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The new WHO reference standard allows for the definition of serum antibodies against various SARS-CoV-2 antigens in terms of binding antibody units (BAU/mL) and thus to compare the results of different ELISA systems. In this study, the concentration of antibodies (ABs) against both the S- and the N-protein of SARS-CoV-2 as well as serum neutralization activity were evaluated in three patients after a mild course of COVID-19. Serum samples were collected frequently during a period of over one year. Furthermore, in two individuals, the effects of an additional vaccination with a mRNA vaccine containing the S1-RBD sequence on these antibodies were examined. After natural infection, the antibodies (IgA, IgG) against the S1-protein remained elevated above the established cut-off to positivity (S-IgA 60 BAU/mL and S-IgG 50 BAU/mL, respectively) for over a year in all patients, while this was not the case for ABs against the N-protein (cut-off N-IgG 40 BAU/mL, N-IgA 256 BAU/mL). Sera from all patients retained the ability to neutralize SARS-CoV-2 for more than a year. Vaccination resulted in a rapid boost of antibodies to S1-protein but, as expected, not to the N-protein. Most likely, the wide use of the WHO reference preparation will be very useful in determining the individual immune status of patients after an infection with SARS-CoV-2 or after vaccination.

Background Severe early-onset obesity (SEOO) in children is a common feature of monogenic obesity. Gene defects of the leptin-melanocortin pathway can be analysed biochemically and genetically. The aim of this study was to search for children with leptin deficiency or biologically inactive leptin in a cohort of children with SEOO and to study associations between leptin parameters and anthropometric data. Methods The cohort included n = 50 children with SEOO (22 boys) who were recruited at one of four study centres (Germany: Ulm; Poland: Katowice, Szczecin, Rzeszow) between October 2015 and October 2017. Weight (kg) and height (m) were measured, Tanner stage was obtained and a fasting serum blood sample was taken. Serum levels of total leptin (LEP, ng/mL), biologically active leptin (bioLEP, ng/mL) and soluble leptin receptor (sLEPR, ng/mL) were measured. The body mass index (BMI [kg/m2]), BMI z-score (World Health Organization [WHO]), quotient of bioLEP/LEP and leptin-standard deviation score (LEP-SDS) (Tanner stage, BMI and sex-adjusted) were calculated. Results We did not find any child with leptin deficiency or biologically inactive leptin in our cohort. The serum LEP and bioLEP levels were strongly correlated with age (r = 0.50, p 0.05) as well as lower LEP-SDS than boys (−1.77 ± 2.61 vs. −1.40 ± 2.60, p > 0.05). sLEPR levels were negatively correlated with BMI values (r = −0.44; p Conclusions In this cohort with SEOO, we identified no new cases of children with leptin deficiency or bioinactive leptin. A strong negative correlation between the LEP-SDS and BMI values could be interpreted as relative leptin deficiency in children with SEOO. In case this hypothesis can be confirmed, these children would benefit from a substitution therapy with methionyl human leptin (metreleptin™).

The relationship between the nasopharyngeal virus load, IgA and IgG antibodies to both the S1-RBD-protein and the N-protein, as well as the neutralizing activity (NAbs) against SARS-CoV-2 in the blood of moderately afflicted COVID-19 patients, needs further longitudinal investigation. Several new serological methods to examine these parameters were developed, validated and applied in three patients of a family which underwent an ambulatory course of COVID-19 for six months. The virus load had almost completely disappeared after about four weeks. Serum IgA levels to the S1-RBD-protein and, to a lesser extent, to the N-protein, peaked about three weeks after clinical disease onset but declined soon thereafter. IgG levels rose continuously, reaching a plateau at approximately six weeks, and stayed elevated over the observation period. Virus-neutralizing activity reached a peak about 4 weeks after disease onset but dropped slowly. The longitudinal associations of virus neutralization and the serological immune response suggest immunity in patients even after a mild clinical course of COVID-19.

SummaryBackgroundPatients infected with SARS-CoV-2 exhibit a highly variable clinical course, varying from barely discernible signs of disease, to moderate flu-like symptoms and, occasionally, with life-threatening pneumonia and/or cytokine storm. The relationship between the nasopharyngeal virus load, IgA and IgG antibodies to both the S1-RBD-protein and the N-protein as well the neutralizing activity (NAbs) against SARS-CoV-2 in the blood of moderately afflicted COVID-19 patients has not been investigated longitudinally so far.MethodsSeveral new serological methods to examine these parameters were developed and validated for the longitudinal investigation in three patients of a family which underwent a mild course of COVID-19.FindingsWe observed that the virus load had almost completely disappeared after about four weeks, whereas serum antibodies showed a contrasting course. IgA levels to S1-RBD-protein and, to a lesser extent, to the N-protein, peaked about three weeks after clinical disease onset but declined soon thereafter. IgG levels rose continuously, reaching a plateau approximately six weeks after disease onset. NAbs in serum reached a peak about four weeks after disease onset but dropped to a lower level about six weeks later.InterpretationOur data establishes associations of virus neutralization and a serological immune response foremost against Sars-CoV-2 S1-RDB-protein in a longitudinal manner.

