Estimating short- and long-term reference change values and index of individuality for tests of platelet function

BackgroundIn order to manage risks of bleeding and thrombosis after some surgical procedures, platelet function is often measured repeatedly over days or weeks using laboratory tests of platelet function. To interpret test results in the perioperative period, it is necessary to understand analytical, biological and between-person variation.MethodsWe collected three separate blood specimens from 16 healthy volunteers on the first study day, and one additional specimen from each volunteer 1, 2, and 3 months later. Arachidonic acid-induced and adenosine diphosphate (ADP)-induced platelet function were measured in duplicate by whole blood impedance aggregometry using Multiplate (ASPI/ADP tests) and VerifyNow (Aspirin Reaction Units [ARU] and P2Y12 Reaction Units [PRU]). The analytical variation (CV_A), within-subject variation (CV_I), between-subject variation (CV_G), index of individuality (II), and reference change values (RCV) were calculated.ResultsVerifyNow ARU demonstrated the smallest short-term and long-term variability (CV_A, CV_I, and CV_G ~1%), resulting in short- and long-term RCV values <5%. II was also higher (1.92) for VerifyNow ARU than other platelet function tests. Multiplate ASPI and ADP tests had the highest RCV both short-(19.0% and 25.2%, respectively) and long-term (32.1% and 39.6%, respectively) due to increased CV_A (>5%) and CV_I (3.9–13.1%). VerifyNow PRU had a lower RCV than Multiplate ADP; but was the only test with II <0.6.ConclusionsVerifyNow ARU results can be interpreted relative to a fixed cut-off or population-based reference interval; or relative to small changes in an individual’s previous values. VerifyNow PRU and Multiplate ASPI and ADP tests should only be interpreted based upon relative change; and can only distinguish relatively large (>23%) changes over several weeks.     

Biological variation of secretoneurin; a novel cardiovascular biomarker implicated in arrhythmogenesis

BackgroundSecretoneurin is a novel prognostic biomarker that may predict mortality in heart failure and the occurrence of ventricular arrhythmias. This study reports the within subject variation (CV_I), between subject variation (CV_G), reference change values (RCV) and index of individuality (II) of secretoneurin.MethodsThirty healthy volunteers were included. Non-fasting samples were obtained between 8 and 10 am once a week for ten weeks. Secretoneurin was analyzed in duplicate using ELISA. No outliers were present according to Burnett and Reeds‘ criteria. Simple linear regression did not identify significant trends. Variance homogeneity in the analytical variance and CV_I were tested using Cochrane’s and Bartlett’s tests and four participants were excluded. Calculation of CV_I, CV_G and RCV were done on ln transformed data as described by Fokkema, the II was calculated using retransformed data.ResultsThe median age of the participants was 36 years and 53% were female. Non-fasting glucose, eGFR_(CKD-EPI), cTnT and NT-proBNP concentrations were within the normal range. Median secretoneurin concentrations were 38 pmol/L (women) and 33 pmol/L (men), p-value < 0.001. CV_I and CV_G were 9.8% (CI 8.7% to 11.0%) and 20.0 (CI 15.4% to 28.0%), respectively. RCV were 38.7% (CI 35.5% to 42.7%) and −27.9 (CI −29.9 to −26.2) and the II were 0.60 (CI 0.42–0.78). No gender differences were present.ConclusionSecretoneurin has a fairly low CV_I, CV_G, RCV and II, indicating that it could be suitable as a diagnostic or prognostic biomarker and that delta values in serial samplings may be preferable for identifying clinical changes.     

Short-term biological variation and Reference change values of urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydroguanosine

