Limitation of finger systolic pressure measurement as a diagnostic test for primary Raynaud's phenomenon in a female population

Summary. The diagnostic value of measurement of the finger systolic pressure (FSP) was assessed during combined local and whole body cooling in a population-based sample of women with a medical history of primary Raynaud's phenomenon. Forty women had mild Raynaud's phenomenon and 40 had pronounced Raynaud's phenomenon. The results were compared with subjective assessments of complaints from Raynaud's phenomenon as indicated on a visual analogue scale (VAS) in the same group of women. The mean FSP at 10°C was significantly lower in the patients than in 24 age- and sex-matched controls, but there was a large overlap in individual responses. The sensitivity of the FSP method was only 51% for the whole group with primary Raynaud's phenomenon. There was no significant difference in FSP at 10°C between subjects with mild and those with pronounced Raynaud's phenomenon. The subjective severity of the symptoms as indicated on VAS was significantly higher in these two combined groups than in the controls. The mean VAS value was significantly higher in the group with pronounced Raynaud's phenomenon (P<0·01) than in that with the mild type. The low sensitivity of FSP measurement implies that this method is of limited value as a diagnostic test in subjects with primary Raynaud's phenomenon. Furthermore, there was no significant correlation between FSP and the VAS values (r= 0·23).     

Effects of externally applied compression on blood flow in the human dependent leg

Summary. In healthy humans placed in a horizontal position, venous transmural pressure was increased from about 10 to 45 mmHg in the mid-calf region by lowering the leg below heart level. This increase in vascular transmural pressure evoked a vasoconstrictor response, as ¹³³Xe-measured blood flow was reduced by 56% (P < 0·01) in subcutaneous tissue and by 31% (P < 0·01) in skeletal muscle, when recorded at the same mid-calf level. The tissue pressure in the dependent leg was elevated stepwise by inflation of a standard whole leg cuff. The vasoconstrictor response was still present when the cuff was inflated to 10 mmHg, but absent in both tissues when external pressures between 20–40 mmHg were applied. The results suggest that the observed absence of vaso-constriction can be ascribed to inhibition of the local veno-arteriolar reflex mechanism. External pressures exceeding 40 mmHg reduced blood flow in both tissues. External pressures of 60 mmHg reduced blood flow by 45% (P < 0·01) in subcutaneous tissue and by 19% (P < 0·02) in skeletal muscle. In conclusion, the vasoconstrictor response evoked in the dependent leg is qualitatively similar, but quantitatively different in the two tissues, possibly due to a difference in basal vascular tone. The vascular adjustments to external compression of the dependent leg is similar in the two tissues at low external pressures (0–40 mmHg), but different at high pressures, the latter probably due to a difference in vessel collapsibility in the compressed tissues.     

Reproducibility of orthostatic changes in cerebral oxygenation in healthy subjects aged 70 years or older

In the elderly, standing can frequently be accompanied by blood pressure (BP) changes and cerebral symptoms such as dizziness, fall, or even syncope, but this may vary from day‐to‐day. Therefore, we aimed to investigate the reproducibility of orthostatic responses of cerebral cortical oxygenation and systemic haemodynamics in elderly subjects. In 27 healthy elderly subjects (age 70–84 years), changes in systolic BP (SBP), diastolic BP (DBP), heart rate (HR) and stroke volume (SV) were continuously monitored by Finapres (Finger Arterial Pressure), and changes in oxyhaemoglobin ([O₂Hb]) and deoxyhaemoglobin ([HHb]) concentrations were continuously measured over the right frontal cortex by near infrared spectroscopy (NIRS) during supine rest and 10 min of active standing on two separate occasions. SBP and DBP increased by 6·7 ± 15·4 mmHg (P<0·05, mean ± SD) and 8·2 ± 6·4 mmHg (P<0·01), respectively, whereas HR increased by 9·5 ± 5·0 bpm (P<0·01) and SV decreased by –8·3 ± 7·4 ml (P<0·01) during standing on the first occasion. [O₂Hb] decreased by –3·9 ± 2·9 μmol l^–1 (P<0·01), while [HHb] increased by 1·8 ± 2·2 μmol l^–1 (P<0·01). Group‐averaged orthostatic changes in cortical oxygenation and systemic haemodynamics were very similar on the two occasions, although an intraindividual variation was found. Cortical oxygenation changes were not accompanied by severe cerebral symptoms. Active standing induced reproducible group‐averaged frontal cortical oxygenation declines in healthy elderly subjects, although an intraindividual day‐to‐day variability was present, possibly related to the variability of orthostatic BP responses. These findings indicate that cerebral autoregulation fails to compensate completely for postural changes in elderly subjects, which might predispose elderly subjects to ischaemic cerebral symptoms.     

