Morphometric analysis of small intestinal mucosa

Summary With the aid of computerised image-analysis, morphometric techniques were used to measure the volumes of crypt epithelium, with reference to a constant test area (10⁴ µm²) of muscularis mucosae, in untreated and treated celiac sprue mucosae in comparison with four other groups of control jejunal specimens. Crypt epithelial lymphocyte populations were also analyzed in terms of absolute numbers (N), mean nuclear ( _N) and cytoplasmic ( _CYT) diameters, and mean nuclear ( _N) and cell ( _CELL) volumes.Untreated celiac sprue crypts, despite a 3–5 fold increase in volume over control mucosae, contained a markedly expanded population of lymphocytes which was localised predominantly to the upper crypt regions and comprised approximately 6% large lymphocytes ( _N>6 µm: _CYT>9 µm). These changes were entirely reversed by dietary treatment and hence were considered to be gluten-driven.The infiltrate might reflect the expression of gluten receptors on maturing upper crypt enterocytes: but why these lymphocytes do not cause any apparent injury to crypt epithelium (unlike surface epithelium) or influence its well-known compensatory response, remains unclear.Supported by the Medical Research Council, Great Britain and the North Western Regional Health Authority     

Body temperature of huddling newborn Zucker rats

Summary Daily mean core temperature ( ) in huddling Zucker rat pups reared at 25°C revealed the onset of a significantly lower in fa/fa pups on day 6. The difference between any pup's and the mean of that half of the litter with the highest on any given day was an early marker for genotype. Calculating the mean difference for any 2 consecutive days from day 6 onwards gave values for each fa/fa pup that were outside the 99% confidence limits for the individual observations in the Fa/-pups.     

Factors which alter the relationship between ventilation and carbon dioxide production during exercise in normal subjects

The slope of the linear relationship between ventilation and carbon dioxide production has been thought to indicate that is one of the major stimuli to . A group of 15 normal subjects undertook different incremental treadmill exercise protocols to explore the relationship between and . An incremental protocol using 1 instead of 3-min stages of exercise resulted in an increase in the to ratio [26.84 (SEM 1.23) vs 31.08 (SEM 1.36) (P < 0.008) for the first stage, 25.24 (SEM 0.86) vs 27.83 (SEM 0.91) (P < 0.005) for the second stage and 23.90 (SEM 0.86) vs 26.34 (SEM 0.81) (P = 0.001) for the third stage]. Voluntary hyperventilation to double the control level of during exercise resulted in an increase in the to slope [from 21.3 (SEM 0.71) for the control run to 35.1 (SEM 1.2) for the hyperventilation run (P < 0.001)]. Prolonged hyperventilation (5 min) during exercise at stage 2 of the Bruce protocol resulted in a continuted elevation of and the slope. A steady state of and metabolic gas exchange can only be said to have been present after at least 3 min of exercise. Voluntary hyperventilation increased the slope of the relationship between and . End-tidal carbon dioxide fell, but remained within the normal range. These results would suggest that a non-carbon dioxide factor may have been responsible for the increase we found in during exercise, and that factors other than increased dead space ventilation can cause an increased ventilation to slope, such as that seen in some pathophysiological conditions, such as chronic heart failure.     

Effect of coupling the breathing- and cycling rhythms on oxygen uptake during bicycle ergometry

Summary The influence of the degree of coupling between the breathing and cycling rhythms (K) on oxygen uptake was examined in 30 volunteers. They cycled on an ergometer with a load equal to 50% of their work capacity 170 in two experimental runs with spontaneous breathing rhythm, and in a further two runs with acoustically triggered breathing. K was continuously ascertained. and other respiratory parameters were measured by an automatic breath-by-breath analysis system.In 16 subjects, -differences between runs were correlated with the differences in K. In the majority of these subjects (12), decreased significantly with increasing K. In 14 subjects, -and K-variations within individual runs were analyzed. Phases with higher K were regularly accompanied by a decrease in .It is concluded that coupling the breathing and cycling rhythms reduces for a given moderate work load, although the magnitude of the -reduction varies considerably between individuals.     

