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Biomedical subjects

H Howald

Publications and source records attributed to H Howald.

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

Is excessive running predictive of degenerative hip disease? Controlled study of former elite athletes.

OBJECTIVE: To determine the effects of regular long distance running on the state of the hips in later life. DESIGN: Retrospective study of a cohort of elite athletes and a group of normal, healthy, untrained controls examined 15 years after initial testing. SETTING: Research project at school for physical education and sports. SUBJECTS: 27 Former long distance runners (mean age 42), nine former bobsleigh riders (mean age 42), and 23 normal, healthy, untrained men (mean age 35) who had been examined in 1973 and who agreed to re-examination in 1988. MAIN OUTCOME MEASURE: Radiological evidence of degenerative hip disease in 1988. RESULTS: Physiological and exercise characteristics of all subjects had been recorded in 1973, and in 1988 these measurements were repeated together with radiological examination of the hips. An additive radiological index of hip disease based on grades of subchondral sclerosis, osteophyte formation, and joint space narrowing was significantly increased among runners as compared with bobsleigh riders and untrained controls. After adjustment for age the significant effect of type of sports activity remained (p = 0.032). In multivariate analyses age and milage run in 1973 (97 km/week) emerged as independent, significant, and positive predictors of radiological signs of degenerative hip disease in 1988 (p = 0.017 and p = 0.024 respectively). Among runners alone running pace in 1973 rather than milage run was the stronger predictor of subsequent degenerative hip disease. The milage run in 1988 was not particularly predictive of the radiological index, but endurance in 1988 was inversely related to degenerative hip disease seen radiologically. CONCLUSION: Long term, high intensity, high milage running should not be dismissed as a potential risk factor for premature osteoarthritis of the hip.

Age Factors↗
PubMed1989

Growth and pubertal development of young female gymnasts and swimmers: a correlation with parental data.

Whereas intensive and regular physical training is known to alter female reproductive function, its potential role in growth is still controversial. At the beginning of a longitudinal growth study of young elite female gymnasts (n = 34, 15-25 h/wk training) and moderately trained swimmers (n = 19, 5-15 h/wk), patterns of recalled parental growth and pubertal maturation were compared with those of parents of 25 sedentary school girls. These data were also correlated to the height, weight, pubertal development as well as adult height prognosis of their daughters. Bone age was estimated using the methods of Greulich-Pyle and Tanner (RUS score) and adult height prognosis using the methods of Bayley-Pinneau (BP), Roche-Wainer-Thissen (RWT), and Tanner et al. (TW2). Parents of gymnasts were significantly lighter (fathers: P = 0.027; mothers: P = 0.038) and shorter (fathers: P = 0.034; mothers: P less than 0.001) than those of swimmers and controls. Consequently, target heights of gymnasts were also significantly shorter (P less than 0.001). Recalled menarche occurred significantly later (P = 0.030) in mothers of gymnasts who, in turn, grow much alike their mothers. At the first visit, the gymnasts were shorter and lighter for age than swimmers and controls. Their bone age (11.0 +/- 1.3 years, mean +/- SD) was retarded (P less than 0.001) when compared with chronological age (12.6 +/- 1.2 years). Adult height prognosis was lower for gymnasts than for other girls (BP: P less than 0.001; RWT: P = 0.023, TW2: P less than 0.001), but adequate for target height range.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Determination by Skeleton↗
PubMed1989

Circulatory counter-regulations induced by continuous administration of nitroglycerin.

In a placebo-controlled, double-blind, cross-over study in seven healthy volunteers, continuous transdermal administration of nitroglycerin over 48 h by means of Nitroderm TTS 10 evoked counter-regulations that interfered with the nitrate effects. These counter-regulations comprised an increase in sympathico-adrenal activity, manifested in elevated plasma levels of adrenaline and noradrenaline, and an internal hemodilution, readily perceptible from the decrease in the hematocrit readings. As a result, several of the circulatory effects of nitroglycerin were no longer in evidence, or much weaker on the second day of the study. The effects concerned were the reduction of systolic and diastolic blood pressure, the increase in heart rate, the prolongation of PEPc, and shortening of LVETc, and the change in digital-pulse morphology (increase in the a/b quotient). On the other hand, the increase in venous distensibility and the decrease in hematocrit were unaltered throughout the observation period. The attenuation of the action of nitroglycerin noticeable 24 h after application of the patches is, therefore, not indicative of any loss of effect of the substance per se, but due to the circulatory counter-regulations, which were largely confined to the arterial side of the circulation and scarcely affected the venous system. One or two hours after removal of the patches, counter-regulations had practically ceased.