Tissue oxygenation,strength and lactate response to different blood flow restrictive pressures

This study aimed to determine whether changes in initial restrictive pressures (IRP, tightness of the cuff before inflation with air) affect tissue oxygenation, lactate production and leg strength before, during and after knee extension exercises. The cuff was positioned on the right thigh, and the IRP of either 40–45 or 60–65 mmHg were applied randomly prior to inflating the cuff to the final restrictive pressure (the pressure reached after inflating the cuff with air). Subjects performed four sets (30, 15, 15 and 15 reps) of isotonic knee extensions with 1‐min rest between sets. Tissue oxygenation and blood lactate levels were assessed prior to, during and after exercise, and leg strength was assessed pre‐ and postexercise. There were significant condition by time interactions (P<0·01) and main effects for both condition (P<0·01) and time (P<0·01) for tissue oxygenation, deoxyhaemoglobin, total haemoglobin. Significant main effects were detected for both condition (P<0·01) and time (P<0·01) for leg strength values. There was only a significant time main effect for lactate concentrations. This study is the first to show that a higher IRP had a significant impact on percent tissue oxygenation, leg strength and deoxygenated haemoglobin accumulation during exercise.     

Mesenteric artery response to head-up tilt-induced centralhypovolaemia and hypotension

Superior mesenteric artery (SMA) blood flow and impedance were evaluated byduplex ultrasound during head-up tilt (HUT)-induced central hypovolaemia and hypotension ineight healthy volunteers. HUT induced a reduction in cardiac stroke volume from88·8±6·3 to 64·7±6·3 ml(mean±SEM; P<0·01) and an increase in thoracic electricimpedance from 38·6±2·1 to 42·6±2·1Ω (P<0·01) reflecting a reduced central blood volume. Maintainedtilt provoked a 30% reduction in mean arterial pressure (from 87·1±3·3to 63·4±3·6 mmHg; P<0·01) and the appearanceof presyncopal symptoms. During both the normotensive and the hypotensive phase of HUT, theSMA diameter (5·7±0·03 mm) and blood flow (514±75 ml min^?1) did not change significantly, although the end-diastolic velocity increasedfrom 9·7±4·8 to 39·7±4·0 cm s^?1 (P<0·01). The increase in diastolic velocity, despite amaintained or reduced arterial pressure, supports a reduction in the SMA impedance as it wasreproduced during a meal test when a moderate reduction in mean arterial pressure (87±4to 80±4 mmHg; P=0·04) was accompanied by a ninefoldincrease in the end-diastolic velocity (P<0·01). The results indicate areduction in the mesenteric vascular impedance to the extent that superior mesenteric artery bloodflow is maintained during HUT-induced central hypovolaemia and hypotension.     

Low-frequency transcutaneous nerve stimulation in mild/moderate hypertension

Summary. Low-frequency peripheral nerve stimulation may induce widespread cutaneous and muscular vasodilatation in animals and humans due to sympatho-inhibition. This response has in humans been shown to be associated with a lowering of the systemic vascular resistance and arterial pressure. In the present study the effectiveness of low-frequency (2 Hz) transcutaneous electrical nerve stimulation (TNS) has been examined in 46 patients, all 41–43 years of age, with a primary diagnosis of uncomplicated mild/moderate hypertension (90–115 mmHg diastolic pressure). The study was designed blind with matched controls in a TNS group and a placebo group. The blood pressure was measured objectively with an automatic monitor. In a short-term experiment TNS produced a significant lowering of systolic, mean arterial, and diastolic pressures amounting to 8 mmHg (P<0·01), 6 mmHg (P<0·01), and 4 mmHg (P<0·02), respectively. In a long-term study, after 2 weeks of daily stimulation, a similar depression was recorded with no stimulation on the day of examination. An eventual clinical use of the depressor effect of TNS demands further clinical research.     

