Echocardiographic Characterization of the Inferior Vena Cava in Trained and Untrained Females.

The aim of the study was to explore the long- and short-axis dimensions, shape and collapsibility of the inferior vena cava in 46 trained and 48 untrained females (mean age: 21 ± 2 y). Echocardiography in the subcostal view revealed a larger expiratory long-axis diameter (mean: 24 ± 3 vs. 20 ± 3 mm, p < 0.001) and short-axis area (mean: 5.5 ± 1.5 vs. 4.7 ± 1.4 cm2, p = 0.014) in trained females. IVC shape (the ratio of short-axis major to minor diameters) and the relative decrease in IVC dimension with inspiration were similar for the two groups. The IVC long-axis diameter reflected short-axis minor diameter and was correlated to maximal oxygen uptake (r = 0.52, p < 0.01). In summary, the results indicate that trained females have a larger IVC similar in shape and respiratory decrease in dimensions to that of untrained females. The long-axis diameter corresponded closely to short-axis minor diameter and, thus, underestimates maximal IVC diameter.

[Being in motion reduces the risk of disease and premature death]. / Att vara i rörelse minskar risk för sjukdom och förtida död.

Regular physical activity affects most organs and tissues through a large number of mechanisms which in various ways contribute to improved function and health. Regular physical activity improves quality of life, cognitive functions, mood state and physical capacity, and lowers the risk of many diseases and premature death. Physical activity affects proteins and gene expression through signalling mechanisms, e.g. epigenetic changes. The biological response to physical activity can be markedly different between individuals, to a large degree due to genetic mechanisms. Regular aerobic physical activity (endurance training) improves cardiac function, partly due to an increased stroke volume, and lowers blood pressure due to e.g. improved vasodilation, lower arterial stiffness and increased capillarisation. Regular physical activity helps to maintain muscle mass and function and can improve brain health and function, e.g. executive and memory functions.

Gait characteristics and influence of fatigue during the 6-minute walk test in patients with post-polio syndrome.

OBJECTIVE: To evaluate gait in patients with post-polio syndrome, using the 6-minute walk test (6MWT) combined with three-dimensional kinematic analysis. DESIGN: Descriptive study. SUBJECTS: Eighteen patients and 11 healthy controls. METHODS: Kinematic data were obtained during a 6MWT by a Vicon motion capture system. Distance, heart rate, leg tiredness, dyspnoea and exertion were also recorded. RESULTS: Patients with post-polio syndrome showed larger increases in leg tiredness (p < 0.001) and dyspnoea (p < 0.05) as a result of the 6MWT than did controls. Walking speed decreased by 14.1% in patients vs 4.7% in controls (p < 0.05). Fourteen out of 18 patients displayed plantar-flexed ankle at initial contact (1/11 controls). At foot-off, the patients had a flexed hip (extended in controls) and a more flexed knee. Walking speed in patients correlated with hip angle at foot-off, at the start (r = -0.60, p < 0.001) and the end of the 6MWT (r = -0.74, p < 0.001), being higher the more the hip was extended. CONCLUSION: The 6MWT is fatiguing for patients with post-polio syndrome, and this was reflected in the kinematic data. Walking speed was negatively correlated with the increased hip flexion, but not with the ankle plantar-flexion at foot-off in the patients with post-polio syndrome. The three-dimensional results underscore the importance of hip function in this patient group.

Blood flow to the extensor carpi radialis brevis muscle following adrenaline infusion in patients with lateral epicondylitis.

PURPOSE: Based on previous evidence of muscle fiber injury and decreased blood flow in the extensor carpi radialis brevis (ECRB) muscle in lateral epicondylitis (LE), we hypothesized that there would also be an abnormal (vasoconstrictive) vascular response to adrenaline in the ECRB muscle in LE. METHODS: In a case-control study, we measured skeletal muscle blood flow in 8 patients with LE and in 8 healthy controls in response to a 30-minute intravenous infusion of adrenaline. We used local clearance of technetium-99m in the main portion of the ECRB muscle to calculate muscle blood flow. RESULTS: In support of the hypothesis, the blood flow response to the adrenaline infusion was markedly different in the 2 study groups. Whereas the continuous decrease in technetium-99m clearance rate over time was interrupted by the adrenaline-induced vasodilatory effect in the control group, we detected no such effect in the patient group. CONCLUSIONS: In the ECRB muscle in LE, there is a shift in the balance of vasodilatory and vasoconstrictory influences of adrenaline, leading to vasoconstriction during low-dose adrenaline infusion. The adverse adrenaline effect is similar to what was previously observed after minor muscle injury. Whether the vasoregulatory change, by causing relative muscle ischemia, represents the primary etiology in LE or results from muscle injury cannot be determined, but it is likely to contribute to the development and continuation of chronic muscle pain in LE. New ways of thinking about the condition may be required, and pharmacological treatment might be an option to improve the blood supply and avoid further damage to the affected ECRB muscle-tendon unit.

