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T Groth

Publications and source records attributed to T Groth.

At least 73 records · Page 4Linked to original sources
PubMed1994

Analysis of 24-hour growth hormone profiles in healthy boys and girls of normal stature: relation to puberty.

To evaluate the developmental and sex-specific changes in spontaneous GH secretion in terms of both secretory rate and pulsatile pattern, we investigated 24-h GH profiles (integrated 20-min samples) in 208 healthy children (91 girls and 117 boys) of normal heights at all stages of puberty. The plasma GH concentrations were transformed to GH secretion rates by means of a deconvolution technique. In prepubertal boys and girls, the mean secretion rates were comparable (0.66 and 0.68 U/24 h), but increased during puberty differently: earlier in girls, already at stage 2, with the highest rates at stages 3 and 4 (1.70 and 1.96 U/24 h); later in boys, at stage 4 (1.66 U/24 h). In both sexes the GH secretion rate decreased to prepubertal values at stage 5. The GH secretion rate correlated negatively with weight for height expressed in SD scores only in puberty (boys, r = -0.44, P < 0.001; girls, r = -0.22; P < 0.05). The number of peaks with high amplitudes increased with the progress of puberty in both boys (stage 2) and girls (stages 3 and 4). In both prepubertal girls and boys, a marked day-night rhythm was observed, which disappeared in midpuberty in boys owing to a greater increase in peak amplitudes during the day than at night. The mean number of peaks per 24 h was unchanged in girls, but decreased in late pubertal boys. In summary, we found a sex-specific increase in the GH secretion rate during pubertal development that occurs at an earlier pubertal stage and is more pronounced in girls than in boys. There are underlying changes in the mean GH amplitudes in both boys and girls as well as an increased baseline secretion in girls. In puberty, body composition modulates the GH secretion rate in both sexes.

Adolescent↗
PubMed1993

Analytical quality goals and assessment to ensure transferability of laboratory results.

About 3 years ago NORDKEM started a project entitled 'Medical Need for Quality Specifications in Clinical Laboratories'. This communication describes the general approach of this project and a subproject oriented towards problems of transferability of clinical laboratory data. Attempts are made to estimate clinical goals for analytical measurements--either used alone or in combinations with other measurements or observations--in defined clinical situations. Various methodologies are used for the assessment of the clinical goals, starting, e.g., from clinical situations or biological reference data. The analytical quality specifications are expressed as total allowable errors. It is necessary to complement specifications of 'clinical goals' with data describing characteristics of the measurement procedure, preanalytical errors and internal and external quality assurance procedures in order to establish the laboratory quality specification guaranteed by the laboratory. Problems of transferability of clinical laboratory results occur both within a laboratory/hospital and between laboratories/hospitals/health care units, problems that sometimes make communication of laboratory results difficult or even meaningless. In order to study the transferability of clinical laboratory data within a health care region, so called 'transformation functions' could be used to characterize each laboratory in a strict quality assessment/proficiency testing procedure on the basis of analytical quality specifications. Under certain conditions, e.g. for analytical procedures with high specificity and documented stable analytical performance, numerical correction of analytical bias could be performed to decrease interlaboratory variation to a level specified by medical needs.

Cholesterol↗
PubMed1993

Medical need for quality specifications--a NORDKEM project for selecting the appropriate quality in clinical laboratories.

The Nordic Clinical Chemistry Project (NORDKEM) has during its existence run several projects dealing with analytical quality requirements and the specifications of such requirements. The latest project-"Medical Need for Quality Specifications in Laboratory Medicine"-started three years ago and is now to be reported. The project consists of three main subprojects and a large number of associated projects. The main subprojects deal with: *External quality assurance for proteins (Per Hyltoft Petersen et al.) *Transferability of clinical laboratory data (Torgny Groth & C-H de Verdier) *Terminology (René Dybkaer) "Clinical goals" are assessed using different kinds of procedures. Comparison with the characteristics of "the analytical procedures" and "the quality assurance programs" gives the Management of the clinical laboratory a background for determining the "analytical quality specifications" of the laboratory. Procedures for setting up clinical goals and analytical quality specifications are given and they are further exemplified in the associated projects. Clinical goals and the analytical quality specifications are expressed and calculated in similar ways as total allowable error (TEa), as a coefficient of variation or an absolute error within defined concentration intervals.

Chemistry, Clinical↗
PubMed1992

A hyaluronan-loading test applied to patients with liver and joint diseases.

The serum hyaluronan disappearance data, after an intravenous bolus injection of hyaluronan, were evaluated in terms of model-based parameters. The loading test was performed in 10 healthy persons (basal serum hyaluronan concentration, C0, 24.9 +/- 8.9 micrograms/l [mean +/- S.D.]), 6 patients with joint disease (62.3 +/- 41.1 micrograms/l) and 19 patients with liver disease (206 +/- 214 micrograms/l). The highest maximum Michaelis-Menten elimination rate (Vmax = 287 +/- 86 micrograms/min) was found in patients with joint disease, significantly higher than in healthy persons (Vmax = 179 +/- 16, P = 0.0015) and in patients with liver disease (Vmax = 149 +/- 59, P = 0.0002). C0 and Vmax were evaluated as discriminants for assessment of residual liver function. In patients with liver disease C0 correlated with liver function score (r = 0.875, P < 0.0001) and serum albumin concentration (r = -0.813, P < 0.0001). The Vmax parameter did not correlate with conventional liver function tests or with the liver score but a significantly negative correlation of Vmax with C0 was found in patients with liver disease. A combination of the C0 level and the Vmax parameter was found to discriminate between healthy persons, patients with joint disease and patients with liver disease and should be of benefit in separating patients, with or without elevated serum hyaluronan levels, into groups having increased influx or reduced elimination, respectively, of circulating hyaluronan.

