Biomedical subjects

H J Gundersen

Publications and source records attributed to H J Gundersen.

At least 19 recordsLinked to original sources

PubMed1995

Solutions to old problems in the quantitation of the central nervous system.

New stereological techniques, superior to conventional methods in quantitating macroscopic and microscopic structures in the central nervous system, have been developed within the last decade. By the use of a new counting method, the dissector, it is possible to obtain an efficient and yet precise estimate of the total number of neurons in any specific region, where a delineation of the region can be made, and the cells identified. The method has been applied to brains from patients with different neurological disorders. The latest effort has concentrated on the estimation of the total neocortical neuron number in brains from normal individuals of both sexes in the age from 20 to 90 years to see whether there are differences in total neocortical neuron numbers between males and females.

Adult↗

PubMed1995

Direct stereological estimation of three-dimensional connectivity in rat vertebrae: effect of estrogen, etidronate and risedronate following ovariectomy.

Newly developed unbiased stereological methods were employed to investigate the effects of estrogen deficiency on the three-dimensional connectivity of vertebral cancellous bone from ovariectomized (OVX) rats. The effects of two classes of antiresorptive agents, estrogen and bisphosphonates, on changes in connectivity in this animal model were also evaluated. Female rats were either sham-operated (sham-op) or surgically OVX at 90 days of age. OVX rats were administered either vehicle, estrogen (10 micrograms/kg 17-beta estradiol, 5 days/week subcutaneously [SC], etidronate disodium (5 mg/kg SC) or risedronate (5 micrograms/kg SC). The bisphosphonates were administered daily for 1 week followed by 3 weeks with no treatment. Treatment duration was 360 days. Systematic random sections, 30-microns thick, were prepared from methylmethacrylate-embedded decalcified second lumbar vertebrae. Total trabecular number and connectivity density were estimated using the ConnEulor principle. Vertebral cancellous bone volume was estimated on undecalcified sections from the first lumbar vertebrae. Connectivity density and cancellous bone volume were significantly reduced (approximately 25% and 40%, respectively) in the OVX group compared with the sham-op group. Estrogen treatment essentially maintained connectivity and cancellous bone volume at the level of the sham-op rats. Connectivity density and total trabecular number were significantly increased in the etidronate- and risedronate-treated rats compared with both the sham-op and OVX rats. These data demonstrate that reduction in the three-dimensional connectivity of vertebral cancellous bone is a long-term consequence of ovariectomy in the rat. This reduction in connectivity can be effectively prevented by the administration of antiresorptive agents such as estrogen, etidronate and risedronate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Unbiased estimation of vertebral trabecular connectivity in calcium-restricted ovariectomized minipigs.

The topological changes in vertebral cancellous bone were estimated in vertebrae from calcium-restricted ovariectomized Sinclair S-1 minipigs, a recently described animal model of cancellous osteopenia. Connectivity was estimated using unbiased stereological principles in disector pairs of sections from the first lumbar vertebrae. Connectivity density was increased approximately twofold when compared with sham-operated minipigs fed a standard diet. These alterations in topology occurred coincident with a 25% increase in final resorption depth and a 150% increase in vertebral marrow star volume. Taken together, these changes suggest that in calcium-restricted ovariectomized minipigs, trabecular plates are transformed into rods by perforation. These changes in topology appear to be due, at least in part, to excessive resorptive cell function at the level of the bone remodeling unit. Conventional two-dimensional estimators of structural parameters of cancellous bone were not only less sensitive to these changes in topology but, in some cases, the estimates were directionally reversed.

Animals↗

PubMed1994

Absolute number and size of pigmented locus coeruleus neurons in young and aged individuals.

Significant loss of noradrenergic neurons of the locus coeruleus in aging and Alzheimer's disease has been reported. The interpretation of these analyses, however, is problematic because of the model- and assumption-based nature of conventional sampling and estimation techniques. In the present study, unbiased stereological methods were used to estimate the total number and mean cell volume of pigmented neurons of the locus coeruleus in the brains of young and aged nondemented persons. No side-to-side differences are seen, and there is no change in pigmented cell number or size in the locus coeruleus of nondemented older persons as compared with that of young individuals. In light of previous studies that show severe locus coeruleus cell loss in Alzheimer's disease, these data support further critical investigations into the possible protective role of noradrenaline in normal cognitive functions and emphasize the importance of avoiding methodological bias in quantitative neuroanatomical studies.

Adult↗

PubMed1992

Stereology: the fast lane between neuroanatomy and brain function--or still only a tightrope?

Precise and unbiased quantitation of the key element of nervous tissue has solved some long-standing problems in neuroscience and the new stereological methods are now very efficient tools for experimental testing of new (and old!) ideas and concepts. Technically, the "zipless" combination of new stereological methods with certain essential principles for observation and recognition is only beginning to be made.

Central Nervous System↗

PubMed1992

Enumeration of organ-associated natural killer cells in mice: application of a new stereological method.