Ventilatory response during incremental exercise tests in weight lifters and endurance cyclists

Summary The effect of a progressively increasing work rate (15 W·min^–1) up to exhaustion on the time course of O₂ uptake ( ), ventilation ( ) and heart rate (HR) has been studied in weight lifters (WL) in comparison to endurance cyclists (Cycl) and sedentary controls (Sed). and were measured as average value of 30-s intervals by a semiautomatic open circuit method. was 2.55±0.33; 4.29±0.53 and 2.86±0.19·min^–1 in WL, Cycl and Sed respectively. With time and work rate, while and HR increased linearly, changed its slope at two levels. The 1st change occured at a work load corresponding to a mean (± SD) of 1.50±0.26; 1.93±0.34; and 1.23±0.14 l·min^–1 in WL, Cycl, and Sed respectively. values corresponding to the second change of slope were 2.18±0.32 in WL; 3.48±0.53 in Cycl and 2.17±0.28 l·min^–1 in Sed. The first change of slope might be the consequence of the different readjustment of on-response and hence of early lactate in the different subjects. The second change seems to be comparable to the conventional anaerobic threshold and is achieved in all subjects when vs time slope is 7–10 l·min^–1/min of exercise.This work has been supported in part by a grant from the Italian National Research Council (CNR)     

Influence of lifting technique on perceptual and cardiovascular responses to submaximal repetitive lifting

Oxygen consumption ( O₂), heart rate, ventilation and central rating of perceived exertion (RPE) in repetitive lifting while executing squat and stoop techniques were investigated in ten male forestry workers. In all five mass/frequency combinations studied, O₂ was significantly higher for the squat than for the stoop technique. No differences were found in RPE between the techniques. The O₂ and RPE recordings were also related to those obtained during maximal repetitive lifting (same lifting technique) and maximal treadmill running. The O₂ expressed as a percentage of that obtained during maximal repetitive lifting with the same lifting technique was defined as relative aerobic intensity (% O_{2max, lifting}). The % O_{2max, lifting} was not significantly different between the techniques except for the lowest mass lifted (1 kg). This study therefore would support the hypothesis that RPE is more closely related to % O_{2max, lifting} than to absolute aerobic intensity. Related to maximal treadmill running, it was demonstrated for both lifting techniques that relative RPE (percentage of the RPE during maximal running) was more accurate than relative O₂ (percentage of maximal O₂ during maximal running) for determining the % O_{2max, lifting} in repetitive lifting. The study showed that the higher O₂ during squat. lifting compared to stoop lifting was caused by the O₂ expended in lifting and lowering the body rather than the O₂ expended lifting and lowering the external mass. It was concluded that the stoop technique was not superior to the squat technique in terms of central RPE. Based on % O_{2max, lifting}, there may be a rationale for choosing the stoop technique during repetitive lifting with light masses, but not with heavy masses.     

Physiological correlates of middle-distance running performance

Summary To compare the relative contributions of their functional capacities to performance in relation to sex, two groups of middle-distance runners (24 men and 14 women) were selected on the basis of performances over 1500-m and 3000-m running races. To be selected for the study, the average running velocity ( ) in relation to performances had to be superior to a percentage (90% for men and 88% for women) of the best French achieved during the season by an athlete of the same sex. Maximal O₂ consumption ( _max) and energy cost of running (C_R) were measured in the 2 months preceding the track season. This allowed us to calculate the maximal that could be sustained under aerobic conditions, _a,max. A : _{a, max} ratio derived from 1500-m to 3000-m races was used to calculate the maximal duration of a competitive race for which = _a,max (t a,max) In both groups _a,max was correlated to . The relationships calculated for each distance were similar in both sexes. The C_R [0.179 (SD 0.010) ml · kg^–1 · m^–1 in the women versus 0.177 (SD 0.010) in the men] andt _a,max [7.0 (SD 2.0) min versus 8.4 (SD 2.1)] also showed no difference. The relationships between _max and body mass (m _b) calculated in the men and the women were different. At the samem _b the women had a 10% lower C_R than the men; their lowerm _b thus resulted in an identical C_R. In both groups C_R and _max were strongly correlated (r=0.74 and 0.75 respectively,P<0.01), suggesting that a high level of _max could hardly be associated with a low C_R. These relationships were different in the two groups (P<0.05). At the same _max the men had a higher _a,inax than the women. Thus, the disparity in track performances between the two sexes could be attributed to _max and to the _max/C_R relationships.     

