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Juhani Sivenius

Publications and source records attributed to Juhani Sivenius.

At least 19 recordsLinked to original sources

A long-term video-EEG and behavioral follow-up after endothelin-1 induced middle cerebral artery occlusion in rats.

The aim was to test the hypothesis that occlusion of the middle cerebral artery (MCA) results in the development of epilepsy in rats. Further, we investigated whether lesion volume, hippocampal pathology, early seizures, or severity of behavioral impairment is associated with the development and severity of epilepsy or interictal spiking. MCA occlusion was induced by intracerebral injection of endothelin-1 (ET; 120 pmol). One group of ET-injected rats were followed-up for 6 months (n = 15) and another for 12 months (n = 20). Sham-operated animals were injected with saline (n = 12). Occurrence of early and late seizures was monitored by intermittent video-electroencephalography. Sensorimotor function was tested with the running wheel and tapered beam-walking tests. Emotional learning and memory were assessed with the fear conditioning test and spatial learning and memory with the Morris water maze. Finally, brains were processed for histology. Only one rat developed late spontaneous seizures (i.e., epilepsy). Epileptiform interictal spiking was detected in 9 of 26 animals. Early seizures did not predict the development of epilepsy, spiking activity, or severity of behavioral impairment. Production of MCA stroke by intracerebral injection of ET was not a strong trigger of epileptogenesis in adult rats. Further studies are needed to investigate the effect of age, genetic background, and location of ET-injection on the development of hyperexcitability and the risk of post-stroke epileptogenesis.

Animals↗

Prolonged bihemispheric alterations in unfolded protein response related gene expression after experimental stroke.

After ischemia, endoplasmic reticulum (ER) stress pathways are activated that include unfolded protein response (UPR) and protein synthesis inhibition (PSI). Both of these mechanisms aim to restore ER functioning mainly by inhibition of translation and increased processing of excess proteins in ER. We were interested in the role of these pathways during spontaneous recovery after transient middle cerebral artery occlusion (MCAO) in rats. The spontaneous recovery of rats was assessed with a limb-placing test. The expression of ER-stress-related genes (IRE1, ATF6, GRP78, eif2alpha, ATF4, PERK) was studied by using in situ hybridization in different brain areas on post-operative days 2, 7, 14 and 28. Elevated signals were detected in striatum contralateral to the lesion on days 2 (PERK and IRE1) and 14 post-ischemia (IRE1). Gene expression was elevated on day 7 in the striatum ipsilateral to the lesion (ATF6 and GRP78) and on day 14 (GRP78) post-ischemia. Furthermore, elevated levels of GRP78 were detected on day 14 after ischemia in the ipsilateral sensorimotor cortex. These results suggest that altered gene expression related to unfolded protein response may be more long lasting than expected following focal cerebral ischemia. In addition, these results show that the response to ER stress differs ipsi- and contralaterally after MCAO in rats. Since these differences are detected in both hemispheres only in areas adjacent to the lesion, UPR may contribute to spontaneous recovery after MCAO in rats.

Animals↗

Metabolic syndrome and the risk of stroke in middle-aged men.

BACKGROUND AND PURPOSE: The metabolic syndrome, a clustering of disturbed glucose and insulin metabolism, obesity and abdominal fat distribution, dyslipidemia, and hypertension is associated with cardiovascular diseases. The aim of this study was to examine the relationship of metabolic syndrome, as defined by National Cholesterol Education Program (NCEP) and World Health Organization (WHO) criteria, with the risk for stroke. METHODS: Population-based cohort study with an average follow-up of 14.3 years from eastern Finland. A total of 1131 men with no history of cardiovascular disease and diabetes at baseline participated. Sixty-five strokes occurred, of which 47 were ischemic strokes. RESULTS: Men with the metabolic syndrome as defined by the NCEP criteria had a 2.05-fold (95% CI, 1.03 to 4.11; P=0.042) risk for all strokes and 2.41-fold (95% CI, 1.12 to 5.32; P=0.025) risk for ischemic stroke, after adjusting for socioeconomic status, smoking, alcohol, and family history of coronary heart disease. Additional adjustment for ischemic changes during exercise test, serum low-density lipoprotein cholesterol, plasma fibrinogen, energy intake for saturated fats, energy expenditure of leisure time physical activity, and white blood cell count, the results remained significant. The risk ratios among men with metabolic syndrome as defined by the WHO criteria were 1.82 (95% CI, 1.01 to 3.26; P=0.046) for all strokes and 2.16 (95% CI, 1.11 to 4.19; P=0.022) for ischemic stroke. After further adjustment, the respective risks were 2.08 (95% CI, 1.12 to 3.87; P=0.020) and 2.47 (95% CI, 1.21 to 5.07; P=0.013). CONCLUSIONS: The risk of any stroke is increased in men with metabolic syndrome, in the absence of stroke, diabetes and cardiovascular disease at baseline. Prevention of the metabolic syndrome presents a great challenge for clinicians with respect to stroke.

