Search

Three dominant techniques are used for downhill turning in cross-country skiing. In this study, kinematic, kinetic, and temporal characteristics of these techniques are described and related to skier strength and power. Twelve elite female cross-country skiers performed six consecutive turns of standardized geometry while being monitored by a Global Navigation Satellite System. Overall time was used as an indicator of performance. Skiing and turning parameters were determined from skier trajectories; the proportional use of each technique was determined from video analysis. Leg strength and power were determined by isometric squats and countermovement jumps on a force plate. Snow plowing, parallel skidding, and step turning were utilized for all turns. Faster skiers employed less snow plowing and more step turning, more rapid deceleration and earlier initiation of step turning at higher speed ( r = 0.80-0.93; all P < 0.01). Better performance was significantly correlated to higher mean speed and shorter trajectory ( r = 0.99/0.65; both P < 0.05) and to countermovement jump characteristics of peak force, time to peak force, and rate of force development ( r = −0.71/0.78/−0.83; all P < 0.05). In conclusion, faster skiers used step turning to a greater extent and exhibited higher maximal leg power, which enabled them to combine high speeds with shorter trajectories during turns. [ABSTRACT FROM AUTHOR]

Background Interleukin (IL)-20 is a recently discovered cytokine displaying increased levels in psoriatic lesions. Interestingly, IL-20 levels decrease with antipsoriatic treatment, correlating with clinical improvement. However, the role of IL-20 in the aetiology of psoriasis is unknown. Objectives In this study, we investigate the effects both of blocking IL-20 signalling in psoriatic plaques and of adding IL-20 to nonlesional psoriasis skin. Methods We employed the human skin xenograft transplantation model in which psoriatic plaques and nonlesional keratome skin biopsies obtained from donors with moderate to severe plaque psoriasis were transplanted on to immuno-deficient mice. The transplanted mice were treated with anti-IL-20 antibodies or recombinant human IL-20. Results We demonstrate that blocking IL-20 signalling with anti-IL-20 antibodies induces psoriasis resolution and inhibits psoriasis induction. We also demonstrate that continuous IL-20 infusion, together with injection of additional nonactivated leucocytes, promotes induction of psoriasis in nonlesional skin from patients with psoriasis. Conclusions The results suggest that IL-20 plays a critical role in the induction and maintenance of psoriasis, and IL-20 is suggested as a new possible specific target in psoriasis treatment. [ABSTRACT FROM AUTHOR]

Aims To compare levels of insulin antibodies in children and adolescents after initiation of insulin therapy using either insulin aspart (IAsp) or human insulin (HI) in combination with Neutral Protamine Hagedorn (NPH) insulin, and to investigate the relationships between insulin antibodies and HbA1c and insulin dose. Methods IAsp-specific antibodies (IAsp-Ab) and antibodies cross-reacting with HI and IAsp (HI-cross-Ab) were analysed by radioimmunoassay at diagnosis of diabetes and every 3–6 months for 30 months. Seventy-two patients (HI = 30, IAsp = 42) with Type 1 diabetes, aged 2–17 years were included. Data on HbA1c, insulin dose and serious adverse events (SAEs) were collected retrospectively. Results IAsp-Ab levels remained low throughout the study. After 9 months, the level of HI-cross-Ab increased [mean (sd) HI, 48.8% (21.53); IAsp, 40.2% (17.92)] and remained elevated. Repeated measurement analysis of HI-cross-Ab levels showed no significant difference between treatments ( P = 0.16). HI-cross-Ab were significantly associated with total insulin dose (U/kg) ( P = 0.001) and time ( P < 0.0001), but not with HbA1c ( P = 0.24). Mean (± sd) HbA1c was similar at diagnosis (HI 9.5 ± 1.97%; IAsp 9.6 ± 1.62%); HbA1c then decreased and stabilized to about 6.0% in both groups. Few SAEs were reported, the majority being hypoglycaemic episodes. Conclusions Treatment with IAsp and with HI was associated with an increase in HI-cross-Ab in insulin-naive children, but this did not influence treatment efficacy or safety. These results support the safe use of IAsp in children and adolescents with Type 1 diabetes. [ABSTRACT FROM AUTHOR]

Abstract: Pulmonary ventilation and gas exchange were determined during prolonged skiing (∼76% of ; cardiac output=26–27Lmin−1) using diagonal technique (DIA) for 40min followed by 10min of double poling (DPOL) and 10min of leg skiing (LEG). Exercise caused ∼2–5% reduction of arterial oxygen saturation . For a given cardiac output and , DPOL presented higher , lower and a more efficient pulmonary gas exchange, revealed by higher and and lower . The widened 2mmHgL−1 of cardiac output increase. However, for a given cardiac output and , exercise mode had an important influence on pulmonary ventilation and gas exchange. Highly trained cross-country skiers’ present about 2units reduction in from resting values during submaximal exercise at 76% of . Half of the reduction in saturation is accounted for by the rightward-shift of the oxygen dissociation curve of the haemoglobin. The exercise duration has almost no repercussion on pulmonary gas exchange in these athletes, with the small effect on associated to the increase in body core temperature. [Copyright &y& Elsevier]

