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.     

Decrease in myoglobin and enzyme contents with haemodilution in non-hypoxaemic polycythaemic patients

Summary. Quadriceps muscle biopsies from five patients with primary polycythaemia and four patients with non-primary polycythaemia, all with normal respiratory functions, were studied before and after normalization of haemoglobin and erythrocyte volume fraction by haemodilution or venaesectio. Since similar results were obtained from both groups of patients data were pooled. After normalization of the erythrocyte volume fraction myoglobin decreased by 19 ± 16%, P<0·01, the activity of creatine kinase and citrate synthase by 12 ± 8 and 14 ± 18%, P<0·05, respectively. The decrease in myoglobin content was related to the decrease in haemoglobin concentration (r= 0·77, P<0·01). In conclusion, these data suggest that in non-hypoxaemic polycythaemia skeletal muscle shows adaptations indicative of an impaired oxygenation and a metabolic stress, adaptations that are reversed by haemodilution.     

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.     

Carbohydrate utilization by exercising muscle following pre-exercise glucose ingestion

Summary. The effect on exercising muscle metabolism of prior ingestion of 200 g glucose was examined in six healthy subjects during 40 min leg exercise at 30% of maximal oxygen uptake. Leg glucose uptake during exercise was on average two- to three-fold higher after glucose (E+G) compared to exercise without glucose (E) and could account for 44–48% of the oxidative leg metabolism (control value: 19%, P<0·05-0·01). In contrast to E, which was associated with a significant release of leg lactate, pyruvate and alanine, E+G gave no leg production of lactate or alanine and an uptake of pyruvate. The respiratory exchange ratios (R) were higher during G + E and corresponded to a carbohydrate oxidation of 54–69% as against 46–49% (P0<·05-0·01) during E. Estimated from R-values and leg oxygen and glucose uptakes, carbohydrate oxidation during G<E was almost completely accounted for by blood glucose. During E, on the other hand, carbohydrate oxidation exceeded leg glucose uptake, indicating a small but significant muscle glycogen breakdown (P<0·01). The rate of glycogen utilization during E or G + E was too small to be detected by direct measurements of muscle glycogen content. The results demonstrate that glucose ingestion prior to light exercise is followed by increased uptake and more efficient oxidation of glucose, as well as by insignificant muscle glycogen degradation by exercising muscle. Although the present findings suggest a glycogen-conserving effect of glucose ingestion under these conditions, the main fuel shift is from fat to glucose oxidation.     

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.     

Volumetric measurements of peripheral oedema in clinical conditions

Water‐displacement volumetry can be used for quantifying the volume of the leg. However, not much is known about its application in patients with peripheral oedema of cardiopulmonary origin. We measured the reproducibility of a water‐displacement apparatus with a solid object and in ten non‐oedematous clinical patients (group A). The day‐to‐day variability of the leg volume was assessed in the same group. The diurnal variability was assessed in ten patients with persisting peripheral oedema (group B). The effect of treatment on the severity of peripheral oedema was evaluated in another nine patients with peripheral oedema, who were in need of diuretic treatment (group C). Volumetric results were compared to the ankle circumference method and the body weight method. The coefficient of variation was 0·16% in the fixed object and 0·47% in group A. The day‐to‐day variability was 1·52% after 1 day and 1·76% after a mean interval of 4·8 days. In group B, leg volume and circumference increased during the day (5·9%, P<0·001, and 2·4%, P<0·01, respectively), while body weight remained unchanged. In group C, leg volume, circumference and body weight decreased significantly after treatment (13·1%, P<0·01, 7·1%, P<0·05, and 5·9%, P<0·05). The correlation between the changes in volume and body weight was poor (r=0·37, P=0·33). In conclusion, (1) water‐displacement volumetry is highly reproducible, (2) a diurnal variability of peripheral oedema was found, and (3) volumetry is a suitable tool for monitoring peripheral oedema, while the body weight method appears to be less accurate.     