Pulmonary vasodilatation and augmentation of right ventricular function following terbutaline infusion in severe chronic pulmonary disease

Summary. Twenty patients with a median age of 61 years and a median forced expired volume in 1 s (FEV₁) after bronchodilatating therapy of 0·55 1 were studied in order to measure the effect of intravenous terbutaline on bronchial tone, cardiac function, pulmonary haemodynamics, gas exchange, and oxygen transport capacity during rest and in 10 patients during exercise. Terbutaline infusion during rest resulted in an increase in heart rate from 84 to 103 beats min^-1 (P < 0·01), a decrease in mean systemic arterial pressure from 95 to 80 mmHg (P < 0·02), an unchanged mean pulmonary arterial pressure (18 mmHg), an increase in cardiac index from 2·89 to 3·86 1 min^-1 m^-2 (P < 0·01), an increase in right ventricular ejection fraction from 45 to 53% (P < 0·01), an increase in left ventricular ejection fraction from 63 to 67% (NS), an unchanged arterial oxygen tension, and an increase in calculated oxygen delivery from 533 to 638 ml O₂ min^-1 m^-2 (P < 0·01). During exercise terbutaline infusion resulted in an increase in heart rate from 108 to 120 beats min^-1 (P < 0·05), a decrease in mean systemic arterial pressure from 117 to 106 mmHg (P < 0·01), a decrease in mean pulmonary arterial pressure from 29 to 22 mmHg (P < 0·01), an increase in cardiac index from 4·53 to 4·64 min^-1 m^-2 (NS), an unchanged arterial oxygen tension, and an increase in the calculated oxygen delivery from 834 to 856 ml O₂ min^-1 m^-2 (NS). It was concluded that terbutaline augments right ventricular function: increases right ventricular ejection fraction and decreases right ventricular end-diastolic volume, and further decreases pulmonary vascular resistance without decreasing arterial oxygen tension, and increases oxygen delivery in patients with chronic pulmonary disease during rest and exercise.     

Whole-body cooling increases plasma endothelin-1 levels in women with primary Raynaud's phenomenon

To understand better the role of endothelin-1 (ET-1) in the pathogenesis of primary Raynaud's phenomenon (PRP), we investigated the basal ET-1 plasma levels and changes after whole-body cooling in healthy women and those with PRP. The study was performed as an open parallel-group comparison during the month of February. The Raynaud group included 21 female patients (mean age 45·3 years, range 21–57 years) who had had disabling Raynaud's phenomenon for a mean period of 17 years (range 2–26 years). The control group consisted of 25 healthy women (mean age 43·6 years, range 27–56 years). Plasma levels of ET-1 were measured on two separate occasions: once after 30 min of rest at room temperature and after 40 min of whole-body cooling. There were no significant differences in baseline plasma ET-1 levels between the two groups of women. The plasma ET-1 levels increased significantly in the PRP group after cold exposure (mean difference 0·11 pmol l^?1, 95% CI 0·005–0·214, P = 0·012). In contrast, the levels of plasma ET-1 in the control group did not change significantly after cold provocation. In conclusion, no differences in plasma basal levels of ET-1 were observed between the two groups. However, women suffering from Raynaud's phenomenon responded with a slight but significant elevation in plasma levels of ET-1 after whole-body cooling, whereas the healthy control subjects did not. The results from the present study confirm previous observations that endothelial dysfunction may be of aetiological importance in PRP.     

Changes in coronary haemodynamics and myocardial metabolism at rest and during exercise after a cardiotonic drug (prenalterol) in patients with coronary artery disease

Summary. To elucidiate the myocardial metabolic and haemodynamic effects of an inotropic drug in patients with coronary artery disease (CAD) without evident congestive heart failure (CHF), the acute effects of prenalterol were studied in nine patients. Patients with documented CAD by leftsided cardioangiography and end-diastolic pressure >15 mm Hg were included in the study. They were examined at rest and during supine exercise at a level just below their anginal threshold before and after prenalterol. At rest, rate pressure product (RPP) increased by 40% (P<0·01), cardiac index rose 20% (P<0·01), cardiac venous flow (CVF) increased by 18% (P<0·05), and myocardial oxygen consumption (MVO₂) increased by 20% (P<0·05) after prenalterol administration. Despite a decrease in mean pulmonary capillary venous pressure (PCV) of 40% (P<0·01), myocardial lactate extraction fell significantly (P<0·01) and lactate production was observed in three of nine patients compared to before prenalterol administration. During exercise, RPP increased by 20% (P<0·01), cardiac index remained unchanged, CVF increased by 25% (NS) and MV0₂ showed a tendency to an increase (NS) after prenalterol administration. Mean PCV pressure decreased by 30% (P<0·01). Myocardial lactate extraction was markedly reduced during exercise (P<0·01) and five of nine patients showed lactate production compared to that before prenalterol administration. Thus, despite a decrease in left ventricular filling pressure, increased myocardial oxygen demand occurred after acute administration of prenalterol. Prenalterol and probably similar inotropic drugs should be used cautiously in patients with CAD without clinical evidence of congestive heart failure.     