Aim: To investigate if training during hypoxia (H) improves the adaptation of muscle oxidative function compared with normoxic (N) training performed at the same relative intensity. Method: Eight untrained volunteers performed one-legged cycle training during 4 weeks in a low-pressure chamber. One leg was trained under N conditions and the other leg under hypobaric hypoxia (526 mmHg) at the same relative intensity as during N (65% of maximal power output, Wmax). Muscle biopsies were taken from vastus lateralis before and after the training period. Muscle samples were analysed for the activities of oxidative enzymes [citrate synthase (CS) and cytochrome c oxidase (COX)] and mitochondrial respiratory function. Results: Wmax increased with more than 30% over the training period during both N and H. CS activity increased significantly after training during N conditions (+20.8%, P < 0.05) but remained unchanged after H training (+4.5%, ns) with a significant difference between conditions ( P < 0.05 H vs. N). COX activity was not significantly changed by training and was not different between exercise conditions [+14.6 (N) vs. −2.3% (H), ns]. Maximal ADP stimulated respiration (state 3) expressed per weight of muscle tended to increase after N (+31.2%, P < 0.08) but not after H training (+3.2%, ns). No changes were found in state four respiration, respiratory control index, P/O ratio, mitochondrial Ca2+ resistance and apparent Km for oxygen. Conclusion: The training-induced increase in muscle oxidative function observed during N was abolished during H. Altitude training may thus be disadvantageous for adaptation of muscle oxidative function. [ABSTRACT FROM AUTHOR]

We compared the prevalence of beta-cell autoantibodies and genetic risk factors in Sweden and Lithuania. Ninety-six patients from Sweden and 96 from Lithuania matched for age and gender (1-15 years old, median age 9.0 years) were included. We analyzed autoantibodies to insulin (IAA), glutamic acid decarboxylase (GADA) and the protein tyrosine phosphatase like IA-2 (IA-2A) as well as risk-associated polymorphisms of HLA, insulin and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) genes. The frequency of patients positive for IAA and GADA was higher in Sweden than in Lithuania (p=0.043 and 0.032). The differences remained even when the patients were matched for HLA, insulin and CTLA-4 risk genotypes. Patients with low levels of IAA had higher levels of HbA1c and ketones at diagnosis. The frequency of the risk haplotype DR4-DQ8 was higher in Swedish than in Lithuanian patients (p=0.004), as well as the high-risk combination of DR4-DQ8 and DR3-DQ2 haplotypes (p=0.009). Our results suggest that autoimmune process against insulin and GAD(65) is more common at diagnosis in children in areas with high incidence of type 1 diabetes (T1D), independent of genetic risk markers. Furthermore, the disease in patients with insulin autoantibodies seems to be clinically milder. [ABSTRACT FROM AUTHOR]

To determine whether conditions for O2 utilization and O2 off-loading from the hemoglobin are different in exercising arms and legs, six cross-country skiers participated in this study. Femoral and subclavian vein blood flow and gases were determined during skiing on a treadmill at ∼76% maximal O2 uptake (Vo2 max) and at Vo2 max with different techniques: diagonal stride (combined arm and leg exercise), double poling (predominantly arm exercise), and leg skiing (predominantly leg exercise). The percentage of O2 extraction was always higher for the legs than for the arms. At maximal exercise (diagonal stride), the corresponding mean values were 93 and 85% (n = 3; P « 0.05). During exercise, mean arm O2 extraction correlated with the Po2 value that causes hemoglobin to be 50% saturated (P50: r = 0.93, P « 0.05), but for a given value of P50, O2 extraction was always higher in the legs than in the arms. Mean capillary muscle O2 conductance of the arm during double poling was 14.5 (SD 2.6) ml·min-1·mmHg-1, and mean capillary Po2 was 47.7 (SD 2.6) mmHg. Corresponding values for the legs during maximal exercise were 48.3 (SD 13.0) ml·min-1, mmHg-1 and 33.8 (SD 2.6) mmHg, respectively. Because conditions for O2 off-loading from the hemoglobin are similar in leg and arm muscles, the observed differences in maximal arm and leg O2 extraction should be attributed to other factors, such as a higher heterogeneity in blood flow distribution, shorter mean transit time, smaller diffusing area, and larger diffusing distance, in arms than in legs. [ABSTRACT FROM AUTHOR]