Aerobic power and pubertal peak height velocity in Belgian boys

Summary To determine the cardiorespiratory response to maximal exercise before, during and after the pubescent growth spurt, thirty boys were tested at yearly intervals over a period of six consecutive years. For each individual, peak height velocity (PHV) was determined. The age at PHV (¯X= 13.6 years) was taken as a standard of maturation. The results from all subjects at 1.5 and 0.5 years before and 0.5 and 1.5 years after PHV are presented. The highest oxygen uptake ( ) obtained during an incremental bicycle ergometer test to voluntary exhaustion was taken as peak oxygen uptake ( peak). Across each of the four years studied, mean peak (min=49.6; max=52.5 ml·kg^–1·min^–1) and mean heart rate (HR) at peak (min=190; max=192) did not change significantly as a function of PHV. On the other hand, the respiratory quotient at peak increased considerably from mean minima and maxima of 0.99 and 1.01 before PHV to 1.07 and 1.10 after PHV. Ventilatory equivalent for ( ), taken as an indicator of ventilatory economy, seemed to be unaffected by the maturation process. The steepest increase in circumpubertal oxygen pulse was found one year after PHV. Average stability coefficients (¯r), calculated from the inter-years correlations were high for height (¯r=0.95), weight (¯r=0.92), HR at peak (¯r=0.74), peak in 1/min (¯r=0.71), oxygen pulse (¯r=0.68) and tidal volume (¯r=0.64).     

Cardiac chemical power: 2 Application of chemical power,work and efficiency equations to characterise left ventricular energetics in man

Thirty patients have been evaluated using single-plane left ventricular cineangiography and the contractile filament stress history, contractile element velocity history, and extrapolated V_max were obtained. Peak chemical power ( ), endcycle chemical work ( ) and average efficiency ( ) for the circumferential (θ) and longitudinal (ϕ) directions were computed. For 11 normal patients was 84·9±25·8 mJ (cycle)⁻¹ cm⁻³ and was 0·48±0·03, There was no significant difference between these values and five compensated volume overload patients. For six decompensated volume overload patients, and were significantly elevated (p<0·025, p<0·05, respectively) and significantly reduced (p<0·025). Peak mechanical stress-velocity power was maintained near normal limits, indicating that the basic defect was a poor coupling of chemical power generated to mechanical power output. For two compensated pressure overload patients, was significantly elevated (p<0·025), but was individually reduced below normal values, indicating that essentially no additional safety margin remained for compensation. Finally, the six congestive cardiomyopathy patients exhibited a reciprocal relationship between chemical power/work and efficiency.     

Are oxygen uptake kinetics at the onset of exercise speeded up by local metabolic status in active muscles?

