Biomedical subjects

H J Gundersen

Publications and source records attributed to H J Gundersen.

At least 55 records · Page 3Linked to original sources

PubMed1990

Efficient estimation of cell volume and number using the nucleator and the disector.

The nucleator allows the unbiased estimation of absolute structural quantities of suitably sampled, arbitrarily shaped structures from observations made from arbitrary points using isotropic probes. A number of time-saving modifications using the nucleator and the consequences of the modifications are studied in terms of their bias and efficiency. Using rat neocortex as an example, a description is given of how to estimate mean neuronal volume and total neuron number efficiently from only a few pairs of plastic sections with a thickness of about 3 microns.

Animals↗

PubMed1990

A direct method for fast three-dimensional serial reconstruction.

A method for accurate three-dimensional reconstruction of openly connected porous structures is described. The method is based on embedding of a specimen in a contrast coloured epoxy resin and serial sectioning in a standard hard tissue microtome. A PC-based image processing system is used for direct digitization of the cut surface, and by thresholding two-phase images are obtained. The process is fully automated, and about 170 sections can be produced, digitized, dichotomized, and stored per hour. As an example of its applications, the method is used on trabecular bone, which is an anisotropic porous structure.

Bone and Bones↗

PubMed1989

Normal postmenopausal women show iliac crest trabecular thickening on vertical sections.

Trabecular thickness and the trabecular star volume were estimated in 49 normal individuals (20 males and 29 females) using an unbiased sampling procedure consisting of anisotropic, vertical sections, and a corresponding anisotropic test system. Eight-microns-thick undecalcified stained vertical sections were obtained from iliac crest specimens. Implying a trabecular plate model mean trabecular thickness (Tb.Th., microns) was estimated by different methods: (a) the ratio between bone volume and bone surface (Tb.Th.ratio); (b) the mean of the orthogonal intercepts multiplied with pi/4 (Tb.Th.l0); and (c) the mean of random linear intercepts divided by 2 (Tb.Th.l1). Trabecular star volume (Vtr*, mm3), a true three-dimensional size parameter independent on any model, was estimated using linear intercepts in random directions. Significant (2p less than 0.001) correlations were found between the different methods with coefficients of correlation ranging from 0.71 to 0.89. The Tb.Th. ratio was overall higher (155 +/- 31 microns, (X, SD), 2p less than 0.001) than the other linear estimates, Tb.Th.l0: 144 +/- 26 microns and Tb.Th.l1: 135 +/- 27 microns. Estimates based on orthogonal intercepts (l0) were slightly higher (2p less than 0.001) than those from random linear intercepts (l1). Among all the individuals no significant age-related changes were seen in the measured parameters. However, postmenopausal women (greater than 50 years of age) had more thick trabeculae than younger women (2p = 0.03). Intra-individual distribution analysis disclosed that this finding could not be explained by preferential perforation and loss of thinner trabeculae during bone remodeling. Therefore, normal postmenopausal women do increase trabecular thickness with age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Star volume of marrow space and trabeculae of the first lumbar vertebra: sampling efficiency and biological variation.

The decrease in the amount of trabecular bone which is seen with age cannot solely be explained by thinning of trabeculae but must also be due to a loss of structural trabecular bone leading to a discontinuity in the trabecular network. Due to the complex architecture and the anisotropy of bone it is difficult to demonstrate this structural change by conventional histomorphometry. Unbiased stereological estimators can however be obtained from anisotropic structures when using vertical sections and a specially designed anisotropic test system. This combined with a new and unbiased stereological parameter for bone structure the star volume can be of major importance in clarifying histological changes of bone structure. The star volume is defined as the mean volume of all the parts of an object which can be seen unobscured in all directions from a particular point with the mean value taken over all points inside the object. It is defined for any type of objects including cavities like marrow space and networks like the trabecular system. Measurements are performed using a frame and a grid with points and lines. The material investigated was the first lumbar vertebra obtained from two females and six males with ages 26 to 75 years without malignant or metabolic bone diseases. The sampling procedure was as required for vertical sections. Results did show a highly significant, five-fold increase in the star volume of the marrow space with age; no such age correlation was found for the star volume of the trabeculae. The only explanation for such an increase in the size of the marrow space is by removing or perforating trabecular bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

New stereological method for obtaining unbiased and efficient estimates of total nerve cell number in human brain areas. Exemplified by the mediodorsal thalamic nucleus in schizophrenics.

