Search PubMed⌕ Search

Biomedical subjects

R Jensen

Publications and source records attributed to R Jensen.

At least 55 records · Page 3Linked to original sources
PubMed2001

Stroke volume does not plateau during graded exercise in elite male distance runners.

UNLABELLED: Stroke volume (SV) responses during graded treadmill exercise were studied in 1) elite male distance runners (N = 5), 2) male university distance runners (N = 10), and 3) male untrained university students (N = 10). METHODS: Cardiac output (Q) and SV were determined by a modified acetylene rebreathing procedure. RESULTS: There were no differences in SV responses among the three groups during the transition from rest to light exercise (P > 0.05). However, the rates of change of SV during light to maximal exercise in untrained subjects (slope = -0.1544 mL x beat(-1)) and university distance runners (slope = 0.1041) did not change, whereas it dramatically increased (P < 0.001) in elite distant runners (slope = 0.6734). Moreover, the elite distance runners showed a further slope increase in SV when heart rate was above 160 bpm, which resulted in an average maximal SV of 187 +/- 14 mL x beat(-1) compared with 145 +/- 8 and 128 +/- 14 mL x beat(-1) in the university runners and untrained students, respectively (P < 0.001). Similarly, max Q reached 33.8 +/- 2.3, 26.3 +/- 1.7, and 21.3 +/- 1.5 L x min(-1) in the three groups, respectively (P < 0.001). On the other hand, there was a nonsignificant tendency for maximal arteriovenous oxygen content difference to be lower in the elite athletes compared with the other groups. CONCLUSION: Results from university distance runners and untrained university students support the classic observation that SV plateaus at about 40% of maximal oxygen consumption despite increasing intensity of exercise. In contrast, stroke volume in the elite athletes does not plateau but increases continuously with increasing intensity of exercise over the full range of the incremental exercise test.

Adult↗
PubMed2001

Recycling for all: preliminary criteria for the design of disability-friendly receptacles.

The design of current waste bins, paper and bottle banks presents barriers for disabled and elderly persons, as pointed out by several Danish studies. In drawing up design criteria for the development of receptacles to be usable by persons with disabilities and senior citizens it is essential to be aware of the problems caused by different types of disability as well as old age. On the basis of general user requirements, preliminary criteria for the design of disability-friendly receptacles are proposed. In collaboration with a collecting agent, current receptacles modified in accordance to the preliminary design criteria will be tested in pilot studies in three selected housing estates in the municipalities of Frederiksberg and Copenhagen. It is the authors' hope that the testing of the modified receptacles will result in achieving more efficient source separation not only for disabled and elderly persons, but for all user groups.

Age Factors↗
PubMed2000

Plasma levels of calcitonin gene-related peptide in chronic tension-type headache.

BACKGROUND: Calcitonin gene-related peptide (CGRP) is involved in the pathophysiology of migraine and cluster headache. Whether CGRP has any role in chronic tension-type headache is unknown. OBJECTIVES: To compare interictal plasma levels of CGRP between patients with chronic tension-type headache and healthy control subjects, to investigate plasma CGRP in relation to headache state, and to compare plasma CGRP between the peripheral and the cranial circulation. METHODS: Blood from the antecubital vein was drawn from 30 patients with chronic tension-type headache and 34 healthy control subjects. In addition, blood samples from the consecutive first 15 patients and from the consecutive first 20 healthy control subjects were also collected from the external jugular vein. RESULTS: CGRP levels measured in the peripheral circulation in patients on days without headache, 63+/-5 pmol/L, tended to be higher than CGRP levels in control subjects, 53+/-3 pmol/L (p = 0.06). In patients, no differences were found between CGRP levels assessed ictally and interictally in either the cranial (p = 0.91) or the peripheral (p = 0.62) circulation. Plasma CGRP level was higher in the external jugular vein than in the antecubital vein on days without headache (p = 0.03) but not on days with headache (p = 0.82). In control subjects, CGRP levels in the cranial circulation did not differ from CGRP levels in the peripheral circulation (p = 0.92). Exploratory analyses showed that 8 patients whose usual headache quality was throbbing had a higher interictal plasma CGRP level than control subjects (p = 0.002), whereas plasma CGRP level was normal in 22 patients with pressing headaches (p = 0.36). CONCLUSIONS: Plasma levels of CGRP are normal in patients with chronic tension-type headache and are unrelated to headache state. Interictal plasma CGRP was increased in patients with a pulsating pain quality. Because the authors have previously shown a similar increase of interictal CGRP levels in migraine, this study suggests that headaches with symptoms that fulfill International Headache Society criteria for tension-type headache may be pathophysiologically related to migraine, if the headache has a pulsating quality.