AimThe DNA and RNA oxidative damage products urinary 8‐oxo‐7,8‐dihydro‐2''‐deoxyguanosine (8‐odGsn) and 8‐oxo‐7,8‐dihydroguanosine (8‐oGsn) have potential use in clinical practice. However, biological variation (BV) and reference change values (RCVs) have not been established. The aim of this study was to establish the short‐term between‐subject BV(CV_G)_, within‐subject BV(CV_I), and RCVs for urinary 8‐odGsn and 8‐oGsn.MethodsFirst‐morning midstream urine specimens were collected from 20 apparently healthy subjects(ten males and ten females) on five consecutive days. 8‐odGsn and 8‐oGsn were measured using LC‐MS/MS, while urine creatinine (U‐Cr) was also measured to correct their results. A two‐level nested ANOVA was used to estimate the CV_I and CV_G. ResultsThe values of CV_G for 8‐odGsn, 8‐odGsn/U‐Cr, 8‐oGsn, and 8‐oGsn/U‐Cr were 31.2%, 39.6%, 35.3%, and 28.8%, respectively, while CV_I for them were 40.5%, 9.0%, 33.5%, and 12.1%, respectively. The RCVs for 8‐odGsn, 8‐odGsn/U‐Cr, 8‐oGsn, and 8‐oGsn/U‐Cr were 112.5%, 26.7%, 93.7%, and 36.5%, respectively.ConclusionBV and RCVs were firstly established for 8‐oxo‐dGsn and 8‐oGsn, and can be used in clinical practice.     

Biological variation and reference change values of CA 19‐9, CEA,AFP in serum of healthy individuals

Objective. The use of tumour markers in diagnosis and monitoring is very common. Tumour marker results vary – preanalytical sources of variation, total random analytical error (CV_a), and within‐subject (intraindividual) normal biological variation. There are not so many studies evaluating the biological variations and reference change values (RCV) of these parameters. The aim of our study was to assess: (i) the average inherent intra‐ and inter‐individual biological variation (CV_i and CV_g) for CA 19‐9, CEA, AFP in a group of healthy individuals; (ii) the significance of changes in serial results of each marker; and (iii) the index of individuality. Material and methods. The study group comprised 49 healthy volunteers ranging in age between 18 and 60 years (25 M and 24 F). Four blood samples were obtained from each subject; one at each 14‐day interval. Each sample from one individual was assayed in duplicate. CA 19‐9, CEA, AFP levels were measured by an immunoluminometric assay on a random‐access analyser (Architect i2000; Abbott Diagnostics Division). The intra‐ (CV_i) and inter‐individual (CV_g) biological variations were estimated from the data generated. Reference change value (RCV) was calculated. Results. The intra‐individual/inter‐individual biological variations (CVs) for CA 19‐9, CEA, AFP were 27.2/64.24?%, 30.87/37.14?% and 26.67/43.65?%, respectively. The critical differences (RCVs) of CA 19‐9, CEA, AFP were 64.71?%, 72.57?% and 62.62?%, respectively (Z = 1.65 for unidirectional changes; p<0.05). Conclusions. Intra‐individual biological variation contributes to the variation in serial results and should therefore be included in the criteria for serum tumour marker assessment.     

The variation in high sensitive cardiac troponin concentration during haemodialysis treatment is not similar to the biological variation observed in stable end stage renal disease patients

Background: Cardiovascular mortality is high in end stage renal disease (ESRD). This study aimed to: (1) calculate within-week within- and between-subject biological variation (CV_I and CV_G) for hs-cTn in ESRD; (2) determine the magnitude of hs-cTn concentration changes during haemodialysis (HD) treatment; and (3) compare the CV_I and CV_G to the within and between-subject variation of cTn concentration changes during HD treatments (CV_DIFF-I and CV_DIFF-G).

Methods: Serum samples were collected from 20 patients before and after 10 consecutive HD treatments. cTn were measured using the hs-cTnT (Roche Diagnostics) and the hs-cTnI (Abbott Diagnostics). The CV_A, CV_I, CV_G, CV_DIFF-I and CV_DIFF-G, were estimated using nested ANOVA.

Results: The within-week data showed hs-cTnT CV_A, CV_I and CV_G of 1.6, 7.3 and 94.4%. Reference change values (RCV) were estimated to ?18.7–23.0%. The Index of individuality (II) was 0.08. Corresponding values for hs-cTnI were 5.3, 13.2 and 142.4%, whilst the RCV was ?32.5–48.2% and the II was 0.10. The mean concentration of cTn decreased by ?6.4% (hs-cTnT) and ?7.6% (hs-cTnI) during HD treatment. The CV_DIFF-I and CV_DIFF-G was 4.2 and 6.3% for hs-cTnT, and 10.7 and 9.4% for hs-cTnI. The RCV_DIFF was ?18.2–5.4% (hs-cTnT) and ?39.0–23.8% (hs-cTnI), respectively, and the II_DIFF-values were 0.7 and 1.3.