PURPOSE: To further the understanding of double poling (DP) through biomechanical analysis of upper and lower body movements during DP in cross-country (XC) skiing at racing speed. METHODS: Eleven elite XC skiers performed DP at 85% of their maximal DP velocity (V85%) during roller skiing at 1 degrees inclination on a treadmill. Pole and plantar ground reaction forces, joint angles (elbow, hip, knee, and ankle), cycle characteristics, and electromyography (EMG) of upper and lower body muscles were analyzed. RESULTS: 1) Pole force pattern with initial impact force peak and the following active force peak (PPF) correlated to V85%, (r = 0.66, P < 0.05); 2) active flexion-extension pattern in elbow, hip, knee, and ankle joints with angle minima occurring around PPF, correlated to hip angle at pole plant (r = -0.89, P < 0.01), minimum elbow angle (r = -0.71), and relative poling time (r = -0.72, P < 0.05); 3) two different DP strategies (A and B), where strategy A (best skiers) was characterized by higher angular elbow- and hip-flexion velocities, smaller minimum elbow (P < 0.01) and hip angles (P < 0.05), and higher PPF (P < 0.05); 4) EMG activity in trunk and hip flexors, shoulder, and elbow extensors, and several lower body muscles followed a specific sequential pattern with changing activation levels; and 5) EMG activity in lower body muscles showed DP requires more than upper body work. CONCLUSIONS: DP was found to be a complex movement involving both the upper and lower body showing different strategies concerning several biomechanical aspects. Future research should further investigate the relationship between biomechanical and physiological variables and elaborate training models to improve DP performance. [ABSTRACT FROM AUTHOR]

That muscular blood flow may reach 2.51 kg-1 min-1 in the quadriceps muscle has led to the suggestion that muscular vascular conductance must be restrained during whole body exercise to avoid hypotension. The main aim of this study was to determine the maximal arm and leg muscle vascular conductances (VC) during leg and arm exercise, to find out if the maximal muscular vasodilatory response is restrained during maximal combined arm and leg exercise. Six Swedish elite cross-country skiers, age (mean ± S.E.M.) 24 ± 2 years, height 180 ± 2 cm, weight 74 ± 2 kg, and maximal oxygen uptake (VO2,max) 5.1 ± 0.1 1 min-1 participated in the study. Femoral and subclavian vein blood flows, intra-arterial blood pressure, cardiac output, as well as blood gases in the femoral and subclavian vein, right atrium and femoral artery were determined during skiing (roller skis) at ∼ 76% of VO2,max and at VO2,max with different techniques: diagonal stride (combined arm and leg exercise), double poling (predominantly arm exercise) and leg skiing (predominantly leg exercise). During submaximal exercise cardiac output (26-27 1 min-1), mean blood pressure (MAP) (∼ 87 mmHg), systemic VC, systemic oxygen delivery and pulmonary VO2 (∼ 41 min-1) attained similar values regardless of exercise mode. The distribution of cardiac output was modified depending on the musculature engaged in the exercise. There was a close relationship between VC and VO2 in arms (r = 0.99, P < 0.001) and legs (r = 0.98, P < 0.05). Peakarm VC (63.7 ± 5.6 ml min-1 mmHg-1) was attained during double poling, while peak leg VC was reached at maximal exercise with the diagonal technique (109.8 ± 11.5 ml min-1 mmHg-1) ... [ABSTRACT FROM AUTHOR]

To study the role of muscle mass and muscle activity on lactate and energy kinetics during exercise, whole body and limb lactate, glucose, and fatty acid fluxes were determined in six elite cross-country skiers during roller-skiing for 40 min with the diagonal stride (Continuous Arm + Leg) followed by 10 min of double poling and diagonal stride at 72-76% maximal O[sub 2] uptake. A high lactate appearance rate (R[sub a], 184 ± 17 µmol·kg[sup -1]·min[sup -1]) but a low arterial lactate concentration (∼2.5 mmol/l) were observed during Continuous Arm + Leg despite a substantial net lactate release by the arm of ∼2.1 mmol/min, which was balanced by a similar net lactate uptake by the leg. Whole body and limb lactate oxidation during Continuous Arm + Leg was ∼45% at rest and ∼95% of disappearance rate and limb lactate uptake, respectively. Limb lactate kinetics changed multiple times when exercise mode was changed. Whole body glucose and glycerol turnover was unchanged during the different skiing modes; however, limb net glucose uptake changed severalfold. In conclusion, the arterial lactate concentration can be maintained at a relatively low level despite high lactate R[sub a] during exercise with a large muscle mass because of the large capacity of active skeletal muscle to take up lactate, which is tightly correlated with lactate delivery. The limb lactate uptake during exercise is oxidized at rates far above resting oxygen consumption, implying that lactate uptake and subsequent oxidation are also dependent on an elevated metabolic rate. The relative contribution of whole body and limb lactate oxidation is between 20 and 30% of total carbohydrate oxidation at rest and during exercise under the various conditions. Skeletal muscle can change its limb net glucose uptake severalfold within minutes, causing a redistribution of the available glucose because whole body glucose turnover was unchanged. [ABSTRACT FROM AUTHOR]

