The Modern Double-Poling Technique Is Not More Energy Efficient Than the Old-Fashioned Double-Poling Technique at a Submaximal Work Intensity

The purpose of the study was to investigate whether there are energy-efficiency differences between the execution of the old-fashioned double-poling technique (DP_OLD) and the modern double-poling technique (DP_MOD) at a submaximal work intensity among elite male cross-country skiers. Fifteen elite male cross-country skiers completed two 4-min tests at a constant mechanical work rate (MWR) using the DP_MOD and DP_OLD. During the last minute of each test, the mean oxygen uptake (VO₂) and respiratory exchange ratio (RER) were analyzed, from which the metabolic rate (MR) and gross efficiency (GE) were calculated. In addition, the difference between pretest and posttest blood-lactate concentrations (BLa_diff) was determined. For each technique, skiers' joint angles (i.e., heel, ankle, knee, hip, shoulder, and elbow) were analyzed at the highest and lowest positions during the double-poling cycle. Paired-samples t-tests were used to investigate differences between DP_MOD and DP_OLD outcomes. There were no significant differences in either VO₂mean, MR, GE, or BLa_diff (all P > 0.05) between the DP_MOD and DP_OLD tests. DP_MOD execution was associated with a higher RER (P < 0.05). Significant technique-specific differences were found in either the highest and/or the lowest position for all six analyzed joint angles (all P < 0.001). Hence, despite decades of double-poling technique development, which is reflected in the significant biomechanical differences between DP_OLD and DP_MOD execution, at submaximal work intensity, the modern technique is not more energy efficient than the old-fashioned technique.

Effect of sub-technique transitions on energy expenditure and physiological load in the classical-style technique among elite male cross-country skiers

Purpose

To investigate whether sub-technique transitions in the classical-style technique are associated with increased energy expenditure and/or metabolic stress among elite male cross-country skiers.

Methods

Fifteen elite male skiers completed three 10-min treadmill roller-skiing tests, each of which consisted of 5 min using the diagonal-stride technique (DS) and 5 min using the double-poling technique (DP), combined in three various modes all ensuring comparable mechanical workload, at an inclination of 2.5° and a speed of 13 km/h. In the first and third tests, the participants used 5 min continuous DS followed by 5 min continuous DP, or vice versa (no transition (NT) test), whereas in the second test, they made transitions between DS and DP every 6 s (repeated transition (RT) test). The last 3 min of each 5-min stage was used to calculate the mean values of oxygen uptake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{\text{V}}\text{O}}_{{2}}$$\end{document}V˙O2), respiratory exchange ratio (RER), metabolic rate (MR), mechanical work rate (MWR), and gross efficiency (GE). In addition, the pre–post-difference in blood lactate concentration (La_diff) was determined for each test. Paired-samples t tests were used to investigate differences between tests.

Results

There were no significant differences between NT and RT tests regarding V̇O₂, MR, MWR, or GE. Conversely, significant differences were found in RER and La_diff, where the NT test was associated with higher RER and La_diff values.

Conclusions

Roller skiing with repeated sub-technique transitions is not associated with an additional aerobic energy contribution; instead, the anaerobic energy contribution was lower compared to that under continuous use of DS and DP.

Differences in nitric oxide airway diffusion after maximum oxygen uptake test in asthmatic and nonasthmatic elite junior cross-country skiers

Asthma is common in cross-country skiers and is often treated with β₂-agonists and inhaled corticosteroids (ICS). Exhaled nitric oxide (NO) is often used to guide ICS treatment in asthma. This study investigated the change in pulmonary NO dynamics before and after a maximum oxygen uptake (V′_O2max) test.

An extended NO analysis was performed among Swedish elite junior cross-country skiers (n=25), with and without declared asthma, before and after a V′_O2max test using roller skis. Asthma was declared by six boys and two girls among whom five occasionally used ICSs.

There were no differences in baseline NO parameters between those with and without declared asthma. The median (interquartile range) diffusion capacity over airway wall (D_awNO) was 21 (17–25) mL·s⁻¹, which is much increased for this age group. After the V′_O2max test, there were statistically significant differences from the baseline fraction of exhaled NO (F_ENO50), NO flux from airways, D_awNO and alveolar NO values; but not in the NO content in airway wall (C_awNO) for all subjects together as one group. However, in the asthma group, differences were only seen in F_ENO50 and C_awNO.

Interestingly, a majority of the subjects had an increase in the D_awNO. An increase in D_awNO has been found with allergic asthma together with elevated C_awNO. The skiers did not have elevated C_awNO, which indicates an absence of inflammation in the airway wall. Modelling of lung NO production clearly shows that the asthma among our skiers is distinct from the allergic asthma in nonathletes.

NO pulmonary dynamics of junior cross-country skiers with asthma respond differently to the V′_O2maxtest than in those without asthma. Analysis of airway inflammation should be considered before inhaled corticosteroids are prescribed.https://bit.ly/3eWB1JZ

Gross and delta efficiencies during uphill running and cycling among elite triathletes

PURPOSE

To investigate the gross efficiency (GE) and delta efficiency (DE) during cycling and running in elite triathletes.

METHODS

Five male and five female elite triathletes completed two incremental treadmill tests with an inclination of 2.5° to determine their GE and DE during cycling and running. The speed increments between the 5-min stages were 2.4 and 0.6 km h^-1 during the cycling and running tests, respectively. For each test, GE was calculated as the ratio between the mechanical work rate (MWR) and the metabolic rate (MR) at an intensity corresponding to a net increase in blood-lactate concentration of 1 mmol l^-1. DE was calculated by dividing the delta increase in MWR by the delta increase in MR for each test. Pearson correlations and paired-sample t tests were used to investigate the relationships and differences, respectively.

RESULTS

There was a correlation between GE_cycle and GE_run (r = 0.66; P = 0.038; R² = 0.44), but the correlation between DE_cycle and DE_run was not statistically significant (r = - 0.045; P = 0.90; R² = 0.0020). There were differences between GE_cycle and GE_run (t = 80.8; P < 0.001) as well as between DE_cycle and DE_run (t = 27.8; P < 0.001).