Myoglobin and enzyme adaptations in erector spinae muscles in thoracal scoliosis

Summary. Bilateral biopsies from the erector spinae muscles were taken during surgery from 10 females and two males (mean age 14, range 13–17 years) with thoracal scoliosis for 6 years (range 2–11 years). The biopsies were analysed for myoglobin (MYO), citrate synthase (CS) and creatine kinase MB (CK-MB). The severity of scioliosis was estimavoted by Cobb's angle, the greater the angle the more severe the disease. The convex/concave side ratio (CVX/CCV) was for CS l·3±0·4 (P<0·01), CK 0·9 ± 01 (P<0·05), CK-MB 1·6±0·4 (P<0·01) and for MYO 1·1±0·2 (P>0·05). No significant correlations were found between the CVX/CCV for CS, CK or CK-MB on the one hand and the Cobb's angle on the other. The CVX/CCV for MYO was, however, directly related to the angle (r= 0·80, P<0·01). For the lower range of angles (≤59°) the CVX/CCV for MYO was below unity (0·88, P>0·05) and for the larger angles (>59°) above unity (1·23, P<0·05). In conclusion, a dissociation in the adaptive response of m. erector spinae in scoliosis between mitochondrial enzyme and myoglobin content was demonstrated.     

Endothelin‐1: increased plasma clearance,pulmonary affinity and renal vasoconstriction in young smokers

Pulmonary and renal haemodynamics and elimination of endothelin‐1 (ET‐1) were studied in six young smokers in response to 20 min intravenous infusion of ET‐1 (4 pmol kg^–1 min^–1) after smoking. At 20 min of ET‐1 infusion fractional ET‐1 extractions in the lungs and kidneys were 60 ± 2 and 60 ± 7%, respectively. Cardiac output and renal blood flow (RBF) fell by 18 ± 4% (P<0·05) and 34 ± 5% (P<0·01). Mean systemic arterial pressure increased (P<0·05) whereas pulmonary pressures were unchanged. Compared with previously published data in non‐smokers ( 38 , 39 ) basal arterial ET‐1 and ET‐1‐values during ET‐1 infusion were lower with a more rapid return to basal value. Smokers had higher pulmonary extraction of ET‐1 at the same pulmonary arterial concentration (P<0·05). RBF reduction was more pronounced (P<0·05). Systemic vascular resistance increased while pulmonary vascular resistance did not increase as in non‐smokers. Increased plasma clearance and more efficient pulmonary elimination of ET‐1 lowers the arterial level in young smokers. In addition ET‐1 evokes more pronounced renal vasoconstriction in these individuals.     

Cardiovascular functioning during the menstrual cycle

Variations in cardiovascular functioning during the ‘normal’ menstrual cycle have been little researched. Resting‐blood pressures, resting‐heart rate, rate‐pressure product (RPP) and a derived index of fitness (Schneider Index) were monitored throughout natural, hormonally defined menstrual cycles. Volunteers were 26 women (20–48 years) who had regular (25–35 days) cycles. Their blood pressures and heart rate (at rest and according to Schneider’s protocol) were measured at the same time daily (Monday–Friday) for 5 weeks. Daily, early morning‐urine samples were assayed for sex hormones enabling accurate definition of cycle phase for each woman. Resting systolic‐blood pressure was significantly higher in the ovulatory phase (P<0·05) than in the follicular or luteal phases, but resting‐diastolic pressures did not differ significantly between phases. Resting‐heart rate was significantly higher in both ovulatory (P<0·01) and luteal (P<0·01) phases than in the menstrual and follicular phases. The Schneider Index was higher during the follicular phase than during the ovulatory (P<0·005) or luteal (P<0·01) phases, the RPP was higher during the ovulatory phase than during the bleeding (P<0·05) and follicular (P<0·005) phases. These findings provide a pattern of menstrual cycle‐related variation in cardiovascular functioning that can be related to established actions of the ovarian steroids.     

