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N Montalbetti

Publications and source records attributed to N Montalbetti.

At least 19 recordsLinked to original sources
PubMed1991

Reference values in the nineties: from theory to practice?

Following a brief summary of the published documents on the theory of reference values, the reasons for the still limited practical implementation of the theory itself in clinical laboratories are discussed. It is suggested that cooperative efforts could overcome the difficulties in obtaining an adequate reference sample group, provided that some basic requirements are strictly fulfilled, such as the stability and the homogeneity of the analytical quality and of the reference population. Banks of biological materials will further reduce the complexity and the cost of production of reference values.

Chemistry, Clinical↗
PubMed1990

Multicentre evaluation of the Boehringer Mannheim/Hitachi 717 analysis system.

We conducted an European multicentre trial to assess the performance of the new Boehringer Mannheim/Hitachi 717 analysis system. The photometer response was linear up to an absorbance of 2.8. The maximal CV of photometric imprecision was 0.5% for the wavelength pair 340/405 nm within the absorbance range 0.9 to 2.4. For the 13 analytes in our study, mean within-run imprecision was less than 2%, and mean between-day imprecision less than 2.5%. The results obtained with the Hitachi 717 instrument correlated closely with those of comparison instruments. Linearity for the various tests was high and exceeded the manufacturer's claims. No drift was detected during an 8-hour work period; carry over could not be detected under the chosen experimental conditions. The new instrument was readily accepted by the evaluators because of its ease of handling and simple daily maintenance.

Blood Chemical Analysis↗
PubMed1988

Circadian and circannual rhythms of several enzymes of lysosomal origin in human plasma.

The circadian and circannual group rhythms in the plasma concentrations of the following lysosomal enzymes were studied in women and men: beta-D-N-acetylglucosaminidase, beta-D-glucuronidase, beta-D-glucosidase, beta-D-galactosidase, alpha-D-galactosidase, alpha-L-fucosidase and alpha-D-mannosidase. The circadian rhythm was detected in all the tested enzymes of women, and only in alpha-D-galactosidase, beta-D-glucosidase, alpha-D-mannosidase and beta-D-N-acetylglucosaminidase of men. A statistically significant difference between genders in the circadian rhythm was exhibited by beta-D-galactosidase, beta-D-glucosidase, beta-D-N-acetylglucosaminidase, beta-D-glucuronidase, alpha-D-galactosidase and alpha-L-fucosidase. A circannual rhythm was detected in all the tested enzymes, with the exception of beta-D-glucuronidase and beta-D-N-acetylglucosaminidase, without any statistically significant difference between genders. The group rhythms of some of the enzymes (alpha-D-galactosidase, beta-D-glucosidase, beta-D-galactosidase) showed similar values of both circadian and circannual acrophases, suggesting that they may be subjected as a group to the same chronobiological coordination. The chronobiological rhythms of lysosomal enzymes were different from those of lactate dehydrogenase and alpha 1-antitrypsin, indicating that these rhythms are not merely reflecting fluctuations of the water content of plasma. No in-phase relationship was observed between the circadian and circannual rhythms of plasma cortisol and those of the tested lysosomal enzymes, excluding a direct chronobiological relationship between this hormone and lysosomal enzymes.

Acetylglucosaminidase↗
PubMed1987

A multicentre evaluation of the Boehringer Mannheim/Hitachi 704 analysis system.

The selective multitest Boehringer Mannheim/Hitachi 704 analysis system was examined according to the ECCLS guidelines in a multicentre evaluation involving four laboratories. Ten routine parameters, covering most of the application settings of the instrument, were measured in the respective laboratory at temperatures 25, 30 or 37 degrees C. The trial lasted four months and gave more than 40,000 data. It yielded the following results: 1. Within the four laboratories the mean coefficients of variation for three control sera at different concentrations were found to be equal to or better than 1.6% for the within-run imprecision and 2.8% or better for the between-day imprecision. 2. No drift was observed during eight hours. 3. Because of the high linear measuring range a re-run analysis was seldom necessary. 4. Sample-related carry-over was not seen. Reagent-dependent carry-over was measured from cholesterol to uric acid and from triacylglycerols to lipase. Through modification of the cholesterol and triacylglycerol reagents, the carry-over effect was practically eliminated. 5. The recovery of the assigned values of control sera showed average values between 99 and 104%. For bilirubin, creatinine, creatine kinase and alanine aminotransferase some control sera showed deviations greater than 10%. 6. In all cases, regression analysis of the results obtained in comparisons of the present instrument with the Hitachi 705 or 737 yielded slopes close to unity with extreme values of 0.95 and 1.06. 7. During the entire evaluation period there was no malfunction or breakdown of the instruments. The evaluators came to the conclusion that the analytical performance as well as the reliability and practicability of the Hitachi 704 can be rated as excellent.