To assess the rate-limiting factor of oxygen uptake ( ) kinetics at the onset of exercise, six healthy male sedentary subjects performed repeated one-legged constant-load cycle exercise. The one-legged constant-load exercise test consisted of two 5-min periods of pedalling at an exercise intensity of 50 W, with a 5-min rest between periods (these exercise periods, i.e. first and second exercises, were performed by the same leg). The exercise was then repeated using the other leg. In addition, two-legged incremental exercise was investigated to establish whether kinetics were affected by slower heart rate kinetics. The incremental exercise test consisted of two-legged pedalling first with the cycle unloaded as a warm-up for 5 min followed by 50-W exercise for 5 min. The exercise intensity was then increased to 100 W for 5 min. During exercise, gas exchange parameters were determined by the breath-by-breath method and cardiac output ( ) was determined continuously by an impedance technique with a computer-based automated system. To determine the kinetics of heart rate (HR), and , a best fit procedure was employed using least-squares criteria with a time delay, except during the initial increase. During the one-legged constant-load exercise test, kinetics were significantly accelerated by repeated exercise using the same leg. On the other hand, when the exercise was changed to the other leg, kinetics were significantly slower, although kinetics continued to be faster. During the incremental exercise test, although the HR response was slower at the transition from 50-W to 100-W exercise than at the transition from warm-up to 50-W exercise, there were no significant changes in kinetics. These findings suggest that kinetics may be affected by metabolic conditions in the muscle, but not by blood flow ( and/or HR) kinetics.     

Das Thrombocyten-Metamorphogramm (TMG) zur Beurteilung von Adhäsions- und Evolutionsneigung während der Geburtsphasen

Zusammenfassung Die Prüfung der Ausbreitungsfähigkeit der Blutplättchen mit Phasenkontrastmikroskopie auf genormten Zaponlackfolien bei 10 gesunden weiblichen Personen mit drei Blutentnahmen im Abstand von je 10 min ergibt einen niedrigen methodischen Fehler vons =±1,41 bei =61,41%. Bei 25 Gebärenden tritt keine statistisch zu sichernde Änderung der Evolutionsfunktion während der Geburtsphasen ein. Der erniedrigte Mittelwert bei Kreißenden von =54,91%,s =±1,81 (p=0,001), kann durch altersbedingte Streuung, zum anderen durch die Gestation selbst bedingt sein.

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Summary The capability of platelets to spread out on standard zapon foils was investigated by phase contrast microscopy in 10 normal female subjects. The methodological standard deviations in 3 blood samples withdrawn in 10 minutes intervals was found to be low (s =±1.41 whereas =61.41%). During different phases of labour (25 women) no significant change in the evolution function could be demonstrated by statistical methods. In these women under labour the mean value was decreased ( =54.91% whereass =±1.81;p=0.001). This might be due to either deviation of age groups or to gestation itself.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Pulmonary gas exchange and ventilatory responses to brief intense intermittent exercise in young trained and untrained adults

To investigate pulmonary gas exchange and ventilatory responses to brief intense intermittent exercise and to study the effects of physical fitness on thes responses, nine trained and nine untrained healthy male subjects aged 18–33 years performed the force-velocity (F-) exercise test. This test consisted of 6-s sprints against increasing braking forces (F) separated by 5-min recovery periods. Oxygen uptake ( ), carbon dioxide output ( CO₂), and ventilation _E) were continuously measured during the test and the magnitudes of their responses to the sprints were then calculated.For all subjects CO₂ increased rapidly after beginning the sprints, and the peaks of the responses (F = 13.4;P < 0.001), end of recovery values (F = 6.5;P < 0.01), and O₂ magnitudes of response (F = 12.4;P < 0.001) rose significantly with the repetition of the sprints. The O₂ magnitudes of response correlated with the corresponding sprint power outputs (r = 0.55;P < 0.001) and with the sprint repetitions (r = 0.51,P < 0.001). The CO₂ (F = 7.1;P < 0.01) and {ie442-8} (F = 5.0;P < 0.01) peaks of response increased with the initial load incrementation, then stabilized when the subjects attained peak power output. End of recovery CO₂ (F = 18.0;P < 0.001) and _E (F = 14.1;P < 0.001) values rose with increasingF. TheF- peak O₂, CO₂, _E, tidal volume and respiratory frequency responses attained 53%, 40%, 44%, 66%, and 82% of the peak values measured at exhaustion of maximal graded exercise, respectively.Trained and untrained subjects had the same first sprint power output and braking, force. Nevertheless, the trained subjects had higher O₂ peaks (F = 35.2;P < 0.001) and CO₂ magnitudes of response (F = 30.0;P < 0.001) than the untrained subjects for all sprints. The higher peak O₂ values represented similar percentages of maximal oxygen uptake in the trained and untrained subjects. In summary, the present study showed that in brief intense intermittent exercise, i.e. theF- test, the O₂, CO₂, and ventilatory responses in young subjects were submaximal with respect to the peak values attained at exhaustion of maximal graded exercise. The CO₂ magnitude of response increase was related to the power output rise in the corresponding sprints and to the repetition of sprints. Moreover, the trained subjects presented higher CO₂ peaks and magnitudes of response to the sprints than the untrained subjects.     