Conclusions: The CV_I and CV_G are similar to earlier findings. Mean hs-cTn concentrations decreased during HD. The within-subject hs-cTn variation during HD is similar to the between-subject variation, i.e. determining a cut-off value for hs-cTn changes during HD may be useful.     

Estimation of biological variation and reference change value of glycated hemoglobin (HbA1c) when two analytical methods are used

Objectives

Available data on biological variation of HbA_1c revealed marked heterogeneity. We therefore investigated and estimated the components of biological variation for HbA_1c in a group of healthy individuals by applying a recommended and strictly designed study protocol using two different assay methods.

Design and methods

Each month, samples were derived on the same day, for three months. Four EDTA whole blood samples were collected from each individual (20 women, 9 men; 20–45 years of age) and stored at − 80 °C until analysis. HbA_1c values were measured by both high performance liquid chromatography (HPLC) (Shimadzu, Prominence, Japan) and boronate affinity chromatography methods (Trinity Biotech, Premier Hb9210, Ireland). All samples were assayed in duplicate in a single batch for each assay method. Estimations were calculated according to the formulas described by Fraser and Harris.

Results

The within subject (CV_I)–between subject (CV_G) biological variations were 1.17% and 5.58%, respectively for HPLC. The calculated CV_I and CV_G were 2.15% and 4.03%, respectively for boronate affinity chromatography. Reference change value (RCV) for HPLC and boronate affinity chromatography was 5.4% and 10.4% respectively and individuality index of HbA_1c was 0.35 and 0.93 respectively.

Conclusions

This study for the first time described the components of biological variation for HbA_1c in healthy individuals by two different assay methods. Obtained findings showed that the difference between CV_A values of the methods might considerably affect RCV. These data regarding biological variation of HbA_1c could be useful for a better evaluation of HbA_1c test results in clinical interpretation.     

Longitudinal variation of circulating Inc‐ITSN1‐2: A novel biomarker reflecting disease severity,inflammation, recurrence,and death risk in acute ischemic stroke patients

BackgroundLong noncoding RNA intersectin 1–2 (lnc‐ITSN1‐2) regulates inflammation and neuronal apoptosis; meanwhile, the latter two factors participate in the pathogenesis of acute ischemic stroke (AIS). Therefore, this study detected lnc‐ITSN1‐2 at multiple time points, aiming to explore its longitudinal variation and clinical value in the management of AIS patients.MethodsThe current study enrolled 102 AIS patients, then detected their lnc‐ITSN1‐2 in peripheral blood mononuclear cell (PBMC) at baseline (D0), day (D)1, D3, D7, month (M)1, M3, M6, and year (Y)1 after admission using RT‐qPCR. Additionally, lnc‐ITSN1‐2 in PBMC of 50 controls was also detected.ResultsLnc‐ITSN1‐2 was up‐regulated in AIS patients than that in controls (p < 0.001). Lnc‐ITSN1‐2 positively associated with NIHSS score, TNF‐α, and IL‐17A (all p < 0.050) but was not linked with IL‐6 (p = 0.093) in AIS patients. Notably, lnc‐ITSN1‐2 was gradually increased from D0 to D3; while it switched to decrease from D3 to Y1 in AIS patients. Lnc‐ITSN1‐2 disclosed similar longitudinal variation during 1 year in non‐recurrent (p < 0.001), recurrent (p = 0.001), and survived patients (p < 0.001), while the variation of lnc‐ITSN1‐2 in died patients was not obvious (p = 0.132). More importantly, lnc‐ITSN1‐2 at D0, D3, D7, M1, M3, M6, and Y1 was higher in recurrent AIS patients than that in non‐recurrent AIS patients (all p < 0.050); moreover, lnc‐ITSN1‐2 at D3, D7, M1, M3, and M6 was up‐regulated in died AIS patients than AIS survivors (all p < 0.050).ConclusionThe dynamic variation of Inc‐ITSN1‐2 could serve as a biomarker reflecting disease severity, inflammatory cytokines, recurrence, and death risk in AIS patients.     

