Sample size, power and effect size revisited: simplified and practical approaches in pre-clinical, clinical and laboratory studies

Calculating the sample size in scientific studies is one of the critical issues as regards the scientific contribution of the study. The sample size critically affects the hypothesis and the study design, and there is no straightforward way of calculating the effective sample size for reaching an accurate conclusion. Use of a statistically incorrect sample size may lead to inadequate results in both clinical and laboratory studies as well as resulting in time loss, cost, and ethical problems. This review holds two main aims. The first aim is to explain the importance of sample size and its relationship to effect size (ES) and statistical significance. The second aim is to assist researchers planning to perform sample size estimations by suggesting and elucidating available alternative software, guidelines and references that will serve different scientific purposes

Association of serum ADMA, SDMA and L-NMMA concentrations with disease progression in COVID-19 patients

IntroductionThis study determines and compares the concentrations of arginine and methylated arginine products ((asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), n-monomethyl-1-arginine (L-NMMA) and homoarginine (HA)) for assessment of their association with disease severity in serum samples of COVID-19 patients. Materials and methodsSerum arginine and methylated arginine products of 57 mild-moderate and 29 severe (N = 86) COVID-19 patients and 21 controls were determined by tandem mass spectrometry. Moreover, the concentrations of some of the routine clinical laboratory parameters -neutrophil lymphocyte ratio (NLR), C-reactive protein, ferritin, D-dimer, and fibrinogen measured during COVID-19 follow-up were also taken into consideration and compared with the concentrations of arginine and methylated arginine products. ResultsSerum ADMA, SDMA and L-NMMA were found to be significantly higher in severe COVID-19 patients, than in both mild-moderate patients and the control group (P < 0.001 for each). In addition, multiple logistic regression analysis indicated L-NMMA (cut-off =120 nmol/L OR = 34, 95% confidence interval (CI) = 3.5-302.0, P= 0.002), CRP (cut-off = 32 mg/L, OR = 37, 95% CI = 4.8-287.0, P < 0.001), and NLR (cut-off = 7, OR = 22, 95% CI = 1.4-335.0, P = 0.020) as independent risk factors for identification of severe patients. ConclusionsThe concentration of methylated arginine metabolites are significantly altered in COVID-19 disease. The results of this study indicate a significant correlation between the severity of COVID-19 disease and concentrations of CRP, NLR and L-NMMA

Sample size, power and effect size revisited: simplified and practical approaches in pre-clinical, clinical and laboratory studies.

Calculating the sample size in scientific studies is one of the critical issues as regards the scientific contribution of the study. The sample size critically affects the hypothesis and the study design, and there is no straightforward way of calculating the effective sample size for reaching an accurate conclusion. Use of a statistically incorrect sample size may lead to inadequate results in both clinical and laboratory studies as well as resulting in time loss, cost, and ethical problems. This review holds two main aims. The first aim is to explain the importance of sample size and its relationship to effect size (ES) and statistical significance. The second aim is to assist researchers planning to perform sample size estimations by suggesting and elucidating available alternative software, guidelines and references that will serve different scientific purposes

Eisenmenger Syndrome: Identifying The Clues For Arrhythmia

Objective: The aim of this case-controlled, cross-sectional study is to investigate the tendency towards arrhythmia using noninvasive arrhythmia markers (QT dispersion and heart rate variability) in children with Eisenmenger syndrome. Methods: We studied 23 patients, whose pulmonary-to-systemic resistance ratio was calculated to be greater than 0.75, and who were diagnosed as Eisenmenger syndrome between 1990 and 2001. Twenty healthy children were studied as the control group. Electrocardiographic recordings with calculation of (IT dispersion, Holter monitoring, echocardiographic studies and heart rate variability (HRV) analysis were performed in both groups. Catheterization records were analyzed in all the patients. Results: (IT and QTc dispersion were higher (p=0.007 and p=0.006, respectively) and PR interval was longer (p=0.009) in the patients with Eisenmenger syndrome, than those in the control group. In addition, low frequency component, high frequency component, very low frequency component, and total power, obtained from HRV analysis were significantly lower in the patients with Eisenmenger syndrome (p=0.001, p=0.006, p=0.009 and p=0.011, respectively). Evaluation of Holter recordings revealed pathologic findings in 21.7% of the patients with Eisenmenger syndrome. Pulmonary-to-systemic resistance ratio of the patients with pathologic Holter findings were higher than in the patients with normal Holter recordings (p=0.011). It was also shown that there was a positive correlation between OT dispersion and pulmonary-to-systemic resistance ratio (p=0.048, r=0.416) and between (IT dispersion and PR interval (p=0.009, r=0.532) in the patients with Eisenmenger syndrome. Conclusion: Dispersion of repolarization, being associated with high pulmonary-to-systemic resistance ratio, is increased and autonomic modulation of heart rate is impaired in patients with Eisenmenger syndrome. These findings suggest that arrhythmia risk for patients with Eisenmenger syndrome is higher than in normal controls.Wo

Comparison of LabUMat-with-UriSed and iQ (R) 200 fully automatic urine sediment analysers with manual urine analysis

