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Biomedical subjects

R Parkkola

Publications and source records attributed to R Parkkola.

14 recordsLinked to original sources
PubMed2007

Adolescent disc degeneration--no headache association.

The objective of the study was to determine whether adolescents with headache have more disc degeneration in the cervical spine than headache-free controls. This study is part of a population-based follow-up study of adolescents with and without headache. At the age of 17 years, adolescents with headache at least three times a month (N = 47) and adolescents with no headache (N = 22) participated in a magnetic resonance imaging (MRI) study of the cervical spine. Of the 47 headache sufferers, 17 also had weekly neck pain and 30 had neck pain less than once a month. MRI scans were interpreted independently by three neuroradiologists. Disc degeneration was found in 67% of participants, with no difference between adolescents with and without headache. Most of the degenerative changes were located in the lower cervical spine. In adolescence, mild degenerative changes of the cervical spine are surprisingly common but do not contribute to headache.

Adolescent↗
PubMed2006

Voxel-based analysis of PET amyloid ligand [11C]PIB uptake in Alzheimer disease.

BACKGROUND: PET studies with N-methyl-[(11)C]2-(4':-methylaminophenyl)-6-hydroxybenzothiazole ([(11)C]PIB) have revealed an increased tracer uptake in several brain regions in Alzheimer disease (AD). OBJECTIVE: To employ voxel-based analysis method to identify brain regions with significant increases in [(11)C]PIB uptake in AD vs healthy control subjects, indicative of increased amyloid accumulation in these regions. METHODS: We studied 17 patients with AD and 11 control subjects with PET using [(11)C]PIB as tracer. Parametric images were computed by calculating a region-to-cerebellum ratio over 60 to 90 minutes in each voxel. Group differences in [(11)C]PIB uptake were analyzed with statistical parametric mapping (SPM) and automated region-of-interest (ROI) analysis. RESULTS: SPM showed increased uptake (p < 0.001) in the frontal, parietal, and lateral temporal cortices as well as in the posterior cingulate and the striatum. No significant differences in uptake were found in the primary sensory and motor cortices, primary visual cortex, thalamus, and medial temporal lobe. These results were supported by automated ROI analysis, with most prominent increases in AD subjects in the frontal cortex ([(11)C]PIB uptake 163% of the control mean) and posterior cingulate (146%) followed by the parietal (146%) and temporal (145%) cortices and striatum (133%), as well as small increases in the occipital cortex (117%) and thalamus (115%). CONCLUSIONS: Voxel-based analysis revealed widespread distribution of increased [(11)C]PIB uptake in Alzheimer disease (AD). These findings are in accordance with the distribution and phases of amyloid pathology in AD, previously documented in postmortem studies.

Aged↗
PubMed2005

In vivo measurements of glucose uptake in human Achilles tendon during different exercise intensities.

Muscular contraction and loading of adjacent tendons has been demonstrated to cause increased blood flow and metabolic activity in the peritendinous region. However, it is poorly known to what extent the human tendon itself takes up glucose during exercise. Thus, the purpose of this study was to measure tendon glucose uptake with increasing exercise intensity and to compare it to muscle glucose uptake at the same intensities. Eight young men were examined on three separate days during which they performed 35 min of cycling at 30, 55 and 75 % of VO2max, respectively. Glucose uptake was measured directly by positron emission tomography (PET) with 2-[ (18)F]fluoro-2-deoxyglucose ([18F]FDG). [18F]FDG was injected after 10 min of exercise that was continued for a further 25 min after the injection. PET scanning of the thigh and Achilles region was performed after the exercise. Glucose uptake of the Achilles tendon (AT) remained unchanged (7.1 +/- 1.5, 6.6 +/- 1.1, and 6.0 +/- 1.1 micromol.kg(-1).min(-1)) with the increasing workload, although the glucose uptake in m. quadriceps femoris simultaneously clearly increased (48 +/- 35, 120 +/- 35, and 152 +/- 74 micromol.kg(-1).min(-1), p < 0.05). In conclusion, the AT takes up glucose during exercise but in significantly smaller amounts than the skeletal muscle does. Furthermore, glucose uptake in the AT is not increased with the increasing exercise intensity. This may be partly explained by the cycle ergometry exercise used in the present study, which probably causes only a little increase in strain to the AT with increasing exercise intensity.

Achilles Tendon↗
PubMed2001

Human adipose tissue glucose uptake determined using [(18)F]-fluoro-deoxy-glucose ([(18)F]FDG) and PET in combination with microdialysis.