Context and aims Functional leptin deficiency is characterized by high levels of circulating immunoreactive leptin (irLep), but a reduced bioactivity of the hormone due to defective receptor binding. As a result of the fact that affected patients can be successfully treated with metreleptin, it was aimed to develop and validate a diagnostic tool to detect functional leptin deficiency. Methods An immunoassay capable of recognizing the functionally relevant receptor-binding complex with leptin was developed (bioLep). The analytical quality of bioLep was validated and compared to a conventional assay for immune-reactive leptin (irLep). Its clinical relevance was evaluated in a cohort of lean and obese children and adults as well as in children diagnosed with functional leptin deficiency and their parents. Results In the clinical cohort, a bioLep/irLep ratio of 1.07 (range: 0.80–1.41) was observed. Serum of patients with non-functional leptin due to homozygous amino acid exchanges (D100Y or N103K) revealed high irLep but non-detectable bioLep levels. Upon treatment of these patients with metreleptin, irLep levels decreased, whereas levels of bioLep increased continuously. In patient relatives with heterozygous amino acid exchanges, a bioLep/irLep ratio of 0.52 (range: 0.48–0.55) being distinct from normal was observed. Conclusions The new bioLep assay is able to diagnose impaired leptin bioactivity in severely obese patients with a homozygous gene defect and in heterozygous carriers of such mutations. The assay serves as a diagnostic tool to monitor leptin bioactivity during treatment of these patients.

Background: Patients infected with SARS-CoV-2 exhibit a highly variable clinical course, varying from barely discernible signs of disease, to moderate flu-like symptoms and, occasionally, with life-threatening pneumonia and/or cytokine storm. The relationship between the nasopharyngeal virus load, IgA and IgG antibodies to both the S1-RBD-protein and the N-protein as well the neutralizing activity (NAbs) against SARS-CoV-2 in the blood of moderately afflicted Covid-19 patients has not been investigated longitudinally so far. Methods: Several new serological methods to examine these parameters were developed and validated for the longitudinal investigation in three patients of a family which underwent a mild course of COVID-19. Findings: We observed that the virus load had almost completely disappeared after about four weeks, whereas serum antibodies showed a contrasting course. IgA levels to S1-RBD and, to a lesser extent, to the N-protein, peaked about three weeks after clinical disease onset but declined soon thereafter. IgG levels rose continuously, reaching a plateau approximately six weeks after disease onset. NAbs in serum reached a peak about four weeks after disease onset but dropped to a lower level about six weeks later. Interpretation: Our data establishes associations of virus neutralization and a serological immune response foremost against Sars-CoV-2 S1-RDB protein in a longitudinal manner. Funding Statement: This study was partly funded by the University Hospital, Tuebingen, and grants from the Baden-Wurttemberg Foundation and the Deutsche Forschungsgemeinschaft (DFG). Declaration of Interests: The authors declare no conflict of interests. Ethics Approval Statement: This study was approved by the University of Tubingen.

Background: Proper ascertainment of the history of alcohol consumption by an individual is an important component of medical diagnosis of disease and influences the implementation of appropriate treatment strategies that include prescription of medication, as well as intervention for the negative physical and social consequences of hazardous/harmful levels of alcohol consumption. Biological (biometric) diagnostic tests that provide information on current and past quantity and frequency of alcohol consumption by an individual, prior to onset of organ damage, continue to be sought. Methods: Platelet monoamine oxidase B (MAO-B) protein was quantitated in 2 populations of subjects who had histories of different levels of alcohol consumption. Levels were assayed by immunoblotting or by ELISA. The development and evaluation of the new ELISA-based measure of platelet MAO-B protein levels is described. Results: One subject population constituted a nontreatment-seeking, cross-sectional subject sample, and the other population was a longitudinally followed, hospitalized group of subjects. An algorithm combining measures of platelet MAO-B protein with the plasma levels of carbohydrate-deficient transferrin (CDT) and with liver enzymes (aspartate aminotransferase or γ-glutamyltransferase [GGT]) can detect hazardous/harmful alcohol use (HHAU) with the highest sensitivity and specificity in the cross-sectional nontreatment-seeking population. In the treatment-seeking population, low MAO-B protein levels at admission are associated with heavy drinking prior to admission, and these protein levels increase over a period of abstinence from alcohol. Conclusions: The platelet MAO-B protein measurement is particularly effective for male alcohol consumers. The combined use of MAO-B protein measures together with measures of CDT and GGT does, however, improve the diagnostic utility of both markers for ascertaining HHAU in women. Furthermore, measurement of changes in platelet MAO-B protein levels during treatment for alcohol dependence may help monitor the success of the treatment program. Language: en

