen receptor mRNA and protein, estradiol treatment had no effect on resorption activity. In contrast to the lack of effect on resorption, estradiol treatment for 30 minutes resulted in steady-state mRNA levels of c-fos and c-jun increasing in osteoclasts from embryonic chickens and decreasing in osteoclasts from egg-laying hens. These data suggest that a nuclear proto-oncogene response may not be involved in estradiol-mediated decreased osteoclast resorption activity. To examine the influence of circulating estrogen on osteoclast estrogen responsiveness, 5-week-old chickens were injected with estrogen for 4 days prior to sacrifice. Estradiol treatment of osteoclasts from these chickens did not decrease resorption activity in vitro. Transfection of an estrogen receptor expression vector into osteoclasts from the estradiol-injected chickens and egg-laying hens restored estrogen responsiveness. Osteoclasts from 5-week-old chickens and estradiol treated 5-week-old chickens transfected with the estrogen receptor expression vector contained significantly higher levels of estrogen receptor protein and responded to estradiol treatment by decreasing secretion of cathepsins B and L and tartrate-resistant acid phosphatase. In contrast, osteoclasts from embryonic chickens, egg-laying hens, and estradiol-treated 5-week-old chickens either untransfected or transfected with an empty expression vector did not respond similarly. These data suggest that modulation of osteoclast estrogen responsiveness may be controlled by changes in the osteoclast estrogen receptor levels.

Comparison of mean cerebral transit time and single-photon emission tomography for estimation of stroke outcome

Mean cerebral transit time (MCTT) scanning is a possible alternative to cerebral single-photon emission tomography (SPET) for early assessment of cerebral perfusion after acute ischaemic stroke. Although MCTT is rapid, inexpensive and does not require sophisticated equipment, the relationship between MCTT and functional outcome is unknown. This study aimed to compare the effectiveness of SPET and MCTT in the prediction of functional outcome. Sixty-three patients undergoing cerebral computed tomography (CT), technetium-99m MCTT, and technetium-99m-labelled hexamethylpropylene amine oxime SPET soon after acute ischaemic stroke had outcome assessed after 3 months. Cerebral CT, SPET and MCTT scans were interpreted without reference to the clinical data; a single independent observer assessed outcome using the Barthel Index. The 3-month Barthel score in survivors was significantly correlated with volume of lesion on SPET (Spearman's r=-0.425, P<0.005) and with the ratio of mean affected hemisphere transit times to mean unaffected hemisphere transit times (Spearmen's r=-0.356, P <0.01), but not with CT lesion volume (Spearman's r = -0.175, P >0.1). Stepwise logistic regression identified volume of lesion on SPET as the only significant predictor of good functional outcome (Barthel score>70). The overall predictive accuracy was 73%. It is concluded that MCTT, although significantly correlated with functional outcome, failed to predict good functional recovery in individual stroke survivors. Since SPET provides more detailed localisation of perfusion deficits, and since SPET lesion volume can be used to predict functional outcome, SPET remains preferable to MCTT when perfusion imaging is required.

A pilot study of streptokinase for acute cerebral infarction

We evaluated intravenous streptokinase in the treatment of cerebral infarction. Following neurological assessment and cerebral computed tomography (CT), patients aged 40-80 years with symptoms of anterior circulation acute ischaemic stroke were given 1.5 M units streptokinase or saline placebo in a double-blind randomized study. Twenty patients (10 streptokinase, 10 placebo), 11 males, 9 females, aged 57-79 years, were treated out of 512 consecutive admissions to the acute stroke unit over a 2-year period. Initial CT was normal in 11 (6 placebo, 5 streptokinase) and showed early signs of cerebral infarction in nine (4 placebo, 5 streptokinase). Median times from symptom onset to treatment were 5.2 h (placebo) and 5.8 h (streptokinase). Streptokinase treatment was associated with symptomatic hypotension in one patient. Repeat CT at 72 h demonstrated intracerebral haematoma in two patients and haemorrhagic infarction in one patient in the streptokinase group; the two cases of haematoma formation were associated with neurological deterioration and death. One patient in the placebo group had evidence of haemorrhagic infarction at 72 h. There were three deaths in each treatment group, all within the first 14 days. Patients with acute stroke can be evaluated with CT and treated with streptokinase within 6 h, but the opportunity for treatment is currently limited to few patients. Streptokinase treatment is not without risk, but potential clinical benefit justifies ongoing multicentre randomized trials.