Screening and Confirmatory Testing for SARS-CoV-2 Antibodies: Comparison of Health and Non-Health Workers in a Nationwide Healthcare Organization in Central Europe.

Despite being located close to the European epicenter of the COVID-19 pandemic in Italy, Austria has managed to control the first wave. In Austria, the largest health insurance fund covers 7 million people and has 12,000 employees, including 3700 healthcare workers (HCW). For patient and staff safety, transmission control measures were implemented and mass testing of employees for SARS-CoV-2 antibodies was conducted. An IgG SARS-CoV-2 rapid test on fingerstick blood was used as a screening test (ST), followed by serologic studies with 3 different immunoassays and confirmatory testing by a neutralization test (NT). Among 7858 employees, 144 had a positive ST and 88 were confirmed by a NT (1.12%, CI: 0.9-1.38%). The positive predictive value (PPV) of the ST was 69.3% (CI: 60.5-77.2). Interestingly, 40% of the NT positive serum samples were tested negative in all 3 immunoassays. Of the total sample, 2242 HCW (28.5%) were identified. Unexpectedly, there was no difference in the prevalence of NT positives in HCW compared to non-HCW (23/2242 vs. 65/5301, p = 0.53). SARS-CoV-2 antibody prevalence was not increased among HCW. Although HCW are at potentially increased risk for SARS-CoV-2 infection, transmission control measures in healthcare facilities appear sufficient to limit transmission of infection.

Serum Free Light Chain Assay: Shift Toward a Higher κ/λ Ratio.

BACKGROUND: The analysis of serum free light chains (FLCs) is clinically relevant for the diagnosis and therapeutic management of clonal plasma cell disorders. This study compares the performance of monoclonal and polyclonal FLC κ and λ assays in clinical samples determined in a single academic center. METHODS: Serum FLCs were analyzed from 102 patients using the Freelite (Binding Site) and N Latex (Siemens) assays on the BN ProSpec System (Siemens). When available, data for protein electrophoresis, immunofixation, C-reactive protein, and estimated glomerular filtration rate (eGFR) were combined with FLC results to evaluate performance. RESULTS: Method evaluation showed acceptable imprecision and inaccuracy measures of <4.4% and 12.9%, respectively. Poor agreement between the methods was observed, including constant and proportional bias and poor correlation (Kendall τ, 0.671-0.901). The N Latex assay was not affected by the renal impairment estimated by eGFR, unlike the FLC κ/λ ratio results by the Freelite assay. With the Freelite assay, 98% of putative controls without monoclonal gammopathy (n = 42) showed a κ/λ ratio that was above the median of the standard diagnostic range or renal diagnostic range. A shift toward higher κ/λ ratios was also observed when retrospective data between 2011 and 2017 were compared. CONCLUSIONS: Unlike the Freelite assay, κ/λ ratios analyzed with the N Latex assay were not affected by renal failure. Both methods showed acceptable performances using nephelometry, but they were poorly correlated. A shift toward κ/λ ratios might impair the specificity of borderline increased κ/λ results. This should be considered when interpreting FLC κ and λ results.

Reduced serum immunoglobulin G concentrations in multiple sclerosis: prevalence and association with disease-modifying therapy and disease course.