Adult↗
PubMed2000

Evidence for increased plasma levels of calcitonin gene-related peptide in migraine outside of attacks.

Although calcitonin gene-related peptide (CGRP) has been shown to be elevated in jugular venous blood of adult migraineurs during acute migraine attacks, it remains unknown whether CGRP is increased outside of attacks in jugular or cubital venous blood. The aim of the present study was to compare interictal plasma levels of CGRP in adult migraine patients and in healthy controls. Twenty patients with a diagnosis of migraine with or without aura and 20 healthy controls were included. In blood from the cubital vein, CGRP levels were significantly higher in patients (75+/-8 pmol/l (mean+/-SEM)) than in controls (49+/-3 pmol/l) (P=0.005). The subgroup of patients suffering exclusively from migraine without aura (n=14) also had significantly higher levels of CGRP (82+/-10 pmol/l) than controls (n=20; 49+/-3 pmol/l) (P=0.001). The findings could not be explained by confounding factors such as age, sex or use of contraceptive pills. We therefore conclude that CGRP is increased in cubital venous blood of migraineurs outside of attack. It is hypothesized that this finding may reflect a long-lasting or permanent abnormal neurogenic vascular control in patients with migraine.

Adult↗
PubMed2000

Amitriptyline reduces myofascial tenderness in patients with chronic tension-type headache.

The tricyclic anti-depressant amitriptyline is widely used in the treatment of chronic tension-type headache. The aim of the present study was to investigate whether the analgesic effect is caused by a reduction of muscle pain or by a general reduction of pain sensitivity. Thirty-three non-depressed patients with chronic tension-type headache were treated with amitriptyline 75 mg/day and with the highly selective serotonin reuptake inhibitor citalopram 20 mg/day in a 32-week, double-blind, placebo-controlled, three-way crossover study. At the end of each treatment period, actual headache intensity and pericranial myofascial tenderness were recorded, pressure pain detection and tolerance thresholds were measured in the finger and in the temporal region and the electrical pain threshold was measured at the labial commissure. Amitriptyline reduced tenderness and headache intensity significantly more than placebo (P=0.01 and P=0.04, respectively). The reduction in tenderness could be ascribed solely to the group of patients who responded to amitriptyline treatment by at least 30% reduction in headache while tenderness was unchanged in non-responders. Amitriptyline did not affect pressure or electrical pain thresholds at any of the examined locations. Citalopram had no significant effect on any of the examined parameters. These findings indicate that amitriptyline elicits its analgesic effect in chronic myofascial pain by reducing the transmission of painful stimuli from myofascial tissues rather than by reducing overall pain sensitivity. We suggest that this effect is caused by a segmental reduction of central sensitization in combination with a peripheral anti-nociceptive action.

Adult↗
PubMed2000

Possible mechanisms of glyceryl-trinitrate-induced immediate headache in patients with chronic tension-type headache.

Nitric oxide (NO) plays an important role in the pathophysiology of primary headaches including chronic tension-type headache (CTTH). Thus, a NO synthase inhibitor reduces headache and muscle hardness while the NO donor glyceryl trinitrate (GTN) causes more headache in patients than in healthy controls. Sensitization of myofascial pain pathways is important in CTTH, and the aim of the present study was to investigate if such mechanisms may also explain GTN-induced immediate headache in patients with CTTH. In a randomized, double-blind, crossover study 16 patients with CTTH and 16 healthy subjects received intravenous infusion of GTN (0.5 microg/kg per min for 20 min) or placebo on two headache-free days separated by at least 1 week. Muscle hardness, myofascial tenderness, mechanical and heat pain thresholds were measured at baseline and at 60 min and 120 min after start of infusion. In patients, GTN infusion resulted in a biphasic response with immediate headache and more pronounced delayed headache. A similar but less pronounced response was seen in controls. There was no difference between GTN and placebo regarding muscle hardness, myofascial tenderness or pressure and heat pain thresholds in either patients or controls (P>0.05). The unchanged sensitivity of pericranial myofascial pain pathways indicates that peripheral and central sensitization is not involved in the mechanisms of GTN-induced immediate headache.

Adult↗
PubMed2000

Nitric oxide-induced headache in patients with chronic tension-type headache.

