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Biomedical subjects

R Jensen

Publications and source records attributed to R Jensen.

At least 109 records · Page 6Linked to original sources
PubMed1994

Body segment growth during infancy.

In order to better understand relationships between physical growth and motor development during infancy, changes in segment inertias were examined. A rationale based on dynamic systems theory and intersegmental moments was used to select the variables: the segment mass and principal moments of nine segments. The hypothesis was that there are differences in growth velocity between segments and these are consistent with the principles of cephalocaudal development and distal to proximal growth. A mathematical model of the segments was used to examine changes of the inertia parameters. Twenty-seven normal infants carried to full term and aged between 2 and 9 months at the beginning of the study were photographed once a month for 6 months. Outlines of segments from front and side 35 mm images were digitized and mass and principal moments of inertia estimates obtained. Polynomial regression was used to give the development curves regression coefficients for the 155 data points. Also, linear regressions were fitted to the six growth data points of each subject. Most of the relationships between chronological age and segment mass and principal moments were significant and linear. The differences in growth velocity between segments were significant and partially consistent with the growth principles. However, there were considerable differences, in particular for the lower trunk and the shank, where it appears that growth may be irregular until after the age of 15 months.

Anthropometry↗
PubMed1994

Quantitative surface EMG of pericranial muscles. Relation to age and sex in a general population.

Quantitative EMG levels in pericranial muscles were studied in 547 subjects randomly selected from the general population aged 25-64 years. Surface EMGs of the right frontal and both temporal muscles were examined during rest and maximal voluntary contraction by a blind, standardized method. The amplitude of the EMG was expressed as the root mean square and mean rectified voltage. The power spectrum was calculated and the mean and median frequencies were extracted. During rest no significant differences were found between amplitude levels of the temporal muscles, while higher frequency levels were detected on the left side. Amplitude and frequency levels were higher in the frontal than the temporal muscles during rest, but lower during maximal voluntary contraction, probably for morphological differences. In the frontal muscle, females had increased amplitudes during rest and decreased levels during maximal voluntary contraction compared to males, indicating a higher tension at rest and a reduced number and/or size of muscle fibers in females. During maximal voluntary contraction a highly significant decrease with age was seen in amplitude and frequency in the temporal muscles. The present study is the first population study of EMG levels in pericranial muscles and constitutes the necessary basis for evaluating the EMG in tension-type headache.

Adult↗
PubMed1994

Quantitative surface EMG of pericranial muscles in headache. A population study.

Quantitative EMG from the right frontal and both temporal muscles was studied in 547 adults randomly selected from the general population. The study was part of a multifaceted, epidemiological study of different headache disorders. Surface EMG was recorded by an observer blinded to the persons' history of headache, previous illness and mental state. The present study provides data on amplitude and mean and median frequency levels in migraine and tension-type headache. Chronic headache sufferers had higher amplitude values at rest in their temporal muscles than migraineurs, subjects with episodic tension-type headache and subjects without any experience of headache, probably due to insufficient relaxation. Frequency values during maximal voluntary contraction were decreased in chronic headache subjects and decreased with increasing frequency of headache in the previous year, indicating that chronic fatigue and/or changed fiber type composition exist in frequent headache sufferers. During experimental cold and pain stimulation no significant differences between headache subjects and the rest of the population were detected. Only subjects without any experience of headache had increased amplitude values during pain stimulation. No significant relation of amplitude values to frequency of tension-type headache or migraine in the previous year was detected. In 66 subjects with actual headache amplitude values were increased in the frontal muscle during rest indicating increased tension. Moreover, amplitude values were decreased in both the temporal and the frontal muscles during maximal voluntary contraction indicating submaximal contraction during pain. The present study supports the importance of peripheral factors such as increased fatigability, morphological, and/or metabolic changes in the pathogenesis of tension-type headache. However, the diagnostic value of EMG in migraine and tension-type headache is limited.

Adult↗
PubMed1994

Plasma serotonin increase during episodes of tension-type headache.

The mechanisms of tension-type headache remain to be determined. Biochemical abnormalities have been rarely demonstrated. We performed a controlled study of 5-hydroxytryptamine (5HT) in platelet poor plasma obtained from 13 female patients during and between episodes of tension-type headache. The 5HT concentration in patients free of headache was not different from controls, whereas a significant increase in 5HT concentration was seen during headache (p < 0.02). This finding is attributed to release of 5HT from platelets or disordered 5HT metabolism during headache attacks, possibly related to pain in the latter case. We conclude that 5HT may be involved in the pathogenesis of tension-type headache but by different mechanisms than migraine.

Adult↗
PubMed1994

Sodium valproate has a prophylactic effect in migraine without aura: a triple-blind, placebo-controlled crossover study.