Autoanalysis↗
PubMed1987

Assessment of an automatic liquid chromatograph for foetal and abnormal haemoglobins.

The DIAMAT TM (Bio-Rad) analyser is a microprocessor-operated HPLC system using a silica-based weak cation exchange column with three phosphate buffers of increasing ionic strength as the step gradient mobile phase. A dual wavelength detector measures absorbance at 415 and 690 nm; each sample is completely processed in 8 minutes. The instrument effectively separates and quantifies HbF in a discrete peak. We have verified that the HbF assay is linear up to about 65% values. We calculated within-run imprecision for n = 20 in 3 different haemolysed blood samples; the results are shown below as percent of total haemoglobin: A) Mean = 1.06 SD = 0.048 CV% = 4.5 B) Mean = 1.90 SD = 0.041 CV% = 2.1 C) Mean = 8.93 SD = 0.047 CV% = 0.5 Between-run imprecision for similar samples (n = 18) was: D) Mean = 3.74 SD = 0.20 CV% = 5.5 E) Mean = 9.94 SD = 0.15 CV% = 1.5 Accuracy was assessed in different series by correlating Hb values (y) with those obtained by the alkali denaturation test (x). The regression line equation was y = 1.03 x - 0.33 (r = 0.999, n = 62). The DIAMAT TM instrument also reveals the presence of any HbS and calculates its peak area correctly, as we found by electrophoretic reassay in heterozygous subjects. We also noted the presence of other abnormal haemoglobins characterized by specific retention times.

Autoanalysis↗
PubMed1987

Glycated proteins in serum: effect of their relative proportions on their alkaline reducing activity in the fructosamine test.

The fructosamine test is considered clinically useful for assessing short-term integrated control of blood glucose, but there are few published data to support this hypothesis. We fractionated glycated and nonglycated proteins by affinity chromatography on phenylboronate columns and, with specific immunochemical methods, determined in the eluted fractions the following proteins, selected according to their biological half-lives and relative concentrations in serum: albumin, IgA, IgG, IgM, apolipoprotein B, haptoglobin, transferrin, alpha 1-antitrypsin, and alpha 2-macroglobulin. We found the following correlations between fructosamine (mmol/L) and, respectively, glycated albumin, IgG, and (albumin + IgG) (each in grams per liter): r = 0.901, 0.702, 0.878. IgM had the highest percentage of glycated molecules (range 11.1-37.5%, mean 22.4%), haptoglobin and alpha 1-antitrypsin the least. This result was almost independent of the proteins' molecular masses and fractional catabolic rate. Albumin evidently contributes most to results of the fructosamine test, confirming conclusions obtained in different ways by others.

Apolipoproteins B↗
PubMed1987

Study of mediators of anaphylaxis in nasal wash fluids after aspirin and sodium metabisulfite nasal provocation in intolerant rhinitic patients.

Nasal histamine (H), leukotriene C4 (I-LTC4) and SRS-A activity were studied in seven aspirin-(ASA)-intolerant patients (AIR) with rhinitis and in five ASA-tolerant control patients with chronic rhinitis after nasal provocation (NP) with a lysine acetylsalicylate solution. The same parameters were also studied after metabisulfite (MBS) NP in four sulfite-intolerant patients with rhinitis and in six control patients with chronic rhinitis. In six ASA-intolerant subjects and in four controls, we studied the PGD2 levels in nasal washes after ASA NP 0.2 mL of lysine acetylsalicylate solution (10 mg/mL) was sprayed intranasally in ASA-intolerant patients and controls and a 25-mg/mL MBS solution in sulfite intolerant patients and controls. Nasal wash fluids were obtained using 5 mL of 0.15 M saline before and 7 1/2, 15, 30, and 60 minutes after nasal provocation. The nasal provocation with ASA induced itching and sneezing in four out of seven intolerant subjects. In this subgroup histamine values in nasal wash fluids were significantly higher versus the remaining ASA-intolerant patients at 30 and 60 minutes (P less than .05 and P less than .01, respectively) and versus controls at 60 minutes (P less than .01). We found significantly higher I-LTC4 (P less than .01) and SRS-A levels in nasal washes collected from ASA-intolerant subjects versus controls at 60 minutes after nasal provocation. There was no significant increase in the mean PGD2 values in either the ASA-intolerant or control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspirin↗
PubMed1975

Circadian rhythm of plasma cortisol in the aged (Cosinor method).

Plasma cortisol circadian rhythm was investigated in 18 apparently healthy elderly subjects, in 11 elderly patients affected by cerebrovascular hemiplegia and in 11 otherwise healthy blind elderly subjects. Results were microscopically analyzed by the least squares and Cosinor methods. The circadian rhythm of plasma cortisol was present and normal both in elderly subjects and in elderly patients with cerebrovascular hemiplegia. By contrast, a plasma cortisol rhythm was not found in blind elderly subjects.

Aged↗