CONCLUSIONS

Elite triathletes with high GE during running also have high GE during cycling, when exercising at a treadmill inclination of 2.5°. For a moderate uphill incline, elite triathletes are more energy efficient during cycling than during running, independent of work rate.

The acute effects of a short technique-intense training period on side-foot kick performance among elite female soccer players

BACKGROUND

Previously, it was shown that elite soccer teams were 24% more likely to win matches if their passing effectiveness were increased by 1%. However, research interventions aiming to improve passing performance are scarce. The current study aimed to investigate the effect of a short technique-intense training period on side-foot kick performance among elite female soccer players.

METHODS

Four side-foot kick tests were completed before and after a training period: kicking a stationary ball using match-relevant (SBRS) and maximal ball speed (SBMS), passing the ball on the move using match-relevant ball speed (RBRS), and repeated side-foot kicks onto a rebound-box with continuously increasing passing distance (RRB). The players were assigned to either the intervention group or the control group. The training intervention consisted of six 55-min training sessions with five side-foot kick exercises. Within-group and between-group differences were investigated using paired-samples t-test and Mann-Whitney U test, respectively.

RESULTS

The intervention group improved the performance in the RBRS and RRB tests (both P<0.05), but no differences were found for the SBRS and SBMS tests (both P>0.05). No improvements were found for the control group independent of test condition (all P>0.05). Significant between-group differences were found for the RBRS and RRB tests (both P<0.05), whereas no differences were found for the SBRS and SBMS tests (both P>0.05).

CONCLUSIONS

The fundamental soccer skill of passing a moving ball was improved in elite female soccer players by a short technique-intense training period.

Immunological Relationship Between Plasminogen Activator Inhibitors from Different Sources

Polyclonal antibodies have been raised against the inhibitor moiety in the purified complex between tissue plasminogen activator and its fast inhibitor (PA-inhibitor) in human plasma/ serum. A radioimmunoassay for quantitation of PA-inhibitor antigen was developed. The polyclonal antiserum and a previously described monoclonal antibody against the PA-inhibitor (14) have been used to study the immunological relationship between PA-inhibitors from plasma, serum, platelets, placenta extract and conditioned media from Hep G2 and HT 1080 cells. It was demonstrated that the ratio between PA-inhibitor activity and antigen varied considerably between the different sources. In the plasma samples studied, similar activity and antigen concentrations were found, suggesting that the PA-inhibitor in these samples mainly was in an active form. On the other hand the other sources seemed to contain variable amounts of inactive PA-inhibitor forms. Immunoadsorption experiments revealed that the PA-inhibitor (activity and antigen) from all the sources were specifically bound to the insolubilized antibodies (polyclonal and monoclonal). In no case, however, could active PA-inhibitor be eluted from the immunoadsorption columns. Also the competitive radioimmunoassays suggested that the PA-inhibitors from the different sources studied, were closely immunologically related.

Physiological Demands of Competitive Sprint and Distance Performance in Elite Female Cross-Country Skiing

Carlsson, M, Carlsson, T, Wedholm, L, Nilsson, M, Malm, C, and Tonkonogi, M. Physiological demands of competitive sprint and distance performance in elite female cross-country skiing. J Strength Cond Res 30(8): 2138-2144, 2016-The purpose was to investigate the relationship between elite females' competitive performance capability in sprint and distance cross-country skiing and the variables of gross efficiency (GE), work rate at the onset of blood-lactate accumulation (OBLA4mmol), maximal oxygen uptake (V[Combining Dot Above]O2max), maximal speed (Vmax), and peak upper-body oxygen uptake (V[Combining Dot Above]O2peak). Ten elite female cross-country skiers (age 24.5 ± 2.8 years) completed treadmill roller-skiing tests to determine GE, OBLA4mmol, and V[Combining Dot Above]O2max using the diagonal-stride technique as well as Vmax and V[Combining Dot Above]O2peak using the double-poling technique. International Ski Federations ranking points for sprint (FISsprint) and distance (FISdist) races were used as competitive performance data. There were correlations between the FISsprint and the V[Combining Dot Above]O2max expressed absolutely (p = 0.0040), Vmax (p = 0.012), and V[Combining Dot Above]O2peak expressed absolutely (p < 0.001) and as a simple ratio-standard (p = 0.049). The FISdist were correlated with OBLA4mmol (p = 0.048), V[Combining Dot Above]O2max expressed absolutely (L·min) (p = 0.015) and as a simple ratio-standard (p = 0.046), and V[Combining Dot Above]O2peak expressed absolutely (p = 0.036) and as a simple ratio-standard (ml·min·kg) (p = 0.040). The results demonstrate that the physiological abilities reflected by V[Combining Dot Above]O2max and V[Combining Dot Above]O2peak are indicators of competitive sprint and distance performance in elite female cross-country skiing. In addition, the ability to generate a high Vmax indicates the performance in sprint races, whereas the skier's OBLA4mmol reflects the performance capability in distance races. Based on the results, when evaluating the performance capacity of elite female cross-country skiers, it is recommended to use physiological variables that reflect competitive performance.