Association between heart rate variability and training response in sedentary middle-aged men

The effect of exercise training on heart rate variability (HRV) and improvements in peak oxygen consumption ( _peak) was examined in sedentary middle-aged men. The HRV and absolute and relative _peak of training (n = 19) and control (n = 15) subjects were assessed before and after a 24-session moderate intensity exercise training programme. Results indicated that with exercise training there was a significantly increased absolute and relative _peak (P < 0.005) for the training group (12% and 11% respectively) with no increase for the control group. The training group also displayed a significant reduction in resting heart rate; however, HRV remained unchanged. The trained subjects were further categorized into high (n = 5) and low (n = 5) HRV groups and changes in _peak were compared. Improvements in both absolute and relative _peak were significantly greater (P > 0.005) in the high HRV group (17% and 20% respectively) compared to the low HRV group (6% and 1% respectively). The groups did not differ in mean age, pretraining oxygen consumption, or resting heart rate. These results would seem to suggest that a short aerobic training programme does not alter HRV in middle-aged men. Individual differences in HRV, however, may be associated with _peak response to aerobic training.     

The influence of inspired oxygen on the oxygen uptake response to ramp exercise

The relation between and work rate (WR) was examined in seven male subjects who performed ramp (1 W·3 s^–1) two-legged cycle ergometry to exhaustion while inspiring either hypoxic (12% O₂), normoxic (21% O₂), or hyperoxic (40% O₂) air. The anaerobic threshold was estimated from respiratory gas exchange data and is thus referred to as the respiratory gas exchange threshold (RGET). Prior to the RGET, the was greater under normoxic [mean (SD); 10. 19(1.04) ml O₂·min^–1·W^–1] and hyperoxic [10.44 (0.72)] conditions compared with hypoxia [9.34 (0.89)]. Above the RGET, the for hypoxia [8.91 (0.63)], normoxia [10.40 (0.77)], and hyperoxia [11.08 (0.48)] were all significantly different from each other. These data indicated that for two-legged, cycle, ramp ergometry in normoxia below the RGET, both the and response time was constant. Above the RGET, the normoxic response was the net result of a declining and a longer response time to the unsteady state character of a ramp exercise protocol.     

Der pulmonale Gaswechsel in der späten Rehabilitationsphase des Myokardinfarktes

Zusammenfassung In der späten Rehabilitationsphase nach Myokardinfarkt (13–25 Monate p. infarctum) wurde die Lungenfunktion von 23 Patienten in Ruhe untersucht. Spirometrische Werte und Parameter des pulmonalen Gaswechsels zeigen änderungen, die ursächlich mit einer pathologischen linksventriculären Funktion verbunden sind. Die arteriellen Sauerstoffpartialdrucke liegen im unteren Normbereich ( =74,5±5,9 die ( =33,6±7.7 Torr) ist erhöht, ebenso die ( =8,6±3,7 Torr), der ein großer Alveolartotraum entspricht. Der arterielle Kohlensäurepartialdruck liegt im normoventilatorischen Bereich ( =40,6±2,5 Torr). 9 Patienten wiesen gemischtvenöse Sauerstoffpartialdrucke und Herzzeitvolumina auf, die eine Herzinsuffizienz annehmen ließen. Für eine Reihe in Ruhe bestimmter pulmonaler Parameter ließ sich durch Korrelation eine Abhängigkeit von der jeweiligen Belastbarkeit des Patienten sichern.Mit Unterstützung der Deutschen Forschungsgemeinschaft, SFB 36.     