Characterization of muscle oxygenation response to vascular occlusion: implications for remote ischaemic preconditioning and physical Performance

Remote ischaemic preconditioning is a non‐invasive intervention with potential to protect a number of organs against ischaemia–reperfusion injury and possibly improve athletic performance. Little mechanistic evidence exists to support either limb choice or cuff inflation pressure that is most effective. This preliminary study aimed to establish the dose–response effect of different occlusion pressures on skeletal muscle oxygenation and blood flow in healthy males (n = 6). In a randomized controlled crossover study, cuff inflation pressures (140,160 and 180 mmHg) were used to induce limb ischaemia (× 3 cycles of 5‐min) in upper (UL) and lower (LL) limbs on three separate occasions. Muscle oxygenation and blood flow properties of UL (flexor carpi ulnaris) and LL (vastus lateralis) were assessed using near infrared spectroscopy. Higher deoxyhaemoglobin (ΔHHb) values were consistently observed in UL (versus LL; P<0·05), no difference between pressures. Occlusion at 140 mm Hg failed to elicit decreases in tissue oxyhaemoglobin (ΔHbO₂) from resting baseline (UL and LL), with significant HbO₂ decreases only observed at 180 mmHg in LL (P<0·05). Increases in ΔHbO₂ and muscle oxygenation index (Hb_diff) above baseline were observed with cuff deflation, lasting up to 15 min into recovery in LL irrespective of occlusion pressure (P<0·05). Muscle oxygenation properties are influenced by choice of limb occluded and findings show that tissue ischaemia can be induced at much lower absolute pressures than traditionally used in RIPC studies. Blood flow and muscle oxygenation may be enhanced for at least 15 min following the last occlusion.     

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.     

Upright body position and weight loss improve respiratory mechanics and daytime oxygenation in obese patients with obstructive sleep apnoea

To determine whether upright body position and weight loss would improve daytime gas exchange in moderately obese patients with obstructive sleep apnoea (OSAS), 13 patients with mild or moderate OSAS were studied before and after weight loss. Pulmonary function tests, arterial blood gases and respiratory gas analysis were measured prior to and after a very low calorie diet (VLCD) period of six weeks. Arterial blood gases were measured in supine and standing positions and closing volume in supine and sitting positions before and after weight loss. In the upright position, there was a significant increase in PaO₂ (P<0·005) accompanied by a significant decrease in alveolar–arterial PO₂ difference (P<0·005) and closing volume (P<0·05). The median weight loss was 11 kg (range 5–18). The number of desaturation episodes (four percentage units or more per hour during sleep) (ODI₄) decreased (P<0·01) after weight loss. The change in PaO₂ with weight loss correlated with the decrease in ODI₄ (r=0·73, P<0·01). The increase in expiratory reserve volume (ERV) was closely related to the amount of weight lost (r=0·895, P<0·01). The results indicate that weight loss and upright body position improved daytime respiratory mechanics and gas exchange in obese patients with OSAS. The findings suggest that obesity plays an important role in the pathogenesis of daytime gas exchange disturbances in obese OSAS patients. The adoption of a more upright sleep posture might improve nocturnal oxygenation in obese patients with OSAS.     

Muscle ammonia and amino acid metabolism during dynamic exercise in man

Summary. The effect of dynamic exercise on muscle and blood ammonia (NH₃) and amino acid contents has been investigated. Eight healthy men cycled at 50% and 97% of maximal oxygen uptake for 10 min and 5·2 min (to fatigue), respectively. Biopsies (quadriceps femoris muscle), arterial and femoral venous blood samples were obtained at rest and during exercise. Muscle NH₃ at rest and after submaximal exercise was (x?±SE) 0·5±0·1 mmol/kg dry muscle (d.m.) and increased to 4·1 ±0·5 mmol/kg d.m. at fatigue (P<0·001). The total adenine nucleotide (TAN) pool (TAN=ATP+ADP+AMP) did not change after submaximal exercise but decreased significantly at fatigue (P<0·01). The decrease in TAN was similar to the increase in NH₃. Muscle lactate was 3±1 mmol/kg d.m. at rest and increased to 104±5 mmol/kg d.m. at fatigue. Whole blood and plasma NH₃ did not change significantly during submaximal but both increased significantly during maximal exercise (P<0·001). During maximal exercise the leg released 7,120 μmol/min of lactate, whereas only 89 μmol/min of NH₃ were released. NH₃ accumulation in muscle could buffer only 3% of the hydrogen ions released from lactate, and NH₃ release could account for only 1% of the net hydrogen ion transport out of the cell. Muscle glutamine was constant throughout the study, whereas glutamate decreased and alanine increased during exercise (P<0·001). No significant changes in either arterial whole blood glutamine or glutamate were observed. Arterial plasma glutamine and glutamate concentrations, however, increased and decreased (P<0·001), respectively, during exercise. It is concluded that (1) muscle and blood NH₃ levels increase only during strenuous exercise and (2) NH₃ accumulation is of minor importance for regulating acid-base balance in body fluids during exercise.     