Aerobic power and lean mass are indicators of competitive sprint performance among elite female cross-country skiers

The purpose of this study was to establish the optimal allometric models to predict International Ski Federation’s ski-ranking points for sprint competitions (FISsprint) among elite female cross-country skiers based on maximal oxygen uptake ( V˙O2max) and lean mass (LM). Ten elite female cross-country skiers (age: 24.5±2.8 years [mean ± SD]) completed a treadmill roller-skiing test to determine V˙O2max (ie, aerobic power) using the diagonal stride technique, whereas LM (ie, a surrogate indicator of anaerobic capacity) was determined by dual-emission X-ray anthropometry. The subjects’ FISsprint were used as competitive performance measures. Power function modeling was used to predict the skiers’ FISsprint based on V˙O2max, LM, and body mass. The subjects’ test and performance data were as follows: V˙O2max, 4.0±0.3 L min⁻¹; LM, 48.9±4.4 kg; body mass, 64.0±5.2 kg; and FISsprint, 116.4±59.6 points. The following power function models were established for the prediction of FISsprint: 3.91×105⋅V˙O2max−6.00 and 6.95 × 10¹⁰ · LM^−5.25; these models explained 66% (P=0.0043) and 52% (P=0.019), respectively, of the variance in the FISsprint. Body mass failed to contribute to both models; hence, the models are based on V˙O2max and LM expressed absolutely. The results demonstrate that the physiological variables that reflect aerobic power and anaerobic capacity are important indicators of competitive sprint performance among elite female skiers. To accurately indicate performance capability among elite female skiers, the presented power function models should be used. Skiers whose V˙O2max differs by 1% will differ in their FISsprint by 5.8%, whereas the corresponding 1% difference in LM is related to an FISsprint difference of 5.1%, where both differences are in favor of the skier with higher V˙O2max or LM. It is recommended that coaches use the absolute expression of these variables to monitor skiers’ performance-related training adaptations linked to changes in aerobic power and anaerobic capacity.

The influence of sex, age, and race experience on pacing profiles during the 90 km Vasaloppet ski race

The purpose of this study was to investigate pacing-profile differences during the 90 km Vasaloppet ski race related to the categories of sex, age, and race experience. Skiing times from eight sections (S1 to S8) were analyzed. For each of the three categories, 400 pairs of skiers were matched to have a finish time within 60 seconds, the same start group, and an assignment to the same group for the other two categories. Paired-samples Student’s t-tests were used to investigate sectional pacing-profile differences between the subgroups. Results showed that males skied faster in S2 (P=0.0042), S3 (P=0.0049), S4 (P=0.010), and S1–S4 (P<0.001), whereas females skied faster in S6 (P<0.001), S7 (P<0.001), S8 (P=0.0088), and S5–S8 (P<0.001). For the age category, old subjects (40 to 59 years) skied faster than young subjects (19 to 39 years) in S3 (P=0.0029), and for the other sections, there were no differences. Experienced subjects (≥4 Vasaloppet ski race completions) skied faster in S1 (P<0.001) and S1–S4 (P=0.0054); inexperienced skiers (<4 Vasaloppet ski race completions) had a shorter mean skiing time in S5–S8 (P=0.0063). In conclusion, females had a more even pacing profile than that of males with the same finish time, start group, age, and race experience. No clear age-related pacing-profile difference was identified for the matched subgroups. Moreover, experienced skiers skied faster in the first half whereas inexperienced skiers had higher skiing speeds during the second half of the race.

Optimal [Formula: see text] ratio for predicting 15 km performance among elite male cross-country skiers

The aim of this study was 1) to validate the 0.5 body-mass exponent for maximal. oxygen uptake [Formula: see text] as the optimal predictor of performance in a 15 km classical-technique skiing competition among elite male cross-country skiers and 2) to evaluate the influence of distance covered on the body-mass exponent for [Formula: see text] among elite male skiers. Twenty-four elite male skiers (age: 21.4±3.3 years [mean ± standard deviation]) completed an incremental treadmill roller-skiing test to determine their [Formula: see text]. Performance data were collected from a 15 km classical-technique cross-country skiing competition performed on a 5 km course. Power-function modeling (ie, an allometric scaling approach) was used to establish the optimal body-mass exponent for [Formula: see text] to predict the skiing performance. The optimal power-function models were found to be [Formula: see text] and [Formula: see text], which explained 69% and 81% of the variance in skiing speed, respectively. All the variables contributed to the models. Based on the validation results, it may be recommended that [Formula: see text] divided by the square root of body mass (mL · min(-1) · kg(-0.5)) should be used when elite male skiers' performance capability in 15 km classical-technique races is evaluated. Moreover, the body-mass exponent for [Formula: see text] was demonstrated to be influenced by the distance covered, indicating that heavier skiers have a more pronounced positive pacing profile (ie, race speed gradually decreasing throughout the race) compared to that of lighter skiers.

Striatal tyrosine hydroxylase-positive neurons are associated with L-DOPA-induced dyskinesia in hemiparkinsonian mice

L-3,4-Dihydroxyphenylalanine (L-DOPA) is the therapeutic gold standard in Parkinson's disease. However, long-term treatment is complicated by the induction of debilitating abnormal involuntary movements termed L-DOPA-induced dyskinesias (LIDs). Until today the underlying mechanisms of LID pathogenesis are not fully understood. The aim of this study was to reveal new factors, which may be involved in the induction of LID. We have focused on the expression of striatal tyrosine hydroxylase-positive (TH+) neurons, which are capable of producing either L-DOPA or dopamine (DA) in target areas of ventral midbrain DAergic neurons. To address this issue, a daily L-DOPA dose was administered over the course of 15 days to mice with unilateral 6-hydroxydopamine-induced lesions of the medial forebrain bundle and LIDs were evaluated. Remarkably, the number of striatal TH+ neurons strongly correlated with both induction and severity of LID as well as ΔFosB expression as an established molecular marker for LID. Furthermore, dyskinetic mice showed a marked augmentation of serotonergic fiber innervation in the striatum, enabling the decarboxylation of L-DOPA to DA. Axial, limb and orolingual dyskinesias were predominantly associated with TH+ neurons in the lateral striatum, whereas medially located TH+ neurons triggered locomotive rotations. In contrast, identified accumbal and cortical TH+ cells did not contribute to the generation of LID. Thus, striatal TH+ cells and serotonergic terminals may cooperatively synthesize DA and subsequently contribute to supraphysiological synaptic DA concentrations, an accepted cause in LID pathogenesis.

Oxygen uptake at different intensities and sub-techniques predicts sprint performance in elite male cross-country skiers

PURPOSE

To investigate the relationship between sprint-prologue performance (using the classical technique) and the oxygen uptake at the lactate threshold (VO₂obla), maximal oxygen uptake (VO₂max), and mean oxygen uptake during double poling (VO₂dp).