Effects of training at and above the lactate threshold on the lactate threshold and maximal oxygen uptake

Summary Thirty-three college women (mean age=21.8 years) participated in a 5 d·wk^–1, 12 week training program. Subjects were randomly assigned to 3 groups, above lactate threshold (> LT) (N=11; trained at 69 watts above the workload associated with LT), =LT (N=12; trained at the work load associated with LT) and control (C) (N=10). Subjects were assessed for , LT, LT/ , before and after training, using a discontinuous 3 min incremental (starting at 0 watts increasing 34 watts each work load) protocol on a cycle ergometer (Monark). Respiratory gas exchange measures were determined using standard open circuit spirometry while LT was determined from blood samples taken immediately following each work load from an indwelling venous catheter located in the back of a heated hand. Body composition parameters were determined before and after training via hydrostatic weighing. Training work loads were equated so that each subject expended approximately 1465 kJ per training session (Monark cycle ergometer) regardless of training intensity. Pretraining, no significant differences existed between groups for any variable. Post training the > LT group had significantly higher (13%), (47%) and LT/ (33%) values as compared to C (p<.05). Within group comparisons revealed that none of the groups significantly changed as a result of training, only the > LT group showed a significant increase in (48%) (p<.05), while both the = LT and > LT group showed significant increases in LT/ (= LT 16%, > LT 42% (p<.05)). No differences were found between or within groups post training for body composition parameters. It was concluded that training above the LT results in an improvement in LT and that large improvements in may not be required for large improvements in .Data were collected at the Human Performance Laboratory, University of Colorado     

Times to exhaustion at 100% of velocity at\dot V{\text{O}}_{\text{2}} max and modelling of the time-limit / velocity relationship in elite long-distance runners

The aim of this study was to measure running times to exhaustion (Tlim) on a treadmill at 100% of the minimum velocity which elicits _{max max} in 38 elite male long - distance runners _max = 71.4 ± 5.5 ml.kg^–1.min^–1 and _max = 21.8 ± 1.2 km.h^–1). The lactate threshold (LT) was defined as a starting point of accelerated lactate accumulation around 4 mM and was expressed in _max. Tlim value was negatively correlated with _max (r = -0.362, p< 0.05) and _max (r = –0.347, p< 0.05) but positively with LT (%v _max) (r = 0.378, p < 0.05). These data demonstrate that running time to exhaustion at _max in a homogeneous group of elite male long-distance runners was inversely related to _max and experimentally illustrates the model of Monod and Scherrer regarding the time limit-velocity relationship adapted from local exercise for running by Hughson et al. (1984) .     

Immunsuppressives saures Protein bei schwangeren Frauen und bei Patientinnen mit Ovarialkarzinom

Summary Serum levels of immunosuppressive acidic protein (IAP) were determined in 48 healthy controls (age: years) and 72 pregnant women (age: ). The mean value of IAP in pregnant women (345.3±94.4 µg/ml) was significantly lower than that of the healthy control group (P<0.0001; 452.0±95.0 µg/ml). Correlated to the clinical status were 207 IAP serum values of 63 patients with ovarian cancer (age: ).The mean value of patients with tumor progression ( ) was significantly increased compared to those of patients in remission ( ) and the control group ( ;P<0.0001). However, no significant difference of the IAP levels was found between the group in remission and the healthy controls. With a threshold value of 640 µg/ml we found right-negative values in 88.7% and right-positive values in 65.1% during the follow-up of patients with ovarian cancer.