Effect of exercise and training on phospholemman phosphorylation in human skeletal muscle.

Phospholemman (PLM, FXYD1) is a partner protein and regulator of the Na(+)-K(+)-ATPase (Na(+)-K(+) pump). We explored the impact of acute and short-term training exercise on PLM physiology in human skeletal muscle. A group of moderately trained males (n = 8) performed a 1-h acute bout of exercise by utilizing a one-legged cycling protocol. Muscle biopsies were taken from vastus lateralis at 0 and 63 min (non-exercised leg) and 30 and 60 min (exercised leg). In a group of sedentary males (n = 9), we determined the effect of a 10-day intense aerobic cycle training on Na(+)-K(+)-ATPase subunit expression, PLM phosphorylation, and total PLM expression as well as PLM phosphorylation in response to acute exercise (1 h at ∼72% Vo(2peak)). Biopsies were taken at rest, immediately following, and 3 h after an acute exercise bout before and at the conclusion of the 10-day training study. PLM phosphorylation was increased both at Ser(63) and Ser(68) immediately after acute exercise (75%, P < 0.05, and 30%, P < 0.05, respectively). Short-term training had no adaptive effect on PLM phosphorylation at Ser(63) and Ser(68), nor was the total amount of PLM altered posttraining. The protein expressions of α(1)-, α(2)-,and ß(1)-subunits of Na(+)-K(+)-ATPase were increased after training (113%, P < 0.05, 49%, P < 0.05, and 27%, P < 0.05, respectively). Whereas an acute bout of exercise increased the phosphorylation of PKCα/ßII on Thr(638/641) pre- and posttraining, phosphorylation of PKCζ/λ on Thr(403/410) was increased in response to acute exercise only after the 10-day training. In conclusion, we show that only acute exercise, and not short-term training, increases phosphorylation of PLM on Ser(63) and Ser(68), and data from one-legged cycling indicate that this effect of exercise on PLM phosphorylation is not due to systemic factors. Our results provide evidence that phosphorylation of PLM may play a role in the acute regulation of the Na(+)-K(+)-ATPase response to exercise.

Gait initiation characteristics in elderly patients with unilateral vestibular impairment.

The study tested the hypothesis that vestibular patients (n=14) with chronic unsteadiness caused by a documented peripheral unilateral vestibular dysfunction would display differences in muscular activation and movement pattern during gait initiation compared to age-, gender- and body-size-matched healthy Controls (n=14). The displacements of the whole body Center of Pressure (CoP) during the preparatory phase before the swing leg is lifted, were markedly different in vestibular patients. The backward shift during this phase was significantly smaller than in Controls, coupled with a larger secondary corrective forward shift of the CoP. Conversely, the CoP-shift in the M-L direction towards the stance leg was larger in the vestibular patients. Most vestibular patients lacked the anticipatory tibialis anterior (TA) burst, which normally is a prerequisite for the backward displacement of the CoP that precedes the forward movement. The vestibular patients displayed more pronounced TA-Gastrocnemius coactivation in the stance leg when the swing leg was lifted. The duration of the preparatory phase was significantly longer in vestibular patients than in Controls, with no time differences in the later gait initiation events. The vestibular patients started from a more symmetrical stance and with less M-L variation than the Controls. It is concluded that chronically impaired vestibular function leads to a different strategy to create forward momentum to the body. In addition, there is evidence that vestibular patients have diminished postural stability, or alternatively a more cautious behaviour, when initiating the second step.

Intravenous adrenaline infusion causes vasoconstriction close to an intramuscular microdialysis catheter in humans.

AIM: To test if a small muscle injury influences the vascular reactivity to adrenaline in human skeletal muscle. METHODS: Blood flow was measured by ¹³³Xenon clearance in the gastrocnemius muscle of eight male subjects at basal and during i.v. infusion of adrenaline (0.1 nmol kg⁻¹ min⁻¹) or placebo. Measurements were done with (expts 2 and 3) or without (expt 1) the influence of a small muscle injury induced by inserting a microdialysis catheter. ¹³³Xenon was administered either (expt 1) conventionally into the muscle via a fine needle, or (expts 2 and 3) through a fine tube close to the inserted microdialysis catheter. Expt 3 (control expt) was identical to expt 2 except that placebo was infused instead of adrenaline. Mean ± SEM, n= 8. RESULTS: The blood flow tended to increase during the adrenaline infusion in expt 1 (1.17 ± 0.10 to 1.39 ± 0.15, N.S.), whereas it decreased during the adrenaline infusion in expt 2, from 1.39 ± 0.14 to 1.03 ± 0.14 ml min⁻¹ 100 g tissue⁻¹ (P<0.001). The blood flow change in response to adrenaline infusion was significantly different in expt 1 and expt 2 (P<0.05). Blood flow also decreased during the placebo infusion in expt 3 (1.15 ± 0.10 to 1.00 ± 0.09, P<0.01), but this decrease was significantly smaller than in response to the adrenaline infusion in expt 2, P<0.01. CONCLUSION: The present results are consistent with the hypothesis that the small muscle injury caused by the inserted microdialysis catheter influences the vascular reactivity to adrenaline in a vasoconstrictive direction.

