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Biomedical subjects

F Aguzzi

Publications and source records attributed to F Aguzzi.

At least 19 recordsLinked to original sources
PubMed1992

Occurrence of monoclonal components in general practice: clinical implications.

We report on the occurrence of monoclonal components observed in a provincial hospital in northern Italy from 1987 to 1990. The monoclonal components were detected by visual inspection of high-resolution acetate serum electrophoreses and typed by immunofixation. The percentage of monoclonal components increases steeply with age, and reaches a plateau of 7-8% in individuals over 55 years old. Besides the high percentage of monoclonal component, the other relevant finding of this study is that approximately 80% of monoclonal components are of low concentration (less than 5 g/l). Most of these subjects with small monoclonal component passed undetected in the previous studies on the prognostic significance of monoclonal gammapathy. These findings indicate the need for a revision of the current concepts on the biological and clinical significance of MC discovered by chance.

Adolescent↗
PubMed1992

Reference values for immunoglobulin kappa and lambda light chains and the kappa/lambda ratio in children's serum.

We analyzed 708 serum samples from healthy children and adolescents by immunonephelometry to obtain reference values for the immunoglobulin kappa (kappa) and lambda (lambda) light chains and for their ratio at a time of life when immunoglobulin synthesis is maturing and continually being stimulated. The lambda chain concentration that is to be maintained throughout the child's life is reached very early, just after 1 year, whereas the concentration of the kappa chains, which increases gradually, reflects the concentration of the immunoglobulins as a whole. These reference values may be useful for studying kappa and lambda chains in illnesses involving the immune system in children.

Adolescent↗
PubMed1991

Immunoturbidimetric method for routine determinations of apolipoproteins A-I and B.

A simple immunoturbidimetric method for quantifying apolipoproteins (apo) A-I and B in serum or plasma is described. A special reagent formulation, including large amounts of suitable detergents, obviates the need for a sample blank even with grossly lipemic specimens. The assay is rapid, easily automated, and thus convenient for routine work. For both apo A-I and apo B, the assay range is about 0.2-3.5 g/L. The performance characteristics were assessed with discrete (Optimate and Olli CD) and centrifugal analyzers (Cobas Fara and IL Monarch 2000). Average analytical recovery was 101.5% for apo A-I and 99.4% for apo B. Dilution tests showed found/expected ratios of 101.2% (apo A-I) and 101.0% (apo B). Overall precision (CV) ranged from 1.4% to 3.3% for apo A-I and from 1.1% to 8.3% for apo B. Comparisons with commercially available rate nephelometry, radial immunodiffusion, and immunoturbidimetric methods gave good correlations (r greater than or equal to 0.938). Using the immunoturbidimetric method, we also established the relationships between apolipoproteins and lipids and determined the reference intervals. We conclude that the proposed method is suitable for routine use in clinical laboratories.

Apolipoprotein A-I↗
PubMed1991

Restricted electrophoretic heterogeneity of immunoglobulin light chains in urine: a cause for confusion with Bence Jones protein.

The detection of Bence Jones protein, an important part of the investigation of suspected myeloma, is most commonly done by agarose or cellulose nitrate electrophoresis followed by immunofixation. Bence Jones protein is recognized as single or multiple bands of one type of light chain. Unfortunately, improvements in sensitivity of these techniques (use of high-affinity antisera and higher resolution electrophoresis) frequently allow detection of multiple light chain bands in the urine of patients who do not have a B-cell dyscrasia. The bands are usually kappa, although they may be accompanied by lambda bands. This pattern may lead to the misdiagnosis of Bence Jones protein and oligoclonal light chain production in patients. Here we show that this pattern is produced by polyclonal light chains; it is present in the urine of all patients with a tubular proteinuria of any etiology and may be induced in healthy individuals by blocking their renal tubular protein reabsorption. Polyclonal light chains separate into monomers and dimers on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and into four major bands with many minor bands by isoelectric focusing. This difference in charge and possibly size results in the banding pattern seen on good-quality electrophoresis and immunofixation.

Aged↗
PubMed1991

Use of immunoglobulin heavy-chain and light-chain measurements in a multicenter trial to investigate monoclonal components: I. Detection.

