Biomedical subjects

Ville Leinonen

Publications and source records attributed to Ville Leinonen.

10 recordsLinked to original sources

PubMed2026

APOE-stratified genome-wide association analyses provide insights into the genetic etiology of Alzheimers's disease.

Among the more than 90 identified genetic risk loci for late-onset Alzheimer's disease (AD) and related dementias, the apolipoprotein E (APOE) gene ɛ2/ɛ3/ɛ4 polymorphisms remain the longstanding benchmark for genetic disease risk with a consistently large effect across studies1-10. Despite this massive signal, the exact mechanisms by which ɛ4 increases and ɛ2 decreases dementia risk remain poorly understood. Notably, recent trials of anti-amyloid therapies suggest less efficacy and higher risks of severe side effects in ε4 carriers11-13, hampering the treatment of those with the highest unmet need. To improve our understanding of the genetic architecture of AD in the context of its main genetic driver, we performed genome-wide association studies (GWASs) stratified by ε4 and ε2 carrier status. HP1BP3, SLC50A1, PTPRC, NPAS3, DDHD1, CHST9, SMYD2, PRAMEF1 and GFRA1 emerged as new genomic signals for AD risk, appearing only when stratified by APOE carrier status. DDHD1 appeared especially promising, showing protective effects in ε4 carriers, being identified as an expression quantitative trait locus and being involved in rare neuronal diseases. Such APOE-stratified insights may help understand and overcome side effects, inform clinical trial enrollment strategies, and create the scientific basis for targeted, mechanism-driven therapies in neurodegenerative diseases.

Journal Article↗

PubMed2024

Tear fluid reflects the altered protein expressions of Alzheimer's disease patients in proteins involved in protein repair and clearance system or the regulation of cytoskeleton.

BackgroundNew biomarkers that improve diagnosis of Alzheimer's disease (AD) are warranted. Tear fluid (TF) containing variety of proteins that reflect pathophysiological changes of systemic diseases makes TF proteins potential biomarker candidates for AD.ObjectiveWe investigated the expression levels of TF proteins in persons with mild AD and cognitively healthy controls (CO) to find out if altered proteins may link to the AD pathophysiology.MethodsWe analyzed the data of the 53 study participants (34 COs, mean age 71 and Mini-Mental State Examination (MMSE) 28.9 ± 1.4 and 19 persons with AD, CDR 0.5-1, mean age 71 and MMSE 23.8 ± 2.8). All went through neurological status examination, cognitive tests, and ophthalmological examination. TF was collected using Schirmer strips. The TF protein content was evaluated via mass spectrometry-based proteomics and label-free quantification.ResultsEleven proteins having a role either in protein repair and clearance system, or regulation of cytoskeleton, showed altered expression in AD group compared to CO group. Seven of them were significantly (p ≤ 0.05) upregulated (Sti1, Twf1, Myl6, Otub1, Pls1 and Caza1) or, downregulated (HSP90) in AD group.ConclusionsAltered expression of all these up- or downregulated proteins may be linked to AD pathophysiology. Thus, our results are encouraging for searching new biomarker candidates for AD. TF is potential biomarker candidate, because TF seems to reflect altered protein levels already in mild AD dementia.

Humans↗

PubMed2007

Dynamic surface electromyographic responses in chronic low back pain treated by traditional bone setting and conventional physical therapy.

OBJECTIVE: This study compared the dynamic surface electromyographic (EMG) activities of back muscles and pain before and after traditional bone setting and physical therapy. METHODS: This study was a prospective clinical trial that compared surface EMG dynamic activities after traditional bone setting and physical therapy. Sixty-one patients (mean age, 41 years) with nonspecific low back pain were randomized into two subgroups by treatment. The patients underwent a dynamic EMG evaluation for which they were asked to stand and then bend forward as far as possible, stay fully flexed, and return to standing. A flexion-relaxation ratio was calculated by comparing maximal EMG activity while flexing with the average EMG activity in full flexion. Concentric (maximal EMG activity during extension) and eccentric (maximal EMG activity during flexion) ratios were also used in the analyses. RESULTS: Disability, depression, and visual analog scale scores decreased significantly after both treatments. The concentric ratio increased statistically in both groups after the treatments. The study failed to show a significant association between experienced back pain and EMG parameters. CONCLUSIONS: Both treatments seem to have a positive influence on back muscle function by improving muscle symmetry; however, the treatments had no effect on the flexion-relaxation phenomenon after 1 month. Active back exercise at home together with rehabilitation treatments might be effective and improve function for patients with chronic low back pain.

Adult↗

PubMed2005

Wireless on-line electromyography in recording neck muscle function: a pilot study.