Metabolism in exercising arm vs. leg muscle

Summary. Arm and leg metabolism were compared by arterial and venous catheterization and blood flow measurements (by dye dilution techniques) in two groups of subjects performing 30-min continuous arm or leg exercise of increasing intensity corresponding to approximately 30, 50 and 80% of max oxygen uptake for arm or leg exercise. The absolute work-loads were 2·5-3 times higher during leg compared to arm exercise. Heart rates were the same in both types of exercise. r-Values were 0·97-1·07 during arm exercise. Arterial noradrenaline and adrenaline levels became higher during leg compared to arm exercise (P< 0·05401). Arterial lactate concentration was 50% higher for arm exercise at the two lower intensities (P< 0·001) and the same at the highest intensity compared to leg exercise. Arm lactate release was three times higher (P< 0·01) or the same as leg lactate output at corresponding exercise intensities. Arm and leg glucose uptake during exercise were of the same magnitude at the lower intensities. In contrast to the leg substrate exchange, arm lactate output was higher than the simultaneous glucose uptake (P< 0·05–0·001), indicating a relatively higher rate of glycogen degradation. In conclusion, exercising arm compared to leg muscles working at the same relative intensities utilize more carbohydrate, mainly muscle glycogen resulting in higher lactate release by the exercising extremity. This cannot solely be explained on the basis of differences in the degree of training and occurs with lower catecholamine levels compared to leg exercise.     

Effect of bicycle exercise on insulin absorption and subcutaneous blood flow in the normal subject

Summary. Elimination of 8 units ¹²⁵I-insulin and ^99mTc-pertechnetate from a subcutaneous depot on the thigh or the abdomen was studied at rest and during intense bicycle exercise in healthy postabsorptive volunteers. Disappearance rates of the tracers as well as plasma insulin and glucose concentrations were determined before, during and after the 20 min exercise period, and compared to corresponding values obtained during a non-exercise, control study on another day. Leg exercise caused a two-fold increase in the rate of ¹²⁵I-insulin disappearance from a leg depot (first-order rate constants rose from 0·68 ± 0·15 to 1·12 ± 0·12%·min^-1, P <0·05), but had no significant effect on the rate of disappearance from an abdominal depot (rate constants were 0·75 ±0·17 and 0·87±0·18%·min^-1 at rest and during exercise, respectively). ^99mTc-pertechnetate clearance from leg or abdomen showed no significant change during exercise, indicating that subcutaneous blood flow was unaltered. Leg, but not abdominal, injection of insulin was associated with a greater rise in plasma insulin during exercise than at rest. The average difference between exercise and control insulin area-under-curve in the leg group (1426 ± 594%·min) was significantly greater (P <0·05) than that from the abdominal group (298 ±251%· min). When the data from the two study groups were pooled, a direct relationship was found to exist between the change in ¹²⁵I-insulin disappearance rate and the change in plasma insulin concentration (r=0·61, P <0·02). Plasma glucose levels fell throughout the observation period both during the exercise and the control study, following leg as well as abdominal injection. The glucose decremental area was greater during exercise than at rest both following leg (P <0·05) and abdominal injection (P <0·01). The exercise-induced mean reduction in plasma glucose was 60% lower following abdominal injection, but this difference was not significant.     