Formation of a macrocyclic lactone, hexadecanolide, from the corresponding ω-hydroxycarboxylic acid has been investigated using lipase as esterification catalyst. The parameters studied were water activity in the reaction medium, solvent polarity, type of lipase, and substrate concentration. Formation of non-cyclic esters, i.e., intermolecular esterification, was found to compete with lactone formation and mixtures of both types of reaction products were obtained in all cases. It was also found that the reaction always yielded a mixture of oligomers of both cyclic and non-cyclic nature. Under appropriate conditions (low water activity, nonpolar solvent) the starting ω-hydroxycarboxylic acid was completely converted to ester products but the yield of the target product, the monomeric lactone, never exceeded 41%. All the reactions were carried out in organic solvents with small amounts of water present. A related investigation performed in microheterogeneous media consisting of water-in-oil microemulsions is reported separately. [ABSTRACT FROM AUTHOR]

Copyright of European Journal of Wood & Wood Products / Holz als Roh- und Werkstoff is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of European Journal of Wood & Wood Products / Holz als Roh- und Werkstoff is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The withdrawal reflex pathways to hindlimb muscles have an elaborate spatial organization in the rat. In short, the distribution of sensitivity within the cutaneous receptive field of a single muscle has a spatial pattern that is a mirror image of the spatial pattern of the withdrawal of the skin surface ensuing on contraction in the respective muscle. In the present study, a search for neurones encoding the specific spatial input-output relationship of withdrawal reflexes to single muscles was made in the lumbosacral spinal cord in halothane/nitrous oxide-anaesthetized rats. The cutaneous receptive fields of 147 dorsal horn neurones in the L4-5 segments receiving a nociceptive input and a convergent input from A and C fibres from the hindpaw were studied. The spatial pattern of the response amplitude within the receptive fields of 118 neurones was quantitatively compared with those of withdrawal reflexes to single muscles. Response patterns exhibiting a high similarity to those of withdrawal reflexes to single muscles were found in 27 neurones located in the deep dorsal horn. Twenty-six of these belonged to class 2 (responding to tactile and nociceptive input) and one belonged to class 3 (responding only to nociceptive input). None of the neurones tested ( n=20) with reflex-like response patterns could be antidromically driven from the upper cervical cord, suggesting that they were spinal interneurones. With some overlap, putative interneurones of the withdrawal reflexes to the plantar flexors of the digits, the plantar flexors of the ankle, the pronators, the dorsiflexors of the ankle, and a flexor of the knee, were found in succession in a mediolateral direction. It is concluded that neurones that are able to encode the specific spatial input-output organization of the withdrawal reflexes to single muscles do exist in the deep dorsal horn. Such reflex encoders appear to have a 'musculotopic' organization. A hypothesis of the organization of the withdrawal reflex system is presented. [ABSTRACT FROM AUTHOR]

GaAs and GaN pn-junctions are fabricated with Mn-doped ferromagnetic layers on top of nonmagnetic substrates. In the case of heavily doped (Ga,Mn)As/GaAs p++ n++ -junctions (Zener diodes) the tunneling current becomes magnetic field dependent at low tem- peratures. This can be explained by a model based on the valence band splitting due to the exchange interaction between the hole spins and the localized spins of the Mn atoms. In the pn-junctions with more lightly doped nonmagnetic regions in the (Ga, Mn)N and (Ga, Mn)As diodes, no magnetic field dependence in the I-V characteristics is observed, probably due the absence of ferromagnetism in the depletion region of the p+ n-junctions. [ABSTRACT FROM AUTHOR]

Heavily Mn-doped GaN thin films were fabricated by using solid-state diffusion. The magnetic properties of the samples were determined by Hall effect measurements and by using a superconducting quantum interference device. The results show ferromagnetic behavior even above room temperature, the Curie temperature being 330 K. The samples were of n-type and the estimated electron concentration was ≈1 × 1020 cm-3. Due to the spin-disorder scattering, a negative magnetoresistance was observed and it was largest at Curie temperature. The measured sheet resistance versus temperature could also be explained by the spin disorder scattering model for ferromagnetic metals. From the measurement results, the value of the exchange interaction parameter between the electron spins and the magnetic moments of the Mn atoms was estimated to be about 1 eV. The material properties were studied also by using secondary ion mass spectroscopy and X-ray diffraction, which showed some segregation of GaxMny. [ABSTRACT FROM AUTHOR]