Administration, Topical↗
PubMed1988

Qualitative changes of white blood cells and perinatal diagnosis of infection in high-risk preterm infants.

A total of 60 preterm infants, aged less than 37 weeks of gestation were studied. Morphological changes of polymorphonuclear neutrophils (PMN) were evaluated in two groups of patients. PMN vacuolization was frequently noted at birth in preterm neonates with culture-proven infection (sensitivity 86%, specificity 90%). Toxic granulations were a less reliable indicator of bacterial infection. A relatively good correlation with other parameters in use for "sepsis screen" we found with band cell/total neutrophil ratio (X2 = 1.66, P greater than 0.1). Examination of peripheral blood smears for vacuolization of WBCs appears to provide adjunct in the early detection of bacterial infection in preterm babies.

Cytoplasmic Granules↗
PubMed1987

Exercise training induces transitions of myosin isoform subunits within histochemically typed human muscle fibres.

Fibre type composition based on histochemical myosin ATPase reaction was studied in cross sections of biopsies from the vastus lateralis muscle of men. In addition, protein composition as well as peptide patterns of isolated myosin heavy chains were examined in batches of individually classified fibres from the same biopsies. High intensity endurance training during 8 weeks induces significant decreases by 31-70% of the type IIB fibre population in 3 of 4 subjects (in one case no change was observed). These decreases were offset by corresponding increases in either type I or type IIA fibres with the type IIC fibres remaining always below 3%. A total of 13 professional cyclists with training periods over several years have a 20 times lower content of type IIB fibres than 4 sedentary controls and a concomitant high content of 80% of type I fibres. The content of type I and type IIB fibres of 8 sprinter athletes did almost not differ from that of controls. Thus the type IIB fibres respond most sensitively with a decrease to aerobic endurance training. Since both type IIA and IIB fibres were identical in protein composition containing the same fast variety of myosin light chains and heavy chains as well as troponin-I, their interconversion could not be seen at the molecular level. However, the slow variety of myosin light chains and of troponin-I started accumulating after 8 weeks of training in type IIA fibres. Furthermore, the myosin heavy chain isoform started shifting by producing new peptide patterns that resemble the digestion pattern of slow myosin heavy chains in fibres which still classified as type IIA. These changes on the molecular level in type IIA fibres mark the beginning of their transition over the intermediate and variable type IIC fibres, towards the slow type I fibre.

Adult↗
PubMed1987

Fetal sex and distribution of peri-intraventricular hemorrhage in preterm infants.

Peri-intraventricular hemorrhage (PIVH) is an important complication of the brain in immature newborn infants. In a real-time ultrasound study with frequent scanning of 78 preterm infants (50 with birth-weight less than 1,500 g and 28 weighing more than 1,500 g), we examined the influence of sex on the occurrence of PIVH. A significant difference between sexes was only found in the group with birth-weight below 1,500 g. PIVH occurred in 72% of male infants and in 28% of females (p less than 0.001). This effect is probably due to a difference in the timing of cerebral vascular maturation in males leading to a difference in the risk of developing PIVH between the sexes before 34 weeks of gestation.

Cerebral Hemorrhage↗
PubMed1987

Impact of physical training on the ultrastructure of midthigh muscle in normal subjects and in patients treated with glucocorticoids.

Exercise-training might be a logical method to reverse muscle atrophy and weakness in patients treated with glucocorticoids. The purpose of the present investigation was to establish whether a treatment with low dose prednisone (10 +/- 2.9 mg/d) modulates the effect of a moderate strength type isokinetic training during 7 wk (21 sessions of 20 min) on "muscle efficiency" (power output/muscle mass) and on concomitant changes in ultrastructure of the thigh muscle measured by quantitative electron-microscopic morphometry. Training caused a similar increase in "muscle efficiency" in patients on prednisone (n = 9) as in normal volunteers (n = 9). In normal subjects the increase in muscle efficiency was associated with an increase in sarcoplasm, whereas in patients on prednisone the functional improvement was associated with an increase in sarcoplasm, capillaries, and mitochondria content. Thus, a therapy with low dose prednisone does not abrogate training-induced improvement of muscle efficiency but modulates the ultrastructural response of the muscle to the training.