We included 43 patients with migraine without aura in a triple-blind, placebo- and dose-controlled, crossover study of the prophylactic effect of slow-release sodium valproate; 34 patients completed the trial. The number of days with migraine was 3.5 per 4 weeks during treatment with sodium valproate and 6.1 during placebo (p = 0.002). The severity and duration of the migraine attacks that did occur were not affected by sodium valproate when compared with placebo. Fifty percent of the patients were responders, ie, their initial migraine frequency was reduced to 50% or less during sodium valproate as compared with 18% during placebo. The number of responders increased during the trial to 65% in the last 4 weeks of the active treatment period. There were no serious side effects requiring withdrawal of patients from the study. We conclude that sodium valproate is an effective and well-tolerated prophylactic medication for migraine without aura.

Adult↗
PubMed1994

Vein surgery with or without skin grafting versus conservative treatment for leg ulcers. A randomized prospective study.

In order for us to evaluate the efficiency of perforator vein surgery and skin grafting in leg ulcer patients, 47 patients were randomized into 3 treatment groups (group A: surgery for incompetent perforators, group B: surgery for incompetent perforators and ulcer excision followed by grafting, group C: control group). All the patients were treated with a compression bandage. When cellulitis was observed, a systemic antibiotic was given; eczema was treated with a steroid ointment. Fourty patients were evaluated regularly during one year after entry. There were no differences between the 3 treatment groups considering base-line characteristics, median ulcer size at entry and after one year. According to a review of the initial phlebograms, the occurrence of post-thrombotic changes in the deep veins were recorded in the majority of the legs. Our results suggest that ligation of incompetent perforators and skin grafting, as used in the present study, may not offer an additional advantage for venous ulcer patients with insufficiency of the deep veins when compared to conservative treatment. However, the removal of insufficient superficial veins was not studied.

Adult↗
PubMed1993

Preliminary crystallographic study of cyclohexadienyl dehydratase from Pseudomonas aeruginosa.

Single crystals of cyclohexadienyl dehydratase from Pseudomonas aeruginosa have been obtained by vapour diffusion from ammonium sulphate solution (pH 6.0) at 4 degrees C. The crystals belong to the tetragonal space group P4(3)2(1)2 or P4(1)2(1)2 with a = b = 105.5 A and c = 165.0 A. The asymmetric unit contains at least one dimeric protein molecule with M(r) = 72 kDa. The crystals diffract to 3 A resolution and are suitable for an X-ray analysis.

Prephenate Dehydratase↗
PubMed1993

BRS-3: a novel bombesin receptor subtype selectively expressed in testis and lung carcinoma cells.

The bombesin (BN)-like peptides mediate a diverse spectrum of biological activities and have been implicated as autocrine growth factors in the pathogenesis and progression of some human small cell lung carcinoma tumors. Previously, two mammalian BN-like peptide receptor subtypes, gastrin-releasing peptide receptor and neuromedin-B receptor, have been cloned and characterized. In this study, we have isolated and characterized human genomic and complementary DNA (cDNA) clones encoding a new BN-like peptide receptor subtype, BN receptor subtype 3 (BRS-3). Expression of BRS-3 cDNA in Xenopus oocytes encodes a functional receptor that is specifically activated by BN-like peptides. Chromosome mapping studies indicate that the BRS-3 gene is located on human chromosome X. BRS-3 mRNA expression in rat tissues is limited to secondary spermatocytes in testis. In contrast, BRS-3 mRNA is widely expressed in a panel of human cell lines from all histological types of lung carcinoma. These results suggest a role for BN-like peptides and their receptors in mammalian reproductive physiology and also indicate that BRS-3 could serve as a potential therapeutic target for human lung carcinoma.

Amino Acid Sequence↗
PubMed1993

Quantitative surface EMG of pericranial muscles. Reproducibility and variability.

We present reproducibility data on a quantitative electromyographic investigation of the temporal and frontal muscles using surface electrodes. Such data have not been published before. They constitute a necessary basis for future evaluation of the importance of pericranial muscles in tension-type headache. Root mean squares and mean rectified values of the electrical activity were measured in 20 healthy subjects. Power spectra were calculated and the mean and median frequencies were extracted. The coefficient of intraindividual variation in RMS from the right temporal muscle within the same examination was 14%, between several examinations on the same day 18% and between measurements on 2 different days 18%. The corresponding coefficients of interindividual variation were 36, 31 and 38%. The left temporal and frontal muscles showed similar coefficients of variation. At rest, no differences were found between muscles, but during maximal voluntary contraction the frontal muscle revealed a 55% lower RMS values than the temporal muscles. The method used was reproducible and reliable in measuring quantitative electrical activity of pericranial muscles.