Assessment of satellite cell number and activity status in human skeletal muscle biopsies.

The primary aim of our study was to validate the assessment of myonuclear and satellite cell number in biopsies from human skeletal muscle. We found that 25 type I and 25 type II fibers are sufficient to estimate the mean number of myonuclei per fiber. In contrast, the assessment of satellite cells improved when more fibers were included. Second, we report that small differences in counting satellite cells using CD56 and Pax7 antibodies can be attributed to the different staining profiles. Third, we provide support for the use of Ki67 in evaluating the proportion of active satellite cells. We observed very few (up to 1.3%) active satellite cells in healthy adult skeletal muscle at rest, but they increased significantly (up to 7-fold) following muscle activity. This study provides valuable tools to assess the behavior of satellite cells, both in pathological conditions and in response to physiological stimuli.

Alterations in forearm position and environmental temperature influences the segmental volume expansion during venous occlusion plethysmography--special attention on hand circulation.

AIM: To find evidence that small changes in the positioning of the strain gauge, the environmental temperature (sympathetic activation) and position of the arm (venous pressure) alters the outcome of the venous occlusion plethysmography (VOP) measurement of forearm blood flow and to investigate if the hand circulation influences the results. METHODS: Forearm blood flow was measured with VOP (n = 6) on three occasions with air temperatures of 13, 20 and 38 degrees C, respectively. At each occasion the arm position was varied; raised by 10 degrees , horizontal or lowered by 15 degrees . Strain gauges were placed on the forearm at the maximal circumference; 5 cm distal; and 5 cm proximal to this site, respectively. The hand circulation was excluded in half of the measurements. RESULTS: The simple main effect of temperature was highly significant (P<0.001). With excluded hand circulation (but not when included), there was a two factor interaction between arm position - strain gauge position (P<0.05). The highest expansion rate was found in the proximal segment when the arm was elevated, but in the distal segment when the arm was lowered. With hand circulation (but not without) there was a two factor interaction between temperature and strain gauge position (P<0.01). The highest expansion rate was found in the distal segment at normal and high temperatures, but in the proximal segment at low temperature. CONCLUSION: The volume expansion rate in a particular segment is dependent not only on arterial inflow. Segmental differences in capacity for venous expansion results in redistribution of blood to and from a segment, thus influencing the results obtained.

The number of satellite cells in slow and fast fibres from human vastus lateralis muscle.

The aim of this investigation was to study the distribution of satellite cells in slow (type I fibres) and fast (type II fibres) fibres from human vastus lateralis muscle. This muscle is characterised by a mixed fibre type composition and is considered as the site of choice for biopsies in research work and for clinical diagnosis. Biopsy samples were obtained from five healthy young volunteers and a total of 1,747 type I fibres and 1,760 type II fibres were assessed. Satellite cells and fibre type composition were studied on serial muscle cross-sections stained with specific monoclonal antibodies. From a total of 218 satellite cells, 116 satellite cells were found in contact with type I fibres (53.6+/-8% of the satellite cells associated to type I fibres) and 102 satellite cells in contact with type II fibres (46.4+/-8% of the satellite cells associated to type II fibres). There was no significant difference (P=0.4) between the percentages of satellite cells in contact with type I and with type II fibres. Additionally, there was no relationship between the mean number of satellite cells per fibre and the mean cross-sectional area of muscle fibres. In conclusion, our results show that there is no fibre type-specific distribution of satellite cells in a human skeletal muscle with mixed fibre type composition.

Effects of one bout of endurance exercise on the expression of myogenin in human quadriceps muscle.

The objective of this study was to investigate the cellular localisation of MyoD and myogenin in human skeletal muscle fibres as well as the possible alterations in the expression of MyoD and myogenin in response to a single bout of endurance exercise at 40% and 75% of maximum oxygen uptake (VO(2) max). Twenty-five biopsies (5 per subject) from the vastus lateralis muscle were obtained before exercise, from the exercising leg at 40% and 75% of VO(2) max and from the resting leg following these exercise bouts. The tyramide signal amplification-direct and the Vectastain ABC methods using specific monoclonal antibodies were used to determine the exact location of myogenin and MyoD, to identify muscle satellite cells and to determine myosin heavy chain (MyHC) composition. At rest, myonuclei did not express MyoD or myogenin. Following a single bout of exercise at 40% and 75% of VO(2) max, an accumulation of myogenin in myonuclei and not in satellite cells was observed in biopsies from the exercised leg but not in biopsies before exercise and from the resting leg. The number of myogenin-positive myonuclei varied among individuals indicating differences in the response to a single exercise bout. In conclusion, this immunohistochemical study showed that a rapid rearrangement of myogenin expression occurs in exercised human skeletal muscles in response to a single bout of exercise.

