Reliability and Validity of Different Lower-Limb Strength Tests to Determine 1RM in the Keiser A300 Leg Press.

ABSTRACT: Larsen, F, Loturco, I, Sigvaldsen, E, Strand, MF, Kalhovde, JM, and Haugen, T. Reliability and validity of different lower-limb strength tests to determine 1RM in the Keiser A300 leg press. J Strength Cond Res 37(10): 1963-1968, 2023-The aim of this study was to explore the reliability and validity of different lower-limb strength tests to determine the one-repetition maximum (1RM) value in the Keiser A300 leg press. Twenty-eight recreationally active subjects performed load-velocity (L-V) relationship, 1RM, isometric midthigh pull (IMTP), and maximal repetitions to failure (MRF) tests on 3 separated sessions. Predicted 1RMs for the L-V relationship were estimated from a linear regression equation, correlating movement velocity and relative loads. The number of repetitions from the MRF tests (at loads relative to bodyweight) and peak force from the IMTP tests were used in regression equations to predict 1RM. The level of significance was set to ρ ≤ 0.05. All 1RM prediction methods were highly comparable with the traditional 1RM test, as only trivial and nonsignificant differences were observed. Furthermore, the L-V relationship was the most reliable (intraclass correlation coefficient [± 95% confidence interval] = 0.99 [0.98, 0.996]; effect size = -0.01 [-0.38, 0.36], standard error of the measurement = 6.4 kg; coefficient of variation = 3.0 [2.2-3.8]% and valid (r = 0.95 [0.89, 0.98], effect size = 0.08 [-0.29, 0.45], standard error of the estimate = 20.4 kg; coefficient of variation = 7.4 [5.5-9.3]%) when compared with direct 1RM measurements. The L-V relationship test showed a significant change score relationship (r = 0.41 [0.04, 0.68]) against the direct 1RM measurements. In conclusion, the tests used in this study cannot be used interchangeably, but they represent a good alternative in training settings where 1RM testing is not feasible.

The Effect of Flying Sprints at 90% to 95% of Maximal Velocity on Sprint Performance.

PURPOSE: Submaximal sprinting allows for larger accumulated work to be reached before the onset of fatigue, compared with maximal efforts. The aim of this study was to investigate the effect of sprint running at 90% to 95% of maximal velocity (Vmax) on sprint performance. METHODS: Recreationally active adults were randomly assigned into a control group (n = 12, 27 [5] y, 172 [9] cm, 72 [15] kg) and a training group (n = 14, 26 [4] y, 171 [9] cm, 69 [11] kg). Both groups completed pretesting and posttesting in form of a 30-m sprint separated by a 6-week period. The training group performed a weekly sprint-training session consisting of 30-m flying sprints at 90% to 95% of Vmax, while the control group performed no intervention training. RESULTS: Significant improvements in the training group were observed for 10- (P = .003), 20- (P = .001), and 30-m sprint time (P = .002). These improvements were accompanied by higher step rate (P = .006) and theoretical Vmax (P = .007) and maximal power (P = .004). Significant between-groups differences were observed for 10- (P = .008), 20- (P < .001), and 30-m sprint time (P < .001), as well as for step rate (P = .015), theoretical Vmax (P = .016), and maximal power (P = .008). All within- and between-groups differences were in the range of trivial to small. CONCLUSION: Sprint running at 90% to 95% of Vmax can enhance 10- to 30-m sprint performance in recreationally active adults.

A school-based physical activity intervention on psychosocial health outcomes among 11- and 12-year-olds - HOPP-project.

The purpose was to investigate the effect of a school-based physical activity (PA)-intervention among 11- and 12-year-olds (6th- and 7th graders) across 4 years. Seven primary schools in Horten municipality in Norway received 45 min daily extra PA as part of the curriculum. The intervention started in 2015 with follow-up in 2016-2019. The effect was measured after 1-4 years of participation, among the same children (6th to 7th grade) and among new children starting in 6th grade. Two control schools received no additional PA beyond the regular PA at school. The Self-reported Strength and Difficulties Questionnaire (SDQ-S) focusing on internalizing and externalizing difficulties were administrated. A statistical model for repeated measurements was used and adjusted for parents' educational level, sex, age, and waist-to-height ratio (WHtR). The significance level was p ≤ 0.01. In total, 1221 children completed the SDQ-S. SDQ-S scores were stable, and difficulties were relatively low. The control group had significantly lower SDQ-S scores than the intervention group at start, indicating fewer difficulties. The adjusted effect within the intervention schools showed a borderline significant increase in total difficulty scores between 2018 and 2019 (mean difference: 1.02, 95% CI: -1.82, -0.23, p ≤ 0.01). Educational level showed a weak negative correlation with total difficulty score (r = -0.1). No significant change was reported within the control schools. Few psychosocial health problems among 11- and 12-year-olds were detected. The borderline increase in total difficulty score that was seen for the intervention schools, is believed to be of limited clinical relevance.