An experimental model of headache offers unique possibilities to study the mechanisms responsible for head pain. Using the glyceryl trinitrate [GTN; nitric oxide (NO) donor] model of experimental headache, we studied the intensity, quality and time profile of headache after infusion of GTN in 16 patients with chronic tension-type headache and in 16 healthy controls. Subjects were randomized to receive intravenous infusion of GTN (0.5 microg/kg per minute for 20 min) or placebo on two headache-free days separated by at least 1 week. Headache intensity was measured on a 10-point verbal rating scale during 2 h of observation and for the next 10 h after discharge from hospital. The primary endpoints were the difference between the area under the curve (AUC-intensities x duration) for headache recorded on the day of GTN treatment and on the day of placebo treatment in patients, and in patients and controls on the days of GTN treatment. In patients, the AUC on a GTN day [2221 (1572-3704); median with quartiles in parentheses], was significantly greater than on a placebo day [730 (60-1678), P: = 0. 008]. On the GTN day, the AUC in patients [2221 (1572-3704)] was significantly higher than in controls [43 (0-972), P: = 0.0001]. In patients, peak pain intensity occurred 8 h after infusion of GTN, whereas in controls it occurred 20 min after the start of infusion. The present study demonstrates that an NO-induced biphasic response with an immediate and a delayed headache is common to chronic tension-type headache and migraine. Furthermore, the NO-induced delayed headache has the characteristics of the primary headache disorder. This suggests that NO contributes to the mechanisms of several types of primary headaches and that NO-related central sensitization may be an important common denominator in the pain mechanisms of primary headaches.

Adult↗
PubMed2000

Tension-type headache: an update on mechanisms and treatment.

Tension-type headache represents one of the most costly diseases in modern society because of its very high prevalence. Very little research on this disease has actually been carried out, and knowledge about key pathophysiological issues such as the nature and site of the noxious stimulus is surprisingly limited. As a result of this and the lack of scientific interest from the medical field, treatment is widely non-specific, very often ineffective and consists mainly of simple analgesics. The only new strategy is the pericranial injection of botulinum toxin. If current progress in our understanding of the mechanisms of tension-type headache continues, this may lead to greater scientific interest and the development of more specific and more effective drugs in the future.

Analgesics↗
PubMed2000

Clinical and para-clinical tests in the routine examination of headache patients.

Para-clinical examinations in the diagnosis and treatment control of headache patients vary considerably between clinics and headache centers. Among the neurological societies in Europe there has been a consensus that some common procedures and recommendations should be created. In the Fall of 1998, the European Federation of Neurological Societies (EFNS) commissioned a Task Force on Neurophysiological Tests and Imaging Procedures in Headache Patients. Members of the Task Force are the present authors and we have reviewed the literature on 1) neurophysiological tests (EEG and evoked potentials), 2) autonomic nervous system and clinical tests and 3) imaging and cerebrovascular tests (X-ray, CT, MR, fMRI, PET, SPECT and transcranial Doppler). The literature was carefully evaluated with respect to validity and strength of the data. The task was to reach conclusions about each technique in the form of guidelines for clinical use. Finally, selected areas for future research will be outlined. The extensive review and the guidelines will be published by the EFNS during 2000.

Electroencephalography↗
PubMed1999

Mammaglobin expression in primary, metastatic, and occult breast cancer.

The mammaglobin gene encodes a novel, breast cancer-associated glycoprotein. In this study, we have evaluated the frequency with which mammaglobin expression can be detected in primary and metastatic breast tumors and in breast tumor cells present in the peripheral circulation. Of 100 primary human breast tumors examined, 81 were strongly immunopositive for mammaglobin protein. Staining was independent of tumor grade and histological type. Ten of 11 lymph nodes from patients with metastatic breast cancer contained detectable mammaglobin mRNA, whereas mammaglobin expression in uninvolved lymph nodes was undetectable. Using a nested reverse transcription-PCR assay, mammaglobin mRNA was also detected in 9 of 15 products (60%) used for autologous stem cell transplant. These results suggest that larger clinical studies are warranted to investigate the full clinical utility of mammaglobin as a tool for breast cancer patient management.

Amino Acid Sequence↗
PubMed1999

[Physiotherapy as manual therapy].