Background: Ghrelin is a 28-amino acid gut-brain peptide, mainly secreted by the gastric mucosa. Its effects are linked to energy homeostasis and particularly seem to increase hunger and food intake. In recent years, studies suggested that appetite-regulating peptides, such as ghrelin play a relevant role in alcoholism. Since data published to date on the potential role of ghrelin as state and/or trait marker in alcoholism and the association with craving are controversial, we aimed at further elucidating these aspects. Patients and Methods: One-hundred nine alcohol-dependent abstinent patients after withdrawal (27 f, 82 m), (ICD 10 F 10.25) and 45 healthy volunteers (12 f, 33 m) were included. Laboratory testing (Ghrelin RIA 90, Mediagnost Inc., Germany) was performed and several craving scales [Obsessive Compulsive Drinking Scale, Alcohol Urge Questionnaire and Visual Analogue Scale (VAS)] were applied at the beginning and at the end of the 3-week rehabilitation program. Results: (1) Ghrelin levels are significantly higher in female alcohol-dependent patients as compared to controls, not, however, in men alcoholics. (2) In several statistical subanalyses, an association of craving and ghrelin was found. The results, however, remain heterogeneous. Conclusion: The data suggest gender-dependent ghrelin levels in alcohol-dependent patients. We therefore conclude, that it might be useful to perform statistical analyses gender-specific. With regard to a potential correlation of ghrelin and craving the results seem to depend on gender, duration of the abstinence period and the instrument used.

Evidence is growing that appetite regulating peptides such as leptin and ghrelin, but also other hormones including prolactin are altered in alcoholism. The brain pro-opiomelanocortin (POMC) system which has important mediating roles in alcohol intake also has important functions in prolactin regulation and energy homeostasis. Furthermore, it has been demonstrated to be functionally integrated with leptin regulation. The satiety factor leptin seems to be counteracted by the gut-derived peptide ghrelin which increases hunger and food intake. Consequently, the POMC system may have a role in integrating regulation of alcohol effects and these seemingly disparate regulatory systems. The goal of this mini-review is to discuss the results of some recent investigations of the potential interactions of these systems with acute and chronic alcohol responses.

As, for ethical reasons, it is difficult to investigate by an experiment the effect of acute intoxication on leptin levels in alcoholics, we tested the hypothesis of lowered levels as an effect of acute ethanol intake inhealthy volunteers. The subjects comprised (1) 17 healthy male participants, recruited via newspaper advertisements [age 29 + 3.75 years, body mass index (BMI) 24.3 + 3.5, leptin at baseline 3.3 + 3.1 ng/ml]; (2) for comparison, leptin levels of 16 male alcoholic patients at day I of withdrawal were used. They were characterized as follows: (mean, median, standard deviation and range) age in years (41.1, 40.5, 10.2, 24, 57), BMI (23.3, 21.7, 5.4, 16.6, 37.5), 1032g of ethanol (median) consumed within the last 7 days, leptin levels 2.3mglml. A placebo-controlled double-blind trial teas performed. Leptin levels of blood samples were taken at baseline (t 1 ), before ethanol intake (t 2 ), when blood alcohol had reached its maximum (t 3 ) and the morning after (t 4 ). The oral dose of ethanol administered was 0.6 g/kg ethanol. (1) Volunteers: (a) the ethanol and placebo group exhibited leptin levels corresponding closely with levels measured at baseline (t 1 ) (rs = 0.85, p < 0.0001) and follow-up (t 4 ) (r s = 0.768, p < 0.0001). (b) Leptin levels for the placebo and the alcohol-consuming (verum) group did not differ significantly at baseline, after ethanol intake or on the morning after [Mann - Whitney U-test (p = 0.669, p = 1.0 and p = 0.887, respectively)]. (2) Leptin levels in relation to BMI did not significantly differ at any measurement time in either group. (3) Leptin levels/BMI of the healthy volunteers at t 1 and t 4 were not significantly different from those of 16 alcoholics. The data do not support the hypothesis of a significant effect of acute moderate alcohol intake on leptin levels in healthy volunteers.