Hematology reference intervals in 6-12-year-old children: the health-oriented pedagogical project (HOPP).

Reference intervals are essential for correct interpretation of laboratory test results, supporting clinicians in distinguishing between healthy and sick individuals. The present study aims to establish pediatric reference intervals for hematological parameters based on a large population of healthy schoolchildren. Blood samples were obtained from 1351 children 6-12 years of age participating in the Health-Oriented Pedagogical Project (HOPP). Reference intervals for hematological parameters were estimated by the nonparametric method following the CLSI C28-A3 guidelines. Reference intervals were estimated as 2.5th and 97.5th percentiles with corresponding 90% confidence intervals. While hematocrit and MCV required age and sex partitioning, hemoglobin and erythrocytes were partitioned for age. The remaining parameters, MCH, MCHC, platelets and white blood cell counts did not require partitioning. While red blood cell parameters exhibited an increasing trend with age, there was a slight decrease in leukocytes, lymphocytes, basophils and platelets with age. The remaining parameters were stable across our age span.

Variation in Child Serum Cholesterol and Prevalence of Familiar Hypercholesterolemia: The Health Oriented Pedagogical Project (HOPP).

Early stages of atherosclerosis may develop in childhood due to hyperlipidemia. The aims are to investigate the prevalence of familiar hypercholesterolemia in 6 to 12-year-old children and to study the deviation in cholesterol measures. Anthropometric data and venous blood were collected from children participating in the Health Oriented Pedagogical Project (HOPP). Out of 18 children with TC > 6.0 mmol/L, 15 were tested genetically and none diagnosed with FH. The prevalence of TC > 6.0 mmol/L declined from 1.3% in 2015 to 0.5% in 2016. The mean TC was 4.30 mmol/L both years, which is lower than in earlier studies. Usage of a single TC measurement and a threshold of TC > 6.0 mmol/L in screening children for FH, may not be a good screening strategy. While lipid values have a good reliability across 2 measurements, there are variations in individual TC levels across 1 year.

Identification of response signatures for tankyrase inhibitor treatment in tumor cell lines.

Small-molecule tankyrase 1 and tankyrase 2 (TNKS1/2) inhibitors are effective antitumor agents in selected tumor cell lines and mouse models. Here, we characterized the response signatures and the in-depth mechanisms for the antiproliferative effect of tankyrase inhibition (TNKSi). The TNKS1/2-specific inhibitor G007-LK was used to screen 537 human tumor cell lines and a panel of particularly TNKSi-sensitive tumor cell lines was identified. Transcriptome, proteome, and bioinformatic analyses revealed the overall TNKSi-induced response signatures in the selected panel. TNKSi-mediated inhibition of wingless-type mammary tumor virus integration site/ß-catenin, yes-associated protein 1 (YAP), and phosphatidylinositol-4,5-bisphosphate 3-kinase/AKT signaling was validated and correlated with lost expression of the key oncogene MYC and impaired cell growth. Moreover, we show that TNKSi induces accumulation of TNKS1/2-containing ß-catenin degradasomes functioning as core complexes interacting with YAP and angiomotin proteins during attenuation of YAP signaling. These findings provide a contextual and mechanistic framework for using TNKSi in anticancer treatment that warrants further comprehensive preclinical and clinical evaluations.

Distribution of creatinine and estimated glomerular filtration rate in healthy schoolchildren: The Health Oriented Pedagogical Project (HOPP).

Glomerular filtration rate (GFR) measured by urinary clearance of inulin is considered the gold standard for assessment of kidney function in both adults and children. Because the procedure is cumbersome, GFR is estimated (eGFR) using algorithms based on the observed relationship between measured GFR (mGFR) and more accessible biomarkers such as creatinine and cystatin C. In children, most of the data on this relationship is retrieved from patients with reduced kidney function. Nonetheless, eGFR equations are widely in use in healthy children to evaluate kidney status and diagnose kidney disease. The aim of the present study was to compare the distribution of eGFR using two established pediatric eGFR equations incorporating age, height and serum creatinine (Schwartz-Lyon and Full Age Spectrum-height) and two recently published equations restricted to age and serum creatinine (Lund-Malmö Revised 18 and European Kidney Function Consortium equation) in 1200 healthy schoolchildren age 6-12 years. In addition, we present 2.5th, median and 97.5th percentiles for serum creatinine stratified by age and gender. Depending on the equation used, mean eGFR ranged from 101.6 to 115.4 mL/min/1.73 m2. The lower 2.5th percentile ranged from 83.3 to 89.0 mL/min/1.73 m2 and the fraction of children with eGFR < 90 mL/min/1.73 m2 ranged from 2.9% to 9.8%. In conclusion, expected values of eGFR in healthy children are significantly dependent on the equation used. When decision limits for diagnosis or classification are applied to eGFR results, the related equation should be clearly stated.