Manual therapy includes methods where the therapist's hands are used to stretch, mobilize or manipulate the spinal column, paravertebral structures or extremity joints. The aims of these methods are to relieve pain and improve function. In Norway only specially qualified physiotherapists and chiropractors are authorized to perform manipulation of joints (high velocity thrust techniques). To become a qualified manual therapist in Norway one must have a minimum of two years of clinical practice as physiotherapist followed by two year full time postgraduate training in manual therapy (a total of six years). Historically the Norwegian manual therapy system was developed in the 1950s by physiotherapists and medical doctors in England (James Cyriax and James Mennell) and Norway. As a result doctors allowed physiotherapists to use manipulation as a treatment method of both spinal and peripheral joints. In 1957 the Norwegian health authorities introduced reimbursement for manual therapy performed by physiotherapists.

Chiropractic↗
PubMed1999

Elevated frequencies of hypoxanthine phosphoribosyltransferase lymphocyte mutants are detected in Russian liquidators 6 to 10 years after exposure to radiation from the Chernobyl nuclear power plant accident.

This study was conducted to determine whether the frequency of hypoxanthine phosphoribosyltransferase (HPRT) deficient lymphocyte mutants would detect an effect of radiation exposure in a population of Russians who were exposed to low levels of radiation while working in 1986 and 1987 as liquidators cleaning up after the Chernobyl nuclear power reactor accident. The HPRT lymphocyte cloning assay was performed on peripheral blood lymphocytes collected between 1992 and 1996 from 142 liquidators and 66 Russian controls, and between 1989 and 1993 from 231 American controls. Russian and American controls were not significantly different for either cloning efficiency or mutant frequency (MF); inclusion of both sets of controls in the analysis increased the ability to detect a Chernobyl exposure effect in the liquidators. After adjusting for age and smoking, the results revealed no significant difference in cloning efficiency of Chernobyl liquidators relative to Russian controls but a significant, 24% increase in liquidator HPRT mutant frequency over Russian controls (90% confidence interval was 7% to 45% increase). The analytical method also accounted for differences in precision of the individual estimates of log CE and log MF and accommodated for outliers. The increase in HPRT mutant frequency of liquidators is an attribute of the exposed population as a whole rather than of individuals. These results demonstrate that, under appropriate circumstances, the HPRT specific locus mutation assay of peripheral blood lymphocytes can be used to detect a semi-acute, low dose radiation exposure of a population, even 6 to 10 years after the exposure.

Adult↗
PubMed1999

Effect of inhibition of nitric oxide synthase on chronic tension-type headache: a randomised crossover trial.

BACKGROUND: Studies in animals have shown that nitric oxide plays an important part in central sensitisation and that inhibitors of nitric oxide synthase (NOS) decrease sensitisation in models of persistent pain. The efficacy of inhibitors of NOS has not been tested in patients with tension-type chronic headache. We aimed to show whether N(G)-monomethyl-L-arginine hydrochloride (L-NMMA), an inhibitor of NOS, is effective in relieving pain in such patients. METHODS: We undertook a randomised double-blind, crossover trial of 16 patients with chronic-tension-type headache. Patients were assigned intravenous infusion of 6 mg/kg L-NMMA or placebo on 2 days separated by at least 1 week in a randomised order. Headache intensity was measured on a 100 mm visual analogue scale, and on a verbal rating scale at baseline and at 30 min, 60 min, and 120 min after start of treatment. The primary endpoint was reduction of pain intensity on the visual analogue scale by the active treatment compared with placebo. FINDINGS: L-NMMA reduced pain intensity on the visual analogue scale significantly more than placebo: 120 min after start of treatment, the mean pain score was decreased from 49 to 33 with L-NMMA and from 44 to 40 with placebo (p=0.01). Pain intensity on the verbal rating scale was also significantly lower for treatment with L-NMMA than for treatment with placebo (p=0.02). INTERPRETATION: Inhibition of NOS had an analgesic effect in chronic tension-type headache. Further tests are required before clinical application.

Adult↗
PubMed1999

Clostridium perfringens: a rare cause of postoperative spinal surgery meningitis.

BACKGROUND: Clostridium perfringens is a rare cause of central nervous system infections, particularly meningitis. The case of a 76-year-old man who developed fatal C. perfringens meningitis after routine decompressive laminectomy for spinal stenosis is described. CASE REPORT: Twelve days after surgery the patient presented with pain and serosangiunous drainage from the surgical incision site. A swab of the drainage revealed Gram-positive bacilli; MRI of the lumbosacral spine showed the appearance of air around the laminectomy site. The patient died within 6 hours of presentation. Autopsy revealed acute cranial and spinal meningitis and choroid plexitis with organisms consistent with C. perfringens. CONCLUSION: No significant enteral pathology or source of endogenous infection was determined, suggesting postoperative wound contamination and meningeal seeding with this ubiquitous organism. Clostridial infection, although rare, should be considered in any patient with meningitis with a history of surgical intervention. Survival with minimal neurological deficits was achieved in half of the previously reported cases.