Using a new stereological technique, the total number of nerve and glia cells can be estimated in selected brain regions. The method is completely independent of precise knowledge of nerve cell size, section thickness and of dimensional changes in brain tissue induced by histological procedures. It therefore provides an unbiased estimate of total nerve cell number. As an example, the total neuron number from the mediodorsal nucleus of thalamus in brains from schizophrenic patients is compared to control cases. The total neuron number was reduced by 40% in the brains from chronic schizophrenic patients.

Adult↗

PubMed1989

Reproducibility of histomorphologic diagnoses with special reference to the kappa statistic.

Systems for classification and grading used in pathology should ideally be biologically meaningful and at least be reproducible from one pathologist to another. A statistical method to evaluate reproducibility (non-chance agreement) for several observers using nominal or ordinal categories has been developed and refined over the past few decades--the kappa statistic. A high level of observed agreement among different pathologists can either signify a high level of reproducibility, if agreement by chance is low, or express a low level of reproducibility, if agreement by chance is almost as high as the observed agreement. Therefore, the observed agreement says nothing in itself, unless it is low. The kappa value, however, indicates how much better the observers are compared to a throw of the dice, and therefore gives the real credit to the agreement which was found. We have developed a user-friendly computer program for calculating inter- and intra-observer agreement of 2 or more observers. By calculating associations between different categories and different observers, the statistic furthermore obtains a function close to the parameter of accuracy. We recommend the use of the above method before a set of nominal or rank scale parameters are used for deciding prognosis and treatment of patients. By submitting a diskette the computer program will be available at no cost.

Histological Techniques↗

PubMed1988

Stereological analysis of three-dimensional structure organization of surfaces in multiphase specimens: statistical methods and model-inferences.

In a multiphase material the structural components or phases are everywhere in contact with each other. The relative area of surface contact between various phases is an important aspect of the short-range ordering or organization of the structure. The stereological quantitation of such specific interfaces is a simple and well-known technique. The proper statistical definition of realistic models for the frequency of contact and the quantitative estimation of phase-specific affinities is studied. The meaningful interpretation of sets of estimated affinities poses a major problem of statistical inference which is dealt with in detail and illustrated by a worked-out biological example.

Animals↗

PubMed1988

Total number of neurons and glial cells in human brain nuclei estimated by the disector and the fractionator.

Unbiased estimates of the total number of neurons and glial cells from central regions of grey matter in human brains are obtained using the disector principle in modifications which are unaffected by the histological processing of paraffin-embedded tissue. Section thickness does not enter into the estimator and need not be known. An analysis of the contributions from all sampling levels to the variance of the estimator of total cell number has been used to design an optimimal sampling scheme. Using this method, a precise and unbiased estimate of the total number of neurons in a defined brain region can be obtained in less than 1 h.

Brain↗

PubMed1988

The nucleator.

A new, fundamental stereological principle is described which allows unbiased estimates of absolute structural quantities in arbitrarily shaped structures to be made from observations sampled in arbitrary points on independently isotropic probes. As an introduction to the principle, method(s) are described which lead to assumption-free estimates of mean volume from the usual number-distribution of particle sizes. Specifically, the estimation is unbiased when arbitrarily shaped particles are sampled with uniform probability using the dissector or one of its many modifications. A special case, of interest when observations are restricted to sections, occurs when the particles are associated with some recognizable unit, like eukaryotic cells in biology. The estimation may then be carried out on a few sections of unknown thickness, or--under verifiable assumptions--on just one random section.

Animals↗

PubMed1988

The new stereological tools: disector, fractionator, nucleator and point sampled intercepts and their use in pathological research and diagnosis.

