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Biomedical subjects

L Ekenvall

Publications and source records attributed to L Ekenvall.

At least 37 records · Page 2Linked to original sources
PubMed1989

Correspondence between neurological symptoms and outcome of quantitative sensory testing in the hand-arm vibration syndrome.

To evaluate neurological symptoms in the vibration syndrome, 55 patients with vascular and neurological symptoms in the hand who had been exposed to vibration were examined. Their exposure to vibration was estimated and neurological vascular symptoms were evaluated according to symptom scales. Temperature thresholds were measured on the right thenar eminence and on the distal volar aspect of the second and third fingers held together on both sides. Vibration thresholds were measured dorsally on the second and fifth metacarpal bones and on the second and fifth fingers proximal to the nail roots. Subjects with advanced neurological symptoms had higher temperature and vibration thresholds than subjects with less advanced symptoms. No such relation was found between vascular symptoms and the outcome of sensory testing. Thus neurological but not vascular symptoms are reflected by the outcome of quantitative sensory testing. In subjects with advanced neurological symptoms the tests gave a high proportion of abnormal results, indicating that these tests may be used for the diagnosis of vibration syndrome on an individual basis. Patients with advanced vascular and neurological symptoms had higher exposure dose scores than patients with less advanced symptoms, indicating a dose response relation between vibration "dose" and neurological and vascular symptoms.

Arm↗
PubMed1989

Effect of tobacco use on vibration white finger disease.

In a cohort of 245 men with vibration white finger disease, the effects of tobacco use on the symptoms of the disease and the results of a cold provocation test were studied. The tobacco habits of 111 patients were confirmed by measurement of nicotine and cotinine in plasma. In a subgroup the cold provocation test was repeated after nicotine absorption according to individual habits. Patients with advanced disease as measured on a symptom scale were found to use tobacco more often and to have higher cotinine levels than patients with less advanced disease. Pathologic test results were found more frequently among users of tobacco than among nonusers. Habitual use of tobacco seems to aggravate the symptoms of vibration white finger disease and to result in an increased reactivity in a cold provocation test.

Adult↗
PubMed1988

Afferent and efferent nerve injury in vibration white fingers.

To study afferent pain and efferent sympathetic nerve function in vibration-induced Raynaud's phenomenon, 10 patients and 11 healthy controls were examined. Thresholds for mechanically and thermally induced pain were determined on the left side of the tip of the second finger, on the skin fold between thumb and second finger and on the ear lobe. Superficial skin blood flow was simultaneously measured by laser Doppler technique on the right third finger. The patients had higher pain thresholds than controls on the vibration-exposed index finger but not on other stimulation areas. Thus receptors or pain-mediating nerve fibres in the fingers are affected by work with vibrating tools. The controls demonstrated vasoconstriction on pain stimulation, whereas the patients showed no or weak vasoconstriction in response to the stimulation. This was true also when areas not included in the disease process were stimulated, indicating that also sympathetic vasoconstrictor nerves or receptors are affected in vibration syndrome.

Afferent Pathways↗
PubMed1988

alpha-Adrenoceptors and cold-induced vasoconstriction in human finger skin.

Experiments were designed to determine how cold-induced vasoconstriction is mediated in superficial vessels of human finger skin. alpha-Adrenoceptor antagonists were administered into the finger skin by iontophoresis, and local cooling was applied by a laser-Doppler probe supplied with Peltier elements. Cold-induced vasoconstriction was abolished after administration of the alpha 2-adrenoceptor antagonist rauwolscine but not after the alpha 1-adrenoceptor antagonist doxazosin. The results indicate that vasoconstriction on local cooling in human finger skin is mainly mediated by adrenoceptors of the alpha 2-subtype.

Adrenergic alpha-Agonists↗
PubMed1987

High vascular tone but no obliterative lesions in vibration white fingers.

To study if obliterative lesions in digital arteries are relevant as the pathogenic factor in vibration white finger, finger blood flow was measured in 15 subjects with advanced symptoms and in 15 controls by venous occlusion plethysmography before and after vasodilation. Before vasodilation, the subjects had lower temperature, blood flow, and peak blood flow after arterial occlusion in the fingers than did the controls, while venous tone was increased. In addition, after sympathicolysis, finger blood flow was lower in the study than in the control group, but there was no difference peak blood flow after arterial occlusion or in venous tone. The results indicate that the subjects have a high vascular tone causing a reduction in blood flow during submaximal flow conditions. Obliterative organic lesions in finger arteries do not seem to be present, since the "maximal" flow values of the subjects are similar to those of the controls.

