Theodor Weber’s research while affiliated with University of Turku and other places

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Publications (7)


FIG. 1. Age distribution of the seroprevalence of IgG and IgA antibodies to C. pneumoniae (A) and M. pneumoniae (B) in a healthy Finnish population. 
TABLE 1 . Distribution of the ages, genders, and geographical locations of subjects giving serum specimens and the year of sampling 
Prevalence of Chlamydia pneumoniae and Mycoplasma pneumoniae Immunoglobulin G and A Antibodies in a Healthy Finnish Population as Analyzed by Quantitative Enzyme Immunoassays
  • Article
  • Full-text available

October 2000

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239 Reads

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74 Citations

Clinical and Diagnostic Laboratory Immunology

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Sirpa Varjo

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Heidi Ingman

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Chlamydia pneumoniae and Mycoplasma pneumoniae immunoglobulin G (IgG) and IgA antibody seroprevalence rates and antibody levels related to age and gender were studied. The samples (n = 742) were collected during a nonepidemic period and analyzed by quantitative enzyme immunoassays (EIAs). Seroprevalence to C. pneumoniae was found to increase sharply in young children, and in the 15- to 19-year-old group it reached levels as high as 70 and 60% for IgG and IgA, respectively. After adolescence, seroprevalence showed a transient decrease and then continued to increase, although less dramatically than in early childhood. In the elderly the seroprevalence of IgG antibodies reached 75 and 100% in women and men, respectively. The corresponding rates of IgA antibodies were 73 and 100%. When a randomly selected subgroup of samples (n = 66) was analyzed in parallel by a microimmunofluorescence test and an EIA for C. pneumoniaeIgA antibodies, similar seroprevalence rates were obtained (36 versus 35%). Seroprevalence to M. pneumoniae was already found to increase very sharply in 2- to 4-year-old children, reaching 16% for IgG and 8% for IgA. Seroprevalence to M. pneumoniae also continued to increase in adolescence, but in contrast to that toC. pneumoniae, the increase leveled off at about 40 to 50% in adulthood. In subjects aged over 65 years, prevalence did not exceed 60% for IgG or 35% for IgA. The seroprevalence patterns as well as the medians and variations of levels of C. pneumoniae andM. pneumoniae IgG antibodies were similar to those of corresponding IgA antibodies. Compared to IgG antibodies, IgA antibodies do not seem to be of additional value in the diagnosis of infections caused by these pathogens when single serum specimens are studied.

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Analytical quality control in neonatal screening

January 1995

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25 Reads

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4 Citations

Clinical Biochemistry

This critical review questions the present understanding in monitoring of analytical quality control in neonatal screening. Current status and historical background of the analytical quality control, particularly of the tests intended for the screening of congenital hypothyroidism and some inborn errors of metabolism, is reviewed. The reasons why attempts to standardize immunoassays through the preparation of a so-called “gold standard” (e.g. for thyrotropin) will not resolve noncomparability of results are discussed. The review presents arguments for the necessity of elaboration of international guidelines for methods assessment and comparison with an emphasis on their clinical relevance.


A rapid fluorometric enzyme immunoassay for the determination of neonatal TSH from blood spots

November 1991

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37 Reads

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7 Citations

Clinica Chimica Acta

We describe a novel method for the detection of thyrotropin from dried blood spots using a horseradish peroxidase-labelled sandwich enzyme immunoassay with fluorometric detection. The detection limit of the present assay is 1.25 mIU/l with within-run and between-run imprecision being in the range 5.2 to 11.4%. The results of the assay correlate well with two commercial methods: an enzyme immunoassay (r = 0.93) and a time-resolved fluorescence assay (r = 0.90). The blood spot values also show a good correlation (r = 0.93) with respective values obtained from plasma using a commercial immunoradiometric method.The assay may also be performed colorimetrically with sensitivity similar to the fluorometric assay. However, the latter provides a wider dynamic range with an upper limit of 400 mIU/l while the colorimetric method reaches a plateau at 25 mIU/l. Due to its simplicity and rapid performance (3 h), the fluorometric assay is suitable for the routine screening of congenital hypothyroidism.