METHODS

Eight elite male cross-country skiers [age 24.8 ± 4.8 years, (mean ± SD)] completed two treadmill roller-skiing tests using the diagonal-stride technique and a 60 s double-poling test on a ski-ergometer to determine their VO₂obla, VO₂max, and VO₂dp. Performance data were generated from a 1.25 km sprint prologue. Power-function modelling was used to predict the skiers' race speeds based on the oxygen-uptake variables and body mass.

RESULTS

There were correlations between the race speed and the absolute expression of the VO₂obla (r = 0.79, P = 0.021), VO₂max (r = 0.86, P = 0.0069), and VO₂dp (r = 0.94, P = 0.00062). The following power-function models were established for race-speed prediction: 1.09 · VO₂obla(0.21), 1.05 · VO₂max(0.21), and 1.19 · VO₂dp(0.20); these models explained 60% (P = 0.024), 73% (P = 0.0073), and 87% (P = 0.00073), respectively, of the variance in the race speed. However, body mass did not contribute to any of the models (P = 0.97, 0.88, and 0.21, respectively).

CONCLUSIONS

Oxygen uptake at different intensities and sub-techniques is an indicator of elite male sprint-prologue performance. The absolute expression of the investigated oxygen-uptake variables should be used when evaluating elite male sprint-prologue performances; if skiers oxygen uptake differs by 1%, their performances will likely differ by 0.2% in favour of the skier with higher oxygen uptake.

Scaling maximal oxygen uptake to predict performance in elite-standard men cross-country skiers

The purpose of this study was to: 1) establish the optimal body-mass exponent for maximal oxygen uptake (VO(2)max) to indicate performance in elite-standard men cross-country skiers; and 2) evaluate the influence of course inclination on the body-mass exponent. Twelve elite-standard men skiers completed an incremental treadmill roller-skiing test to determine VO(2)max and performance data came from the 2008 Swedish National Championship 15-km classic-technique race. Log-transformation of power-function models was used to predict skiing speeds. The optimal models were found to be: Race speed = 7.86 · VO(2)max · m(-0.48) and Section speed = 5.96 · [VO(2)max · m(-(0.38 + 0.03 · α)) · e(-0.003 · Δ) (where m is body mass, α is the section's inclination and Δ is the altitude difference of the previous section), that explained 68% and 84% of the variance in skiing speed, respectively. A body-mass exponent of 0.48 (95% confidence interval: 0.19 to 0.77) best described VO(2)max as an indicator of performance in elite-standard men skiers. The confidence interval did not support the use of either "1" (simple ratio-standard scaled) or "0" (absolute expression) as body-mass exponents for expressing VO(2)max as an indicator of performance. Moreover, results suggest that course inclination increases the body-mass exponent for VO(2)max.

Validation of physiological tests in relation to competitive performances in elite male distance cross-country skiing

The purpose of the present study was to establish which physiological test parameters reflects the distance performances in the Swedish National Championships in cross-country skiing (SNC) and the International Ski Federation's ranking points for distance performances (FISdist). The present study also aimed to create multiple regression models to describe skiing performance for the SNC distance races and International Ski Federation's (FIS) ranking. Twelve male, Swedish, national elite, cross-country skiers (maximal oxygen consumption [·VO₂max] = 5.34 ± 0.34 L·min⁻¹) volunteered to participate in the study. Their results in the 2008 SNC (15 km race [SNC15] and 30 km race [SNC30]) and FISdist points were used as performance data. On the week preceding the Championship, subjects completed a test battery consisting of 7 physiological tests: isokinetic knee extension peak torque (PT), vertical jumps (VJ), lactate threshold (LT), ·VO₂max, and 3 double poling tests of different durations (DP20, DP60, and DP360). Correlations were established using Pearson's correlation analysis, and models to describe skiing performance were created using standard multiple linear regression analysis. Significant correlations were found between the performance parameters and test parameters derived from LT, ·VO₂max, and DP60 tests. No correlations with any performance parameter were found for PT, VJ, DP20, and DP360 tests. For FISdist and SNC15, the models explain 81% and 78% of the variance in performance, respectively. No statistically valid regression model was found for SNC30. The results of this study imply that the physiological demands in male elite distance cross-country skiing performances are different in different events. To adequately evaluate a skier's performance ability in distance cross-country skiing, it is necessary to use test parameters and regression models that reflect the specific performance.

Cell adhesion molecule expression in human lens epithelial cells after corticosteroid exposure

Aim:

The aim of the study was to investigate changes in cell adhesion molecule expression in human lens epithelial cells (HLEC) subjected to glucocorticoids.

Methods:

Human lens epithelial cells were exposed to different concentrations of dexamethasone for 24 hours. Cell adhesion molecule expression was studied by western blot and immunohistochemistry of vimentin, N-cadherin, E-cadherin, α-catenin, β-catenin and γ-catenin. Expression of the glucocorticoid receptor (GR) was also studied. Cell morphology was examined by transmission electron microscopy (TEM).

Result:

Expression of N-cadherin, α-catenin, β-catenin and GR was significantly decreased in dexamethasone exposed cells as compared to unexposed cells. No significant change in γ-catenin was present. Visualization of adhesion molecules, N-cadherin and α-catenin, by immunohistochemistry showed decreased antigen reactivity in dexamethasone exposed as compared to the unexposed cells. However, no change was seen for β-catenin and γ-catenin. E-cadherin was not detectable using western blot or immunohistochemistry.

TEM showed multilayering of cells, vacuole formation and appearance of electron-dense multivesicular bodies in HLEC exposed to 0, 0.1, 1, 10 and 100 αM dexamethasone.

Conclusion:

Glucocorticoids affect several adhesion molecules in lens epithelial cells, something that may contribute to the pathogenesis of posterior subcapsular opacification.