Biological variation of holotranscobalamin and cobalamin in healthy individuals

Data on biological variation for cobalamin and holotranscobalamin (holoTC) are limited. The aim of this study was to determine within-subject (CV_I) and between-subject (CV_G) biological variations for these analytes in a healthy population. We collected blood samples from 15 healthy volunteers (12 women and three men, 22–66 years) on the same weekday for 10 consecutive weeks. Serum samples were stored at –80?°C until analysis in duplicate in a single analytical run. The CV_I and CV_G were estimated by nested ANOVA. The CV_I (95% CI) for cobalamin and holoTC was 6.7% (5.7–7.7) and 13.0% (11.5–15.0), respectively. The corresponding CV_G was 24.1% (16.4–36.0) and 24.6% (16.3–37.7). The analytical variation (CV_A) (95% CI) was 3.5% (3.2–4.0) for cobalamin and 2.4% (2.1–2.6) for holoTC. The index of individuality (II) was low (<0.6) for both cobalamin and holoTC and the reference change value (RCV) was 20.1% for cobalamin and 36.6% for holoTC. Our study describes the components of biological variation of cobalamin and holoTC in a healthy population, contributing to a better clinical interpretation of these biomarkers.     

Light‐initiated chemiluminescent assay of 17β‐estradiol metrological traceability system established by manufacturer according to ISO17511:2020 and basic performance evaluation performed by clinical end‐users

BackgroundIn order to ensure the accuracy of the product, we established 1^st model of metrological traceability hierarchy for light‐initiated chemiluminescent assay (LICA) of 17β‐estradiol (E₂) at the manufacturer, based on International Organization for Standardization (ISO) 17511:2020. Moreover, we verified/validated the basic performance (such as matrix effect and long‐term stability of end‐user IVD MD calibrator, precision, linearity interval, accuracy/ trueness, and detection capability) at the clinical end‐user.MethodsHuman serum samples were used in this study. E₂ was detected by mass spectrometry (MS) and LICA. The metrological traceability of LICA for E₂ was established according to ISO 17511: 2020 standards, and pools of human samples were used as the m.3. secondary calibrator. Precision was validated according to Clinical and Laboratory Standards Institute (CLSI) EP05‐A3. The linear interval was verified according to CLSI EP06‐ED2. Comparison of accuracy and trueness of E₂ with MS and Roche according to CLSI EP09‐A3. The detection capability was validated according to EP17‐A2. Matrix effect and long‐term stability evaluation of end‐user IVD MD calibrator were carried out according to CLSI EP14‐A2, EP25‐A. Statistical software was used for data analyses.ResultsThe use of pools of human samples and fine adjusting calibrators ensured the accuracy of end‐user test results. The metrological traceability of LICA for E₂ was established. It showed excellent precision, meeting the requirements of allowable imprecision (7.5%). The allowable deviation from linearity (ADL) of 5% was allowed to show a good linear interval (12.52–4167.25 pg/ml). The accuracy/ trueness was verified, and relative deviation in the medical decision level met the performance specification of 10.03% compared with MS or Roche. The validated limit of blank, limit of detection, and limit of quantitation of E₂ were 4.95 pg/ml, 8.93 pg/ml, and 9.88 pg/ml, respectively (the allowed imprecision is 20.00%). The interference rate of E₂ ranged from −5.5% to 6.6%.ConclusionLICA showed high sensitivity, high specificity, excellent precision, wide linearity interval, IVD MD calibrator has long‐term stability, and no matrix effect. The metrological traceability of E₂ established by using pools of human samples as M.3. can deliver accuracy to the end‐user IVD MD and show good consistency with MS and Roche.     