Adult↗

Gene expression profiling in the hippocampus of rats subjected to focal cerebral ischemia and enriched environment housing.

PURPOSE: Enriched environment housing enhances brain plasticity and improves recovery of impaired sensorimotor and cognitive functions of rats subjected to transient middle cerebral artery occlusion (MCAO). The present study applied microarray technique to investigate the molecular basis through which enriched environment might improve spatial learning in MCAO rats. METHODS: MCAO rats were housed in enriched environment or in standard single cages, and sham-operated rats were housed in standard single cages. Spatial learning was assessed using the Morris water-maze on postoperative days 22 to 24. Total RNA from the ipsilateral hippocampus was extracted for microarray analysis after the follow-up period. RESULTS: Water-maze performance on postoperative days 22 to 24 showed that rats subjected to transient MCAO were impaired in the hippocampus-dependent Morris water-maze test. Enriched environment housing reversed the spatial learning impairment on postoperative day 23. Gene expression in the hippocampus was not affected by MCAO or following enriched environment housing. CONCLUSION: Spatial learning impairment following transient MCAO in rats and cognitive improvement following housing in enriched environment is not related to % related to extrahippocampal brain regions rather than altered hippocampal gene expression.

Animals↗

Footprint peak time and functional ambulation profile reflect the potential for hemiparetic gait recovery.

OBJECTIVE: Gait disturbances were monitored in patients with chronic stroke with a walkway built with pressure sensors in order to assess whether detailed gait and footprint information could provide verification for the potential for gait recovery. METHODS: Gait variables (footprint peak times, temporal and spatial parameters and Functional Ambulation Profile, FAP, scores), were first recorded in 25 patients with chronic stroke at their preferred speed and 10 healthy volunteers walking from very slow to very fast. Patients and controls were divided into four groups based on the velocity performance. Secondly, the effect of rehabilitation on the footprint peak times was evaluated in another group of 20 chronic stroke patients. RESULTS AND CONCLUSIONS: The footprint peak time behaviour of different patients with chronic stroke reflected their hemiparetic gait pattern. The slower patients had prolonged footprint peak times on the non-affected side (NS) and shorter values on the lateral footprint on the affected side (AS). The increased gait velocity and the FAP scores decreased the footprint peak times on both sides, especially on the NS. The rehabilitation increased the gait velocity with 18.2%, decreased the duration of the mid-foot and forefoot peak times on the NS and the lateral mid-foot peak times on the AS. A detailed analysis of the individual gait performance allows more accurate assessment of the potential for gait recovery.

Adult↗

Transformation of diffuse beta-amyloid precursor protein and beta-amyloid deposits to plaques in the thalamus after transient occlusion of the middle cerebral artery in rats.

BACKGROUND AND PURPOSE: The present study examined the long-term presence of beta-amyloid precursor protein (APP) and beta-amyloid (Abeta) accumulation in the rat thalamus after focal cerebral ischemia. METHODS: Male Wistar rats were subjected to transient middle cerebral artery occlusion (MCAO) for 2 hours. Sensorimotor outcome was assessed using a tapered/ledged beam-walking task after operation. The distribution of APP and Abeta was examined immunohistochemically at 1 week, 1 month, and 9 months after MCAO. RESULTS: MCAO caused a long-lasting deficit in forelimb and hind limb function assessed using the beam-walking test. Histologic examination revealed a transient increase in APP and Abeta staining in axons in the corpus callosum and in neurons at the border of the ischemic region. APP and Abeta deposits persisted in the thalamic nuclei (ventroposterior lateral and ventroposterior medial nuclei), eventually leading to dense plaque-like deposits by the end of the 9-month follow-up. The deposits were surrounded by an astroglial scar. The deposits were positive for Abeta and N-terminal APP, but not for C-terminal APP. Antibodies against the C-terminal of Abeta, ie, Abeta42 and Abeta40, showed a preferential staining for Abeta42. Congo red or thioflavine S did not stain the deposits. CONCLUSIONS: The present results demonstrated the persistent presence and aggregation of APP and Abeta, or their fragments, to dense plaque-like deposits in the ventroposterior lateral and ventroposterior medial nuclei of rats subjected to focal cerebral ischemia.