Evaluation of Factors Affecting Diffusion in Compacted Bentonite

The information available from the open literature and our studies on exclusion, sorption and diffusion mechanisms of ionic and neutral species in bentonite has been compiled and re-examined in relation to the microstructure of bentonite. The emphasis is placed on a more thorough understanding of the diffusion processes taking place in compacted bentonite. Despite the scarcity of experiments performed with neutral diffusants, these imply that virtually all the pores in compacted bentonite are accessible to neutral species. Anion exclusion, induced by the overlap of electrical double layers, may render the accessible porosity for anions considerably less than the porosity obtained from the water content of the clay. On the basis of the compiled data, it is highly probable that surface diffusion plays a significant role in the transport of cations in bentonite clays. Moreover, easily soluble compounds in bentonite can affect the ionic strength of porewater and, consequently, exclusion, equilibrium between cations, and surface diffusion.

Experimental Study of the Nickel Solubility in Groundwater and Cement Water Under Anoxic Conditions

The solubility of nickel under anoxic conditions was investigated in groundwater and in cement-conditioned water. The solubility was studied at 30 °C using the over-saturation method. The nickel concentrations were determined using 63Ni and liquid scintillation counting. The results indicate a nickel solubility of 1–10−4 mol/L in the cement water. The same solubility was also seen in groundwaters that had a pH of 9 or higher. No solubility limit was determined for groundwaters with pH values in the range of 7 to 9.

Coprecipitation of Ni With Calcite: An Experimental Study

At the Finnish candidate sites for a nuclear waste repository calcite (CaCO3) is a common fracture mineral, that may participate in coprecipitation processes. The objective of this work was to study the coprecipitation of the trace element Ni with CaCO3 under controlled conditions. The experiments were carried out at 30 °C in vessels closed to the atmosphere. Calcite-saturated 0.05 M NaCI solutions containing trace amounts of Ni2+ were contacted with calcite for periods of up to 42 days. The experimental data indicate that Ni coprecipitates with calcite as a result of recrystallization. The amounts of coprecipitated Ni and recrystallized calcite were determined using liquid scintillation counting and the isotopes 63Ni and 45Ca. The results are supported by a complementary SEM/EDS analysis of the solid phase.

Effects of dexamethasone on human lens epithelial cells in culture

PURPOSE

Treatment with glucocorticoids is a well known risk factor for cataract development, although the pathogenic mechanism has not been elucidated. The aim of the study was to investigate the effects of glucocorticoids in cultured human lens epithelial cells.

METHODS

Human lens epithelial cells (HLECs) were exposed to dexamethasone for 24 h. The number of viable cells was determined using the 3-[4, 5-dimethylthiazolyl-2]-2, 5-diphenyltetrazolium bromide (MTT) assay, and proliferation was quantified using Ki-67. Apoptosis was investigated by measuring caspase-3 activity and by evaluating nuclear morphology of cells stained with Hoechst 33342. Mitochondria depolarization was measured using the potential-sensitive color, JC-1. Cells were assayed for changes in superoxide production using dihydroethidium (HET), for alterations in peroxide production using dichlorofluorescein diacetate (DCFH-DA), and for glutathione (GSH) variations using monochlorobimane (MCB). Caspase-3 activity was also measured in HLECs simultaneously exposed to dexamethasone and the glucocorticoid antagonist, RU486.

RESULTS

Low doses of dexamethasone (0.1 microM) resulted in increased proliferation of HLECs. Apoptosis was increased in HLECs exposed to 1 microM, 10 microM, and 100 microM of dexamethasone as revealed by nuclear morphology studies. Apoptosis was also confirmed by measuring caspase-3 activation. No effect on superoxide production by dexamethasone was seen. There were no effects on GSH levels or mitochondrial depolarization either. Only the highest concentration of dexamethasone (100 microM) caused an increase in peroxide production. In HLECs incubated with the glucocorticoid antagonist, RU486, apoptosis was induced at a lower concentration of dexamethasone (0.1 microM) than with dexamethasone alone.

CONCLUSIONS

Low doses of dexamethasone cause a moderate increase in proliferation of cultured HLECs. Slightly higher but still physiologically relevant concentrations of dexamethasone result in a dose-dependent increase in apoptosis. Dexamethasone-induced apoptosis in HLECs does not seem to involve oxidative mechanisms. The proapoptotic effect of dexamethasone does not appear to act through the glucocorticoid receptor. Effects on proliferation and/or dysregulation of apoptosis in lens epithelial cells may be an important factor in human steroid-induced posterior subcapsular cataract.

The proteasome and intracellular redox status: implications for apoptotic regulation in lens epithelial cells

PURPOSE

This study aimed to investigate redox regulation of the proteasome as well as the effect of proteasome inhibition on intracellular oxidative status and apoptosis.

METHODS

Oxidative stress was induced in cultured human lens epithelial cells (HLECs) and intact mouse lenses by 100 microM H2O2. HLECs were also exposed to the reduced and the oxidized forms of glutathione (GSH/GSSG) and the reducing agent dithiotreitol (DTT). The chymotrypsin-like, the trypsin-like, and the peptidylglutamyl peptidase activities of the proteasome were measured using synthetic fluorogenic substrates. Superoxide as well as peroxide production, mitochondrial membrane potential, and the level of GSH was measured in HLECs after proteasome inhibition by MG-132 or lactacystin. Apoptosis was determined by measuring caspase-3 activation and by studying apoptotic nuclei after staining with Hoechst 33342.

RESULTS

All three peptidase activities of the proteasome were inhibited by 100 microM H2O2 and by the oxidized form of glutathione (GSSG), whereas the reduced form (GSH) stimulated chymotrypsin-like and peptidylglutamyl peptidase activities in HLECs lysates. Intact mouse lenses exposed to 100 microM H2O2 exhibited loss of transparency and trends of decreased chymotrypsin-like proteasome activity as well as decreased GSH levels. Inhibition of the proteasome in cultured HLECs caused significant increase in apoptosis and disturbed intracellular redox balance. Simultaneous addition of exogenous GSH completely abolished the increased apoptosis seen after MG-132 treatment.