Aged↗
PubMed1999

Muscle hardness in patients with chronic tension-type headache: relation to actual headache state.

It has recently been reported that the pericranial muscles in patients with chronic tension-type headache are harder, i.e. have a higher consistency, than in controls. The primary aim of the present study was to investigate whether muscle hardness is influenced by the presence or absence of actual headache and whether hardness is correlated to tenderness. The secondary aim was to compare muscle hardness between patients and healthy controls. Hardness of the trapezius muscle was measured with a hardness meter in 20 patients with chronic tension-type headache and in 20 healthy controls. The patients were examined on 2 days, 1 day with headache and 1 day without headache. Pericranial myofascial tenderness was recorded with manual palpation. In addition, muscle hardness was measured in another five patients out-side headache and in 30 healthy controls. The muscle hardness recorded in patients (n = 20) on days with headache, 98 +/- 26 kPa/cm, did not differ significantly from the muscle hardness recorded on days without headache, 100 +/- 21 kPa/cm, (P = 0.62). The muscle hardness was positively correlated to the local tenderness score recorded from the trapezius muscle both on days with headache (R = 0.52, P = 0.02) and on days without headache (R = 0.53, P = 0.02). The total tenderness score (TTS) recorded in patients on days with headache, 23 +/- 10, was significantly higher than the TTS recorded on days without headache, 15 +/- 11, (P = 0.0001). There was a significant difference between the TTS recorded in patients without headache, 15 +/- 11, and in controls, 4 +/- 4, (P = 0.002). The muscle hardness was significantly higher in patients on days without headache (n = 25), 97 +/- 20 kPa/cm, than in controls (n = 30), 87 +/- 16 kPa/cm (P = 0.03). On basis of previous and present results, we suggest that muscle hardness and muscle tenderness are permanently altered in chronic tension-type headache and not only a consequence of actual pain. In addition, the positive correlation between muscle hardness and tenderness supports the common clinical observation that tender muscles are harder than normal muscles.

Adult↗
PubMed1999

Plasma levels of substance P, neuropeptide Y and vasoactive intestinal polypeptide in patients with chronic tension-type headache.

Animal and human studies have shown that substance P (SP), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) are involved in the pathophysiology of acute and chronic pain conditions. The primary aim of the present study was to compare plasma levels of SP, NPY and VIP in external jugular vein between patients with chronic tension-type headache and healthy controls. The secondary aim was to examine plasma levels of these neuropeptides in relation to headache state. In addition, we wanted to study the relation between cranial circulation (jugular vein) and peripheral circulation (antecubital vein). Blood from the external jugular and antecubital vein was drawn from 20 patients with chronic tension-type headache and 20 healthy controls. Plasma SP in patients, 2.0 (1.4-2.2) pmol/l, did not differ significantly from plasma SP in controls, 1.7 (1.1-2.1) pmol/l, (P=0.44). No significant differences were found between SP levels on days with headache, 1.5 (0.3-1.7) pmol/l, and SP levels on days without headache, 1.7 (1.1-1. 9) pmol/l, (P=0.06). Plasma NPY in patients, 118+/-3 pmol/l, did not differ significantly from plasma NPY in controls, 113+/-5 pmol/l, (P=0.40). There was no difference between NPY levels on days with headache, 120+/-3 pmol/l, and on days without headache, 118+/-3 pmol/l, (P=0.73). VIP levels in patients, 6 (4-7) pmol/l, did not differ significantly from VIP levels in controls, 5 (5-7) pmol/l, (P=0.50). No significant differences were found between VIP levels measured on days with headache, 5 (4-6) pmol/l, and VIP levels measured on days without headache, 6 (4-7) pmol/l, (P=0.81). Plasma levels of SP, NPY and VIP did not significantly differ between the peripheral and the cranial circulation neither in patients nor in controls (0.05). In summary, the present study indicates that plasma levels of SP, NPY and VIP are normal in chronic tension-type headache patients and largely unrelated to headache state.

Adult↗