Adult↗
PubMed1992

Development of a new dynamic method for quantitative evaluation of in vitro hemocompatibility of biomedical materials.

In this study a new dynamic method is introduced allowing the estimation of blood cell adhesion on flat test surfaces by measuring the cell loss in the bulk phase of surface contacting test blood under defined rheological conditions. This was achieved by constructing a novel test chamber permitting the contact of small amounts of blood with a large geometrical test surface. The construction consists of a spiral-shaped flow channel of 0.3 cm width, 0.02 cm height and 78 cm length covered with the biomaterials to be tested from both sides. Laminarity of blood flow in the conduit was confirmed theoretically by the calculation of an equivalent to the Reynolds number for curved systems the so-called Dean number. Furthermore, flow laminarity was proved experimentally finding that the flow rate of blood with different hematocrit values was proportional to the hydrostatic pressure applied. The applicability of the novel 'spiral method' for the estimation of hemocompatibility was demonstrated by evaluation of platelet adhesion onto different polymers in comparison to siliconized and fibrinogen coated glass as reference surfaces. Additionally, it was possible under distinct conditions to determine the adhesion of leucocytes and the detachment of platelet aggregates. Therefore, it was concluded that the spiral method can be used for the assessment of the hemocompatibility of flat biomedical polymers. As main advantages of the new method can be considered the high time efficiency and accuracy without labelling or optical detection of adherent cells.

Acrylic Resins↗
PubMed1992

Transferability of clinical laboratory data within a health care region.

Analytical data for S-Creatinine and S-Urate are presented from seventeen laboratories in the Swedish Uppsala-Orebro regional quality assessment program. The bias and imprecision as well as the instability of the measurement procedures in the participating laboratories were estimated over three 14-week periods. Bias was estimated by a linear least squares fit of the difference between measured and assigned values vs. assigned values, and expressed in absolute and relative terms. Instability of the measurement procedures was estimated by comparing slope and intercept of regression lines of measured vs. assigned values from three fourteen week periods. According to our experiences we recommend regression analysis to describe the performance of the analytical methods of a laboratory over time. The results show that most laboratories fell within the limits of +/- 15% bias for S-Creatinine above 100 mumol l-1 and +/- 17% for S-Urate at concentrations above 250 mumol l-1. Various steps to reduce the inter-laboratory variability are suggested, including numerical correction of individual laboratory results using correction functions. In a few laboratories, instability was too high to allow for numerical corrections of analytical results.

Bias↗
PubMed1991

INFORM: integrated support for decisions and activities in intensive care.

Many medical decision support systems that have been developed in the past have failed to enter routine clinical practice. Often this is because the developers have failed to analyse in sufficient detail the precise user requirements, because they have produced a system which takes too narrow a view of the patient, or because the decision support facilities have not been sufficiently well integrated into the routine clinical data handling activities. In this paper we discuss how the AIM-INFORM project is setting out to deal with these issues, in the context of the provision of decision support in the intensive care unit.

Artificial Intelligence↗
PubMed1990

Clinically based quality goals; a NORDKEM project.

The three main aspects of analytical quality are 'goals for analytical quality', 'creation of analytical quality', and 'control of analytical quality'. In the NORDKEM-project 'medical need for quality specifications within laboratory medicine' the aspects of analytical quality are combined. The aims is to make an appraisal of the different approaches to goal setting, and to develop a practical procedure for assessing analytical quality requirements. The goals are used to define which demands should be met by the process of establishing and maintaining the quality, and for design of internal as well as external quality assurance procedures. The project is an umbrella project with three main subprojects and several satellite projects. In this presentation a model for evaluation of influence of analytical bias and imprecision on the outcome from a diagnostic classification based on bimodal distribution is described.

Clinical Laboratory Techniques↗
PubMed1990

The use of knowledge-based information systems for interpreting specialized clinical chemistry analyses--experience from erythrocyte enzymes and metabolites.

A knowledge-based information system has been constructed to facilitate and standardize the interpretation of data obtained from specialized analyses in clinical chemistry. For illustration the system was applied to metabolic studies of erythrocytes from patients in whom hereditary disorders are suspected to explain the presence of a haemolytic anaemia or a polycythaemia. The study includes assay of the catalytic activity of 10 different enzymes and the concentration of some key metabolites. The knowledge-based system is an excellent tool for documentation, updating and transfer of knowledge of the interpretative process. This will reduce the risk of changes in this process being made without sound motivation and documentation. Furthermore, the statistical and graphic features of the system provide data for long-term quality assessment and insights into reference sample groups which are used to update decision levels.

Anemia, Hemolytic↗
PubMed1990

Investigation of blood-biomaterial interaction by means of a new quantitative dynamic measuring principle.

In this study a new dynamic measuring chamber for flat biomaterials allowing the estimation of cell adhesion on test surfaces by measuring the cell lost from surface contacting test blood under defined rheological conditions is introduced. This was achieved by constructing a test chamber permitting the contact of small amount of blood with a large geometrical test surface. The construction consists of a spiral-shaped flow channel of 0.3 cm width, 0.02 cm height and 78 cm length. The applicability of the new method was demonstrated by evaluation of platelet adhesion on siliconized glass, fibrinogen coated glass, cuprophane and polyacrylnitrile.

Biocompatible Materials↗