CONCLUSIONS

This study supports the hypothesis that intracellular proteolytic and oxidative regulatory systems are tightly coupled. The current data also indicate that apoptosis by proteasome inhibition is mediated through oxidative mechanisms.

Possible model of an antiferroelectric twist grain boundary phase

Using x-ray and optical methods we have probed the structural organization of an antiferroelectric twist grain boundary phase (TGBC(a)) lying between the regular antiferroelectric smectic-C (SmC(a)* and the smectic-Q (SmQ) or isotropic phase. We find that the twist axis is everywhere perpendicular to the local smectic layer normal and that the helical superstructure is incommensurate with the smectic layer structure. The twist grain boundaries consist of a periodic lattice of alternating +1/2 and -1/2 dispirations, i.e., unit screw dislocations in combination with half unit disclinations. The molecular tilt plane is alternatingly parallel and perpendicular to the twist axis. We find that the optically measured tilt angle in the SmC(a)* phase is smaller than that measured by x rays, which is the opposite to what is found in the SmC* phase. This means that the core part tilts less than the end chains in the SmC(a)* phase, while it tilts more in the SmC* phase. On entering the TGB phase a clear decrease is measured in the tilt angle. This is explained by the elastic influence from the disclinations, which appear in this phase.

Irreducible memory function and slow dynamics in disordered systems

We show how the irreducible memory function can be obtained in a rather straightforward way, and that it can be expressed in terms of two contributions representing two parallel decay channels. This representation should be useful for treating systems with a slow time dependence and where eventually some internal degrees of freedom enters in the relaxation process, and cuts off an underlying ideal ergodic to nonergodic transition. We also show how the irreducible memory function under certain mild conditions defines a regenerative stochastic process, or a two level stochastic system. This leads to a picture with dynamical heterogeneities, where the statistical properties asymptotically are ruled by limit processes. This can explain the universal behavior observed in many glass-forming systems.

Pegylated interferon and ribavirin treatment for hepatitis C in haemodialysis patients

Standard therapy for chronic hepatitis C (HCV) is pegylated interferon in combination with ribavirin. There is limited experience with either drug in dialysis [end stage renal disease (ESRD)]. Six haemodialysis patients, four with HCV genotype 1, one with genotype 4 and one genotype 2 were treated with pegylated interferon-alfa-2b (n = 4) and pegylated interferon-alfa-2a (n = 2) for 24-48 weeks according to genotype with a dose of 50 or 135 mug/week respectively. All patients were given reduced ribavirin doses, initially 200-400 mg/day. Ribavirin trough plasma concentrations were measured with a HPLC method previously developed for earlier treatment studies, aiming at a target concentration of 10-15 micromol/L. Interferon related side-effects were common, in one patient peg-alfa-2b was permanently reduced to 50 mug every 9-10 days with improvement in tolerance. Average ribavirin dose was 170-300 mg/day. Ribavirin-induced anaemia was treated with high doses of erythropoietin and low doses of iron. Blood-transfusions were not needed. All patients became HCV-RNA-PCR negative during treatment which was completed or nearly completed in four patients. One patient terminated therapy prematurely due to pronounced interferon related side-effects and another died of myocardial infarction probably not related to therapy. Three patients have remained HCV-RNA negative with extended follow-up, two of whom have had a successful kidney transplant. Pegylated interferons are likely to become a valuable addition for HCV therapy in ESRD and are possible to combine with ribavirin. However the pharmacokinetics and tolerability of both peg-alfa-2a and 2b need to be studied more closely in prospective studies before definite dosing recommendations can be made.

Continuous exposure to glial cell line-derived neurotrophic factor to mature dopaminergic transplants impairs the graft’s ability to improve spontaneous motor behavior in parkinsonian rats

Functional recovery following intrastriatal transplantation of fetal dopaminergic neurons in animal models of Parkinson's disease is, at least in part, dependent on the number of surviving dopaminergic neurons and the degree of graft-derived dopaminergic reinnervation of the host striatum. In the present study, we analyzed whether continuous exposure of glial cell line-derived neurotrophic factor (GDNF) to mature dopaminergic grafts could further boost the functional outcome of widespread intrastriatal dopaminergic grafts. Rats with dopamine-denervating lesions received multiple intrastriatal transplants of fetal dopaminergic cells and graft-induced behavioral effects were analyzed in drug-induced and spontaneous motor behaviors. At three months after grafting, animals received intrastriatal injections of recombinant lentiviral vectors encoding for either human GDNF or the green fluorescent protein. Continuous exposure of GDNF to the grafts did not boost the functional recovery beyond what was observed in the control animals. Rather, in some of the spontaneous motor behaviors, animals in the GDNF-group showed deterioration as compared with control animals, and this negative effect of GDNF was associated with a down-regulation of the tyrosine hydroxylase enzyme. Based on these and our earlier results, we propose that intrastriatal administration of GDNF at the time of or shortly after grafting is highly effective in initially promoting the cell survival and fiber outgrowth from the grafts. However, once the grafts are mature, GDNF's ability to boost dopaminergic neurotransmission follows the same dynamics as for the native nigral dopaminergic neurons, which appears to be dependent on the concentration of GDNF. Since rather low doses of glial cell line-derived neurotrophic factor at nanogram levels appear to saturate these effects, it may be critical to adjust GDNF levels using tightly regulated gene expression systems.

