Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

BioVar: an online biological variation analysis tool

Objectives: Biological variation (BV) analysis of laboratory tests gets increased attention due to its practical applications. These applications include correct interpretation of laboratory tests, the decision on the availability of reference intervals, contributions to clinical decision-making. It is critical to derive the BV information accurately and reliably. Another crucial step is to perform the statistical analysis of the BV data. Although there are updated and comprehensive guidelines, there is no reliable and comprehensive tool to perform statistical analysis of BV data

Effects of carbon dioxide pneumoperitoneum on renal function in obstructive jaundice: an experimental study in a rat model Efectos del neumoperitoneo por dióxido de carbono sobre la función renal en la ictericia obstructiva: un estudio experimental en un modelo de rata

Introduction: Both pneumoperitoneum (PNP) and obstructive jaundice (OJ) are known to lead to acute kidney injury (AKI) potentially, but the combined effect has not been investigated. Aim: This study aimed to investigate the effects of PNP on renal functions in a rat model of OJ. Methods: We divided forty-eight rats into eight groups of six rats. Group 1 was the control (sham-operated) group; Groups 2, 3, and 4 were induced 5, 10, and 15 mmHg of CO2 PNP, respectively (Groups 1-4: “non-OJ Groups”); Group 5 was the OJ group; and Groups 6, 7 and 8 were OJ groups that were induced with 5, 10, and 15 mmHg CO2 PNP was respectively (Groups 5-8: “OJ Groups”). The common bile duct was ligated and divided into OJ Groups. After 48 hours, a 5-10-15 mmHg PNP was induced by mini-laparotomy with a Veress needle in Groups 6, 7, and 8, maintained for 60 minutes. Results: There were no statistically significant differences between groups regard-ing blood urea Nitrogen and Creatinin levels (p> 0.05). Neutrophil gelatinase-associated lipocalin (NGAL) values were significantly higher in OJ Groups than in non-OJ Groups (p< 0.05). Serum Cystatin-C values were significantly higher in OJ Groups with 10 and 15 mmHg PNP than in non-OJ Groups (p< 0.05). Conclusion: In the early stage of AKI, NGAL and Cystatin-C levels might be higher, while standard renal function tests were normal. Our findings highlight the apparent unfa-vorable effect of OJ with PNP on renal functions and early recognition of AKI with the measurement of NGAL and Cystatin-C in these conditions

Biological variation estimates of prothrombin time, activated partial thromboplastin time, and fibrinogen in 28 healthy individuals

Korkmaz, Selcuk (Trakya author)Background Although tests of global hemostasis prothrombin time (PT) and activated partial thromboplastin time (aPTT) should not be used for prediction of bleeding risk, these tests are often used by many clinicians in daily practice particularly as a preoperative screening test. Robust biological variation (BV) data are needed for safe clinical applications of these tests. In this study, a stringent protocol was followed to estimate the BV's for PT, aPTT, and fibrinogen levels. Methods Results Weekly blood samples were obtained from 28 healthy individuals (18 females, 10 males) during 10 weeks study period. All measurements were performed with Stago STA-R coagulation analyzer. Prior to coefficient of variation (CV)-analysis of variance (ANOVA), the data were assessed for normality, trends, outliers, and variance homogeneity. Sex-stratified within-individual (CVI) and between-individual (CVG) BV estimates were determined for PT, aPTT, and fibrinogen tests. No difference was found between male and female estimates of BV. The observed CVI and CVG estimates were found to be lower than those previously published. Only for fibrinogen, CVI was higher than CVG. Conclusion Following a meticulous protocol, our study results provide up-to-date and more stringent BV estimates of global hemostasis tests

Cost analysis of 25-hydroxy vitamin D tests in Turkiye with big data: A cross-sectional study

OBJECTIVE: The high prevalence of vitamin D deficiency in the population causes physicians to request more vitamin D tests and increases laboratory costs. It is aimed at investigating the demanded numbers and cost analyzes of 25-hydroxyvitamin D (25(OH)D) tests with the big data obtained from the national information health system of the Turkish Ministry of Health. METHODS: Between 2017 and 2018, all inpatient and outpatient tests and 25(OH)D tests in all medical biochemistry laboratories in Turkiye were determined based on department and institution type. The cost amount, distribution among health institutions, and test request rates were calculated. In both years, the top ten most expensive tests, according to health institutions, were evaluated. RESULTS: The total number of medical biochemistry tests performed in 2017 and 2018 was 1.424.948.155 and 1.713.134.326, respectively. The number of 25 (OH)D tests analyzed in the same years was 8.698.393 and 13.919.127, respectively. When the data of the 2 years are compared, the consumption of 25 (OH)D tests increased by 37% in General hospital laboratories, whereas it increased by 115.09% in primary health laboratories. When all health institutions were evaluated, the increase rate in 25 (OH)D test demand was 60%, while the cost increase rate was 23%. CONCLUSION: This report showed that the demands for 25(OH)D testing are increasing steeply, especially in primary health-care facilities. In this direction, laboratory information system test demand restrictions in accordance with national and international guidelines are important issues for policymakers. © 2023 by Istanbul Provincial Directorate of Health

The Effect of Calcium Dobesilate on Liver Damage in Experimental Obstructive Jaundice

Purpose/Aim of the study: Inflammation and oxidative stress are two significant factors affecting the degree of liver damage in obstructive jaundice. The aim of this study was to evaluate the effect of calcium dobesilate (CaDob), an effective antioxidant and anti-inflammatory drug, on damage to liver caused by experimental obstructive jaundice. Materials and Methods: 30 rats in total were randomly placed into three groups, each group consisting of 10 rats. The sham group (Group 1) only received solely laparotomy. In the control group (Group 2), ligation was applied to the biliary tract and no treatment was implemented. In the CaDob group (Group 3), following ligation of the biliary tract, 100 mg/kg/day CaDob was implemented via an orogastric tube for a 10–day period. Liver tissue and blood samples were taken for histopathological and biochemical examination. Results: The CaDob group had significantly lower test values for serum liver functions when compared to the control group. Statistically lower levels of tissue malondialdehyde (MDA) and fluorescent oxidation products (FOP) were detected in the CaDob group, and the CaDob group had significantly higher levels of sulfydryl (SH) than the control group. Histopathological scores in the CaDob group were found out to be statistically less than the scores the control group received (p < 0.05). Conclusions: CaDob treatment repaired the histpatological changes induced by bile duct ligation. The hepatoprotective effects of CaDob can be associated with its antioxidant properties of the drug

Biological variation of peripheral blood T-lymphocytes

Background: Flow cytometric analysis of the lymphocyte subsets has become one of the most commonly used techniques in the routine clinical laboratory. It is frequently used in monitoring lymphocyte recovery after hematopoietic stem cell transplantation (HSCT), as well as diagnosis and treatment of acquired immunodeficiency syndrome (AIDS). Reliable biological variation (BV) data is needed for safe clinical application of these tests. In this study, similar preanalytical and analytical protocols to the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) checklist were followed and a stringent statistical approach was applied to define BV of T-lymphocytes