Exercise Therapy↗
PubMed1987

Incidence of peri-intraventricular hemorrhage in premature neonates weighing more than 1500 g.

With the advent of modern methods of neonatal care, intracranial hemorrhage probably has become the most common neurological complication in premature infants weighing less than 1500 g at birth. This paper is a prospective study of 75 preterm infants of 34 weeks gestation or more and birth weight above 1500 g (range 1500 g to 2500 g). All neonates were screened by cranial ultra-sonography for evidence of peri-intraventricular hemorrhage (PIVH). Perinatal risk factors, incidence of PIVH and neurological outcome were studied. Sonographic abnormalities were detected in 16 (21.3%) of our patients. Intracranial hemorrhage was frequently associated with a low Apgar score, need of resuscitation and/or assisted ventilation immediately after birth (P less than 0.005). This study suggests, that ultrasound screening should be reserved to those large premature infants (greater than 1500 g) with high risk of hypoxic-ischemic injury.

Birth Weight↗
PubMed1986

Acute effects of endurance exercise on mitochondrial distribution and skeletal muscle morphology.

Biopsies of vastus lateralis from seven well-trained males were studied 1 month before and 15-30 min after a 100-km race. The distribution of interfibrillar mitochondria was analyzed to determine whether a long bout of exercise induced a redistribution of mitochondria. Capillary densities and mean fiber areas were also estimated. Capillary density and mean interfibrillar mitochondrial volume density were found to be significantly correlated with running time in the race. An earlier study on these biopsies found that the mean volume densities of interfibrillar and subsarcolemmal mitochondria did not change after a race, but the volume densities of lipid droplets and interfibrillar glycogen decreased significantly. In the present study, volume density of interfibrillar mitochondria [Vv(mi,fim)] before the race was highest with a value of 0.098 +/- 0.007 near the fiber border, and decreased progressively with distance to 0.045 +/- 0.004 at the fiber center. After the race, Vv(mi,fim) was unchanged at the fiber border, but was significantly higher (0.062 +/- 0.005) in the center of the fiber. This increase in mitochondrial volume density was attributable to the shrinkage of the fibers from consumption of energy stores, which was relatively greater for interfibrillar glycogen than for subsarcolemmal glycogen. Thus the primary effect of this extended bout of endurance exercise on vastus lateralis was the nearly complete depletion of the interfibrillar glycogen and lipids, but there was no evidence of an acute redistribution of mitochondria.

Adult↗
PubMed1986

Altered skeletal muscle ultrastructure in renal transplant patients on prednisone.

Treatment with glucocorticoids causes wasting of proximal skeletal muscles. The purpose of the present investigation was to quantify in the thigh muscle the areas of the different fiber types determined by histochemical methods, and the muscle ultrastructure by means of electron microscopy, in normal subjects (N = 41) and in renal transplant patients treated with prednisone (N = 12). The cross-sectional area of all three fiber types was reduced in renal transplant patients treated with prednisone (10.6 +/- 4.3 mg/day), the fast glycolytic fibers being most affected (slow oxidative fibers: 2642 +/- 625 vs. 3677 +/- 970 micron2, P less than 0.001; fast oxidative fibers: 3275 +/- 735 vs. 4443 +/- 1343 micron2, P less than 0.01; fast glycolytic fibers: 2305 +/- 802 vs. 3920 +/- 1522 micron2, P less than 0.001). This was mostly due to a decrease in the volume of myofibrils per unit volume of muscle fiber (-30%). The intracellular lipid content and the volume density of subsarcolemmal mitochondria were increased by more than 70% in prednisone treated patients. In conclusion, the decreased myofibril areas might account for the muscle weakness in renal transplant patients treated with prednisone, and the decrease in myofibrils is in part functionally compensated by an increase in subsarcolemmal mitochondria and intracellular lipid content.

Adult↗
PubMed1986

Structural changes in skeletal muscle tissue with heavy-resistance exercise.

