Biomedical subjects

I H Stamhuis

Publications and source records attributed to I H Stamhuis.

5 recordsLinked to original sources

PubMed1988

Evaluation of univariate ranges with a multivariate standard.

In medical decision making generally many test results are produced. Several authors have discussed the problems involved and concluded that a multivariate approach often has to be preferred. Because until now such an approach has not often been used in practice and qualitative arguments for a multivariate approach are seldom supported by quantitative results, in this paper the use of univariate reference ranges is evaluated with a multivariate range as the standard, taking into account correlation coefficients. Probabilities of false positive and false negative results and predictive values are computed and displayed for decision rules based on two separate test results with an elliptic region as the gold standard. The conclusion is that the quality of the univariate approach is dependent on the correlation coefficient and on the choice of the decision rule. In the most important cases, however, it falls short compared with a multivariate approach. For example, the probability that a univariate positive result is false is around 50% for all values of the correlation coefficient, which is unacceptably high.

Decision Making↗

PubMed1985

Frequency and coordination of ciliary beat after cryopreservation of respiratory epithelium.

The effect of cryopreservation on human nasal mucosal biopsies was evaluated by determining the frequency and coordination of the ciliary beat. Samples were cryopreserved in a medium containing 80% Gey's balanced salt solution, 10% dimethyl sulfoxide, and 10% fetal calf serum. After thawing, the samples were put in a solution of 90% Gey's balanced salt solution and 10% fetal calf serum. Video recordings of the samples before and after cryopreservation were compared using a semiquantitative method. All the frequencies and coordination patterns seen before cryopreservation could be found in the sample after cryopreservation. It is concluded that ciliated epithelial biopsies can be stored in liquid nitrogen with the maintenance of ciliary beat frequency. In the recorded ciliated cells the ciliary beat coordination was slightly reduced; a lack of coordination was present in 20% of cells after cryopreservation as compared to 10% before cryopreservation.

Adult↗

PubMed1985

Bone marrow mitotic index: a methodological study.

The mitotic index (MI) of bone marrow specimens is assessed in 3 different ways: method I determines the number of mitotic figures per 1,000 nucleated cells; method II counts the number of mitoses seen per 1,000 nucleated cells belonging to the proliferative pool, and method III is the same as method I, but excludes all lymphoid cells. 30 Giemsa-stained bone marrow smears from 6 children were screened by 3 independent investigators. MI of method II is found to be approximately twice as high as the MI of method I. The results of method III indicate that the size of the lymphoid population introduces a bias, which renders method I less reliable. It is concluded that method II is the method of choice for a reliable assessment of bone marrow MI.

Bone Marrow Cells↗

PubMed1984

Handmirror cells and central nervous system relapse in childhood acute lymphoblastic leukaemia.

In 53 children with acute lymphoblastic leukaemia (ALL), initial handmirror cell (HMC) count among lymphoblasts was studied in relation to the occurrence of a relapse in the central nervous system (CNS), taking into account the white blood cell count (WBC) and the immunological phenotype. The children were followed for a period limited by (1) the first CNS relapse, (2) death or (3) the closing day of this study. The median follow-up period was 30 months, range 2-106 months. HMC counts were available in bone marrow smears of 41 children and in cytospins of 35 children. Cytospins proved to give more reliable and consistent results than bone marrow smears. In the 35 'cytospin' children no CNS relapses occurred in the group of 16 children with non-T-non-B-ALL and HMC counts above 10%. However, in the group of 10 children with non-T-non-B-ALL and HMC counts below 10%, and in the group of 9 children with T-ALL (HMC less than or equal to 11%), 6 and 5, respectively, got a CNS relapse. The CNS relapse-free period was not significantly different between these last two groups, whereas both groups did differ significantly from the group mentioned first (p less than 0.01). This was not found in bone marrow smears of 41 children, presumably because of the inaccurate counting results. A low initial HMC count in cytospins is associated with an increased risk for the occurrence of a CNS relapse in children with ALL. This prognostic factor seems to be independent of other prognostic signs such as immunological phenotype and high WBC.

Adolescent↗

PubMedDate not supplied

Determining reference ('normal') limits in medicine: an application.

We provide an account of a study to assess reference limits for eight routine laboratory determinations at the Academic Hospital of the Free University, Amsterdam and emphasize methodological issues rather than results. We argue that reference limits have use mainly in the first phase of the diagnostic process. Reference and target populations should be grossly comparable, and therefore patients (after slight selection) could well serve as references. However, we found major differences between in- and out-patients, so we suggest that this factor, together with age and sex, be taken into account. To arrive at reliable limits, the size of the reference sample should be at least 100. Laboratory reports should provide percentiles, which enable a more flexible decision than do fixed limits.

Adult↗