Population-based reference intervals for ferritin, iron, transferrin and transferrin saturation and prevalence of iron deficiency in 6-12-year-old children: the Health Oriented Pedagogical Project (HOPP).

Appropriate reference intervals are important for correct interpretation of laboratory test results. The primary objective of the present study was to establish pediatric reference intervals for biochemical markers essential in the assessment of iron status. As a secondary objective we calculated the prevalence of iron deficiency according to WHO recommendations. Blood samples were obtained from 1355 healthy children 6-12 years of age participating in the Health Oriented Pedagogical Project (HOPP). For our primary objective, data from 1333 children were used to establish reference intervals for ferritin, iron, transferrin and transferrin saturation. Following the CLSI C28-A3 guidelines, the 2.5th and 97.5th percentiles with corresponding 90% confidence intervals, were estimated by the nonparametric method. None of the measured analytes required partitioning for age or sex. The prevalence of iron deficiency was 8.2%, which is higher than reported in other populations.

Tankyrase inhibition sensitizes melanoma to PD-1 immune checkpoint blockade in syngeneic mouse models.

The development of immune checkpoint inhibitors represents a major breakthrough in cancer therapy. Nevertheless, a substantial number of patients fail to respond to checkpoint pathway blockade. Evidence for WNT/ß-catenin signaling-mediated immune evasion is found in a subset of cancers including melanoma. Currently, there are no therapeutic strategies available for targeting WNT/ß-catenin signaling. Here we show that a specific small-molecule tankyrase inhibitor, G007-LK, decreases WNT/ß-catenin and YAP signaling in the syngeneic murine B16-F10 and Clone M-3 melanoma models and sensitizes the tumors to anti-PD-1 immune checkpoint therapy. Mechanistically, we demonstrate that the synergistic effect of tankyrase and checkpoint inhibitor treatment is dependent on loss of ß-catenin in the tumor cells, anti-PD-1-stimulated infiltration of T cells into the tumor and induction of an IFNγ- and CD8+ T cell-mediated anti-tumor immune response. Our study uncovers a combinatorial therapeutical strategy using tankyrase inhibition to overcome ß-catenin-mediated resistance to immune checkpoint blockade in melanoma.

MEK Inhibition Induces Canonical WNT Signaling through YAP in KRAS Mutated HCT-15 Cells, and a Cancer Preventive FOXO3/FOXM1 Ratio in Combination with TNKS Inhibition.

The majority of colorectal cancers are induced by subsequent mutations in APC and KRAS genes leading to aberrant activation of both canonical WNT and RAS signaling. However, due to induction of feedback rescue mechanisms some cancers do not respond well to targeted inhibitor treatments. In this study we show that the APC and KRAS mutant human colorectal cancer cell line HCT-15 induces canonical WNT signaling through YAP in a MEK dependent mechanism. This inductive loop is disrupted with combined tankyrase (TNKS) and MEK inhibition. RNA sequencing analysis suggests that combined TNKS/MEK inhibition induces metabolic stress responses in HCT-15 cells promoting a positive FOXO3/FOXM1 ratio to reduce antioxidative and cryoprotective systems.

Reference intervals for serum lipids and prevalence of dyslipidaemia in 6-12-year-old children: The Health Oriented Pedagogical Project (HOPP).

AIMS: Elevated serum lipid concentrations in childhood are thought to be risk factors for the development of cardiovascular disease later in life. The present study aims to provide age- and gender-related reference intervals for total cholesterol (TC), high-density lipoprotein (HDL) cholesterol, and non-HDL cholesterol in healthy school children. We also investigated the prevalence of dyslipidaemia using the published criteria for these biomarkers. METHODS: Venous blood and anthropometric data were collected from 1340 children in the HOPP study, aged between 6 and 12 years. Age- and gender-related reference intervals (2.5th and 97.5th percentiles) were established according to the IFCC recommendations, using the software RefVal 4.10. RESULTS: Gender differences were observed for total cholesterol and non-HDL cholesterol, but not for HDL cholesterol. Age differences were observed for total cholesterol. The reference intervals were in the range of 3.1-5.9 mmol/L for total cholesterol, 1.0-2.4 mmol/L for HDL cholesterol and 1.4-4.2 mmol/L for non-HDL cholesterol. Dyslipidaemia prevalence was as follows: increased TC 9.6%, decreased HDL 1.6%, and increased non-HDL 5.6%. CONCLUSIONS: Age- and gender-related reference intervals in a Norwegian population are similar to those reported in other countries. The prevalence of dyslipidaemia among Norwegian children is significant, emphasising the importance of appropriate reference intervals in clinical practice.

