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At least 1,513 records · Page 84Linked to original sources
PubMed2001

Establishment of reference values of five amniotic fluid enzymes. Analytical performances of the Hitachi 911. Application to complicated pregnancies.

OBJECTIVES: to evaluate the analytical performances of the Hitachi 911 analyzer (Roche Diagnostics, F) for gamma-glutamyl-transferase, 5'nucleotidase, amylase, aspartate-amino-transferase and total-alkaline-phosphatase assay in amniotic fluid. To establish reference intervals for these five enzymes throughout gestation. To determine their antenatal diagnostic value. DESIGN AND METHODS: amniotic fluid samples were collected between 14 and 35 weeks of gestation. Weekly numbers ranged from 31 to 92. Techniques developed for serum enzyme assays were applied to amniotic fluid. Two pools of amniotic fluid containing low and high marker levels were used. Within-day and between-day variations were calculated, together with the limits of detection and linearity. Reference ranges were established on 508 amniotic fluid samples, including 23 samples from pregnancies with chromosomal aberrations, 14 with gastrointestinal tract defects and 5 with gastroschisis. RESULTS: the assay technique for total-alkaline-phosphatase assay had to be adapted to amniotic fluid, but no adaptation was necessary for the other markers. The within-day CV ranged between 2.2 and 11.2% for low-level samples and from 1.1 to 3.4% for high-level samples. The between-day CV ranged from 6.3 to 13.3% for low-level samples and 1.2 to 4.7% for high-level samples. Total-alkaline-phosphatase activity fluctuated throughout gestation. Amylase levels and aspartate-amino-transferase levels increased whereas gamma-glutamyl-transferase and 5'nucleotidase levels fell until delivery. All trisomy 18 and trisomy 13 pregnancies, 65% of Down's syndrome pregnancies and all pregnancies with digestive tract defects were associated with marked changes in the level of at least one enzyme. CONCLUSION: The Hitachi 911 is suited to rapid, reliable quantification of amniotic fluid enzymes with only minor adaptation. Useful reference intervals can be obtained throughout gestation. Gamma-glutamyl-transferase, 5'nucleotidase, total-alkaline-phosphatase and amylase assay can help to confirm echographic evidence of bowel disorders and thereby improve patient management especially in case of gastroschisis.

Alkaline Phosphatase↗
PubMed1984

Reference values for CSF-IgM, CSF-IgM/S-IgM ratio and IgM index, and its application to patients with multiple sclerosis and aseptic meningoencephalitis.

Immunoglobulin M (IgM) concentrations were determined in cerebrospinal fluid (CSF) and serum (S) by enzyme-linked immunosorbent assay (ELISA). In 52 reference subjects, the upper reference limit was 0.46 mg/l for CSF-IgM, 0.32 X 10(-3) for CSF-IgM/S-IgM ratio, and 0.061 for IgM index equal to CSF-IgM X S-albumin/S-IgM X CSF-albumin ratio. No correlation to age over 15-85 years was found for any of these variables. Among 22 patients with aseptic meningoencephalitis (AM) elevated values of CSF-IgM were found in 68%, CSF-IgM/S-IgM ratio in 73%, and IgM index in 73%. The corresponding values among 35 patients with multiple sclerosis (MS) were 66%, 60% and 63%. The differences in diagnostic sensitivities for the three IgM variables were not significant. Eleven of 16 AM patients and two of 22 with MS had elevated IgM index in the presence of normal IgG and IgA indices. Determination of IgM index should therefore be performed in suspected inflammatory nervous system disorders.

Adolescent↗
PubMed1998

Reference values for cystatin C serum concentrations in children.

Cystatin C, a low molecular weight protein, is a new endogenous marker of renal function whose serum concentration correlates better with glomerular filtration rate than creatinine. The aim of the present study was to define a reference interval for cystatin C concentrations in children. Cystatin C was measured by an immunoturbidimetric assay in sera obtained from 258 children (93 girls, 165 boys, median age 6.29 years, range 1 day to 18 years) without evidence of kidney disease. The reference interval was calculated non-parametrically using the 2.5th and 97.5th percentiles. For comparison, creatinine was measured in the same samples. The cystatin C concentration was highest on the first days of life (range 1.64-2.59 mg/l) with a rapid decrease during the first 4 months. Beyond the 1st year, the cystatin C concentration was constant, with a reference interval of 0.7-1.38 mg/l. In contrast, serum creatinine concentrations steadily increased with age until adulthood. Compared with creatinine, cystatin C facilitates the recognition of abnormal renal function in children as its reference range is constant beyond the 1st year of life. The higher levels of cystatin C in the 1st year of life probably reflect the low glomerular filtration rate of neonates and infants.