Hepatitis C virus RNA kinetics during the initial 12 weeks treatment with pegylated interferon-alpha 2a and ribavirin according to virological response

To optimize treatment of chronic hepatitis C early identification of patients who will not achieve a sustained virological response (SVR) is desirable. We investigated hepatitis C virus (HCV) RNA kinetics at day 1 (in 15 patients; genotypes 1 and non-1, 9 and 6 respectively) at weeks 1, 4 and 12 (in 53 patients; genotypes 1 and non-1, 19 and 34, respectively) during treatment with pegylated interferon alpha-2a and ribavirin. Patients with SVR had a significantly more pronounced mean log10 decline from baseline in HCV RNA levels at weeks 1 and 4 compared with patients who failed to achieve SVR (1.99 vs 0.85 at week 1, P = 0.0003 and 2.89 vs 1.72 at week 4, P = 0.0159), whereas no difference was noted after day 1. For patients with a 2-log10 decrease in HCV RNA levels at day 7, the positive predictive value (PPV) for a SVR was 92%, whereas week 12 was the best time point for predicting a later nonresponse [negative predictive value (NPV) 92%] in patients failing to achieve a 2-log10 drop. For patients with genotype non-1 and a 2-log10 decrease in HCV RNA levels the PPV for a SVR was 89% week 1, and 79% weeks 4 and 12. The corresponding NPV for patients with genotype non-1 were 43, 40 and 100% respectively. During treatment with pegylated interferon alpha-2a plus ribavirin the HCV RNA decline at week 1 was an accurate predictor of SVR in patients who had achieved a 2-log10 drop in HCV RNA levels, whereas the lack of such decline week 12 was an accurate marker of a nonresponse.

Viral kinetics and treatment response in patients with hepatitis C during induction and standard interferon therapy in combination with ribavirin

BACKGROUND

The early decline of hepatitis C virus (HCV) RNA levels during therapy may predict the outcome and can be utilized to improve treatment regimens. We studied the HCV RNA levels during induction and standard interferon (IFN) and ribavirin treatment.

METHODS

Patients received IFN 3 MU daily for 14 days followed by 3 MU three times a week (induction group; n = 10), or IFN 3 MU three times a week from start (standard group; n = 21), in combination with ribavirin 1000-1200 mg/day. HCV RNA was quantified day 0, 1, 2, 3, 7, 14, 28, 56 and 84 during treatment, and tested qualitatively at the end of treatment and at follow-up.

RESULTS

The initial viral load decline was more pronounced in the induction group, and in patients infected with genotype non-1. The sustained response rate was not significantly different between the study groups. At day 1, the mean viral load decline from baseline was significantly greater in patients who became sustained responders than in those who became non-responders; 1.4 log (96%) versus 0.3 log (55%) (P < 0.05). All sustained responders had a viral load decline of at least 0.7 log (79%) after the first IFN dose.

CONCLUSIONS

Our short-term induction treatment did not improve the long-term treatment outcome significantly, although a trend was seen. An absent or low initial viral load decline can be used to predict non-response in the individual patient.

Hepatitis C virus kinetics during induction and standard 3 times a week interferon-alpha therapy

We studied HCV kinetics during the first 84 d of interferon-alpha (IFN) treatment. IFN was administered either at a dose of 3 million units daily for the first 14 d and thereafter 3 times per week (t.i.w.) (induction treatment), or at a dose of 3 million units t.i.w. throughout (standard treatment). No patient had received HCV treatment previously, and all had a pretreatment viral load of < 1.2 x 10(6) IU/ml at screening. Ten patients were given induction treatment and 21 received the standard t.i.w. regimen. Twenty patients were infected with genotype 1. At Day 2, the median HCV RNA level in the induction group was significantly lower compared to that of the standard treatment group. This significant difference persisted during the study period for patients infected with genotype 1, but was not maintained from Day 14 onwards for patients with genotype non-1. At Day 84, 80% (8/10) of patients in the induction group, compared to 16% (3/19) in the standard treatment group, had undetectable (< 600 IU/ml) HCV RNA levels (p < 0.05). We conclude that induction treatment resulted in a significantly greater decline in HCV RNA levels than standard treatment.

HCV RNA levels during therapy with amantadine in addition to interferon and ribavirin in chronic hepatitis C patients with previous nonresponse or response/relapse to interferon and ribavirin

Interferon (IFN) alpha in combination with ribavirin (RIB) is standard therapy for patients with chronic hepatitis C virus (HCV) infection. However, many patients do not respond with sustained HCV clearance to this therapy. At present, no accepted treatment strategy exists for these patients. Recent preliminary data have suggested that amantadine (AMA) is effective against HCV infection. In a pilot study, we treated 13 nonresponders and 10 response/ relapsers to previous IFN/RIB therapy with AMA 200 mg per day in combination with IFN 3 MU thrice weekly, and RIB 1000 mg per day for 24 weeks, with a 24-week follow-up period after end-of-treatment. At the end-of-treatment, 1 previous nonresponder and 5 previous response/relapsers were HCV RNA negative. At the end of follow-up, only 1 previous response/relapser remained HCV RNA negative and had a sustained response. During therapy, serum HCV RNA became undetectable in 4 previous nonresponders, of whom 3 had a breakthrough at week 24. Twenty-one patients continued therapy without dose reductions. One patient discontinued therapy prematurely due to sleeping disturbances, and another patient was withdrawn from therapy due to heavy alcohol intake. We conclude that the addition of AMA to IFN and RIB was well tolerated but had little, if any, impact on HCV RNA eradication in nonresponders or response/relapsers to previous IFN/RIB combination therapy.

Theoretical model for layer rotations in smectic-A* liquid crystals subject to asymmetric electric fields

Recently, observations of the rotation of smectic layers under certain experimental conditions have been reported in the literature. In this work, the mechanism of such rotations in chiral smectic-A* liquid crystals under the action of asymmetric, periodic electric fields is studied theoretically. The general conditions for layer rotations have been established using symmetry arguments, and a generalized dynamical theory of the chiral smectic-A* phase, coupling layer rotations and the electroclinic effect, has been developed. The theory is applied in the specific case when an asymmetric sawtooth electric field is applied over the system, and the dependence of the average angular velocity of the smectic layers on the relevant material constants of the liquid crystal and experimental control parameters is calculated. By rewriting the final equations into dimensionless form, it is demonstrated that the system exhibits a universal behavior, reducing the number of independent material constants and control parameters considerably.