Exercise-induced protein kinase C isoform-specific activation in human skeletal muscle.

We determined whether protein kinase C (PKC) isoforms are redistributed and phosphorylated in response to acute exercise in skeletal muscle. Muscle biopsies were obtained from six healthy subjects (four women, two men; age 25 +/- 1 years) before, during, and after 60 min of one-leg cycle ergometry at approximately 70% VO(2peak). Exercise for 30 and 60 min was associated with a three- and fourfold increase in PKC-zeta/lambda abundance and a four- and threefold increase in phosphorylation, respectively, in total membranes (P < 0.05) and a decrease in PKC-zeta/lambda phosphorylation in cytosolic fractions. During exercise recovery, PKC-zeta/lambda abundance and phosphorylation remained elevated. PKC-zeta/lambda abundance and phosphorylation were increased in nonexercised muscle upon cessation of exercise, indicating a systemic response may contribute to changes in PKC abundance and phosphorylation. Exercise did not change PKC-delta or -epsilon abundance or phosphorylation in either the cytosolic or total membrane fraction. In conclusion, exercise is associated with an isoform-specific effect on PKC. PKC-zeta/lambda are candidate PKC isoforms that may play a role in the regulation of exercise-related changes in metabolic and gene-regulatory responses.

Quantification and analysis of pain in nonsurgical scaling and/or root planing.

BACKGROUND: Three efficacy studies, comprising a database of 337 subjects, were conducted as part of the clinical evaluation of the noninjectable anesthetic gel Oraqix (AstraZeneca, Södertälje, Sweden). The authors discuss some of the challenges encountered when they interpreted the results of the clinical studies and present the results from an alternative analysis of the anesthetic efficacy. METHODS: The three multicenter studies were double-blind, randomized and placebo-controlled. Clinicians applied gel in the subjects' periodontal pockets before scaling and/or root planing, or SRP. Subjects recorded overall pain on a 100-millimeter visual analog scale, or VAS. In the studies, the evaluation of the anesthetic efficacy was based on absolute treatment difference (active-placebo). Investigators used an alternative post hoc approach to evaluate the effect expressed as a ratio (active:placebo). RESULTS: The studies demonstrated consistent and significant lower pain scores for the anesthetic gel versus the placebo gel, with point estimates of absolute treatment difference being 8, 4 and 10 mm. The alternative analysis verified that the estimated treatment effect in terms of a ratio was close to 50 percent in all three studies. CONCLUSIONS: Treatment effects of the anesthetic gel relative to the placebo gel were described more appropriately by means of ratios instead of absolute differences. In this sample of 337 subjects, it was shown that pain was reduced by 50 percent when the anesthetic gel was used compared with when the placebo gel was used. CLINICAL IMPLICATIONS: The authors found that the anesthetic periodontal gel is effective in reducing pain resulting from SRP.

Evidence for genetic exchange and hybridization in Trypanosoma cruzi based on nucleotide sequences and molecular karyotype.

Trypanosoma cruzi is thought to undergo predominant clonal evolution, as determined by population genetics studies. However, this model does not exclude occasional recombination, which existence is strongly suggested by several recent studies. We sequenced a portion of the maxicircle cytochrome b (CYb) gene and of the nuclear rRNA promoter region from representative strains of six T. cruzi genetic lineages isolated from anthroponotic environments and man (lineages IIb, IId and IIe), sylvatic environments (lineages IIa and IIc) or both (lineage I). Phylogenetic analyses based on the two genes were incongruent. Remarkably, in lineage IIe, CYb and rRNA sequences were very closely related to those of lineages IIc and IIb, respectively. One stock of lineage IId showed rRNA sequence heterogeneity, with both IIb-like and IIc-like copies. Analysis of the size variation of six distinct pairs of putative homologous chromosomes revealed a bimodal distribution of chromosomal sizes across T. cruzi. Notably, stocks of lineages IId and IIe had several chromosomal pairs distributed in distinct modes, with the corresponding modes individually found in lineages IIb and IIc. Together, these data indicate the origin of lineages IId and IIe by hybridization between representatives of lineages IIb and IIc. CYb and rRNA sequences clustered into three and four major lineages, respectively. Data were in agreement with the distinction of six genetic lineages, but not with their proposed grouping into two primary lineages, as lineage II was not monophyletic. Based on a CYb substitution rate of 1% per million years (Myr), the major lineages are estimated to have diverged around 10 million years ago.