Amyloid beta-Peptides↗

Behavioral and histological effects of chronic antipsychotic and antidepressant drug treatment in aged rats with focal ischemic brain injury.

Psychotropic drugs are commonly used in the elderly, including those who may sustain ischemic attacks. Concomitant CNS medication may interfere with functional recovery. The present study evaluated the effect of risperidone, an atypical neuroleptic, and fluoxetine, a selective serotonin reuptake inhibitor, on histological and functional outcome after experimental stroke in aged rats, which might be more vulnerable to brain insults. Aged Wistar rats were treated with risperidone at a dose of 1 mg/kg (i.p., once a day), fluoxetine at a dose of 5 mg/kg (i.p., once a day), or their combination. Drug treatment was started 7 days before focal cortical photothrombosis (Rose Bengal, 20 mg/kg) and continued for 28 days thereafter. Sensorimotor recovery was assessed by a new beam-walking test and spatial learning by the Morris water-maze before cortical stroke, immediately after stroke, and at the end of follow-up. Infarct volumes were measured from nitroblue tetrazolium-stained sections at the end of follow-up. The high slip ratio for the contralateral hindlimb in ischemic rats treated with risperidone indicated sensorimotor impairment when tested 2 h after drug administration. Sensorimotor impairment was not observed, however, when the rats were tested 24 h after risperidone administration. Similarly, water-maze performance was impaired 2 h after risperidone. Fluoxetine did not affect sensorimotor or water-maze performance. Cortical infarct volumes were not different in ischemic controls and ischemic rats treated with antipsychotic drugs. The present study showed that an atypical neuroleptic, risperidone, acutely impairs behavioral performance, but does not affect histological or functional outcome in aged rats subjected to cortical photothrombosis.

Affect↗

Diabetes worsens the outcome of acute ischemic stroke.

OBJECTIVE: To characterize acute stroke events in diabetic patients in a population-based stroke register and to determine the influence of diabetes on the outcome of acute stroke. METHODS: Four thousand three hundred and ninety patients were recorded in the FINMONICA and FINSTROKE registers after their first ischemic stroke from 1990 to 1998. We followed mortality and stroke outcome for up to 4 weeks after the onset of acute stroke. RESULTS: Of the 4390 patients who had had an ischemic stroke, 43.6% were male and 25.1% (1103) had diabetes. Their mean age was 72.4 (S.D. 12.0) years and this was similar in patients with and without diabetes (72.9 years versus 72.3 years, p=0.18). Subjects with diabetes were more likely to be hypertensive (55% versus 38%, p<0.001) and have a history of myocardial infarction (20% versus 16%, p<0.001) than the non-diabetic stroke patients. Mortality at 4 weeks from the onset was higher in diabetic than in non-diabetic patients (20.0% versus 16.9% p=0.020). At day 28 after the stroke attack, diabetic patients were more likely to be disabled when compared with non-diabetic subjects (43.3% versus 33.5%, p<0.001). Using logistic regression analysis, adjusted for age-group, sex, previous medical history (MI, AF or TIA), diabetes was found to be a significant predictor of disability after stroke (OR=1.51, 95% CI 1.27-1.81). CONCLUSIONS: Diabetes, which affected one-fourth of the ischemic stroke patients on our register, was associated with a higher risk of death and disability after the onset of stroke. Preventing diabetes in the elderly population improves the short-term prognosis of acute ischemic stroke.

Acute Disease↗

Behavioral effects of photothrombotic ischemic cortical injury in aged rats treated with the sedative-hypnotic GABAergic drug zopiclone.