Blood Flow Velocity↗
PubMed1987

Vibration white finger: a follow up study.

To study the course of vibration white finger (VWF) 55 men were re-examined three and a half to six years after the first examination. The patients were interviewed and finger systolic pressure after general body and local finger cooling was measured. The test results at the two examinations were compared. At the follow up examination some patients experienced a subjective improvement of VWF symptoms but not until more than three years had passed after they had stopped working with vibrating tools. To study the effect of diminished cold exposure on subjective symptoms, vibration exposed outdoor workers who changed to unexposed indoor work were studied separately. In this subgroup also improvement was reported only when more than three years has passed after the change of work, indicating that diminished cold exposure is not the primary explanation for the improvement. The cold provocation test, however, showed no tendency towards a diminished reaction of the vessels to cooling. Patients who continue to work with vibrating tools report a subjective increase in symptoms. This subjective impairment was reflected in an increased reaction to cold as measured in the cold provocation test.

Adult↗
PubMed1987

Clinical assessment of suspected damage from hand-held vibrating tools.

The case history is still the cornerstone in the clinical assessment of suspected vibration injury. Objective tests to verify the symptoms are needed for legal reasons in insurance cases and for research purposes. The minimum requirement of a test used to obtain objective signs of Raynaud's phenomenon is that patients with vibration-induced white finger be evaluated along with symptom-free, but vibration-exposed, subjects for reference. The measurement of systolic blood pressure in the finger after local finger and general body cooling is a test that has been evaluated in this way, as has restitution of finger temperature after local cooling and ischemia combined with general body heating. If neurological symptoms are present, electroneurographic examination is essential since carpal tunnel syndrome, a treatable condition, is common in vibration-exposed patients. Measurements of vibration and temperature thresholds are complementary examinations. The so-called vibrogram may be a method with which to obtain objective neurological signs of vibration injury, but the test needs further evaluation. Until more is known of the pathophysiological mechanisms behind the disease, the patient's description of his symptoms, combined with a detailed exposure history, will remain essential for a diagnosis of vibration injury--irrespective of the results of the tests used.

Carpal Tunnel Syndrome↗
PubMed1986

Laser Doppler flow-meter assessment of iontophoretically applied norepinephrine on human finger skin circulation.

A miniaturized technique to administer vasoactive substances iontophoretically into the human finger skin and to continuously assess the resulting reaction of the vessels is described. Cutaneous blood flow is measured with a laser Doppler flow-meter. The technique has been used in 9 healthy volunteers with norepinephrine as test substance. The described method is a convenient way to evaluate the effects of transdermally applied vasoactive substances in a semiquantitative way without risking central effects of the substance to influence the registered blood flow.

Fingers↗
PubMed1986

Alpha-adrenoceptors in the vessels of human finger skin.

To characterize alpha-adrenoceptors in the blood vessels of finger skin the effects of selective alpha-1 and alpha-2 adrenoceptor agonists and antagonists on skin blood flow were studied in vivo. The vasoactive substances were administered into the skin by iontophoresis and the effects on blood flow were evaluated with a laser-doppler. After blockade of alpha-1 adrenoceptors with doxazosine, the blood flow reduction induced by the alpha-1 selective agonist, phenylephrine, was diminished but not that caused by the alpha-2 selective agonist, B-HT 933. In contrast, after alpha-2 selective blockade by rauwolscine, phenylephrine but not B-HT 933 caused a marked decrease in blood flow. The results are compatible with the concept that postjunctional alpha-adrenoceptors in human finger skin vessels are of both alpha-1 and alpha-2 subtypes.

Adrenergic alpha-Agonists↗
PubMed1986

Is vibration white finger a primary sympathetic nerve injury?