The new stereological methods for correct and efficient sampling and sizing of cells and other particles are reviewed. There is a hierarchy of methods starting from the simplest where even the microscopic magnification may be unknown to the most complex where typically both section thickness and the magnification must be known. Optical sections in suitably modified microscopes can be used to improve the ease and speed with which even the most demanding of these methods are performed. The methods are illustrated by practical examples of applications to a wide range of histological entities including synapses, neurons and cancer cells, glomerular corpuscles and ovarian follicles.

Animals↗

PubMed1988

Some new, simple and efficient stereological methods and their use in pathological research and diagnosis.

Stereology is a set of simple and efficient methods for quantitation of three-dimensional microscopic structures which is specifically tuned to provide reliable data from sections. Within the last few years, a number of new methods has been developed which are of special interest to pathologists. Methods for estimating the volume, surface area and length of any structure are described in this review. The principles on which stereology is based and the necessary sampling procedures are described and illustrated with examples. The necessary equipment, the measurements, and the calculations are invariably simple and easy.

Humans↗

PubMed1988

Glomerular morphology by light microscopy in non-insulin-dependent diabetes mellitus. Lack of glomerular hypertrophy.

We quantitated glomerular structure by light microscopy in 19 subjects with non-insulin-dependent diabetes mellitus (NIDDM) and studied the possible connection between morphology and urinary albumin concentration. Autopsy material was collected retrospectively from diabetic subjects in whom urinary albumin concentration had been measured within 1.5 yr. Nineteen consecutive sex- and age-matched nondiabetic subjects were controls. A quantitative study of a random sample of glomeruli was performed blindly on periodic acid-Schiff (PAS)-stained sections. The main parameters obtained were 1) mean volume of open glomeruli, 2) frequency of glomerular occlusion, and 3) volume fraction of red-stained material (PAS-positive substance) in open glomeruli [Vv(R/G)]. There was no increase in glomerular volume in these NIDDM subjects, contrary to the glomerular hypertrophy found early as well as late in insulin-dependent diabetes mellitus. An increase in Vv(R/G) was found in diabetic subjects, demonstrating the presence of glomerulopathy as it is diagnosed by light microscopy. The frequency of glomerular occlusion was not significantly different between the groups. A high urinary albumin concentration did not necessarily reflect more advanced glomerulopathy.

Aged↗

PubMed1988

Reduced pupillary unrest. Autonomic nervous system abnormality in diabetes mellitus.

Pupillary unrest (fluctuations in pupil size) was measured by infrared television videopupillography in 80 insulin-dependent diabetic patients (age 25-43 yr, diabetes duration 0-35 yr) and 26 control subjects (age 26-39 yr). In darkness, pupillary unrest was 21% less in diabetic subjects than in controls. During prolonged and brief illumination, pupillary unrest was 35 and 37% less in diabetic subjects than in controls, respectively, and in both cases the unrest was inversely correlated to the duration of diabetes. There were inverse correlations between 1) vibratory perception threshold, long-term high blood glucose levels, and severity of retinopathy, and 2) pupillary unrest in darkness and during prolonged illumination. The fractional reduction in pupil size (relative miosis) was 19% less during prolonged illumination in diabetic subjects than in controls and was positively correlated to the pupillary unrest in both groups. For a given fractional reduction in pupil size during illumination, diabetic subjects still had a smaller unrest than controls. Pupil size in darkness was 19% smaller in diabetic subjects than in controls, and in diabetic subjects it was positively correlated to the unrest in darkness and during prolonged and brief illumination. None of the pupillary abnormalities showed correlation to biomicroscopic changes in the iris. The autonomic nervous system abnormalities reflected in the pupil in longstanding diabetes are 1) a reduction in pupillary unrest in light and in darkness, more pronounced in light, 2) a reduction in the ability to maintain miosis in continuous light, and 3) a reduction in size.

Adult↗

PubMed1988

Stereological estimates of nuclear volume correlated with clinical stage and progression of prostatic cancer: clinical aspects.

