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Biomedical subjects

H Jørgen

Publications and source records attributed to H Jørgen.

6 recordsLinked to original sources
PubMed2000

Efficiency of systematic sampling in histomorphometric bone research illustrated by hydroxyapatite-coated implants: optimizing the stereological vertical-section design.

The sampling efficiency of the unbiased stereological vertical-section method was analyzed in five hydroxyapatite-coated implants. They were inserted into humans and harvested after 1 year. To find an optimal sampling design for histomorphometric analyses, sampling efficiency was estimated by variance analyses at different sampling levels (humans, sections, fields of view, and number of counting items) and intensities. Only minor changes in variance were observed when the initial scheme was reduced to include just one of the two possible implant sides, every third field of view, and half the density of the probe; this reduced the total workload at the microscope to less than 10% for all sections. In addition, the number of sections for analysis could be reduced to every fourth section per implant (three to four sections for evaluation) without significantly increasing variance. The study demonstrated that biological variation contributed to the majority of the total observed variance. Optimizing the sampling design could significantly reduce the workload at the hard-tissue microtome and the microscope without reducing the quality of the data that were unbiased and that had low sampling variance as compared with the true biological variation.

Adult↗
PubMed1981

Comparison of semiautomatic digitizer-tablet and simple point counting performance in morphometry.

A comparison is made between the efficiency of an opto-manual digitizer-tablet (MOP-AM 03) and simple point counting in the analysis of drawings of basal cells in the normal and pathologically altered chonchal epithelium. The analysis included estimation of the areas of cellular, nuclear and nucleolar sectional profiles as well as the cell basal width, i.e. the length of cell profile attachment to the basement membrane. The morphometric results obtained with the two methods are virtually identical. The efficiency of point counting is somewhat higher than that of the digitizer, but the prices of the two sets of equipment differ by one or two orders of magnitude. In general, the unquestionable measuring precision of the digitizer is unlikely to be of much impact in most biological studies due to the inevitable biological variation between individuals under study and the large variation which is always added at the level of single features by random sectioning.

Anthropometry↗
PubMed1981

Quantitative relationship between glomerular foot process width and proteinuria in glomerulonephritis.

The relationship between foot process fusion (retraction) and proteinuria in glomerular diseases has been known for many years, but only a few quantitative studies have been performed. The quantitative morphometrical method used here makes it possible to estimate the distribution of true foot process width from the observed apparent width on electron micrographs. The true foot process width was analyzed in a consecutive material of patients with glomerulonephritis and related to the diurnal urinary protein excretion. Only a weak correlation was found between these two parameters. Albeit an abnormal foot process width was invariably associated with proteinuria, a rather large fraction of patients with gross proteinuria had normal foot process width compared to control subjects. Thus, if foot process fusion causes proteinuria, this can not be the only mechanism leading to this permeability alteration. On the other hand, our results show that foot process fusion is not a necessary consequence of proteinuria. In addition, a methodologic study was performed, analyzing the relationship between the quantitative and a semiquantitative method for estimating foot process fusion. It is concluded that the latter method is fast and sufficiently precise for most evaluations of foot process width in human kidney biopsies.

Biopsy↗
PubMed1979

Estimation of tubule or cylinder LV, SV and VV on thick sections.

The estimators of tubule or cylinder LV = 2NA, SV = 2IL, and VV = PP are considered in terms of bias due to section thickness, diameter, overlap, and grazing or fuzzy profiles. The superiority in a number of cases of the indirect estimation of SV and VV as functions of LV and profile diameter is discussed. Statistical aspects are dealt with in a practical example.

Animals↗
PubMed1979

Evaluation of a procedure for systematic semiquantitative analysis of glomerular ultrastructure in human renal biopsies.

A method is described for systematic semiquantitative investigation of glomerular ultrastructure in renal biopsies from patients with glomerulonephritis. Three glomeruli per biopsy were studied by electron microscopy. Ten systematically recorded micrographs at x12,000 and a montage covering the whole glomerular cross-section at x3,000 were analyzed from each glomerulus. The severity of each of 34 different ultrastructural lesions was semiquantitatively evaluated on a 4-degree scale, 0 to +++. The usefulness of the method was evaluated by calculating different parameters for the reproducibility of semiquantitative scoring, representativeness of micrographs, and representativeness of glomeruli. The reliability of the method was considered good or acceptable with respect to 17 of the lesions. Ten lesions obtained a high reproducibility of scoring but the usefulness of the scores was limited due to a segmental and/or focal distribution of these lesions. The evaluation of these lesions can be improved by analyzing a larger number of micrographs, or glomeruli, or both. Seven lesions were so rare in the present biopsies that no statistical evaluation was possible. When applied to a large number of biopsies, this practical and useful method allows a reproducible comparison of the patterns of ultrastructural lesions in various types of glomerulonephritis.

Basement Membrane↗