BACKGROUND: In multiple sclerosis (MS), the frequency of hypogammaglobulinemia is unknown. We aimed to evaluate the frequency of reduced immunoglobulin (Ig) concentrations and its association with immunotherapy and disease course in two independent MS cohorts. METHODS: In our retrospective cross-sectional study, MS patients and control patients with head or neck pain from Bern University Hospital (Bern, Switzerland) and Eginition University Hospital (Athens, Greece) were included. The lower limits of normal (LLN) for serum Ig concentration were IgG < 700 mg/dl, IgM < 40 mg/dl, and IgA < 70 mg/dl. Mann-Whitney U test, analysis of variance test, and multiple linear regression analysis were employed. RESULTS: In total, 327 MS patients were retrospectively identified (Bern/Athens: n = 226/101). Serum IgG concentrations were frequently under LLN in both MS cohorts (Bern/Athens: 15.5%/14.9%), even when considering only untreated patients (Bern/Athens: 7.9%/8.6%). MS patients (n = 327) were significantly more likely to have IgG concentrations below LLN and below 600 mg/dl in comparison with controls (n = 58) (p = 0.015 and 0.047, respectively). Between both patient groups, no significant differences were found in frequencies of IgA and IgM concentrations under LLN [n (MS patients/controls): IgA 203/30, IgM 224/24]. Independently of age, secondary progressive MS patients had lower IgG concentrations than relapsing-remitting and primary progressive patients (both: p ⩽ 0.01). After adjusting for sex, age, and disease course, IgG concentrations were lower in patients treated with rituximab (p = 0.001; n = 42/327), intravenous corticosteroids (p < 0.001; n = 16/327), natalizumab (p < 0.001; n = 48/327), and fingolimod (p = 0.003; n = 6/327). CONCLUSION: Our study demonstrated high prevalence rates of reduced serum IgG concentrations in MS patients with and without disease-modifying treatments. The significance of lower IgG concentrations at the levels noted is unclear considering that infections or interference with antibody production generally occur when IgG levels are much lower, at or below 400 mg/dl. However, the information is useful to monitor IgG levels especially with anti-B-cell therapies and consider IgG substitution when levels drop below 400 mg/dl.

Influence of vascular risk factors on executive function among an age-homogeneous elderly cohort.

The pathogenesis of executive dysfunction in geriatric depression remains uncertain although causal bidirectional relationships with depression have been discussed. Previous studies have described a potential link with 'vascular depression'. In this study, we investigate the influence of vascular risk factors and magnetic resonance imaging markers of structural brain ageing, such as increasing deep white matter hyperintensities (DWMH), on executive function in an age-homogeneous population-based study cohort. A total of 606 participants of identical age (75.8 years; standard deviation 0.45 years) took part in the baseline investigation of the Vienna Transdanube Ageing (VITA) study. Each participant underwent a full psychometric examination with standardised neuroimaging and clinical chemistry investigations. Participants were re-examined with the same protocol after exactly 30 and 60 months. Data refer to the individuals who completed the examination at baseline. In the ordinal logistic regression, fewer years of education (P < 0.0001), Trail Making Test-A (P < 0.0001), high homocysteine (P = 0.001), and depression (P < 0.0001) were significantly associated with Trail Making Test-B (TMT-B) values. A significant influence of other vascular risk factors, such as lipids, diabetes, and smoking, on executive dysfunction was not observed. A comparison of both lacunes and DWMH with respect to the TMT-B results showed no significant correlation. Our data do not support the notion that vascular pathogenesis might underlie executive dysfunction.

Advancing haemostasis automation--successful implementation of robotic centrifugation and sample processing in a tertiary service hospital.

BACKGROUND: Laboratories today face increasing pressure to automate operations due to increasing workloads and the need to reduce expenditure. Few studies to date have focussed on the laboratory automation of preanalytical coagulation specimen processing. In the present study, we examined whether a clinical chemistry automation protocol meets the preanalytical requirements for the analyses of coagulation. METHODS: During the implementation of laboratory automation, we began to operate a pre- and postanalytical automation system. The preanalytical unit processes blood specimens for chemistry, immunology and coagulation by automated specimen processing. As the production of platelet-poor plasma is highly dependent on optimal centrifugation, we examined specimen handling under different centrifugation conditions in order to produce optimal platelet deficient plasma specimens. To this end, manually processed models centrifuged at 1500 g for 5 and 20 min were compared to an automated centrifugation model at 3000 g for 7 min. RESULTS: For analytical assays that are performed frequently enough to be targets for full automation, Passing-Bablok regression analysis showed close agreement between different centrifugation methods, with a correlation coefficient between 0.98 and 0.99 and a bias between -5% and +6%. For seldom performed assays that do not mandate full automation, the Passing-Bablok regression analysis showed acceptable to poor agreement between different centrifugation methods. CONCLUSIONS: A full automation solution is suitable and can be recommended for frequent haemostasis testing.