The anti-HBs response after 2 different accelerated intradermal and intramuscular schemes for hepatitis B vaccination

To study early seroconversion rates after hepatitis B vaccination intramuscular (i.m.) and low-dose intradermal (i.d.) vaccination was compared when given either according to the registered 0, 4, 8 weeks scheme (scheme A), or to an accelerated 0, 2, 6 weeks scheme (scheme B). Medical staff received either 2 microg i.d. or 20 microg i.m. of a recombinant hepatitis B vaccine, in a non-randomized open trial. Two weeks after the third dose i.m. vaccinees overall had significantly higher rates of protective anti-HBs levels (anti-HBs > or = 10 IU/I), (23/30, 77%) compared with i.d. vaccinees (75/166, 45%) (p < 0.001). We conclude that when rapid protection against hepatitis B virus (HBV) infection is desirable, such as for post-exposure prophylaxis, an accelerated low-dose i.d. vaccination schedule cannot be used.

N-terminal proANF in acute atrial fibrillation: a biochemical marker of atrial pressures but not a predictor for conversion to sinus rhythm. Digitalis in Acute Atrial Fibrillation (DAAF) Trial group

BACKGROUND

Atrial filling pressures are increased in acute atrial fibrillation, which stimulates the release of atrial natriuretic factor pro-hormone, proANF.

METHODS

In a randomized trial comparing digoxin with placebo in 216 patients, we investigated whether the baseline plasma level of N-terminal proANF is a predictor for conversion to sinus rhythm and the relation among N-terminal proANF, conversion to sinus rhythm, and changes in heart rate.

RESULTS

N-terminal proANF was increased at baseline and decreased significantly in patients converting to sinus rhythm, whereas it was mainly unchanged in nonconverters. N-terminal proANF was not a predictor of conversion to sinus rhythm. A relation was found between relative changes in heart rate and N-terminal proANF in nonconverters.

CONCLUSION

The level of N-terminal proANF does not predict conversion to sinus rhythm, which indicates that hemodynamics per se is not important. There is a correlation between relative changes in heart rate and N-terminal proANF in nonconverters.

Interferon-alpha 2b treatment in hepatitis B carriers. Effect on hepatitis B virus DNA levels in children infected with different genotypes

Eleven hepatitis B virus (HBV) carrier children, infected with genotypes A-D, were treated with interferon-alpha. Two children had a sustained loss of hepatitis B e-antigen and HBV DNA. They were infected with the non-Asian genotypes A and D, and had low HBV DNA and high ALT levels in serum before treatment. However, HBV DNA titres decreased during treatment also in children infected with the East-Asian genotypes B and C.

Use of an enzyme thermistor for semi-continuous blood glucose measurements

A method to monitor glucose in whole blood is presented. The aim of the project was to develop a prototype for a bedside monitor system for semi-continuous monitoring of the blood glucose concentration, requiring only one calibration. This was made possible by using the special advantage of the thermal sensor technique in combination with the adjustment of flow. The glucose concentration was determined from the difference between the sensor response and an estimated background signal. Using standard addition technique, calibration factors for background and sensitivity were set and remained unchanged during the monitoring. The background signal was 45 +/- 8 mV (mean +/- S.D., n = 8) and the sensitivity was 28 +/- 1 mV/mmol (mean +/- S.D., n = 4). Recovery in whole blood was 90-98% (mean 94%, n = 12). With an injection interval of 3 min the precision with the sensor was < 3% over more than 100 blood samples. Response time was about 60 s. The calculated glucose values correlated, r = 0.98, with the values obtained with an YSI glucose analyser (Yellow Springs Instruments. Yellow Springs, OH, USA), over the range 2-20 mmol/l.

Homeopathic Resistant Malaria

Multiresistant Plasmodium falciparum malaria is a major threat to travelers to subSaharan Africa. However, even if chemoprophylaxis does not prevent clinical malaria in some individuals, it does lead to a reduction in the severity of the disease.1 In Sweden, we have recently seen five patients with malaria (three due to P. ovale and two due to P. falciparum) who have used homeopathic drugs for prophylaxis during visits to West Africa. We are concerned about this incidence and afraid that reduced confidence in modern medical malaria prophylaxis will encourage some individuals to try totally ineffective alternatives. Three women (57, 40, and 39 years old) visited Guinea Conacry in January 1995 as members of a group of 24 persons learning about African dances. The 57-year-old woman took mefloquine irregularly but vomited each time after intake. She also used Spenglersan M, which is a homeopathic drug that is administered (one drop daily in the bend of the arm) as malaria prophylaxis. The two other women used Spenglersan M only. They all fell ill with P. ovale malaria despite ongoing intake. Spenglersan M is said to contain both antigen from P. falciparum and antibodies against the parasite diluted to 1:1,000,000,000 concentration. The fourth case was a 26-year-old man who visited Ghana and Burkina Faso in October and November 1994. He used China D-6 for prophylaxis. This is a homeopathic preparation of the bark from the cinchona tree. Not even trace amounts of quinine were found in the tablets with a very sensitive high-performance liquid chromatographic method.2 Four days after returning from Africa he fell ill with P. falciparum malaria and received sulphadoxine-pyrimethamine treatment. After clinical relapse (RI), mefloquine was given and the patient was eventually cured. The fifth case was a 34-year-old woman admitted to hospital because of P. falciparum malaria after a visit to Guinea Conacry in January 1995. She had taken a homeopathic drug, Charaka comp 118, as prophylaxis. The drug is said to contain different extracts from herbs diluted 30 times. At first she refused to stay in hospital, but 2 days later she was readmitted and treated in the intensive care unit because of severe malaria with hypotonia and anemia. She had hyperparasitemia with 23% infected erythrocytes. Exchange transfusion was done, quinine was given, and the patient recovered without sequelae. The mortality is about 1% in people with P. falciparum infection.3 We therefore urge the readers to stand up against the dangerous use of homeopathic drugs and instead motivate travelers to use protective malaria prophylaxis.