Changes in the sympathetic nerve system have been suggested as the pathophysiological mechanism underlying vibration white finger (VWF). The aim of the present study was to investigate if experimental support for such a mechanism could be found in VWF. Drugs with a known effect on sympathetic alpha receptors were administered into the finger skin by iontophoresis and their effects on blood flow in the same area evaluated using a laser Doppler technique. The effects of noradrenaline (stimulating alpha-1 and alpha-2 receptors), phenylephrine (an alpha-1 stimulator), and B-HT 933 (an alpha-2 stimulator) were studied in 12 patients with vibration white finger and 12 healthy controls. The reactions to noradrenaline and B-HT 933 were similar in both patients and controls, but the reaction of the patients to phenylephrine was significantly weaker than the controls. In additional experiments in six patients and six controls concentration effect curves to phenylephrine were derived. The curves for the patients were shifted to the right--that is, they reacted less strongly than the controls at all doses of the drug which induced an appreciable vasoconstriction. The results of this study are compatible with the hypothesis that the alpha-1 receptor mediated responses are weakened in VWF. The predominance of alpha-2 receptors in the digital arteries has, on the basis of animal experiments, been suggested as a possible mechanism for Raynaud's phenomenon.

Adrenergic alpha-Agonists↗
PubMed1986

Temperature and vibration thresholds in vibration syndrome.

In a study to investigate whether the quantitative assessment of temperature and vibration thresholds can improve the evaluation of the neurological symptoms in vibration syndrome 37 patients with neurological symptoms (paraesthesias, numbness, pain) in the hands who had worked with hand held vibrating tools and 46 healthy controls not exposed to vibration were examined. Temperature thresholds were measured on the thenar eminence and on the volar side of the second and third fingers held together. Vibration thresholds were determined on the dorsum of the hand and on the dorsal side of the second and fifth fingers proximal to the nail. The neutral zone between thresholds for warmth and cold was much wider in the patients than in the controls. Patients older than 45 had higher vibration thresholds than controls. Electroneurography was abnormal in 18 of 34 patients and a carpal tunnel syndrome was diagnosed in six subjects. This investigation is thus indicated in patients with neurological symptoms. Seven of the patients with normal electroneurographic findings had impaired temperature or vibration thresholds or both. Determination of sensory thresholds seems to add valuable information and the methods are, by contrast with electroneurography, easily adapted to the screening of exposed groups outside hospital. Our results indicate that thin myelinated and unmyelinated nerve fibres might be damaged in the vibration syndrome.

Adult↗
PubMed1986

Vibration white finger and digital systolic pressure during cooling.

A cold provocation test (measurement of finger systolic pressure during combined body and local finger cooling) was performed on 111 male patients exposed to vibration and with a typical history of cold induced white finger. A new method of calculating the test result is described--namely, digital systolic blood pressure in the cooled test finger as a percentage of the systolic pressure in the arm (DP%). The conventional way of calculating the result, the systolic pressure in the cooled test finger as a percentage of the systolic pressure in the test finger when heated to 30 degrees C, corrected for changes in systemic pressure by the use of a reference finger (FSP%), requires the measurement of the systolic pressure in a reference finger. The two ways of calculating the test results give a similar sensitivity (74% for FSP%, 79% for DP% if all histories are regarded as true) but the new method does not require pressure measurements in a reference finger. This makes the test easier to perform and the result easier to understand.

Blood Pressure↗
PubMed1983

Single cell protein as an occupational hazard.

Single cell protein (SCP) intended for animal feed purposes was produced in a pilot plant. The SCP consisted of Methylomonas methanolica, a pseudomonas species which is an obligate methanol user. The SCP was cultured in fermenters and later dewatered and dried in a spray-drier. Seven of eight research workers had febrile reactions 6-12 hours after exposure to SCP dust. All workers had high titres of IgG and IgM antibodies against the pseudomonas species as measured with indirect ELISA and passive haemagglutination techniques. The mechanism behind the febrile reaction is judged to be a non-immunological reaction caused by endotoxins. By increasing the particle size of the SCP through using different drying procedures, a product which generated less dust was obtained.

Animal Feed↗
PubMed1982

Digital blood pressure after local cooling as a diagnostic tool in traumatic vasospastic disease.

Measurement of digital blood pressure before and after local cooling was performed in 10 men with traumatic vasospastic disease (TVD), 10 men who worked with vibrating tools but had no symptoms in arms or hands, and 10 men who had never worked with vibrating tools. The reduction in finger systolic pressure was significantly larger in the group with TVD than in either of the reference groups (p less than 0.001). There was no difference between the two reference groups. Nine of the 10 patients with TVD had a larger reduction in their finger systolic pressure after local cooling than anyone in either control group. The effects of two different room temperatures (17 degrees C and 23 degrees C) were evaluated. At the higher temperature the overlap between patients with TVD and controls was greater. The method described seems a feasible way to obtain an objective verification of TVD.

Blood Pressure↗