Adolescent↗
PubMed1989

The intravenous bile Acid loading test in the goat: determination of a procedural protocol and reference values.

An intravenous bile acid loading test was performed on 16 goats using various dosages and sampling protocols. A recently developed enzymatic bile acid assay provided an economical and technologically simple method for bile acid analysis. Intravenous injection of bile salts into goats was well tolerated. Clearance times were rapid. A protocol for performance of the test was suggested and a practical reference range for T 1/2 clearance of 4+/-1 minute was determined. Further investigations of this test in the assessment of liver function in the ruminant appear warranted.

Journal Article↗
PubMed1998

[The development of reference values for the brachial perimeter and body height in comparison with other indicators used for screening of the nutritional status].

Mid-upper-arm circumference (MUAC) based on a single cut-off value for all children under 5 years of age has been used for many years as an alternative nutritional status index for children during famines or refugee crises, and as an additional screening tool in nonemergencies. However, it has recently been questioned whether MUAC is age- and sex-independent. After reviewing the scientific evidence underlying the use and interpretation of MUAC, a WHO Expert Committee recommended a new MUAC-for-age reference for under-5-year-olds. In some settings, however, it is difficult to assess a child's age and in such circumstances MUAC-for height may be a good alternative. The height-based QUAC stick offers a simple means of adjusting MUAC cut-offs according to height, and the MUAC-for-height reference and construction and use of the QUAC stick are described in this article. Also described is the use of the receiver operating characteristic (ROC) curve method to evaluate the performance of MUAC, MUAC-for-age, and MUAC-for-height in screening malnourished children.

Arm↗
PubMed1981

[The reference values of the hemoglobin content, the hematocrit and the mean concentration of corpuscular hemoglobin of calves reared without iron substitution. 1. Dependence on the rearing period].

A total of 1.088 blood samples (1 to 6 per animal) were taken from 491 rearing calves in the colostral period, the milk feeding period and the weaning period (at the age of 4, 22, 51, 79, 105, 122 and 145 days); the hemoglobin content (Hb), the hematocrit (Hc) resp. the mean corpuscular hemoglobin concentration (MCHC) were determined resp. calculated. Hb, Hc and MCHC were drawn in diagrams in dependence on the rearing period as arithmetic means with standard deviations, as quartiles and as frequency distributions on an interval scale. During the rearing periods with milk feeding the anaemic frequency was considerable. Anaemia resp. hypochromia frequency had an inverse relation to the developing increase of concentrated feed and roughage consumption and thus makes it probable that the cause of anaemia is the intake and/or absorption of iron insufficient for the weight gain performance achieved. The consumption of solid feed by the hematologically examined calves developed more quickly than in other GDR rearing farms due to the early ad libitum supply with this feed component and the composition of fluid feed with milk. Reference is made that the frequency of hypoferric anaemia can also be considerable during the milk feeding period in the intensive rearing of lambs and kids if an effective iron intervention is not made.

Anemia↗
PubMed2006

Determination of thiopurine S-methyltransferase (TPMT) activity by comparing various normalization factors: reference values for Estonian population using HPLC-UV assay.

Thiopurine S-methyltransferase (TPMT; EC 2.1.1.67) is the key enzyme in the metabolism of thiopurine drugs. Determination of TPMT activity has been used for the individualization of thiopurine dose. We developed HPLC-UV assay for the determination of TPMT activity in human erythrocytes using 6-mercaptopurine as a substrate. Various extraction and chromatographic conditions were compared. In-house developed extraction with acetonitrile provided the lowest limit of quantification. TPMT activity was determined in 99 previously genotyped healthy Estonians. TPMT activity was expressed as the formation of 6-methylmercaptopurine ng/ml/h and normalized either to haemoglobin, haematocrit, erythrocyte count or protein content. The receiver-operating characteristic curve analysis revealed similar accuracy values for TPMT activity in predicting heterozygous and wild type individuals for each method of calculation. In healthy Estonians, TPMT activity varied from 21.5 to 129.6 ng/ml/h. For heterozygous individuals (n = 18), TPMT activity was 48.1 +/- 11.7 ng/ml/h. Wild type individuals (n = 81) revealed significantly higher TPMT activity 79.3 +/- 20.7 ng/ml/h (P < 0.001). This sensitive HPLC assay for quantitative determination of TPMT activity could easily be used in clinical settings. Under constant experimental conditions for haemolysate preparation no normalization is required.