We assessed the combined use of serum protein electrophoresis (SPE) and nephelometric measurement of immunoglobulin heavy- and light-chain components for detecting serum monoclonal immunoglobulins (monoclonal components, MC) in 4788 unselected samples from 4173 patients. MC were detected in 514 samples from 390 patients. In 356 these were detected by SPE; the other 34 had a normal SPE pattern but an abnormal kappa:lambda light-chain ratio (KLR). Only 208 of the 356 (58%) samples with bands by SPE had abnormal KLRs. Samples with MC concentrations greater than 5 g/L had a higher proportion of abnormal KLRs (75%) than those with concentrations less than 5 g/L (42%). The KLR was abnormal in 13% of samples in which no MC were visible by SPE or immunofixation electrophoresis (IFE). Compared with quantitative measurements of immunoglobulin heavy and light chains, high-quality SPE remains the method of choice for the detection of MC. Quantitative methods, however, are able to detect additional MC, especially those containing free light chains, and in the absence of SPE and IFE will detect about 75% of MC present at greater than 5 g/L.

Antibodies, Monoclonal↗
PubMed1991

Use of immunoglobulin heavy-chain and light-chain measurements in a multicenter trial to investigate monoclonal components: II. Classification by use of computer-based algorithms.

We describe a computer algorithm for classifying serum monoclonal proteins (MC) based on serum protein electrophoresis (SPE) and the automated measurement of kappa and lambda light chains and IgG, IgA, and IgM. We developed the algorithm by using a large database of unselected samples containing MC collected in a multicenter study. The performance of the algorithm was optimized by using iterative computational procedures and was tested on both the development database and on an independent set of MC-containing samples. With the development database, the algorithm correctly classified 50% and misassigned 2.5% of the MC. Where the MC were present in concentrations greater than 10 g/L, the rate of successful classification increased to 72% with 3% misclassification. When the algorithm was tested on a group of 101 MC-containing samples from an independent source, 67% were correctly classified and 8% misclassified, half of the latter being unusual IgD myelomas. We discuss the scope for the application of the algorithm in routine laboratory practice involving personal computer software.

Algorithms↗
PubMed1990

Immunochemical assays of serum proteins: a European external quality assessment survey and the effects of calibration procedures on interlaboratory agreement.

An external quality assessment survey of immunochemical assays of 9 proteins (immunoglobulins G, A and M, complement components C3 and C4, alpha1-antitrypsin, orosomucoid, haptoglobin and transferrin) in 5 European countries (Austria, France, Hungary, Italy and UK) showed inter-country differences in the mean values obtained. Reprocessing of the results using one of the two specimens distributed as a 'calibrant' effectively eliminated or reduced substantially these differences. Consideration of the methods used by participants confirmed previous indications from national surveys that the differences were due to lack of agreement among commercial calibrants. Such interlaboratory variations were also minimised by the 'calibration' in this survey. The role of European working calibration materials in ensuring interlaboratory agreement on an international basis is discussed.

Blood Proteins↗
PubMed1989

Serum protein electrophoresis: Italian survey 1986.

In 1986 the Protein Commission of the Italian Society of Clinical Biochemistry (SIBIOC) carried out its second survey on the use of serum protein electrophoresis in Italian laboratories. Three serum samples plus a questionnaire were sent to the 253 laboratories which agreed to take part. The three samples had the following characteristics: Serum 1: a 60 g/L IgM-lambda monoclonal component (MC); Serum 2: an artificially split alpha-2 zone; Serum 3: a very faint lambda chain MC. These features were chosen to assess (a) the type of report; (b) the resolution quality of the electrophoretic technique; and (c) the laboratory capacity to detect a small MC. The most significant features revealed by the survey were: (a) the poor capacity of assessment of the small MC in Serum 3 (only detected by 23.1% of laboratories); (b) the discouraging tendency to delegate electrophoretic diagnostic interpretation to ward physicians (44.4% of participating laboratories provided only densitometric values and graphs).

Blood Protein Electrophoresis↗
PubMed1988

Anti-streptolysin O titer, fifty-five years after Todd: a reappraisal of its clinical significance.