Increased sympathetic tone in forearm subcutaneous tissue in primary hypothyroidism

Summary. Sympathetic reflex regulation of subcutaneous blood flow (SBF) in the forearm was studied in eight patients with primary hypothyroidism. Diastolic arterial pressure was ≥95 mmHg in five patients. SBF was determined by local clearance of Na^99mTcO₄. Sympathetic vasoconstriction normally seen after lowering the forearm 40 cm below heart level was absent since SBF only decreased by 4% (± 7%, P > 0·1) during these conditions. In head-up vertical position we noticed a diminished baroreceptor response as SBF at heart level was reduced by 11% (±7%, P < 0·1) compared to supine position. After proximal local anaesthesia SBF increased by 351% (±81%, P < 0·01) and disclosed a normal vasoconstrictor response as SBF was reduced by 53% (±5%, P < 0·01) during arm lowering. Five of the treated patients were restudied in the euthyroid state. Mean arterial pressure was reduced in mean by 20 mmHg (± 6 mmHg, P < 0·02) during treatment and a significant vasoconstriction was observed both during arm lowering (SBF =-52% (±6%, P<0·02)) and in head-up vertical position (SBF= -45% (± 11%, P<0·02)). In conclusion sympathetic vasoconstrictor activity in adipose tissue is markedly increased in primary hypothyroidism. Sympathetic tone and arterial pressure are reduced during treatment.     

Disturbances in airflow dynamics and tracheal sounds during forced and quiet breathing in subjects with unilateral vocal fold paralysis

Variable extra thoracic obstruction has been found in spirometric studies in subjects with unilateral vocal fold paralysis. The aim of the study was to further evaluate airflow dynamics in these subjects with body plethysmography and tracheal sound analysis. Ten patients with unilateral vocal fold paralysis without a history of chronic pulmonary diseases and 10 healthy control subjects were studied. Flow‐volume spirometry, body plethysmography and tracheal sound analysis were performed within 1 day. The study shows that peak inspiratory flow (PIF) and specific airway conductance (SG_aw) expressed as percentage of Finnish reference values were significantly lower and airway resistance (R_aw) was higher among the patients than among the controls (P=0·004, P=0·026 and P=0·004, respectively). The patients had higher sound amplitude of both inspiratory and expiratory tracheal sounds than the controls [root mean square (RMS) values of the power spectra were 31·5 and 25 dB, P=0·006 in inspiration and 31·5 and 26 dB, P=0·013 in expiration, respectively]. Quartile frequencies (F25 and F50) and RMS of expiratory tracheal sounds had significant negative correlation with PIF (P=0·02, P<0·001, P=0·02, respectively) and forced inspiratory volume in 1 s (FIV₁) (P=0·01, P<0·001, P=0·01, respectively). There was also an association between F50 and peak expiratory flow (PEF) (P=0·02). According to the present study, both quiet breathing and forced inspiration are disturbed in subjects with unilateral vocal fold paralysis. A close relationship between tracheal sounds and respiratory function tests exists.     

Left ventricular response to graded isometric exercise in patients with coronary heart disease

Summary. The effects of graded isometric exercise on left ventricular performance were characterized in 11 male patients (53 ± 2 years) with coronary artery disease (CAD) and in 12 normal subjects (11 male and one female, 36 ± 5 years). The echocardiographic indices of left ventricular function at rest were similar in both groups. Heart rate and blood pressure increased significantly in both groups in response to 40 and 60% of handgrip maximal voluntary contraction (MVC). Left ventricular end-diastolic dimension increased significantly (from 50 ± 1 to 56 ± 1 mm; P < 0·01) with 60% of MVC in CAD group but not in the healthy subjects. The patients with CAD also exhibited significant (P < 0·01) increases in end-systolic dimension (from 34 ± 1 to 40 ± 2 with 40% and to 44 ± 1 mm with 60% MVC). End-diastolic and end-systolic dimensions did not change during isometric exercise in the healthy subjects. Mean velocity of circumferential shortening (mV_CF) increased with 60% MVC in normal subjects. In the CAD group mV_CF decreased significantly (from 1.08 ± 0·06 to 0·86 ± 0·06 with 40% and to 0·74 ± 0·04 d·s^-1 with 60% MVC; P < 0·01). At comparable mean blood pressures, mV_CF was significantly lower in the CAD group than in normal subjects. These results demonstrate that progressive deterioration of left ventricular function during increasing levels of isometric exercise in patients with CAD can be detected with echocardiography.     