Fifty-one transurethral prostatectomies were reviewed regarding the possible prognostic value of stereological estimation of cell nuclear volume in prostatic cancer. Patients with manifest cancer had a larger nuclear volume than those with incidental cancer, even though the two groups were matched concerning age and histological grade of the cancer. The nuclear volume was larger in patients with incidental cancer than in those with prostatic hyperplasia. Stereological estimation of nuclear volume may be a useful objective supplement to other prognostic parameters in prostatic cancer.

Aged↗

PubMed1988

Stereological estimation of the number of capillaries, exemplified by renal glomeruli.

A capillary structural unit can be given an unambiguous, topological definition which forms the basis for the practical stereological estimation of the total number of such units in a capillary network. This definition of a capillary is in accordance with the concept of formation of new capillars. The principle is illustrated by the (simple) example of glomerular tufts in the kidney.

Animals↗

PubMed1987

Unbiased stereological estimation of osteoid and resorption fractional surfaces in trabecular bone using vertical sections: sampling efficiency and biological variation.

The conventional stereological procedure for estimating bone surface densities in iliac crest biopsies provides biased estimates because bone substructure is anisotropic and the sectioning of the biopsies is intended to be parallel to the cylindrical axis of the iliac crest biopsy. It has recently been shown that random anisotropic sections with an identifiable axis or direction which is arbitrary but fixed can be used for unbiased estimates of surface areas. The arbitrary axis is called "vertical," a denomination which does not imply anything about its relation to directions in the world's field of gravity. Sampling efficiency and biological variation of fractional osteoid and resorptive surfaces were investigated in 14 paired bone specimens obtained from two females and five males (mean age 64) using an integral anisotropic test system constructed of cycloids. Results obtained at direct microscopy were compared to results obtained with projection onto the table. Mean fractional osteoid and resorption surfaces were 6.2 and 1.4% using direct microscopy and 5.6 and 1.7% using projection. Estimation of variance at each level of sampling showed that the majority of the total observed variance was due to true variance between individuals; for fractional osteoid surface the unavoidable biological variation was 80.5% of the observed variation and for fractional resorption surfaces it was 57%. The efficiency of the estimation procedure is therefore close to optimal and the only way to improve the precision in groups of patients and controls would be to include more individuals in the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1987

Unbiased stereologic estimation of surface density in bone using vertical sections.

The conventional stereologic procedure for estimating bone surface densities in iliac crest biopsies gives biased estimates because bone substructure is anisotropic and the sectioning of the biopsies is intended to be parallel to the cylindrical axis of the iliac crest biopsy. It has recently been shown that random anisotropic sections with an identifiable axis or direction that is arbitrary but fixed can be used for unbiased estimates of surface areas. The arbitrary axis is called "vertical," which does not imply anything about its relation to direction of gravity. To describe the methodology and the practical sampling procedure for vertical sections, surface density of trabecular bone was estimated in 16 bone samples obtained at autopsy from eight persons (mean age 64 years) using an anisotropic cycloid test system designed for vertical sections. In addition, variation in the estimation procedure was quantitated. The average surface density of trabecular bone was 2.8 +/- 0.4 mm-1 (+/- SD). No systematic difference was observed between the two bone specimens from each of the eight persons. Estimation of the variance at each level of sampling showed that the majority of the total observed variance was due to true variance between individuals. Vertical section is, in general, the method of choice when dealing with surfaces not known to have an isotropic orientation distribution. The cycloid test system is easy and fast to use, and the estimate is truely unbiased. The requirements are all sections must be parallel to the vertical axis, the rotation around this axis must be random, the position of the section or of the biopsy must be random, and the vertical axis must be identified in the section.

Aged↗

PubMed1987

The efficiency of systematic sampling in stereology and its prediction.

The superior efficiency of systematic sampling at all levels in stereological studies is emphasized and various commonly used ways of implementing it are briefly described. Summarizing recent theoretical and experimental studies a set of very simple estimators of efficiency are presented and illustrated with a variety of biological examples. In particular, a nomogram for predicting the necessary number of points when performing point counting is provided. The very efficient and simple unbiased estimator of the volume of an arbitrary object based on Cavalieri's principle is dealt with in some detail. The efficiency of the systematic fractionating of an object is also illustrated.

Animals↗