Anti-streptolysin O (ASO) antibodies are an expression of the frequent encounters even during the first years of life with beta hemolytic Streptococci, they are easily measured by quantitative laboratory tests and so possess the characteristics of a screening test for impaired antibody production. We have assessed ASO titers in 1955 healthy subjects of different ages (range: 1 month to 97 years). The behaviour of ASO titer is extensively described in the text. The percentage of people with less than 10 TU titers is under 5% after the age of 5 years up to 15 years; from 15 to 60 years there are no subjects with undetectable ASO titer and after this age the percentage is still under 5%. It seems therefore advisable not to define a "normal" treshold when titrating these antibodies to avoid the risk of missing low antibody producers.

Adolescent↗
PubMed1987

Serum protein binding of phenytoin and valproic acid in insulin-dependent diabetes mellitus.

The serum protein binding of valproic acid (VPA) and phenytoin (PHT) was determined in spiked serum samples collected from 17 patients with insulin-dependent diabetes mellitus and 16 healthy control subjects. The free fraction of VPA was significantly greater in patients than in controls (7.6 +/- 1.6% vs. 6.2 +/- 1.2%, p less than 0.01); for PHT, free fraction values were similar in the two groups (8.2 +/- 1.1% vs. 8.4 +/- 1.2%). The free fraction of VPA in diabetic patients was positively correlated with free fatty acid (FFA) concentration (r = 0.79, p less than 0.01). No significant relationships could be found between free drug fraction and either serum albumin or glycosylated protein concentration.

Adolescent↗
PubMed1987

Nutritional status of non institutionalized elderly people in north Italy.

The nutritional status of some elderly people - 313 non institutionalized and 37 assisted by public organization - was investigated. As regards weight, muscle and fat area, BMI and fat %, lower values were found for assisted people. The mean daily nutrient intakes in assisted people are below the recommended values for all nutrients, except fats; free living people have higher intakes of protein and fat, and lower intakes of thiamin and retinol equivalents. About 10% and 15% of non institutionalized people showed respectively an inadequate thiamin and riboflavin nutritional status (determined by alpha ETK and TPP levels and by alpha EGR and FAD levels); a worse situation was found for assisted people. Vitamin B6 levels appear adequate for all the population tested.

Aged↗
PubMed1986

Nutritional status of institutionalized elderly people in north Italy.

The nutritional status of 91 institutionalized elderly people over 60 years of age was investigated. Particular attention was given to diet, body composition and some biochemical determinations of vitamin nutriture. It was found that approximately 40% of the population are at risk for obesity. Mean daily intake of nutrients, compared with the recommended values for Italy, is insufficient in thiamin, both for men and for women, and in vitamin A for women. The level of fat in the diet is higher than desired. Consumption of eggs, fish, legumes and sweets is low, while milk and dairy products are consumed in large quantities. Thiamin and riboflavin nutriture determined by biochemical tests is not significantly correlated to dietary intake.

Age Factors↗
PubMed1977

"Immunosubtraction" electrophoresis: a simple method for identifying specific proteins producing the cellulose acetate electrophoretogram.

To identify the proteins that are responsible for the electrophoretic pattern on cellulose acetate, we propose a method based on the precipitation of various individual proteins at the beginning of the electrophoretic run. Any non antibody proteins in the monospecific antisera were removed with a preliminary electrophoretic fractionation of the antiserum. Using this method, we could remove a band or a zone from the pattern, leaving the rest of the pattern unaltered. This permitted us not only to locate a protein in the pattern, but also to better interpret the electrophoretogram. The method requires no special apparatus and it is fast and cheap.

Blood Protein Electrophoresis↗
PubMed1976

The problem of peak identification in crossed immunoelectrophoresis: a modification of the technique of Platt et al.

After a brief review of the known techniques for the identification of crossed immunoelectrophoresis peaks, the authors claim that the technique of Platt et al (1973), Clin. Chim. Acta 46, 419-429) is the most effective. This consists of blocking a protein in the first run, thereby causing the disappearance of the corresponding peak in the second dimension. The advantages of this technique with respect to the others are discussed.

Humans↗