Sedative-hypnotic drugs commonly used in the elderly may affect functional recovery following cerebrovascular events. Previous research has shown that prolonged exposure to diazepam can interfere with recovery of function and exaggerate tissue loss after brain injury. The present study evaluated the effect of zopiclone, a widely used hypnotic drug, on functional and histological outcome after cortical photothrombosis in aged rats, which might be particularly vulnerable to brain insults and inhibitory sedative-hypnotic drugs. Aged Wistar rats were treated with zopiclone at a dose of 3 mg/kg (i.p., once a day) beginning 4 days before ischemia induction and continuing for 23 days. Sensorimotor recovery was assessed by a new ledged beam-walking test and spatial learning by the Morris water-maze. After a 7-day washout period all rats were administered a single dose of zopiclone (3 mg/kg, i.p.) and retested. Infarct volumes were measured from nitroblue tetrazolium-stained sections at the end of the experiment. Beam-walking data showed that ischemic rats treated with zopiclone were not more impaired than untreated rats. Indeed, they showed fewer faults with the impaired hindlimb than ischemic controls on post-operative day 16. Water-maze performance was not affected by zopiclone. After the washout period a single dose of zopiclone did not worsen forelimb or hindlimb function, but seemed to improve performance in the water-maze test. Cortical infarct volumes were similar in ischemic controls and ischemic rats treated with zopiclone. In conclusion, zopiclone was not detrimental and even seemed to improve behavioral outcome without affecting ischemic damage in aged rats subjected to cortical photothrombosis.

Aging↗

Effect of cholinergic medication, before and after focal photothrombotic ischemic cortical injury, on histological and functional outcome in aged and young adult rats.

The present study evaluated the effect of galanthamine, a selective competitive cholinesterase inhibitor, on histological and functional outcome after experimental stroke in rats. Cholinesterase inhibitors are commonly used as cognitive enhancers for dementia in aged people, including those who may sustain ischemic attacks. Young adult (5 months) and aged (24 months) rats were treated with saline or galanthamine at a dose of 2.5 mg/kg (i.p., once a day). Drug treatment started 4 days before focal cortical photothrombosis (Rose Bengal, 20 mg/kg) and continued for 21 days thereafter. Sensorimotor recovery was assessed by a new beam-walking test and spatial learning by the Morris water-maze over a 3-week follow-up period. Infarct volumes were measured from nitroblue tetrazolium-stained sections at the end of follow-up. Infarct volumes in the cortex were similar in ischemic controls and ischemic rats treated with galanthamine. In the beam-walking test, there was a transient impairment forelimb function and a permanent impairment in hindlimb after cortical infarct both in young adult and aged rats. Galanthamine treatment did not affect the sensorimotor recovery rate. Analysis of water-maze data did not reveal significant differences in length of path, escape latency, or swim speed between sham-operated, ischemic controls and ischemic rats treated with galanthamine. In conclusion, present findings suggest that the aging brain has considerable plastic capacity to maintain functioning after focal cerebral insults restricted to the motor cortex. Galanthamine is not beneficial with respect to the histological or functional outcome in rats subjected to cortical photothrombosis.

Age Factors↗

Efficacy of aspirin plus extended-release dipyridamole in preventing recurrent stroke in high-risk populations.

OBJECTIVE: To assess the efficacy of aspirin plus extended-release dipyridamole compared with aspirin alone for the prevention of recurrent stroke among high-risk groups. DESIGN: A post hoc analysis was conducted using data from the European Stroke Prevention Study 2. Rates of annual strokes and vascular events were determined for the aspirin plus extended-release dipyridamole group (n = 1650) and the aspirin-only group (n = 1649), and were stratified by risk subgroup and univariate risk factors. Stroke models from the Framingham Study and the Stroke Prognostic Instrument II were applied to subjects in the European Stroke Prevention Study 2 to categorize patients into risk groups. RESULTS: Compared with aspirin alone, aspirin plus extended-release dipyridamole demonstrated a more pronounced efficacy in reducing the risk for stroke and vascular events among patients younger than 70 years; those with hypertension, prior stroke, or transient ischemic attack; current smokers; and those with any prior cardiovascular disease. Relative hazard reductions favored the combination of aspirin plus extended-release dipyridamole, and were greatest for the high-risk Framingham Study group and the moderate-risk Stroke Prognostic Instrument II subgroup. CONCLUSION: Aspirin plus extended-release dipyridamole is more effective than aspirin alone at preventing stroke, and the difference in efficacy increases in higher-risk patients.