Cardiac performance during exercise in patients with Fabry's disease

Background Fatigability and dyspnoea on effort are present in many patients with Fabry's disease. We assessed the determinants of cardiac performance during exercise in patients with Fabry's disease and preserved left ventricular ejection fraction at rest. Materials and methods Sixteen patients with Fabry's disease and 16 control subjects underwent radionuclide angiography at rest and during exercise, tissue Doppler echocardiography and magnetic resonance imaging at rest. Results The exercise‐induced change in stroke volume was +25 ± 14% in controls and +5·8 ± 19% in patients with Fabry's disease (P < 0·001). In 10 patients (group 1), the stroke volume increased (+19 ± 10%), and in 6 patients (group 2) it decreased (–16 ± 9%) with exercise. Patients of group 2 were older, had worse renal function, higher left ventricular mass and impaired diastolic function compared to group 1. The abnormal stroke volume response to exercise in group 2 was associated with a decrease in end‐diastolic volume (P < 0·001) and a lack of reduction of end‐systolic volume (P < 0·01) compared with both controls and group 1. The ratio of peak early‐diastolic velocity from mitral filling to peak early‐diastolic mitral annulus velocity was the only independent predictor of exercise‐induced change in stroke volume (B –0·44; SE 0·119; β–0·70; P < 0·005). Conclusions The majority of patients with Fabry's disease were able to augment stroke volume during exercise by increasing end‐diastolic volume, whereas patients with more advanced cardiac involvement may experience the inability to increase cardiac output by the Frank Starling mechanism.     

Evaluation of the dynamic cutaneous post-ischaemic hyperaemia and thermal response in elderly subjects and in an area at risk for pressure sores

Summary. The response of skin blood cell flux (SBF) to locally applied pressure was evaluated with the laser-Doppler technique in the areas of the sacrum and the gluteus maximus muscle of geriatric patients and healthy young and elderly subjects. The SBF over the sacrum stopped at a lower external skin pressure than over the gluteus muscle in all groups studied (P<0·05·0·001). The SBF at rest was lower among geriatric patients and over the sacrum, with men showing the lowest value (P<0·001). The initial slope of the SBF curve and the peak SBF during the post-occlusive reactive hyperaemia (PRH) were lower among geriatric patients compared to younger healthy subjects (P<0·05·0·01) over both areas studied. During the last part of the PRH response rhythmic oscillations started, known as vasomotion. The mean skin temperature at rest was higher over the sacrum (P<0·001) than over the gluteus area, but no difference was found between the groups. The temperature increase during the PRH was larger over the gluteus muscle (P<0·01) than over the sacrum area in the healthy subjects. Among the patients the temperature increase was larger over the gluteus only during the first half of the PRH, after which the temperature increased most over the sacrum. It is concluded that SBF and skin temperature show different responses in microvascular reactivity to external pressure in elderly vs. younger subjects and also between sexes. The described technique may be useful in clinical practice for predicting the risk of pressure sores in different areas and subjects.     