Adding ischaemic hand exercise during occlusion of the brachial artery increases the flow-mediated vasodilation in ultrasound studies of endothelial function

A non-invasive method has been introduced to study endothelial function by evaluating flow-mediated, endothelium-dependent vasodilation of the brachial artery. One weakness of this method is that the post-occlusion vasodilation response is very small in subjects above the age of 60 years, which is a problem when quantifying endothelial dysfunction above this age. We have therefore evaluated whether a higher post-occlusion flow stimulus and a larger vasodilation response can be achieved by adding ischaemic hand exercise during the occlusion of the brachial artery. The subject population was men (n=12), aged 60 years, free from cardiovascular disease. B-mode ultrasound images for the measurement of lumen diameter of the brachial artery were recorded before and after reactive hyperaemia induced by occlusion of the artery. Blood flow velocity was recorded intermittently using a Doppler technique. Hyperaemia was induced in two different ways: first by occlusion only and then by adding ischaemic hand exercise during the occlusion. The results showed that flow velocity was higher and the duration of flow increase was longer after ischaemic hand exercise compared with occlusion only. Two minutes after cuff pressure release, the increase in blood flow velocity was significantly higher after ischaemic hand work compared with occlusion only (P<0·01). The corresponding maximal lumen diameters after cuff pressure release were 4·63 ± 0·35 and 4·45 ± 0·34 respectively (P<0·01). The flow-mediated vasodilation increased significantly from 2·24 ± 2·00% after occlusion only to 7·42 ± 3·32% after occlusion plus ischaemic hand exercise (P<0·01). In conclusion, this study showed that a maximal endothelial-dependent vasodilation was not achieved after occlusion only in these 60-year-old men. Adding ischaemic hand exercise may therefore be of value when quantifying endothelial dysfunction in this age group.     

A comparison of head motion and prefrontal haemodynamics during upright and recumbent cycling exercise

The aim of this observational study was to compare head motion and prefrontal haemodynamics during exercise using three commercial cycling ergometers. Participants (n = 12) completed an incremental exercise test to exhaustion during upright, recumbent and semi‐recumbent cycling. Head motion (using accelerometry), physiological data (oxygen uptake, end‐tidal carbon dioxide [P_ETCO₂] and heart rate) and changes in prefrontal haemodynamics (oxygenation, deoxygenation and blood volume using near infrared spectroscopy [NIRS]) were recorded. Despite no difference in oxygen uptake and heart rate, head motion was higher and P_ETCO₂ was lower during upright cycling at maximal exercise (P<0·05). Analyses of covariance (covariates: head motion P>0·05; P_ETCO₂, P<0·01) revealed that prefrontal oxygenation was higher during semi‐recumbent than recumbent cycling and deoxygenation and blood volume were higher during upright than recumbent and semi‐recumbent cycling (respectively; P<0·05). This work highlights the robustness of the utility of NIRS to head motion and describes the potential postural effects upon the prefrontal haemodynamic response during upright and recumbent cycling exercise.     

Haematocrit,plasma volume and noradrenaline in humans during simulated weightlessness for 42 days

Previous results from our laboratory demonstrate that changes in haematocrit (Hct) and haemoglobin concentration (Hb) underestimate the relative (%) change in plasma volume (PV) in seated subjects during simulation of weightlessness by water immersion. Therefore, we examined whether changes in Hct and Hb would accurately reflect the changes in PV in seven subjects during simulation of weightlessness by another model, 6° head-down tilted bed rest (HDBR), for 42 days. Since we have previously observed unexpectedly high plasma levels of noradrenaline (NA) in astronauts during space flight, we also took the opportunity to measure this variable. The measurements were compared with those of the supine horizontal position before and after HDBR. During HDBR, PV measured by the Evans blue dye dilution technique decreased by 6·1±2·8% (P<0·05) on day 2 and 9·6±2·2% (P<0·05) on the 42nd day compared with that of the supine, horizontal position. Based on changes in Hct and Hb, PV decreased similarly by 8·3±2·8 and 10·2±3·2% (P<0·05) respectively. There were no differences comparing the results of the two methods (P>0·05). Forearm venous plasma NA was unchanged during the whole course of HDBR compared with that of the pre-HDBR supine position. It is concluded that changes in Hct and Hb reliably reflect the changes in PV comparing prolonged HDBR with the pre- and post-HDBR horizontal, supine position. Thus, changes in Hct and Hb might accurately reflect the change in PV during weightlessness in humans provided that the horizontal supine position is used as the ground-based reference. Furthermore, the results of this study, as well as of previous studies from space, confirm that NA release is unchanged or even increased during weightlessness.     