Week-to-week biological variation of methylmalonic acid and homocysteine in healthy women

Metylmalonic acid (MMA) and homocysteine (HCY) are important biomarkers in the assessment of cobalamin and folate metabolism. Correct interpretation of patient results benefit from knowledge of biological variation. The aim of the present study was to determine within-subject (CV_I) and between-subject (CV_G) biological variations of serum MMA and HCY in healthy women. We collected blood samples from 12 healthy volunteers (33–61?years) on the same weekday for 10 consecutive weeks. Samples were stored at ?80?°C until analysis in duplicate in a single analytical run in random order. The CV_I and CV_G biological variations were estimated by CV-ANOVA after the data were first subjected to outlier and homogeneity analysis. The CV_I (95% CI) for MMA and HCY were 7.2% (6.1–8.5) and 7.4% (6.5–8.5), respectively. The corresponding CV_G were 21.1% (14.0–32.2) and 24.2% (16.2–36.8). The index of individuality (II) was 0.34 for MMA and 0.31 for HCY and the reference change value (RCV) was ?17.7; 21.0 (% decrease; increase) for MMA and ?16.2; 19.4 for HCY. We provide within- and between-subject biological variation estimates for MMA and HCY in healthy women using an updated protocol. The results will contribute to a better clinical interpretation of these biomarkers and be of aid when setting analytical performance specifications.     

Evaluation of automated molecular tests for the detection of SARS‐CoV‐2 in pooled nasopharyngeal and saliva specimens

BackgroundPooling of samples for SARS‐CoV‐2 testing in low‐prevalence settings has been used as an effective strategy to expand testing capacity and mitigate challenges with the shortage of supplies. We evaluated two automated molecular test systems for the detection of SARS‐CoV‐2 RNA in pooled specimens.MethodsPooled nasopharyngeal and saliva specimens were tested by Qiagen QIAstat‐Dx Respiratory SARS‐CoV‐2 Panel (QIAstat) or Cepheid Xpert Xpress SARS‐CoV‐2 (Xpert), and the results were compared to that of standard RT‐qPCR tests without pooling.ResultsIn nasopharyngeal specimens, the sensitivity/specificity of the pool testing approach, with 5 and 10 specimens per pool, were 77%/100% (n = 105) and 74.1%/100% (n = 260) by QIAstat, and 97.1%/100% (n = 250) and 100%/99.5% (n = 200) by Xpert, respectively. Pool testing of saliva (10 specimens per pool; n = 150) by Xpert resulted in 87.5% sensitivity and 99.3% specificity compared to individual tests. Pool size of 5 or 10 specimens did not significantly affect the difference of RT‐qPCR cycle threshold (C_T) from standard testing. RT‐qPCR C_T values obtained with pool testing by both QIAstat and Xpert were positively correlated with that of individual testing (Pearson''s correlation coefficient r = 0.85 to 0.99, p < 0.05). However, the C_T values from Xpert were significantly stronger (p < 0.01, paired t test) than that of QIAstat in a subset of SARS‐CoV‐2 positive specimens, with mean differences of −4.3 ± 2.43 and −4.6 ± 2 for individual and pooled tests, respectively.ConclusionOur results suggest that Xpert SARS‐CoV‐2 can be utilized for pooled sample testing for COVID‐19 screening in low‐prevalence settings providing significant cost savings and improving throughput without affecting test quality.     

Genetic research and clinical analysis of β‐globin gene cluster deletions in the Chinese population of Fujian province: A 14‐year single‐center experience

BackgroundHeterozygotes of HPFH and δβ thalassemia are clinically asymptomatic or have mild hemoglobin (Hb) values. However, when both HPFH and δβ‐thalassemia are coinherited with heterozygous β‐thalassemia, patients may progress to a clinical phenotype of thalassemia intermedia or thalassemia major. The purpose of this study was to characterize the genotypes and analyze the phenotypes of these disorders in Fujian Province, to offer advice for genetic counseling and accurate prenatal diagnosis in this region. A total of 55 001 subjects were participated in thalassemia screening. 142 subjects with HbF levels ≥10%, before the blood transfusion, were selected for further investigation.MethodsMultiplex ligation‐dependent probe amplification (MLPA) and Gap‐PCR were used to screen for three β‐globin gene cluster deletions: Chinese ^Gγ(^Aγδβ)⁰ thalassemia and Southeast Asia HPFH (SEA‐HPFH) deletion and 1357 bp deletion (NG‐000007.3:g.69997‐71353 del 1357).ResultsA total of 142 patients with HbF (≥10%) were enrolled to characterize the molecular basis of β‐globin gene cluster deletions in our study; 22 cases 0.04% (22/55 001) were definitively diagnosed with β‐globin gene cluster deletions. Ten cases were heterozygous for the Chinese ^Gγ(^Aγδβ)⁰‐thal mutations, 10 cases were heterozygous for SEA‐HPFH, and one case was compound heterozygous for SEA‐HPFH and the α‐thal mutation. The 1357 bp deletion (NG‐000007.3:g.69997‐71353 del 1357) was detected in one case. Moreover, the hemoglobin A₂ levels in patients who were heterozygous for Chinese ^Gγ(^Aγδβ)⁰‐thal were statistically lower than in cases with SEA‐HPFH deletion(p < 0.05).ConclusionIn Fujian Province, the prevalence of common β‐globin gene cluster deletions was 0.04%. What''s more, the most common β‐globin cluster deletions are the Chinese ^Gγ(^Aγδβ)⁰ and SEA‐HPFH.     