AIM: The surface electromyography (SEMG) records muscle activity without causing pain and therefore it can be used in the on-line kinetic evaluation of rehabilitation methods. The cables are a problem in the clinical work. The aim of this pilot study was to introduce a wireless on-line SEMG method in the measurements of neck muscle activity and preliminarily evaluate its usability in dynamic exercises in a healthy and a neck pain subject. METHOD: The bilateral wireless on-line SEMG measurements were performed at the level C4-C5 of the cervical spine. The subjects (one healthy 32-year-old female and one neck pain patient, 35-year-old female) were performing slow cervical flexions with eyes open. The angle of the flexion was measured with inclinometer. RESULTS: In healthy subjects, the SEMG curve demonstrated clear flexion-relaxation rhythm whereas in the patient the rhythm was blurred. The SEMG signal quality was, however, good in both cases. CONCLUSION: Wireless on-line SEMG method seems promising in daily clinical work for the measurements of neck muscle activity.

Journal Article↗

PubMed2005

Back and neck extensor loading and back pain provocation in urban bus drivers with and without low back pain.

This study assessed low back and trapezius muscle activity in bus drivers, with or without recurrent low back pain (LBP), during the long term driving. In addition, low back and neck-shoulder pain intensities and fatigue were measured and the effect of low back support was observed. Also the possible source of LBP was attempted to assess by vibration pain provocation test and lumbar MRI. Forty bus drivers (recurrent LBP n = 25) participated in this study. Low back and neck-shoulder pain and subjective fatigue intensity was assessed by visual analogue scales (VAS) before and after driving. Lumbar paraspinal and trapezius muscle activation during driving was measured by surface EMG. Vibration pain provocation test was applied for all subjects. Average paraspinal myoelectric activity during driving was approximately 1% of MVC in both groups. Average trapezius myoelectric activity during driving was from 2 to 4% of MVC. Trapezius muscle activity was higher in back healthy drivers than in those with LBP. The low back support had no effect either on paraspinal or trapezius EMG activity. Low back and neck-shoulder fatigue increased during driving in both groups especially in those subjects with positive vibration pain provocation. The neck-shoulder pain and fatigue were more severe in drivers suffering from LBP. Low back support had no effect on low back and neck-shoulder subjective fatigue and neck-shoulder pain but tended to limit the LBP increase during driving. Paraspinal muscle loading in urban bus drivers was very limited and either LBP or ergonomic low back support had no effect on it. Trapezius muscle seemed to be less active in drivers suffering from recurrent LBP. Internal disc disruptions may expose to pain and fatigability during driving.

Journal Article↗

PubMed2005

Postural control in male patients with hip osteoarthritis.

Earlier studies have demonstrated that postural control is worse in patients with knee osteoarthritis (OA) than in control subjects, whereas little information is available about the postural control in patients with hip OA. The aim of this study was to investigate the standing balance in different test conditions in men with hip OA and to compare the results with those of age- and sex-matched healthy controls. Twenty-seven volunteers 47-64-year-old men with hip OA and 30 randomly selected, healthy age-matched men were tested using the sensory organisation test (SOT). The center point of force velocity (CPFV (cm/s)) was also determined during one- and two-footed standing. There was no difference between the patients and controls in the SOT test, in the strategy analysis or during one-footed standing. There were no significant differences in CPFV values between the better and worse hip side. Fatiguing exercise had no effect on two-footed CPFV with eyes open, but when the eyes were closed both two and one-footed CPFV values were significantly increased (p<0.01-0.05) in both groups. No differences were found in fatiguing exercise between control and OA subjects with eyes open or closed or in one-footed trials. In OA patient's subjective pain was related to increasing CPFV (p<0.05). In conclusion, the hip OA had no effect on static balance in men.

Humans↗

PubMed2003

Lumbar paraspinal muscle function, perception of lumbar position, and postural control in disc herniation-related back pain.

STUDY DESIGN: A follow-up study evaluating postural control, lumbar movement perception, and paraspinal muscle reflexes in disc herniation-related chronic low back pain (LBP) before and after discectomy. OBJECTIVES: To assess the effect of discectomy on postural control, lumbar perception, and reflex activation of paraspinal muscles during sudden upper limb loading. SUMMARY OF BACKGROUND DATA: Impaired muscle function, postural control, and lumbar proprioception have been observed in LBP. However, they have not been studied in sciatica patients after surgery. METHODS: The study included 20 patients selected for an operation for chronic LBP caused by disc herniation and 15 controls without chronic LBP. The paraspinal muscle responses for upper limb loading during unexpected and expected conditions were measured by surface electromyography. The ability to sense lumbar rotation was assessed in a previously validated motorized trunk rotation unit in the seated position. The postural control was measured with a vertical force platform. Pain, disability, and depression scores were recorded. RESULTS: Patients had poorer lumbar perception (P = 0.012) and postural control (P < 0.05) than did healthy controls. The postural control remained unchanged, but lumbar perception (P = 0.054) and the lumbar feed-forward control (P = 0.043) improved after the surgery. CONCLUSIONS: The results demonstrate impaired lumbar proprioception and postural control in sciatica patients. During short-term follow-up after operative treatment, postural control does not seem to change, but impaired lumbar proprioception and feed-forward control of paraspinal muscles seem to recover.

Chronic Disease↗

PubMed2003

Paraspinal muscle denervation, paradoxically good lumbar endurance, and an abnormal flexion-extension cycle in lumbar spinal stenosis.