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.     

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.     

Relationship of red-cell 2,3-diphosphoglycerate with anaemia,hypoxaemia and acid—base status in patients with cirrhosis of the liver

The red-cell 2,3-diphosphoglycerate (DPG) concentration is determined in 60 patients with hepatic cirrhosis, in 33 with ferropenic anaemia and in 86 healthy subjects. In all cases, the erythrocyte volume fraction and the haemoglobin concentration are simultaneously measured, while the cirrhotic patients undergo, at the same time, analyses of the arterial pH, po₂ and pco₂ and of the levels of inorganic phosphate, bicarbonate and lactate in their venous blood. In the 60 cirrhotic patients the red-cell DPG concentration (7.40 ± 1.23 mmol/1) is significantly higher (P<0.001) than in the 86 control subjects (4.58 ± 0.59 mmol/1) and the 33 patients with ferropenic anaemia (5.86 ± 1.06 mmol/1), although the level of anaemia in the latter is greater (P<0.001) than in the patients with liver cirrhosis. The DPG concentration found in the cirrhotic patients was far higher (P<0.001) than the theoretical value attributable to them by virtue of their grade of anaemia (5.21 ± 0.95 mmol/1), which value is deduced mathematically from the equation of the regression line between haemoglobin and DPG normal in patients with ferropenic anaemia. Anaemia, hypoxaemia and acid-base disturbances are disorders frequently associated with cirrhosis of the liver. In the present study we deduce that alkalosis, and therefore the plasma pH level, is the most important factor causing the increased DPG concentration in patients with liver cirrhosis for any level of haemoglobin, with respect to other subjects with anaemia.     

A comparison of dynamic contrast‐enhanced CT and MR imaging‐derived measurements in patients with cervical cancer

This work is to compare the kinetic parameters derived from the DCE‐CT and ‐MR data of a group of 37 patients with cervical cancer. The modified Tofts model and the reference tissue method were applied to estimate kinetic parameters. In the MR kinetic analyses using the modified Tofts model for each patient data set, both the arterial input function (AIF) measured from DCE‐MR images and a population‐averaged AIF from the literature were applied to the analyses, while the measured AIF was used for the CT kinetic analysis. The kinetic parameters obtained from both modalities were compared. Significant moderate correlations were found in modified Tofts parameters [volume transfer constant(K^trans) and rate constant (k_ep)] between CT and MR analysis for MR with the measured AIFs (R = 0·45, P<0·01 and R = 0·40, P<0·01 in high‐K^trans region; R = 0·38, P<0·01 and R = 0·80, P<0·01 in low‐K^trans region) as well as with the population‐averaged AIF (R = 0·59, P<0·01 and R = 0·62, P<0·01 in high‐K^trans region; R = 0·50, P<0·01 and R = 0·63, P<0·01 in low‐K^trans region), respectively. In addition, from the Bland–Altman plot analysis, it was found that the systematic biases (the mean difference) between the modalities were drastically reduced in magnitude by adopting the population‐averaged AIF for the MR analysis instead of the measured ones (from 51·5% to 18·9% for K^trans and from 21·7% to 4·1% for k_ep in high‐K^trans region; from 73·0% to 29·4% for K^trans and from 63·4% to 24·5% for k_ep in low‐K^trans region). The preliminary results showed the feasibility in the interchangeable use of the two imaging modalities in assessing cervical cancers.