Urine analysis is one of the most common tests for assessing urinary-tract and kidney diseases. In recent years there have been new developments in the automation of this test. The objective of the present study was to compare the performances of two urine sediment analysers, namely LabUMat with UriSed (77 Elektronika Kft, Budapest, Hungary) and iQ (R) 200 (Iris Diagnostics, Chatsworth, CA, U.S.A.), with the KOVA (R) method for manual urine measurement by evaluating the results in terms of similar parameters (cells or particles per lower-power field or high-power field). The results obtained using the UriSed and iQ (R) 200 analysers were more reproducible (7.1-30.2 and 14.9-35.4% respectively) than those obtained using the manual technique (17.9-44.4%). Significant correlations were established among the three techniques in the evaluation of leucocytes, erythrocytes and epithelial cells. Although the UriSed, iQ (R) 200 and visual-microscopic measurements were in agreement, confirmation of the results from automated methods by manual urine analyses is significantly useful, especially for pathological cases that were close to the limits of the techniques

Relationship Between Visceral Adipose Tissue and Adiponectin, Inflammatory Markers and Thyroid Hormones in Obese Males with Hepatosteatosis and Insulin Resistance

Background and Aims. In our detailed analysis of the recent academic publications, we have not found sufficient evidence regarding the changes of metabolism that occur in cases of insulin resistance (IR) and nonalcoholic fatty liver disease (NAFLD). We aimed to investigate the changes in various biomarkers of obese patients by taking into consideration the IR and NAFLD, which occur increasingly together

In vitro IL-1 beta release from gingival fibroblasts in response to pure metals, dental alloys and ceramic

Little information is available on the immunological basis for side-effects of dental materials. The objective of this study is to evaluate effects of pure metals, dental alloys and ceramic on cell viability and interleukin-1 beta (IL-1 beta) release in three-dimensional human gingival fibroblast cultures as an indicator of their biological performance in gingival tissues. The gingival fibroblast cultures were exposed to test specimens fabricated from nickel, iron, molybdenum, copper, indium, gold, Ni-Cr-Mo alloy (Remanium CS), Au-Pt-In alloy (Pontostar) and a dental ceramic (In-ceram). Cell viability was determined by the MTT method 24 and 48 h after exposure. Assays for IL-1 beta were carried out by ELISA. Statistical analysis was performed applying the non-parametric Mann-Whitney pairwise test. Dental ceramic and gold did not influence cell viability after 24 and 48 h. Cell viability was determined after 24 and 48 h to nickel (79-77%), iron (92-90%), molybdenum (86-83%), copper (48-36%), indium (90-90%), Remanium CS (83-80%), Pontostar (94-91%) compared with control cultures. Dental ceramic, Pontostar and gold had no significant influence on IL-1 beta secretion. The highest amounts of IL-1 beta (10-fold) levels were determined in cell cultures exposed to copper. Indium, molybdenum and iron induced twofold IL-1 beta levels compared with untreated control cultures. These results support that some metals may alter immune responses and thereby contribute to a variety of dental pathological conditions and three-dimensional cell culture models for gingival fibroblasts appear to be suitable for in vitro studies

Salivary and serum oxidative stress biomarkers and advanced glycation end products in periodontitis patients with or without diabetes: A cross-sectional study

Background Non-invasive methods for periodontitis diagnosis would be a clinically important tool. This cross-sectional study aimed to investigate the association between oxidative stress, glycation, and inflammation markers and periodontal clinical parameters in periodontitis and periodontally healthy patients with type 2 diabetes and corresponding systemically healthy controls. Material and methods Sixty-seven periodontally healthy (DM-H, n = 32) and periodontitis (DM-P, n = 35) patients with type 2 diabetes, and 54 systemically healthy periodontitis (H-P, n = 26) and periodontally healthy (H-H, n = 28) controls were included. Clinical periodontal parameters, body mass index, fasting glucose, hemoglobin A1c (HbA1c), along with saliva and serum 8-hydroxy-2 '-deoxyguanosine (8-OHdG), malondialdehyde (MDA), 4-hydroxy-2-nonenal (4-HNE), advanced glycation end products (AGE), AGE receptor (RAGE) and high sensitivity C-reactive protein (hsCRP) levels were recorded and analyzed. Results Salivary 8-OHdG levels were significantly higher in periodontitis compared to periodontally healthy patients, regardless of systemic status (P < 0.001). Salivary MDA levels were significantly higher in all disease groups compared to H-H group (P <= 0.004). Serum AGE levels were significantly higher in diabetic groups than systemically healthy groups (P < 0.001) and in H-P compared to H-H (P < 0.001). Bleeding on probing (BOP) and clinical attachment level (CAL) strongly correlated with salivary 8-OHdG and serum hsCRP (P < 0.001). In systemically healthy patients, salivary 8-OHdG was the most accurate marker to differentiate periodontitis from controls (AUC = 0.84). In diabetics salivary 4-HNE and RAGE were the most accurate (AUC = 0.85 for both). Conclusion Salivary 8-OHdG alone or in combination with 4-HNE, AGE and RAGE for diabetics, and salivary 8-OHdG alone or in combination with MDA and hsCRP for systemically healthy persons, could potentially serve as non-invasive screening marker(s) of periodontitis.Ankara University Scientific Research Projects Office, Ankara, Turkey [12B3334002]; Ankara University Department of Periodontology and Department of Endocrinology; Ohio State University Division of PeriodontologyThis study was supported by the Ankara University Scientific Research Projects Office, Ankara, Turkey (12B3334002). The authors declare that they have no conflicts of interest.; Ankara University Department of Periodontology and Department of Endocrinology; Ohio State University Division of Periodontolog