Frequency of serological markers of rheumatoid arthritis in patients with IgA anti‐β2 glycoprotein I antibodies

AimTo determine the frequency of serological markers of RA in patients with anti‐β2 glycoprotein I antibodies (aβ2GPI) of IgA isotype.Material and MethodsA retrospective study was conducted on 67 patients with aβ2GPI‐IgA. Ninety healthy blood donors (HBD) were used as a control group. IgG anti‐cyclic citrullinated peptides antibodies (CCP‐Ab) and rheumatoid factors (RF) IgG, IgA, and IgM were detected by enzyme‐linked immunosorbent assay (ELISA).ResultsSeventeen patients and eight HBD had CCP‐Ab and/or RF (25.4% vs. 8.9%, p = 0.005, CI 95% [14.95; 35.79], odds ratio = 3.5). The frequency of CCP‐Ab was significantly higher in patients than in healthy subjects (14.9% vs. 3.3%, p = 0.009). IgA isotype of RF was significantly higher in patients than in controls (7.5% vs. 0%, p = 0.02). In male patients, CCP‐Ab and/or RF were more frequent than in healthy male subjects (37.5% vs. 11.8%, p = 0.02). In patients, no correlation was found between the levels of aβ2GPI‐IgA and CCP‐Ab (r = 0.082, p = 0.51). There was no correlation between the level aβ2GPI‐IgA and the level of the isotypes of RF (IgG, IgA, and IgM) in patients (r = 0.1, p = 0.37; r = 0.17, p = 0.17 and r = 0.07, p = 0.59 respectively).ConclusionFrequencies of CCP‐Ab and RF are high in patients with aβ2GPI‐IgA suggesting that these patients are susceptible to developing RA.     

Characteristics of ST11 KPC‐2‐producing carbapenem‐resistant hypervirulent Klebsiella pneumoniae causing nosocomial infection in a Chinese hospital

BackgroundThe purpose of our study is to analyze the microbiological and clinical characteristics of carbapenem‐resistant hypervirulent Klebsiella pneumoniae (CR‐hvKP) that causes nosocomial infection.MethodsWe collected the carbapenem‐resistant K. pneumoniae (CRKP) strains that caused nosocomial infection in a hospital in China and collected the relevant clinical data. We characterized these strains for their antimicrobial and virulence‐associated phenotype and genotype and analyzed the clonal relatedness. We screened hypervirulent strains and compared them with non‐hypervirulent strains.ResultsWe retrospectively analyzed 62 CRKP strains that caused nosocomial infection in a tertiary hospital within 1 year, of which 41 (41/62, 66.1%) CRKP were considered as CR‐hvKP. All CR‐hvKP strains were multi‐drug resistance (MDR) and the vast majority of isolates (39/41, 95.1%) were ST11 KPC‐2‐producing strains. Two hypermucoviscous isolates and 4 capsular types were found in 41 CR‐hvKP. Twenty‐nine isolates (29/41, 70.7%) showed hypervirulence in Galleria mellonella infection model. PFGE showed that ST11‐KL47 CR‐hvKP and ST11‐KL64 CR‐hvKP exhibited a high degree of clonality, while non‐hypervirulent strains were not significant. CR‐hvKP had higher positive rates of bla _KPC‐2 and bla _CTX‐M‐65 and higher levofloxacin resistance (p < 0.001, p = 0.005 and p = 0.046, respectively) when compared to the non‐hypervirulent strains. There was no significant difference between the two groups in terms of in‐hospital mortality (7/41, 17.1% vs 5/21, 23.8%, p = 0.743).ConclusionOur research finds that ST11 KPC‐2‐producing CR‐hvKP is the main type of CRKP that caused nosocomial infection, and clonal spread has occurred. We provide more information about CR‐hvKP in health care.     