Metabolites in vertebrate Hedgehog signaling.

The Hedgehog (HH) signaling pathway is critical in embryonic development, stem cell biology, tissue homeostasis, chemoattraction and synapse formation. Irregular HH signaling is associated with a number of disease conditions including congenital disorders and cancer. In particular, deregulation of HH signaling has been linked to skin, brain, lung, colon and pancreatic cancers. Key mediators of the HH signaling pathway are the 12-pass membrane protein Patched (PTC), the 7-pass membrane protein Smoothened (SMO) and the GLI transcription factors. PTC shares homology with the RND family of small-molecule transporters and it has been proposed that it interferes with SMO through metabolites. Although a conclusive picture is lacking, substantial efforts are made to identify and understand natural metabolites/sterols, including cholesterol, vitamin D3, oxysterols and glucocorticoides, that may be affected by, or influence the HH signaling cascade at the level of PTC and SMO. In this review we will elaborate the role of metabolites in HH signaling with a focus on oxysterols, and discuss advancements in modern analytical approaches in the field.

High sensitivity measurements of active oxysterols with automated filtration/filter backflush-solid phase extraction-liquid chromatography-mass spectrometry.

Oxysterols are important in numerous biological processes, including cell signaling. Here we present an automated filtration/filter backflush-solid phase extraction-liquid chromatography-tandem mass spectrometry (AFFL-SPE-LC-MS/MS) method for determining 24-hydroxysterol and the isomers 25-hydroxycholesterol and 22S-hydroxycholesterol that enables simplified sample preparation, high sensitivity (~25 pg/mL cell lysis sample) and low sample variability. Only one sample transfer step was required for the entire process of cell lysis, derivatization and determination of selected oxysterols. During the procedure, autoxidation of cholesterol, a potential/common problem using standard analytical methods, was found to be negligible. The reversed phase AFFL-SPE-LC-MS/MS method utilizing a 1mm inner diameter column was validated, and used to determine levels of the oxysterol analytes in mouse fibroblast cell lines SSh-LII and NIH-3T3, and human cancer cell lines, BxPC3, HCT-15 and HCT-116. In BxPC3 cells, the AFFL-SPE-LC-MS/MS method was used to detect significant differences in 24S-OHC levels between vimentin+ and vimentin- heterogenous sub-populations. The methodology also allowed monitoring of significant alterations in 24S-OHC levels upon delivery of the Hedgehog (Hh) antagonist MS-0022 in HCT-116 colorectal carcinoma cell lines.

Hedgehog antagonists cyclopamine and dihydroveratramine can be mistaken for each other in Veratrum album.

A toxic plant, Veratrum album (ssp. viriscens), was found to have an inhibitory effect on Hedgehog (Hh), a developmental signaling pathway that has been shown to be active during development, in adult stem cells and in numerous human tumors. Based on earlier studies it was believed that the known Hh inhibitor cyclopamine was present in V. album (ssp. viriscens). Here we show that instead of cyclopamine, dihydroveratramine (DHV) was found in V. album (ssp. viriscens). These compounds are easily mistaken for each other, as both substances share the same molecular weight, and the same main MS/MS fragments. DHV was found to be a less potent Hh inhibitor compared to cyclopamine. This is the first reported occurrence of DVH in nature.

Hedgehog antagonist cyclopamine isomerizes to less potent forms when acidified.

The effect of acid treatment of cyclopamine, a natural antagonist of the hedgehog (Hh) signaling pathway and a potential anti-cancer drug, has been studied. Previous reports have shown that under acidic conditions, as in the stomach, cyclopamine is less effective. Also, it has been stated that cyclopamine converts to veratramine, which has side effects such as hemolysis. In this study, we examined in detail the influence of acidification on structure and activity of cyclopamine. We found that of acidified cyclopamine converts to two previously unreported isomers, which we have called cyclopamine (S) and cyclopamine (X). These have likely gone undetected because cyclopamine is often analyzed with fast and hence lower resolving chromatographic methods. Compared to natural cyclopamine, these cyclopamine isomers have a significantly reduced effect on the ciliary transport of the Hh receptor smoothened, and reduced inhibition on the Hedgehog signaling pathway. The side effects of these isomers are unknown. Our findings can partly explain a reduced efficiency of cyclopamine in a gastric environment, and may help with the rational design of more pH independent cyclopamine analogues.