Diagnostic value of cerebrospinal fluid adenosine deaminase determination

February 1991

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19 Reads

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66 Citations

Scandinavian Journal of Infectious Diseases

We measured the activity of adenosine deaminase (ADA) in the cerebrospinal fluid of 3 patients with tuberculous meningitis, 38 with viral meningitis, 15 with bacterial meningitis, 5 with malignant lymphoma, 11 with cerebrovascular diseases and 13 with miscellaneous neurological disorders. The highest ADA activities were observed in patients with tuberculous meningitis (median 21.3 U/l, range 20.0-23.0) and lymphoma (13.0 U/l, range 4.0-25.0). The sensitivity of the test for diagnosing tuberculous meningitis was 100% and the specificity 99% when a cut-off value of 20.0 U/l was used. We conclude that determination of ADA in cerebrospinal fluid is useful for the diagnosis of tuberculous meningitis, but that high activity also can be seen in some other CNS disorders, e.g. lymphoma with meningeal involvement.


3-p-Hydroxyphenylpropionic Acid—A Sensitive Fluorogenic Substrate for Automated Fluorometric Enzyme Immunoassays

February 1991

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61 Reads

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19 Citations

Journal of Immunoassay

The application of 3-p-hydroxyphenylpropionic acid (HPPA), a fluorogenic substrate of horseradish peroxidase (HRP) to an automated microplate fluorometric enzyme immunoassay is described. Fluorescence intensity of the end product was highly dependent on the pH of the buffer and on the concentrations of the substrate mixture ingredients. The determination of human thyrotropin (TSH) and recombinant hepatitis B surface antigen (rHBsAg) were performed using a fluorometric enzyme immunoassay (FEIA) with HPPA as the substrate, and a colorimetric one with tetramethylbenzidine (TMB) as the chromogenic substrate. The sensitivity of both types of assays proved comparable. The distinct advantage of a fluorometric assay is the possibility to perform a quantitative detection of analyte over a very wide dynamic range. Clinical evaluation of both assays showed good correlation between the FEIA and conventional methods.


Endogenous interference in imunoassays in clinical chemistry. A rewiev

February 1990

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117 Reads

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104 Citations

Scandinavian journal of clinical and laboratory investigation. Supplementum

The increasing availability and use of immunoassays in clinical chemistry have revealed a number of endogenous interferences. Solid-phase sandwich immunoassays based on monoclonal antibodies are particularly sensitive to any factor able to bridge immunoglobulins together. Heterophilic immunoglobulin antibodies have been demonstrated in up to 40% of patient samples and to cause spuriously elevated results unless certain precautions are taken. Rheumatoid factors belong to the same category, but their affinity is usually too low to cause significant interference. Immunoscintigraphy generates high-titre anti-immunoglobulin responses causing serious interferences in immunoassays. Recently interfering factors of unknown nature causing nonspecific binding of enzyme-labelled antibodies have been observed. Spuriously decreased values can be caused by complement, which may interfere with antigen-binding to solid phase antibody. The aforementioned and other endogenous interferences in immunoassays are reviewed and methods for their elimination discussed.


Endogenous interference in imunoassays in clinical chemistry. A rewiev

January 1990

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40 Reads

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55 Citations

Scandinavian Journal of Clinical and Laboratory Investigation

The increasing availability and use of immunoassays in clinical chemistry have revealed a number of endogeneous interferences. Solid-phase sandwich immunoassays based on monoclonal antibodies are particularly sensitive to any factor able to bridge immunoglobulins together. Heterophilic immunoglobulin antibodies have been demonstrated in up to 40% of patient samples and to cause spuriously elevated results unless certain precautions are taken. Rheumatoid factors belong to the same category, but their affinity is usually too low to cause significant interference. Immunoscintigraphy generates high-litre anti-immunoglobulin responses causing serious interferences in immunoassays. Recently interfering factors of unknown nature causing nonspecific binding of enzyme-labelled antibodies have been observed. Spuriously decreased values can be caused by complement, which may interfere with antigen-binding to solid phase antibody. The aforementioned and other endogeneous interferences in immunoassays are reviewed and methods for their elimination discussed.

Citations (7)


... Besides mechanism and degree of the effect of macro-analyte in each PRL assay is not always exactly the same for the samples containing this molecule. Therefore, macroPRL related interaction is thought to be dependent on the immunoassay system used as well as the sample [10,11,19,20]. In a study by Byrne et al. [21] results of 317 hyperprolactinemic samples analysed for prolactin on Beckman DxI 800 were compared with those determined with the PEG screening technique on the Wallac AutoDELFIA. ...