Adult↗

Epileptogenesis after experimental focal cerebral ischemia.

Cerebrovascular diseases are one of the most common causes of epilepsy in adults, and the incidence of stroke-induced epileptogenesis is increasing as the population ages. The mechanisms that lead to stroke-induced epileptogenesis in a subpopulation of patients, however, are still poorly understood. Recent advances in inducing epileptogenesis in rodent focal ischemia models have provided tools that can be used to identify the risk factors and neurobiologic changes leading to development of epilepsy after stroke. Here we summarize data from models in which epileptogenesis has been studied after focal ischemia; photothrombosis, middle cerebral artery (MCA) occlusion with filament, and endothelin-1-induced MCA occlusion. Analysis of the data indicates that neurobiologic changes occurring during stroke-induced epileptogenesis share some similarities to those induced by status epilepticus or traumatic brain injury.

Animals↗

The effectiveness of body weight-supported gait training and floor walking in patients with chronic stroke.

OBJECTIVE: To compare body weight-supported exercise on a gait trainer with walking exercise overground. DESIGN: Randomized controlled trial. SETTING: Rehabilitation hospital. PARTICIPANTS: Forty-five ambulatory patients with chronic stroke. INTERVENTIONS: Patients were randomized to 3 groups: (1) gait trainer exercise with functional electric stimulation (GTstim), (2) gait trainer exercise without stimulation (GT), and (3) walking overground (WALK). All patients practiced gait for 15 sessions during 3 weeks (each session, 20 min), and they received additional physiotherapy 55 minutes daily. MAIN OUTCOME MEASURES: Ten-meter walk test (10MWT), six-minute walk test (6MWT), lower-limb spasticity and muscle force, postural sway tests, Modified Motor Assessment Scale (MMAS), and FIM instrument scores were recorded before, during, and after the rehabilitation and at 6 months follow-up. RESULTS: The mean walking distance using the gait trainer was 6900+/-1200 m in the GTstim group and 6500+/-1700 m in GT group. In the WALK group, the distance was 4800+/-2800 m, which was less than the walking distance obtained in the GTstim group (P=.027). The body-weight support was individually reduced from 30% to 9% of the body weight over the course of the program. In the pooled 45 patients, the 10MWT (P<.001), 6MWT (P<.001), MMAS (P<.001), dynamic balance test time (P<.001), and test trip (P=.005) scores improved; however, no differences were found between the groups. CONCLUSIONS: Both the body weight-supported training and walking exercise training programs resulted in faster gait after the intensive rehabilitation program. Patients' motor performance remained improved at the follow-up.

Analysis of Variance↗

Increased perfusion in motor areas after constraint-induced movement therapy in chronic stroke: a single-photon emission computerized tomography study.

Hemiparesis is the most common deficit after cerebral stroke. Constraint-induced movement therapy (CIMT) is a new neurorehabilitation method that emphasizes task-relevant repetitive training for the stroke hand. Twelve chronic stroke patients were studied with single-photon emission computerized tomography at rest before and after the two-week CIMT period. Increased perfusion was found in motor control related areas. The specific areas with an increase in perfusion in the affected hemisphere were in the precentral gyrus, premotor cortex (Brodmann's area 6 (BA6)), frontal cortex, and superior frontal gyrus (BA10). In the nonaffected hemisphere, perfusion was increased in the superior frontal gyrus (BA6) and cingulate gyrus (BA31). In the cerebellum increased perfusion was seen bilaterally. The brain areas with increased perfusion receive and integrate the information from different sensory systems and plan the movement execution. Regional cerebral perfusion decreased in the lingual gyrus (BA18) in the affected hemisphere. In the nonaffected frontal cortex, two areas with decreased perfusion were found in the middle frontal gyrus (BA8/10). Also, the fusiform gyrus (BA20) and inferior temporal gyrus (BA37) in the nonaffected hemisphere showed decreased perfusion. Intensive movement therapy appears to change local cerebral perfusion in areas known to participate in movement planning and execution. These changes might be a sign of active reorganization processes after CIMT in the chronic state of stroke.