Muscle strength, muscle cross-sectional area, fiber size, fiber type distribution, capillarity, and mitochondrial volume were estimated before and after 6 weeks of heavy-resistance exercise. Isokinetic torque production of the knee extensor muscles increased by a total of 17.6%, mainly during the first half of the training period. The cross-sectional area of the vastus lateralis muscle increased by 8.4%, mainly during the second half of the training period. Morphometrically determined fiber size, fiber type distribution, and capillarity from biopsies of vastus lateralis did not change significantly with training. Likewise, the surface densities of inner and outer mitochondrial membranes as well as the volume density of myofibrils remained unchanged. In contrast, the volume density of mitochondria decreased by 9.6%. However, due to the increase in total muscle volume, the calculated absolute volume of mitochondria remained constant, whereas the absolute volume of myofibrils increased by 10%. It is concluded that strength training of short duration in previously untrained young male subjects does not change the ultrastructural composition of mitochondria and that the apparent dilution of mitochondria can quantitatively be accounted for by the increase in myofibrillar volume.

Adenosine Triphosphatases↗
PubMed1986

Correlation of raised cord-blood CK-BB and the development of peri-intraventricular hemorrhage in preterm infants.

This study concerns the prognostic value of total cord-blood CK-BB activity measured with a new method in preterm infants at risk of PIVH. Twenty-six patients with gestational age less than 36 weeks were studied. The presence of PIVH was proved by either ultrasound scans or autopsy. Total CK-BB values in cord-blood of infants who developed PIVH were significantly higher than those of patients without cerebral bleeding (P less than 0.001).

Cerebral Hemorrhage↗
PubMed1986

Physiological profile of world-class high-altitude climbers.

The functional characteristics of six world-class high-altitude mountaineers were assessed 2-12 mo after the last high-altitude climb. Each climber on one or several occasions had reached altitudes of 8,500 m or above without supplementary O2. Static and dynamic lung volumes and right and left echocardiographic measurements were found to be within normal limits of sedentary controls (SC). Muscle fiber distribution was 70% type I, 22% type IIa, and 7% type IIb. Mean muscle fiber cross-sectional area was significantly smaller than that of SC (-15%) and of long-distance runners (LDR, -51%). The number of capillaries per unit cross-sectional area was significantly greater than that of SC (+ 40%). Total mitochondrial volume was not significantly different from that of SC, but its subsarcolemmal component was equal to that of LDR. Average maximal O2 consumption was 60 +/- 6 ml X kg-1 X min-1, which is between the values of SC and LDR. Average maximal anaerobic power was 28 +/- 2.5 W X kg-1, which is equal to that of SC and 40% lower that that of competitive high jumpers. All subjects were characterized by resting hyperventilation both in normoxia and in moderate (inspired O2 partial pressure = 77 Torr) hypoxia resulting in higher oxyhemoglobin saturation levels in hypoxia. The ventilatory response to four tidal volumes of pure O2 was similar to that of SC. It is concluded that elite high-altitude climbers do not have physiological adaptations to high altitude that justify their unique performance.

Adaptation, Physiological↗
PubMed1986

Specificity of leg power changes to velocities used in bicycle endurance training.

Increases in leg power production resulting from 8 wk of bicycle endurance training (30 min/day, 5 times/wk) were studied using an isokinetic dynamometer. In addition, biopsies of vastus lateralis were analyzed to characterize muscle ultrastructural changes. Performance increased on the dynamometer specifically near the estimated average knee angular velocity used during the bicycle training (200 degrees/s). Power measurements were made during the first 5 contractions (maximal power: Pmax) and last 5 contractions (final power: Pend) of 25 and 50 consecutive contractions (at 60 and 240 degrees/s, respectively). Pmax and Pend increased only at 240 degrees/s but not at 60 degrees/s. These increases in Pmax (86 W) and Pend (78 W) resulted primarily from longer torque maintenance but also from increased peak torque during each contraction and were close to the increase in mechanical power output maintained on the bicycle (Pb; 78 W) during the training sessions. The specificity of these changes to the angular velocities used in the bicycle training indicates a neural basis to these adaptations. We suggest that these neural adaptations, coupled with the observed enhancement of muscle mitochondrial and capillary density (+41 and +15%, respectively) underlie the increased ability to maintain power production on a bicycle after endurance training.

Adult↗