Objective: IGFBP3 immunoreactivity may appear elevated in patients with chronic kidney disease (CKD), in part due to accumulation of low molecular fragments. The importance of these IGFBP3 variants for binding and inactivation of IGF1 and their relevance for the impaired growth of uremic children are unclear. Nevertheless, IGFBP3, measured as total (t-)IGFBP3, is frequently used as a diagnostic parameter in pediatric CKD patients. A new assay for functional (f-)IGFBP3 exclusively detects IGFBP3 capable of IGF binding. The aim of the study was to evaluate the significance of f-IGFBP3 measurements for the assessment of uremic abnormalities of the GH/IGF1 axis. Design: Prospective cross-sectional study. Methods: t-IGFBP3, f-IGFBP3, and IGF1 were measured in pediatric CKD patients, including patients with CKD stage 3–4 not on dialysis (CKD, nZ33), on dialysis treatment (DT, nZ26), patients after renal transplantation (RTx, nZ89), healthy children (nZ29), children with GH deficiency (GHD, nZ42), and small for gestational age (SGA) children (SGA, nZ34). Results: Mean t-IGFBP3 SDS was elevated in CKD, DT, and RTx children compared with controls and GHD patients (P%0.0004). Highest values were reached in DT (P!0.0001 vs all groups). In contrast, mean f-IGFBP3 was similar in all groups (PZ0.30). Conclusions: Pediatric CKD patients displayed elevated serum concentrations of t-IGFBP3 but not f-IGFBP3, supporting the hypothesis that IGFBP3 fragments not binding IGF1 accumulate during uremia. f-IGFBP3 is an indicator of IGFBP3 fragmentation and seems to reflect IGF1 binding in CKD better than t-IGFBP3. However, the role of f-IGFBP3 for the diagnosis of disturbances of the GH/IGF hormonal axis appears to be limited.

Proper ascertainment of the history of alcohol consumption by an individual is an important component of medical diagnosis of disease and influences the implementation of appropriate treatment strategies that include prescription of medication, as well as intervention for the negative physical and social consequences of hazardous/harmful levels of alcohol consumption. Biological (biometric) diagnostic tests that provide information on current and past quantity and frequency of alcohol consumption by an individual, prior to onset of organ damage, continue to be sought.Platelet monoamine oxidase B (MAO-B) protein was quantitated in 2 populations of subjects who had histories of different levels of alcohol consumption. Levels were assayed by immunoblotting or by ELISA. The development and evaluation of the new ELISA-based measure of platelet MAO-B protein levels is described.One subject population constituted a nontreatment-seeking, cross-sectional subject sample, and the other population was a longitudinally followed, hospitalized group of subjects. An algorithm combining measures of platelet MAO-B protein with the plasma levels of carbohydrate-deficient transferrin (CDT) and with liver enzymes (aspartate aminotransferase or γ-glutamyltransferase [GGT]) can detect hazardous/harmful alcohol use (HHAU) with the highest sensitivity and specificity in the cross-sectional nontreatment-seeking population. In the treatment-seeking population, low MAO-B protein levels at admission are associated with heavy drinking prior to admission, and these protein levels increase over a period of abstinence from alcohol.The platelet MAO-B protein measurement is particularly effective for male alcohol consumers. The combined use of MAO-B protein measures together with measures of CDT and GGT does, however, improve the diagnostic utility of both markers for ascertaining HHAU in women. Furthermore, measurement of changes in platelet MAO-B protein levels during treatment for alcohol dependence may help monitor the success of the treatment program.

Background: Multiple sclerosis (MS) is a frequent and often severe autoimmune disease of the central nervous system. We describe a newly developed enzyme-linked immunosorbent assay (ELISA)-based test system for the assessment of neuronal autoantibodies in serum and cerebrospinal fluid (CSF). This tool could help define autoimmune status and thus be a potential means of therapeutic surveillance. Methods: We used an assay system (ELISA, E100, Mediagnost) based on purified bovine antigens [myelin-oligodendrocyte glycoprotein (MOG), myelin basic protein (MBP), myelin-associated glycoprotein (MAG), proteolipid protein (PLP) and alpha-B-crystalline (CRY)] antibodies for the measurement of specific immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies. Assay characteristics and preliminary validation were conducted by measurement of serum and CSF samples from 41 MS patients and 128 patients with other neurological diseases (OND). Results: We measured the inter- (17.8/10.1%) and intra-assay variability (5.5/6.7%); linearity (1:250– 1:16,000), and specificity of IgG and IgM. We demonstrate that by the results of this test system MS patients can be differentiated from patients with OND. Conclusions: The ELISA kit we evaluated is suitable for the measurement of neuronal autoantibodies. The initial validation demonstrates its potential use in the differential diagnosis of central neuronal system diseases. Clin Chem Lab Med 2009;47:1395–400.