AIMS/HYPOTHESIS: To determine the lumped constant (LC), which accounts for the differences in the transport and phosphorylation between [(18)F]-2-fluoro-2-deoxy-d-glucose ([(18)F]FDG) and glucose, for [(18)F]FDG in human adipose tissue. METHODS: [(18)F]FDG-PET was combined with microdialysis. Seven non-obese (29 +/- 2 years of age, BMI 24 +/- 1 kg/m2) and seven obese (age 32 +/- 2 years of age, BMI 31 +/- 1 kg/m2) men were studied during euglycaemic hyperinsulinaemia (1 mU/kg. min-1 for 130 min). Abdominal adipose tissue [(18)F]FDG uptake (rGUFDG) and femoral muscle glucose uptake were measured using [(18)F]FDG-PET. Adipose tissue perfusion was measured using [15O]-labelled water and PET, and interstitial glucose concentration using microdialysis. Glucose uptake (by microdialysis, rGUMD) was calculated by multiplying glucose extraction by regional blood flow. The LC was determined as the ratio of rGUFDG to rGUMD. RESULTS: Rates of adipose tissue glucose uptake (rGUMD) were 36 % higher in the non-obese than in the obese patients (11.8 +/- 1.7 vs 7.6 +/- 0.8 micromol/kg. min-1, p < 0.05, respectively) and a correlation between rGUMD and rGUFDG was found (r = 0.82, p < 0.01). The LC averaged 1.14 +/- 0.11, being similar in the obese and the non-obese subjects (1.01 +/- 0.15 vs 1.26 +/- 0.15, respectively, NS). Muscle glucose uptake was fourfold to fivefold higher than adipose tissue glucose uptake in both groups. CONCLUSION/INTERPRETATION: [(18)F]FDG-PET seems a feasible tool to investigate adipose tissue glucose metabolism in human beings. Direct measurements with [(18)F]FDG-PET and microdialysis suggest a LC value of 1.14 for [(18)F]FDG in human adipose tissue during insulin stimulation and the LC does not appear to be altered in insulin resistance. Furthermore, the obese patients show insulin resistance in both adipose tissue and skeletal muscle.

Adipose Tissue↗
PubMed2000

Newer techniques to study neonatal hypoglycemia.

Severe neurological sequelae may occur after symptomatic neonatal hypoglycemia. New neuroimaging techniques allow both structural and functional detection of these disturbances. The new diagnostic modalities have shown also transient structural findings associated with neonatal hypoglycemia. The prognostic value of these techniques remains still obscure.

Animals↗
PubMed1999

Cerebral magnetic resonance imaging and ultrasonography findings after neonatal hypoglycemia.

OBJECTIVE: The aim of this study was to investigate sequential neuroradiologic changes in the brains of infants after transient neonatal hypoglycemia. We used magnetic resonance imaging (MRI) and ultrasonography (US) head scans. METHODS: Eighteen symptomatic full-term infants whose serum glucose concentrations were </=45 mg/dL (2.5 mmol/L) without any other diseases were included in the hypoglycemic group. MRI and US head scans were performed at full-term age and at the age of 2 months. The imaging results were compared with the findings of MRI and US scans in 19 healthy normoglycemic term newborn infants at the respective ages. The neurologic outcome was followed in the both groups. RESULTS: MRI or US showed evidence of abnormality in 39% the hypoglycemic infants. MRI detected more abnormalities in the brains than US. Four infants showed patchy hyperintensity lesions either in the occipital periventicular white matter or the thalamus on T1-weighted images. These lesions had a good tendency to recover and only 1 of these infants appeared to be neurologically affected. Of the 19 controls, 10% (2 of 19) had caudothalamic cysts, which were detected both with MRI and US. The relative risk of the hypoglycemic child compared with nonhypoglycemic child, to have any abnormality detected in the brain, was 3.7, with a 90% confidence interval from 1.11 to 12.28. CONCLUSIONS: Postnatal full-term MRI and US scans showed abnormalities four times more often after transient neonatal hypoglycemia than in the healthy control group. However, most often lesions were absent 2 months later. The clinical relevance of these abnormal findings remains to be clarified with detailed neurologic examinations and follow-up.

Brain↗
PubMed1997

Age-dependent correlation of low-back pain and lumbar disc regeneration.

The prevalence of lumbar disc degeneration in subjects suffering from low-back pain (n = 207; age range 10-49 years) and in age-matched asymptomatic controls (n = 216) was investigated by magnetic resonance imaging. The percentage of subjects with degenerated discs increased with age; starting from the age of 15 years, this increase was more rapid in subjects with low-back pain. Concurrently, the number of degenerated discs was higher in the pain group than in controls. Lumbar disc degeneration manifests earlier and in a greater percentage of subjects with low-back pain than in asymptomatic controls.

Adolescent↗
PubMed1995

Cross-sectional areas of lumbar muscles after surgical treatment of lumbar disc herniation. A study with magnetic resonance imaging after microdiscectomy or percutaneous nucleotomy.