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Abkürzungsverzeichnis IAP Immunosuppressive Acidic Protein     

Biologische Halbwertzeit und Stoffwechsel-Umsatzrate des Gesamtk?rper-Eisen-Pools bei Lebercirrhose und portaler Hypertension

Zusammenfassung Bei Patienten mit Lebercirrhose mit bzw. ohne portocavaler Anastomose und Patienten mit portaler Hypertension und normaler Leberfunktion wurde die Gesamtkörperretention des resorbierten⁵⁹Fe in einem 4-Großraum-Radioaktivitäts-Detektor mit flüssigem organischem Szintillator bestimmt. Aus der über den Zeitraum von 170 Tagen gemessenen⁵⁹Fe-Gesamtkörperretention wurde für die Patienten mit Lebercirrhose und angelegter portocavaler Anastomose eine biologische Halbwertszeit von 1004±422 ( ±s) Tagen entsprechend einer relativen⁵⁹Fe-Umsatzrate von 0,069±0,029 ( ±s) %/Tag berechnet. Bei den Patienten mit Lebercirrhose ohne portocavale Anastomose wurde eine damit praktisch übereinstimmende biologische Halbwertszeit von 1018±404 ( ±s) Tagen entsprechend einer relativen⁵⁹Fe-Umsatzrate von 0,068±0,027 ( ±s) %/Tag ermittelt. Die bei Patienten mit Lebercirrhose (ohne oder mit portocavaler Anastomose) auf das Zehnfache der Norm heraufgesetzte intestinale Eisenresorption sowie die auf die Hälfte der Norm herabgesetzte Gesamtkörper-Umsatzrate (=Exkretion) des resorbierten Eisens erklären die bei Patienten mit Lebercirrhose häufig sich ausbildende Hämochromatose.

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Biological half life and metabolic turnover rate of the whole body iron pool in patients with liver cirrhosis and portal hypertension

Summary The whole body retention of absorbed⁵⁹Fe was measured over a period of 170 days with a 4 large volume radioactivity detector with liquid organic scintillator in patients with liver cirrhosis (with and without a portacaval shunt) as well as in patients with portal hypertension and normal liver function. From the estimated⁵⁹Fe whole body retention a biological half life of 1004±422 ( ±s) days and a relative⁵⁹Fe turnover rate of 0.069±0.029 ( ±s) %/day was calculated for the patients with liver cirrhosis and a portacaval shunt. An identical biological half life of 1018±404 ( ±s) days and relative⁵⁹Fe turnover rate of 0.068±0.027 ( ±s) %/day was measured in patients with liver cirrhosis without a portacaval shunt. The intestinal iron absorption is increased tenfold and the relative whole body⁵⁹Fe-turnover rate (=excretion) is reduced to 50% of the normal value in patients with liver cirrhosis independent of the existence of a portacaval anastomosis. These results may explain the development of haemochromatosis in patients with liver cirrhosis.

     

Changes in ventilation at the start and end of moderate and heavy exercise of short and long duration

Summary These experiments examined the effect of exercise intensity and duration on the magnitude of the abrupt change in ventilation at the start ( ) and end ( ) of exercise. Five subjects performed constant load treadmill exercise at 50% and 80% of their maximum oxygen consumption ( ) for 6 and 10 min while inspiring atmospheric air. The subjects also completed additional exercise tests at 80% for 10 min while inspiring an oxygen-enriched gas mixture. During each exercise trial ventilation was measured breath-by-breath. The and were determined by using non-linear curve-fitting techniques. The results showed that was greater at the start of the 80-% exercise tests compared to the 50-% tests and that at each level of exercise was greater than . The results also demonstrated that was inversely related to the intensity and duration of exercise. Furthermore, the was not altered subsequent to the inspiration of oxygen-enriched air. These findings have led us to postulate that the stimulus responsible for is reduced during exercise and that the degree of reduction is related to the intensity and duration of exercise. In addition, it was concluded that these changes might occur independently of peripheral chemoreceptor activity.