Adult↗
PubMed1993

Exteroceptive suppression periods in jaw-closing muscles. Variability and relation to experimental pain and sustained muscle contraction.

The duration of the late exteroceptive suppression period (ES2) of temporal muscle EMG activity has been reported to be reduced in patients suffering from chronic tension-type headache. Methods of recording and analysing ES2 have varied between centers and reproducibility of results within subjects, although insufficiently studied, has generally been poor. ES2 was investigated in 30 healthy subjects, using a computerized technique of recording, rectifying and averaging the EMG signals. Hour to hour and week to week variations of ES2 durations were calculated, and the influence of pain during a cold pressor test and of sustained muscle contraction on ES2 durations was investigated. The intra-individual variation of ES2 durations was 16.0% from hour to hour and 20.7% from week to week. The inter-individual variation was 36.7%. The present method for analysis of ES2 periods proved to be reliable, as the intra-observer variation was 4.2% and the inter-observer variation 4.6%. ES2 periods were significantly shorter on the first compared to the second day of examination (p = 0.006) and during experimental pain (p = 0.0005). We recommend the use of the computerized average technique in future studies and caution against the dependence of results upon factors such as conditioning and pain.

Adult↗
PubMed1993

Follow-up study of patients with clinically suspected deep venous thrombosis and a normal venogram.

OBJECTIVES: To evaluate the clinical course in patients with clinically suspected deep venous thrombosis (DVT) of the leg and a normal venogram. DESIGN: Prospective study over 15 months with a follow-up of 4-12 (median 8.6) months after a normal venogram. A questionnaire survey was performed at follow-up. Information from general practitioners and medical records was reviewed. An alternative diagnosis was established at presentation and at the time of follow-up. SETTING: The Department of Internal Medicine in a Danish university hospital. SUBJECTS: A total of 133 consecutive out-patients referred with clinical suspicion of DVT and a normal venogram. MAIN OUTCOME MEASURES: The state of symptoms at follow-up. The frequency of referrals to hospitals and contacts with general practitioners or medical specialists in the follow-up period. Clinical diagnoses provided at presentation and at follow-up. RESULTS: The follow-up response rate was 78% (n = 104). The symptoms were still present at follow-up in 53 (51%) patients. More than half of the patients had been referred to medical facilities for the same disorder. Diagnoses could be established in 93 (70%) of the 133 patients at presentation and in 119 (89%) at follow-up. CONCLUSIONS: The majority of patients with clinical signs and symptoms of a DVT and a normal venogram may require a follow-up surveillance programme to ensure correct diagnosis and adequate treatment. Further studies are recommended to confirm our results and to assess the cost-effectiveness.

Adolescent↗
PubMed1993

Severe low-back pain. I: Clinical assessment of two weeks conservative therapy.

A standard clinical examination was performed by two independent investigators, before and after two weeks of conservative therapy, on 33 patients with severe low-back pain. Kappa coefficients indicated a higher reproducibility of neurological tests than of e.g. muscular tenderness or scoliosis. All patients were diagnosed by CT-scan and a disc herniation was found in 20. The clinical diagnosis was more in agreement with the CT-diagnosis after than before treatment. By discriminant analyses six variables were found to classify the clinical diagnosis correctly in 32 of the 33 patients: sensory loss, ankle jerk, soreness of back extensors, lumbosacral soreness, radiating pain and back extension test. Similarly, the CT-diagnosis was classified in 25 of 33 patients by the variables: sensory loss and limping.

Acute Disease↗
PubMed1993

Severe low-back pain. II: Changes in CT scans in the acute phase and after long-term observation.

No significant changes were noted in the CT-scan before and after 14 days of conservative therapy for low-back pain. Twenty of 33 patients had a disc herniation diagnosed on CT, and of these 18 patients were re-scanned after two weeks. Twelve patients were subsequently treated surgically, and of the remaining 8 patients 6 were re-scanned after 18 months. At this time the disc herniation had diminished significantly and was located in a more median position. In the 8 conservatively treated patients, the pain score at follow-up was related to the original size of the herniation (r = 0.72, p < 0.05).

Adult↗
PubMed1993

Prevalence of oromandibular dysfunction in a general population.

The prevalence of oromandibular dysfunction was studied in 735 subjects from a random sample population of 1,000 subjects aged 25 to 64 years. A diagnosis of oromandibular dysfunction was based on criteria established by the International Headache Society, as a subgroup to tension-type headache. Tenderness in pericranial or jaw muscles was not included. The most common symptoms were clenching (22%) and grinding of teeth (15%). The most common sign was irregular jaw movements on opening and closing (29%). The ratio of men to women for most symptoms and signs ranged from 2:3 to 1:3. This study serves as a base in evaluating the importance of oromandibular dysfunction as a causative factor for tension-type headache.

Adult↗