Reference:

Assessment of macroprolactinemia rate in a training and research hospital from Turkey
Endogenous interference in imunoassays in clinical chemistry. A rewiev
  • Citing Article
  • January 1990

Scandinavian Journal of Clinical and Laboratory Investigation

... Using of DBS technology for the preparation and analysis of target antigens in dried blood spots by immunoassay for the purposes of medical and veterinary diagnostics was described earlier. [16][17][18][19][20][21] DBS cards of conventional format are manufactured with cellulose bres and samples are applied dropwise onto marked round parts of the card. Aer drying, the paper discs with applied sample are punched. ...

A rapid fluorometric enzyme immunoassay for the determination of neonatal TSH from blood spots
  • Citing Article
  • November 1991

Clinica Chimica Acta

... Adding to the contention about further expansion of screening is debate about how to respond to technological advancement that makes it technically possible to screen for Fragile X (Bailey and Murray 2008; Coffee et al. 2009), lysosomal storage diseases (Li et al. 2004; Meikle et al. 2006), immune deficiencies (Cassol et al. 1994; Puck 2007), Duchenne muscular dystrophy (Parsons and Bradley 2008; van Ommen and Scheuerbrandt 1993) and other rare disorders (Röschinger et al. 2003). Differentials in the uptake of disorders into screening programmes are suggestive of discrepancies between screening criteria and a lack of international standardization (Tuuminen et al. 1994). The development of screening programmes and the differences that have evolved are the consequence of context-specific interpretations of and amendments to screening criteria (Clague and Thomas 2002; Padilla et al. 2010). ...

Analytical quality control in neonatal screening
  • Citing Article
  • January 1995

Clinical Biochemistry

... In most of the included studies, ADA of the CSF was measured using the methods of Giusti et al. [19, 20, 31-38, 40-43, 45, 46, 48, 51-53, 55, 58, 60, 63], although other methods, such as spectrophotometric, commercial kit, modified Berthlot, colorimetry, Trinder enzyme-coupled method, and the enzyme-linked immunosorbent assay, and so forth were also applied. The ADSA cutoff was <10 U/L in 18 studies [15-17, 21, 22, 31, 32, 35, 36, 39, 43, 44, 51, 53, 54, 57, 60, 63], =10 U/L in 18 studies [18-20, 23, 24, 34, 38, 40, 45-49, 52, 55, 56, 58, 59], and >10 U/L in 7 studies [33,37,41,42,50,61,62]. Details of the quality evaluation of the included studies via the QUADAS-2 criteria are shown in Table 2. ...

Diagnostic value of cerebrospinal fluid adenosine deaminase determination
  • Citing Article
  • February 1991

Scandinavian Journal of Infectious Diseases

... The adaptation to HRP was attempted by Zapata and co-workers using 4-hydroxybenzoic acid (HBA) [5]. The oxidation products of 4-hydroxyphenylpropionic acid (pHPPA) [6], chavicol [7], Amplex red [8] and prochlorperazine [9] did not sensitize their fluorescence measurements in the corresponding experiment setup. The other common drawbacks of aforementioned fluorogenic substrates are their insufficient reaction rates, relatively low stability in air or toward H 2 O 2 in the absence of HRP, tending to cause strong background signals and poor water-solubility [10,11]. ...

3-p-Hydroxyphenylpropionic Acid—A Sensitive Fluorogenic Substrate for Automated Fluorometric Enzyme Immunoassays
  • Citing Article
  • February 1991

Journal of Immunoassay

... Serum dilution helps eliminate the influence of complement proteins or the prozone effect observed in the case of high antibody titers and thus may improve the sensitivity of MIA [28]. Meanwhile, increased serum dilution can decrease sensitivity [29]. MIA of WNV was performed at a serum dilution of 1:100 [30], whereas other ...

Endogenous interference in imunoassays in clinical chemistry. A rewiev
  • Citing Article
  • February 1990

Scandinavian journal of clinical and laboratory investigation. Supplementum

... Earlier studies reported varying prevalence rates in asymptomatic adults, ranging from 58.9% in Jordanian adults [26] and 64.9% in German adults [27], to 77.7% in Finnish adults [28]. Generally, C. pneumoniae seroprevalence increases with age and is notably influenced by the employed testing method [29][30][31]. ...

Prevalence of Chlamydia pneumoniae and Mycoplasma pneumoniae Immunoglobulin G and A Antibodies in a Healthy Finnish Population as Analyzed by Quantitative Enzyme Immunoassays

Clinical and Diagnostic Laboratory Immunology