Circulating retinol-binding protein 4 and metabolic syndrome in the elderly.

BACKGROUND: Retinol-binding protein (RBP) 4, a human adipokine that specifically binds to retinol, has been reported to provide a link between obesity and insulin resistance. Plasma RBP4 concentration may be under the influence of age and obesity, but only a few studies has investigated this link in elderly individuals. Consequently, we tested the correlation between RBP4 concentrations and type 2 diabetes/metabolic syndrome (MetS) components in a large population based cohort study (VITA) of elderly [1, 2]. Using a single birth cohort, this investigation could exclude the influence of age. METHODS: We evaluated the correlation of RBP4 with type 2 diabetes and MetS components including Body Mass Index (BMI), blood pressure, lipid parameters, fasting glucose insulin, homeostasis model assessment insulin resistance (HOMA-IR), and smoking in exclusively 75-76 year old participants (N = 232). RESULTS: In the present study, RBP4 concentrations were associated with type 2 diabetes and metabolic syndrome (MetS) components. Of all the individual components of metabolic syndrome that were associated with RBP4 concentrations, the correlations of RBP4 with serum triglycerides and a negative correlation with HDL were the strongest ones observed in our study cohort (p<0.0001). CONCLUSIONS: RBP4 plays a role in biological mechanisms that are responsible for insulin resistance and development of type 2 diabetes.

Diagnosis of infection with human herpes viruses in routine laboratory practice.

BACKGROUND: The potential for faster detection of human herpes viruses using PCR compared to other methods is undisputed. However, because of fear of contamination, the clinical implication of nucleic amplification methods in routine laboratories is not widespread. Herpes viruses cause a wide spectrum of diseases and can cause morbidity and mortality in immune-compromised patients. Using real-time PCR, most of the problems associated with PCR (contamination, cumbersome detection, and rather expensive tests) are solved, and a rapid, economical, and--most importantly--closed system is at hand. METHODS: We evaluated work procedures in our laboratory that enable the routine diagnosis of viral infections with high accuracy and rapid turn-around time. In parallel, inherent problems usually associated with PCR testing, especially cross-contamination could be suppressed to a minimum. The start of the work flow process begins with an automated nucleic acid extraction procedure that yields high quality DNA. A common--internally and externally controlled--PCR program for all six viruses allows rapid sample turn around. RESULTS: In all, 7500 analyses for human herpes virus infection were performed in the last 5 years. Results for various different specimens were produced within 24 h. Contamination occurred rarely and could be ameliorated easily. The use of internal controls identified rare PCR-inhibited samples. The detection limits for our assays are markedly below the clinically relevant range. CONCLUSIONS: Our workflow allowed rapid, cost-efficient, and labor saving routine diagnostic detection of viral infections.

Correlated downregulation of estrogen receptor beta and the circadian clock gene Per1 in human colorectal cancer.

There is a growing body of evidence that disturbed circadian clock gene expression is associated with tumor development and tumor progression. Based on our initial experiments demonstrating decreased period 1 (Per1) expression in colon cancer, we evaluated clock gene and estrogen receptor (ER) alpha/beta expression in colon cancer cells of primary colorectal tumors and adjacent normal colon mucosa (NM) by real-time RT-PCR. Analysis of gene expression in G(2) and G(3) colorectal tumors revealed a decrease of Per1 mRNA compared with paired NM (G(2): 0.52-fold; P = n.s. and G(3): 0.48-fold; P = 0.03). A significant gender specific difference of Per1 expression was observed in G(2) tumors as compared with NM (female: 0.38-fold; P = 0.004 vs. male: 0.73-fold; P = n.s.). Expression of CLOCK was significantly elevated in G(2) tumors of male patients (1.63-fold, P = 0.01). The expression of ER-beta was significantly decreased in G(2) and G(3) tumors (G(2): 0.32-fold; P = 0.003 and 0.27; P = 0.001). No significant gender specific differences of ER-beta reduction in tumors were observed. A significant correlation between the decrease of Per1 and ER-beta in colorectal tumors (r = 0.61; P < 0.001) was found. No changes in gene expression were detected for ER-alpha and Per2. Our data demonstrate a correlated decrease of Per1 and ER-beta in colorectal tumors, mediated probably by epigenetic mechanisms. The observed gender differences in the expression of CLOCK and Per1 in G(2) tumors might suggest a gender-specific, distinctive role of the cellular clock in colorectal tumorigenesis.