We assessed in this study the potential development of postoperative muscle atrophy in the operation area in 39 patients treated by either microdiscectomy or percutaneous nucleotomy for lumbar disc herniation. The cross-sectional areas of the lumbar muscles were measured on magnetic resonance images created on the day preceding the operation and 6 months postoperatively. The cross-sections of the lumbar muscles remained unchanged during the observation period in all treated patients indicating that no muscle atrophy had developed in the operation area. Since peroperative tissue trauma may correlate with subsequent muscle denervation and atrophy, this finding may be due to the tissue sparing nature of microdiscectomy and percutaneous nucleotomy, thus encouraging the use of these techniques in the treatment of lumbar disc herniation.

Adult↗
PubMed1994

Phenotypic variation and magnetic resonance imaging (MRI) in Salla disease, a free sialic acid storage disorder.

Salla disease (SD) is a recessively inherited lysosomal storage disorder particularly common in the Finnish population. Patients with SD are normal at birth, but develop psychomotor delay and ataxia during the first year of life. Phenotypic variation of SD is wide, ranging from severely disabled children to mentally retarded adults capable of living under sheltered conditions. In the present study four unusually severely affected patients were investigated by detailed clinical examination, magnetic resonance imaging (MRI) and analysis of the excretion of free sialic acid in urine. MRI study, reported here for the first time, revealed a similarly defective myelination pattern in seven patients. The myelination process seemed to cessate at the level of an infant of a few months of age. Genetic linkage study of the families of the severely affected patients suggested linkage to the recently discovered SD locus on the long arm of chromosome 6. Locus heterogeneity therefore is an unlikely explanation of the phenotypic variation in SD.

Adolescent↗
PubMed1993

Magnetic resonance imaging of the discs and trunk muscles in patients with chronic low back pain and healthy control subjects.

This study aimed to evaluate the lumbar intervertebral discs and the maximum isometric strength and size of the trunk muscles of middle-aged healthy volunteers (60 persons) and low back pain patients (48 persons). Disc degeneration was more frequently seen in the patients than in the healthy volunteers. The psoas and back muscles (erector spinae and multifidus) of the patients were smaller than those of the volunteers. Patients had also more fat deposits in the back muscles than controls. The maximum isometric strength of trunk muscles of the patients was on average weaker than that of the volunteers. However, the size of the back muscles was not related to the maximum isometric extension strength of the trunk.

Adipose Tissue↗
PubMed1993

MR relaxation times and fiber type predominance of the psoas and multifidus muscle. An autopsy study.

MR relaxation times, fiber composition, nonmyofiber space, water content, and fat content of human psoas and multifidus muscle samples of 10 male cadavers were studied in vitro. The T1 and T2 relaxation times of multifidus muscle were significantly longer than those of the psoas muscle. On average, type 1 fibers (slow fibers with a small cross-sectional diameter) predominated in both muscles. There was no correlation between the relative mass of type 1 or 2 fibers (fast fibers with a large cross-sectional diameter) or nonmyofiber space and the relaxation times. The quantity of fat in the muscle did not correlate with the relaxation times either.

Adolescent↗
PubMed1992

Response of the trunk muscles to training assessed by magnetic resonance imaging and muscle strength.

A group of 12 sedentary medical students (1 man and 11 women aged 21-27 years) participated in a strength training programme for the trunk muscles lasting 18 weeks. The maximal isometric flexion and extension forces of the trunk muscles were measured before the training and at 18 weeks by dynamometer. The cross-sectional area of the back muscles, i.e. erector spinae, multifidus and psoas muscles, was measured from magnetic resonance images (spin echo sequence TR/TE 1500/80, slice thickness 10 mm) obtained at the L4-L5 disc level before the training, at 11 and 18 weeks. During training, no significant change in the body mass or body fat content was found. Muscle forces or muscle cross-sectional area were not related to body mass. There was a significant increase in both trunk muscle cross-sectional area (psoas muscle P < 0.001 and back muscles P < 0.01) and trunk muscle forces (flexion and extension forces P < 0.01) during the training but no direct association between the muscle cross-sectional area and strength of the flexors and extensors was detected before or after the training.

Adipose Tissue↗
PubMed1992

Lumbar disc and back muscle degeneration on MRI: correlation to age and body mass.

Lumbar intervertebral discs and paraspinal muscles in 74 healthy volunteers ranging in age from 19 to 74 years were evaluated with MRI, and the occurrence of degeneration was correlated to age and body mass. Muscle size and the amount of fat in the muscles was studied from MRI cross sections. When the back muscles were degenerated, they were small and contained fat deposits. By contrast, the psoas muscles never showed gross fat deposits. Degeneration of both the lumbar discs and muscles increased with age. No correlation was found between muscle degeneration and overweight. Muscle degeneration is as common as disc degeneration in the lumbar area. MRI is an excellent method to assess both muscle and disc degeneration.

Adipose Tissue↗