STUDY DESIGN: A descriptive study was conducted to investigate the paraspinal muscle function in patients with lumbar spinal stenosis. OBJECTIVE: To evaluate paraspinal muscle innervation and endurance in lumbar spinal stenosis. SUMMARY OF BACKGROUND DATA: Abnormal lumbar paraspinal muscle function is associated with chronic low back pain. Abnormal neurophysiologic findings of the lower limbs often are observed in lumbar spinal stenosis, and abnormal lumbar function also can be expected. However, paraspinal muscle function and innervation have not been studied in lumbar spinal stenosis. METHODS: The study evaluated 25 patients with clinically and radiologically diagnosed lumbar spinal stenosis. Electromyography of the paraspinal muscles was performed from L3 to S1 bilaterally using a concentric needle. At least 20 insertions were analyzed from each muscle. The aim of the examination was to detect abnormal spontaneous activity associated with axonal damage (fibrillation potentials, positive sharp waves, and complex repetitive discharges). Paraspinal muscle activity during trunk flexion-extension movement and muscle endurance during the dynamic isoinertial back endurance test were assessed by surface electromyography. Muscle fatigue was calculated using mean power frequency analysis. RESULTS: Abnormal findings in needle electromyography of the paraspinal muscles were observed in 18 of the 22 (81.8%) examined patients. Abnormal flexion-extension activation of the paraspinal muscles was observed in all the examined patients. The change in mean power frequency was significantly smaller than in previously evaluated healthy subjects and patients with nonspecific chronic low back pain (P < 0.001) who were not experiencing symptoms of lumbar spinal stenosis. Paraspinal muscle fatigability was not associated with the denervation of the muscles. CONCLUSIONS Denervation and abnormal activation of lumbar paraspinal muscles are frequent findings in patients with lumbar spinal stenosis who have not undergone surgery. The paraspinal muscle endurance of the patients was unexpectedly good.

Adult↗

PubMed2002

Paraspinal muscle responses during sudden upper limb loading.

The paraspinal muscle responses for unexpected and expected upper limb loading were investigated by surface EMG of 20 healthy volunteers. The simultaneous trunk and hand accelerations with paraspinal, biceps brachii and soleus muscles EMG were measured in four subjects. A short-latency response of approximately 50 ms was observed in paraspinal muscles. The latency was approximately 3 ms shorter (P = 0.017) during "expected" trials on average and the latency shortened during the first three expected trials (P = 0.02). Anticipation also decreased the magnitude of the response (P < 0.05). Trunk movement initiated approximately 35 ms and approximately 50 ms after the impact of the load at T6 and T12 levels, respectively. In conclusion, visual expectation shortens the latency and decreases the magnitude of the paraspinal muscle response to sudden upper limb loading. Also, the trial repetition has an effect on reflex latency if visual information is available. These results indicate that anticipation modulates the reflex control of paraspinal muscles, which may be significant in understanding spinal function.

Acceleration↗

PubMed2002

Impaired lumbar movement perception in association with postural stability and motor- and somatosensory-evoked potentials in lumbar spinal stenosis.

STUDY DESIGN: A descriptive study of the associations between different neurophysiologic findings in patients with lumbar spinal stenosis. OBJECTIVES: To evaluate the ability to sense a change in lumbar position and the associations between lumbar movement perception, postural stability, and motor-evoked potentials and somatosensory-evoked potentials. SUMMARY OF BACKGROUND DATA: Patients with low back pain have impaired postural control and impaired lumbar proprioception. Altered motor-evoked potentials and somatosensory-evoked potentials have been often observed in lumbar spinal stenosis. METHODS: The study included 26 patients with clinically and radiologically diagnosed lumbar spinal stenosis. Their ability to sense lumbar rotation was assessed in a previously validated motorized trunk rotation unit in the seated position. The abilities to indicate the movement direction and the movement magnitude were used as indexes of the ability to sense the lumbar rotatory movement. The postural stability was measured with a vertical force platform. The motor-evoked potentials were elicited by transcranial and lumbar stimulation and recorded from anterior tibialis muscles. The somatosensory-evoked potentials were elicited by transcutaneous electrical stimulation of the tibial nerve at the ankle. RESULTS: Twenty patients (76.9%; P = 0.006) reported the wrong movement direction. Furthermore, the patients consistently localized the movement sensation in their shoulders instead of the lumbar region. The altered motor-evoked potentials and somatosensory-evoked potentials were observed in 11 and 16 patients, respectively. Abnormal motor-evoked potentials had inconsistent associations with impaired movement perception and postural stability and abnormal somatosensory-evoked potentials had no associations with other findings. CONCLUSIONS: Many patients with lumbar spinal stenosis have difficulties in sensing the lumbar rotational movement, which may indicate impaired proprioceptive abilities. Abnormal motor-evoked potentials and somatosensory-evoked potentials are also frequent in lumbar spinal stenosis but do not necessarily occur in the same patients as the abnormal ability to sense trunk movement. These new findings add to our understanding of the pathophysiology of lumbar spinal stenosis.

Evoked Potentials, Motor↗