Clinical chemistry reference values for 75-year-old apparently healthy persons.

BACKGROUND: Clinical chemistry reference values for elderly persons are sparse and mostly intermixed with those for younger subjects. To understand the links between metabolism and aging, it is paramount to differentiate between "normal" physiological processes in apparently healthy elderly subjects and metabolic changes due to long-lasting diseases. The Vienna Transdanube Aging (VITA) study, which began in 2000 and is continuing, will allow us to do just that, because more than 600 male and female volunteers aged exactly 75 years (to exclude any influence of the "aging" factor in this cohort) are participating in this study. METHODS: Extensive clinical, neurological, biochemical, psychological, genetic, and radiological analyses, with a special emphasis on consumption of medication and abuse of drugs, were performed on each of the probands. The multitude of data and questionnaires obtained made possible an a posteriori approach to select individuals fulfilling criteria for a reference sample group of apparently healthy 75-year-old subjects for our study. Specific analytes were quantified on automated clinical analyzers, while manual methods were used for hormonal analytes. All clinical chemistry analytes were evaluated using in-depth statistical analyses with SPSS for Windows. RESULTS: In all, reference intervals for 45 analytes could be established. These include routine parameters for the assessment of organ functions, as well as hormone concentrations and hematological appraisals. Because all patients were reevaluated after exactly 30 months in the course of this study, we had the opportunity to reassess their health status at the age of 77.5 years. This was very useful for validation of the first round data set. Data of the second round evaluation corroborate the reference limits of the baseline analysis and further confirm our inclusion and exclusion criteria. CONCLUSIONS: In summary, we have established a reliable set of reference data for hormonal, hematological, and clinical chemistry analytes for elderly subjects. These values will be very useful for our future attempts to correlate disease states and aging processes with metabolic factors.

Concentrations of N-terminal pro-brain natriuretic peptide and troponin T in plasma of 75-year-old apparently healthy persons.

Clinical chemical reference values for older persons are sparse and mostly intermixed with those for younger persons. We had a unique opportunity to obtain blood samples from volunteers who were 75 years old and living in two districts of Vienna, Austria. Consequently, we utilized stored plasma samples to obtain reference intervals for 120 apparently healthy 75-year-old participants for pro-brain natriuretic peptide (proBNP), as well as for troponin T. The N-terminal (NT)-proBNP protein assay is currently used as a diagnostic and prognostic aid in patients with heart failure and as a prognostic marker in acute coronary syndromes. Specifically, the concentration of NT-proBNP in serum or plasma aids in the prognosis of ventricular systolic dysfunction and helps to differentiate between cardiac and non-cardiac causes. The median NT-proBNP plasma value for men and women in our cohort was calculated as 98 pg/ml, comparing favorably with reported values, in that a NT-proBNP concentration less than 100 pg/ml excludes acutely decompensated heart failure. Our calculated 97.5 percentile was slightly higher (359 pg/ml) than the 97.5 percentile in a group of 50-65-year-old persons (198 and 222 pg/ml for men and women, respectively) revealing the influence of age on this parameter. Because of its high tissue-specificity, cardiac troponin T is a cardiospecific, highly sensitive marker for myocardial damage. However, the troponin T concentrations in the plasma specimens from this cohort were all below the detection limit of 0.01 ng/ml, preventing any further data handling.