Chromatography, High Pressure Liquid↗
PubMed1992

Specificity of auditory brainstem response audiometry criteria in acoustic neuroma screening as a function of deviations of reference values in patients with cochlear hearing loss.

On the basis of 79 patients with cochlear hearing loss, the statistical distribution of two criteria commonly used in auditory brainstem response audiometry (ABR) was analyzed: the interaural V latency difference (ILD V) and the interaural difference of I-V interpeak interval (ID I-V). The distribution of both criteria was Gaussian. By evaluating their standard deviations the percentages of statistical false-positives were estimated. The estimated results were 24% false-positive findings using the decision criterion ILD V greater than 0.2 ms and 5.4% false-positive findings using ID I-V greater than 0.3 ms. This corresponds closely to the actual false-positive ABR rates obtained in this sample: 21.5% and 6.3%, respectively. In a separate series of 301 unselected cases with asymmetric sensorineural hearing loss, 29 ABRs were suspect for retrocochlear pathology. In 20 patients, ABRs were absent due to severe hearing loss. Retrocochlear pathology could be confirmed in only 2 cases (both from the group with ABR present). Thus, 47 ABRs (15.7% of 299) were false-positive.

Cochlear Diseases↗
PubMed1976

[Isoenzymes of alkaline phosphatase - reference values in young people and effects of protein diet (author's transl)].

In 260 normal students, 20-25 years old, the variation in the activities of serum alkaline phosphatase and its isoenzymes with sex, ABO blood groups, and protein intake were studied. The values are on the whole higher in males than in females. The activity of the intestinal isoenzyme was higher in subjects taking protein-rich diet than in those taking protein poor diet.

Adult↗
PubMed2002

[Age- and education-specific reference values for the cognitive test of the SIDAM (Structured interview for the diagnosis of dementia of the Alzheimer type, multi-infarct dementia and dementias of other etiology according to ICD-10 and DSM-IV)].

The SIDAM (Structured Interview for the diagnosis of Dementia of the Alzheimer type, Multi-infarct dementia and dementias of other etiology according to ICD-10 and DSM-IV) is a standardized interview for the diagnosis of dementia. It can also be used as a screening instrument for the diagnosis of different syndromes of dementia and mild cognitive impairment. At present there is no age- or education-specific standardization. This report presents age- and education-specific norms for the cognitive assessment of the SIDAM, obtained in a population-based sample of elderly people aged 75 and over (n=1001).

Age Factors↗
PubMed1990

Solid-phase immunofluorometric assay for quantification of CSF immunoglobulins. Determination of normal reference values.

Because a highly sensitive method is required to quantify low concentrations of immunoglobulin (Ig) classes in cerebrospinal fluid (CSF), there have been a few papers reporting normal values of CSF IgG, IgA and IgM determined in the same samples. Enzyme immunoassay (EIA) is most frequently used, but has such drawbacks as susceptibility of enzyme to inhibition and denaturation and the requirement for additional incubation with a substrate. Therefore, solid-phase immunofluorometric assay was evaluated for quantification of CSF IgG, IgA and IgM in the nanogram range. We found this to be rapid and reproducible. The mean (SD) values of normal CSF samples obtained from 22 subjects with tension headache were 23.9 (7.6) micrograms/ml for IgG, 2.00 (0.90) microgram/ml for IgA and 197 (87) ng/ml for IgM. The normal mean (SD) values of indexes were 0.51 (0.10) for IgG, 0.25 (0.05) for IgA and 0.044 (0.017) for IgM. These values agreed quite well with those determined by EIA. The values of CSF albumin correlated significantly with those of CSF IgG or IgA, but did not with those of CSF IgM. Levels of each of the three Ig classes in CSF and serum were significantly correlated. When CSF/serum ratio was introduced, a significant correlation between the albumin ratio and each Ig ratio was found. These results suggest that the Ig content of normal CSF may depend upon that of serum and upon the characteristics of the Ig molecule.

Adolescent↗