Aims: Leptin is a cytokine-type peptide hormone, recently implicated as a putative state marker of alcohol use and in craving. Our goal was to evaluate the potential of leptin as a state and trait marker and to rule out the role of current alcohol intoxication on leptin levels. Methods: Eighteen alcohol withdrawal patients (16 males, 2 females) whose blood contained 202 mg/dl (median) of ethanol at hospitalization, who had a median age of 43.5 years and had consumed 1075 g of ethanol (median) in the last 7 days were included in the study. Leptin was determined in samples at day 1 (when still intoxicated) and day 7 of withdrawal. Expected leptin levels were calculated with a formula. For comparison, 27 blood samples of 18 abstinent persons, matched for gender, age and body mass index were used. Furthermore, mean cell volume, γ-glutamyl transferase (GGT), blood glucose, cholesterol, triglycerides and body composition (bioimpedance device) were determined. For statistical analysis, SPSS 11 was used. Results: Expected leptin levels were 1.71 ng/ml (median), leptin measured at day 1 was 2.65 ng/ml (median) and 2.85 ng/ml on day 7 for the alcohol withdrawal patients and 2.2 ng/ml (median) for the abstainers. These concentrations were not significantly different. Significant correlations were found between leptin day 1 and expected leptin levels, percentage fat body mass, cigarettes smoked per day, GGT and blood alcohol concentration. Conclusions: Our preliminary data do not support the hypothesis of leptin as a state or trait marker and suggest only a minor influence of acute intoxication on leptin levels in alcohol detoxification patients.

In clinical as well as in forensic practice, occupational medicine, at court, for both traffic safety and safety at workplaces biological state markers of high sensitivity and specificity, capable of monitoring those in treatment for alcohol dependence or poly-drug-abusers as well as social drinkers in risky situations (driving, workplaces) are required. The known markers can not be considered to be satisfying with regard to these parameters. Furthermore, they do not cover the whole time axis for alcohol intake — i.e. there is a gap with regard to alcohol consumption of between 1 day and 1 – 2 weeks between short- and long-term-markers like ethanol, methanol, HTOL/HIAA ratio and CDT, GGT or MCV respectively. These traditional markers are in many cases besides alcohol influenced by age, gender and a variety of substances and non-alcohol-associated diseases. Ethyl glucuronide (EtG) is a non-volatile, water-soluble, stable upon storage, direct metabolite of ethanol with a molecular weight of 222 g/mol that can be detected in body fluids, tissues and hair. With its specific time frame of detection intermediate between between short- and long term markers and a high sensitivity and specificity, ethyl glucuronide is a promising marker of alcohol consumption in general that can be detected for an extended time period after the complete elimination of alcohol from the body and a marker for relapse control that enables the therapist to intervene at an early stage of relapsing behaviour.

Major histocompatibility complex class I (MHC-I) molecules are heterotrimers composed of polymorphic alpha-chains, monomorphic beta-chains, and peptides of eight or nine amino acids. The peptides are derived from various intracellularly occurring proteins and are very heterogeneous. They are essential for a stable conformation of the MHC-I protein at physiological temperature. This study presents results from stabilization experiments that were designed to determine the impact of the amino acids in every sequence position of octapeptides on the thermal stability of the mouse MHC-I molecule H2-Ld. OX7 octapeptide libraries with one defined and seven randomized positions were employed as they allow the effects of individual amino acids to be determined. The results confirm the importance of the motif amino acids proline and leucine for positions 2 and 8, respectively, of octapeptides. They are among the most efficient amino acids for these positions. However, with a few exceptions, all amino acids are permitted in all eight sequence positions. Hydrophobic amino acids are generally favored. Charged amino acids, especially aspartic acid and glutamic acid, are disfavored. Stabilization indices were defined as measures for the MHC stabilization power of the amino acids. These indices can serve to predict the efficiency of peptide binding to H-2Ld and can guide the design of T-cell epitopes.