Associations of complete blood count parameters with pancreatic beta‐cell function and insulin resistance in prediabetes and type 2 diabetes mellitus

IntroductionPrevious studies found controversial associations of CBC parameters with pancreatic beta‐cell function (BCF) and insulin resistance (IR). The aim of this was to determine the independent associations of CBC parameters with BCF and IR in prediabetes and type 2 diabetes mellitus (T2DM).MethodsThis study selected subjects who underwent health checkups at 16 health‐promotion centers in 13 Korean cities during 2021. The subjects comprised 1470 patients with normoglycemia, 1124 with prediabetes, and 396 with T2DM. BCF and IR were assessed using the homeostasis model assessment (HOMA)‐β and HOMA‐IR, respectively. Correlation and multiple linear regression analyses were used to determine the correlation between CBC parameters and HOMA.ResultsWhile HOMA‐IR gradually increased according to red blood cell count quartiles (1.22, 1.40, 1.47, and 1.91, in the first, second, third, and fourth quartiles, respectively; p < 0.001), there was no correlation after adjusting for waist circumference (WC) and HbA1c. The red blood cell distribution width (RDW) was associated with HOMA‐β [coefficient (β) = 15.527, p = 0.002], but not with HOMA‐IR. White blood cells (WBCs) were associated with HOMA‐IR and HOMA‐β, which was stronger in HOMA‐β (β = 0.505 vs 15.171, p = 0.002) after adjusting for WC and HbA1c. The platelet count was correlated with HOMA‐IR and HOMA‐β, which only remained in HOMA‐β (β = 15.581, p = 0.002) after adjusting for WC and HbA1c.ConclusionRDW, WBC, and platelet counts were independently associated with only HOMA‐β in prediabetes and T2DM. This suggests that these CBC parameters could represent BCF in prediabetes and T2DM.     

Exploratory assessment of serological tests to determine antibody titer against SARS‐CoV‐2: Appropriateness and limits

BackgroundSerological tests can be used to detect antibodies in the serum of subject''s after SARS‐CoV‐2 infection and vaccination. Currently, variability in antibody titers and the availability of a multiplicity of serological tests have made it necessary to highlight their appropriateness and limitations in various diagnostic settings.MethodsThis study is part of Covidiagnostix, a multicenter project aimed at the assessment of the health technology used in SARS‐CoV‐2 serological tests. Based on data gained from the analysis of over 5000 subjects, a selected number of serum samples, representative of different diagnostic settings, were analyzed first by qualitative immunoassays (IgA, M, and G MILLIPLEX^® SARS‐CoV‐2 tests based on Luminex^®) to define the immunoglobulins serum composition and subsequently by four serological diagnostic tests (Elecsys Anti‐SARS‐CoV‐2 and Elecsys Anti‐SARS‐CoV‐2 S by Roche, SARS‐CoV‐2 IgG by Siemens Healthcare, and CHORUS SARS‐CoV‐2 “NEUTRALIZING” Ab by DIESSE). The first WHO International Standard for SARS‐CoV‐2 was also analyzed using the same methods.ResultsThis study evaluated the antibody content and titer of the WHO Standard and serum of subjects with/without previous infection and before/after vaccination for SARS‐CoV‐2.ConclusionThe definition of antibodies in the WHO standard and the analysis of serum samples allowed for the identification of the appropriateness of serological tests in each diagnostic setting, increasing the effectiveness of the resulting laboratory data. Furthermore, we found that it would be optimal to produce new international standards against the S1 domain and RBD of the SARS‐CoV‐2 spike protein for a more effective serological monitoring of vaccination.     