Adult↗

Serum homocysteine, folate and risk of stroke: Kuopio Ischaemic Heart Disease Risk Factor (KIHD) Study.

BACKGROUND: Homocysteine and folate have been suggested to have opposite effects on the risk of stroke, although the results are controversial. DESIGN AND METHODS: The purpose of this study was to assess the effects of serum total homocysteine (tHcy) and serum folate levels on the risk of stroke in a prospective cohort study. The subjects were 1015 men aged 46-64 years and free of prior stroke, examined in 1991-1993 in the Kuopio Ischaemic Heart Disease Risk Factor (KIHD) Study. RESULTS: At baseline the mean serum tHcy concentration was 10.9 micromol/l (SD 3.4). During an average follow-up time of 9.6 years, 49 men experienced a stroke, of which 34 were ischaemic. In Cox proportional hazards models, men in the highest tHcy third had a risk factor-adjusted hazard rate ratio (RR) of 2.77 [95% confidence interval (CI): 1.23-6.24] for any stroke and 2.61 (95% CI: 1.02-6.71) for ischaemic stroke, compared with men in the lowest third. The mean baseline serum folate concentration was 10.4 nmol/l (SD 4.1). Men in the highest third of serum folate (>11.2 nmol/l) had an adjusted RR for any stroke of 0.35 (95% CI: 0.14-0.87) and for ischaemic stroke of 0.40 (95% CI: 0.15-1.09), compared with men in the lowest third. CONCLUSION: Elevated serum tHcy is associated with increased risk of all strokes and ischaemic strokes in middle-aged eastern Finnish men free of prior stroke. On the other hand, high serum folate concentration may protect against stroke.

Age Factors↗

Paretic hand rehabilitation with constraint-induced movement therapy after stroke.

OBJECTIVE: Hemiparesis of the upper limb after stroke can be severely disabling. We studied the effectiveness of constraint-induced movement therapy in improving motor abilities in very chronic stroke subjects. We assessed whether the obtained changes, if any, would endure after the intervention program. DESIGN: Participants were 27 consecutive chronic stroke subjects (mean age, 56 +/- 13 yrs) who fulfilled specific motor criteria. The design was an uncontrolled preintervention to postintervention comparison. The subjects participated in a 2-wk-long constraint-induced movement therapy program. The motor function of the affected arm and its daily use were assessed using a structured motor performance test in a control test 2 wks before the intervention, then again immediately before and after the intervention, and at the follow-up. The intervention was undertaken in a rehabilitation hospital. RESULTS: The motor abilities of the affected arm improved significantly as measured by the structured motor performance test. The obtained improvements in the affected arm motor behavior endured for 5 mos after the therapy. CONCLUSIONS: Chronic stroke subjects, who have sufficient residual motor control for exercise, benefit from highly concentrated therapy and can still enhance their voluntary motor control of the affected arm even years after the incident.

Adult↗

Gait characteristics after gait-oriented rehabilitation in chronic stroke.

PURPOSE: To assess the effects of rehabilitation in thirty-seven ambulatory patients with chronic stroke during three weeks in-patient rehabilitation period. METHODS: In the intervention group, each patient received 75 min physiotherapy daily every workday including 20 minutes in the electromechanical gait trainer with body-weight support (BWS). In the control group, each patient participated in 45 min conventional physiotherapy daily. Motor ability was assessed with the first five items of the Modified Motor Assessment Scale (MMAS1-5) and ten meters walking speed. Spatio-temporal gait characteristics were recorded with an electrical walkway. RESULTS: The MMAS1-5 (p<0.0005 and p=0.005) and ten meters walking time (p<0.0005 and p=0.006) improved in both groups. The improvements in MMAS1-5 and ten meters walking time did not differ between the groups (p=0.217 and p=0.195). Specific gait characteristics improved only in the intervention group, as seen in increased Functional Ambulation Profile score (p=0.023), velocity (p=0.023), the step lengths (affected side, p=0.011, non-affected side p=0.040), the stride lengths (p=0.018, p=0.006) and decreased step-time differential (p=0.043). Furthermore, all gait characteristics and other motor abilities remained in the discharge level at the six months in the intervention group. CONCLUSIONS: It appears that BWS training gives a long-lasting benefit in gait qualities even in chronic stroke patients.

Adult↗