Diurnal metabolic profiles in hyperthyroidism

Abstract. Hormone and metabolite profiles during a 12 h period of normal meals and activity were examined in nine hyperthyroid subjects with Graves' disease and sixteen matched controls. Six hyperthyroid subjects were restudied when euthyroid on carbimazole and thyroxine. Thyrotoxic patients had mild fasting hyperglycaemia (mean pL SEM blood glucose, 5·5 pL 0·2 v. 4·8 pL 0·1 mmol/l, P < 0·01), elevated blood glycerol (0·15 pL 0·02 v. 0·08 pL 0·01 mmol/l, P < 0·001) and elevated plasma non-esterified fatty acid (NEFA) concentrations (0·91 pL 0·06 v. 0·58 pL 0·03 mmol/l, P < 0·001) when compared to controls. Fasting blood concentrations of the gluconeogenic precursors lactate, pyruvate and alanine, blood ketone body concentrations and circulating insulin and growth hormone levels were similar in hyperthyroid and control subjects. Blood glucose responses to meals were exaggerated and the mean 12 h blood glucose was increased (6·1 pL 0·1 v. 5·5 pL 0·1 mmol/l, P < 0·01) in hyperthyroidism. Similarly, hyperlactataemia and hyperpyruvicaemia were observed after meals. Blood ketone body, blood glycerol and plasma NEFA levels showed exaggerated pre-prandial peaks and the mean 12 h values for blood glycerol (0·12 pL 0·01 v. 0·08 pL 0·01 mmol/l, P < 0·01) and plasma NEFA (0·71 pL 0·03 v. 0·53 pL 0·04 mmol/l, P < 0·01) were increased. Concentrations of insulin and growth hormone remained similar to control values throughout the study period. Blocking therapy with carbimazole and thyroid hormone replacement with thyroxine for 5–10 months suppressed blood glycerol, plasma NEFA and blood ketone body levels to normal or subnormal values but had no effect on the elevated blood glucose, blood lactate or blood pyruvate profiles. Graves' disease with hyperthyroidism is thus associated with abnormalities of carbohydrate metabolism which are not restored to normal by 5–10 months oral antithyroid therapy. The changes in lipid metabolism in hyperthyroidism are normalized by this treatment.     

Reproducibility of contractile properties of the human paralysed and non‐paralysed quadriceps muscle

This study assessed the reproducibility of electrically evoked, isometric quadriceps contractile properties in eight people with spinal cord injury (SCI) and eight able‐bodied (AB) individuals. Over all, the pooled coefficients of variation (CV_ps) in the SCI group were significantly lower (ranging from 0·03 to 0·15) than in the AB group (ranging from 0·08 to 0·21) (P<0·05). Furthermore, in all subjects, the variability of force production increased as stimulation frequency decreased (P<0·01). In subjects with SCI, variables of contractile speed are clearly less reproducible than tetanic tension or resistance to fatigue. Contractile properties of quadriceps muscles of SCI subjects were significantly different from that of AB subjects. Muscles of people with SCI were less fatigue resistant (P<0·05) and produced force–frequency relationships that were shifted to the left, compared with AB controls (P<·01). In addition, fusion of force responses resulting from 10 Hz stimulation was reduced (P<·05) and speed of contraction (but not relaxation) was increased (P<0·05), indicating an increased contractile speed in paralysed muscles compared with non‐paralysed muscles. These results correspond with an expected predominance of fast glycolytic muscle fibres in paralysed muscles. It is concluded that quadriceps dynamometry is a useful technique to study muscle function in non‐paralysed as well as in paralysed muscles. Furthermore, these techniques can be reliably used, for example, to assess therapeutic interventions on paralysed muscles provided that expected differences in relative tetanic tension and fatigue resistance are larger than ～5% and differences in contractile speed are larger than ～15%.     

Whole‐body vibration dosage alters leg blood flow

The effect of whole‐body vibration dosage on leg blood flow was investigated. Nine healthy young adult males completed a set of 14 random vibration and non‐vibration exercise bouts whilst squatting on a Galileo 900 plate. Six vibration frequencies ranging from 5 to 30 Hz (5 Hz increments) were used in combination with a 2·5 mm and 4·5 mm amplitude to produce twelve 1‐min vibration bouts. Subjects also completed two 1‐min bouts where no vibration was applied. Systolic and diastolic diameters of the common femoral artery and blood cell velocity were measured by an echo Doppler ultrasound in a standing or rest condition prior to the bouts and during and after each bout. Repeated measures MANOVAs were used in the statistical analysis. Compared with the standing condition, the exercise bouts produced a four‐fold increase in mean blood cell velocity (P<0·001) and a two‐fold increase in peak blood cell velocity (P<0·001). Compared to the non‐vibration bouts, frequencies of 10–30 Hz increased mean blood cell velocity by approximately 33% (P<0·01) whereas 20–30 Hz increased peak blood cell velocity by approximately 27% (P<0·01). Amplitude was additive to frequency but only achieved significance at 30 Hz (P<0·05). Compared with the standing condition, squatting alone produced significant increases in mean and peak blood cell velocity (P<0·001). The results show leg blood flow increased during the squat or non‐vibration bouts and systematically increased with frequency in the vibration bouts.