Performance comparison of two nucleic acid amplification systems for SARS‐CoV‐2 detection: A multi‐center study

BackgroundMany rapid nucleic acid testing systems have emerged to halt the development and spread of COVID‐19. However, so far relatively few studies have compared the diagnostic performance between these testing systems and conventional detection systems. Here, we performed a retrospective analysis to evaluate the clinical detection performance between SARS‐CoV‐2 rapid and conventional nucleic acid detection system.MethodsClinical detection results of 63,352 oropharyngeal swabs by both systems were finally enrolled in this analysis. Sensitivity (SE), specificity (SP), and positive and negative predictive value (PPV, NPV) of both systems were calculated to evaluate their diagnostic accuracy. Concordance between these two systems were assessed by overall, positive, negative percent agreement (OPA, PPA, NPA) and κ value. Sensitivity of SARS‐CoV‐2 rapid nucleic acid detection system (Daan Gene) was further analyzed with respect to the viral load of clinical specimens.ResultsSensitivity of Daan Gene was slightly lower than that of conventional detection system (0.86 vs. 0.979), but their specificity was equivalent. Daan Gene had ≥98.0% PPV and NPV for SARS‐CoV‐2. Moreover, Daan Gene demonstrated an excellent test agreement with conventional detection system (κ = 0.893, p = 0.000). Daan Gene was 99.31% sensitivity for specimens with high viral load (C _t < 35) and 50% for low viral load (C _t ≥ 35).ConclusionsWhile showing an analytical sensitivity slightly below than that of conventional detection system, rapid nucleic acid detection system may be a diagnostic alternative to rapidly identify SARS‐CoV‐2‐infected individuals with high viral loads and a powerful complement to current detection methods.     

Carbapenem antibiotic stress increases bla KPC ‐2 gene relative copy number and bacterial resistance levels of Klebsiella pneumoniae

BackgroundThe clinical isolation rates of carbapenem‐resistant Klebsiella pneumoniae (CR‐KP) continue to increase. In China, clinical CR‐KP isolates are mainly attributed to the bla _KPC‐2 gene carried on plasmids, and the bla _KPC‐2 copy number correlates with the expression of KPC enzymes, which can cause elevated carbapenem MICs.MethodsThirty‐seven CR‐KP isolates were collected at the Second People’s Hospital of Lianyungang City between January 2020 and March 2021, with no duplicate isolates, and were screened for the bla _KPC‐2 gene with PCR. Analysis of current CRKP resistance to clinically relevant antimicrobials using the bioMérieux VITEK^® 2 bacterial identification card. The multilocus sequence types of the strains were confirmed with PCR and DNA sequencing. Recombinant plasmids pET20b‐bla _KPC‐2 and pET20b‐CpsG were constructed, and the copy numbers of the recombinant plasmids per unit volume was calculated based on the molecular weight of the plasmids. After the genomes DNA of clinical isolates of K. pneumoniae carrying the bla _KPC‐2 gene were purified, the bla _KPC‐2 gene relative copy number in individual K. pneumoniae strains was indicated by the double standard curve method. Detection of MIC values changes of K. pneumoniae under imipenem selection pressure by broth microdilution method.ResultsAmong the 37 CR‐KP strains isolated, only the bla _KPC‐2 gene was detected in 30 strains, three strains were positive for the bla _NDM‐1 gene, two strains carried both the bla _KPC‐2 and bla _NDM‐1 genes, and two strains without detectable carbapenem resistance genes. The ST11 clone was predominant among the 37 carbapenem‐resistant K. pneumoniae isolates. Drug sensitivity testing showed that except for polymyxins (100% susceptible) and tigecycline (75.7% intermediate), the 37 CR‐KP strains were resistant to almost all antimicrobial drugs. The bla _KPC‐2 relative copy number in nine ST11 clinical isolates of K. pneumoniae was 7.64 ± 2.51 when grown on LB plates but 27.67 ± 13.04 when grown on LB plates containing imipenem. Among these nine isolates, five CRKP strains exhibited elevated MICs to imipenem, while the remaining four strains showed unchanged MIC values to imipenem.ConclusionCarbapenem‐resistant Klebsiella pneumoniae isolates may have multiple pathways to achieve high levels of carbapenem resistance, and moderate carbapenem pressure can increase the copy number of KPC enzyme genes in CRKP strains and enhance the degree of carbapenem resistance in the strains.