We here describe a method for estimation of the absolute number of NK cells in various organs of C57BL/6 mice. Using anti-asialo-GM1 heteroantisera to identify NK cells in tissue sections routinely stained by two-layer immunoperoxidase techniques, scoring was performed using light microscopy. Extrapolation to the absolute number of NK cells/organ was done after counting 10 systematically sampled sections of each organ. Due to the thinness of the sections (8 microns) many cells are cut and will appear in at least two sections, and a correction factor was constructed to eliminate this bias. With this method we show that spleens of eight-week-old C57BL/6 male mice contain about 4 x 10(6) NK cells, which is consistent with previous findings obtained by other methods. However, application of this stereological method to liver and lungs revealed the existence of as many as 0.75 and 2.5 x 10(6) NK cells in these organs, respectively, i.e. three to 10 times as many as previously found in single-cell suspensions obtained by enzymatic dissociation of liver and lung tissue. This stereological method for enumeration of the absolute number of small subpopulations of cells is generally applicable to other organs and to other antigens, and does not require the application of cumbersome single-cell isolation procedures, during which an unknown number of cells might be lost.

Animals↗

PubMed1991

Unbiased stereological estimation of the total number of neurons in thesubdivisions of the rat hippocampus using the optical fractionator.

A stereological method for obtaining estimates of the total number of neurons in five major subdivisions of the rat hippocampus is described. The new method, the optical fractionator, combines two recent developments in stereology: a three-dimensional probe for counting neuronal nuclei, the optical disector, and a systematic uniform sampling scheme, the fractionator. The optical disector results in unbiased estimates of neuron number, i.e., estimates that are free of assumptions about neuron size and shape, are unaffected by lost caps and overprojection, and approach the true number of neurons in an unlimited manner as the number of samples is increased. The fractionator involves sampling a known fraction of a structural component. In the case of neuron number, a zero dimensional quantity, it provides estimates that are unaffected by shrinkage before, during, and after processing of the tissue. Because the fractionator involves systematic sampling, it also results in highly efficient estimates. Typically only 100-200 neurons must be counted in an animal to obtain a precision that is compatible with experimental studies. The methodology is compared with those used in earlier works involving estimates of neuron number in the rat hippocampus and a number of new stereological methods that have particular relevance to the quantitative study of the structure of the nervous system are briefly described in an appendix.

Animals↗

PubMed1991

Biologically meaningful determinants of the in vitro strength of lumbar vertebrae.

Applying unbiased stereological methods and a new stereological parameter, star volume of cancellous bone, the bone structure of the first vertebral body was examined and compared with the compressive strength of the second lumbar vertebra. The material came from eight males, aged 33-69 years (mean 49 years) and seven women, aged 22-87 years (mean 52 years) without malignant or metabolic bone disease. From these individuals, first and second lumbar vertebral body were obtained at autopsy. The heights and weights of the individuals were recorded. The following structural parameters were estimated on undecalcified, seven-microns, Goldner-Trichrome stained vertical sections: fractional volume of trabecular bone (BV/TV%), mean trabecular thickness (Tb.Th.l1 microns), trabecular star volume (V*tr mm3), marrow space star volume (V* m.space mm3), and mean thickness of the lateral cortical ring (microns). The compressive strength of whole vertebral body, mean cross sectional area (cm2), and ash density (g/cm3) were estimated and the data were compared to bone histomorphometric estimates. A significant decrease with age for all parameters was found except for marrow space star volume, which increased. With compressive strength as the dependent variable and all other parameters as independent variables, it was shown by standard multiple regression analysis that the in vitro tested compressive strength could be predicted from mean cortical thickness, mean cross sectional area, and marrow space star volume or ash density with a multiple, squared coefficient of regression (r2) of 0.95 when the height and sex of the individual were known.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Marrow space star volume in the iliac crest decreases in osteoporotic patients after continuous treatment with fluoride, calcium, and vitamin D2 for five years.

Iliac crest biopsies in osteoporotic patients were obtained before and after five years of continuous treatment with sodium fluoride (40-60 mg/d), vitamin D2 (18,000 IE/d), and calcium phosphate (45 mmol/d). Star volume of marrow space and trabeculae, mean trabecular thickness, and fractional amount of trabecular bone were estimated on so-called vertical sections before and after treatment. Results showed a significant decrease in marrow space star volume after five years of treatment (35 mm3 versus 19 mm3) (2p less than 0.02). No significant changes were observed in trabecular star volume (0.149 mm3 versus 0.104 mm3) (2p greater than 0.50) or mean trabecular thickness (85 microns versus 79 microns, 2p greater than 0.30). A slight but insignificant increase in the fractional amount of trabecular bone was found (9.7% versus 10.4%, 2p greater than 0.50). A rather close inverse correlation was obtained, however, between individual changes in trabecular bone volume fraction and marrow space star volume (r = -0.72, 2p = 0.011). The findings suggest that the large marrow "cavities" had been split into two or more "cavities" by some newly generated trabecular structures leading to increased trabecular connectivity. The strength of trabecular bone may be increased due to this beneficial effect of fluoride on trabecular bone structure.

Aged↗

PubMed1991

Surface areas of basolateral membranes in renal distal tubules estimated by vertical sections.

The surface area of the Na,K-ATPase-rich basolateral membranes in the medullary thick ascending limb of the distal tubule in the rabbit kidney was determined stereologically using the method of 'vertical sections', whereby unbiased surface estimates are obtained by imposing a cycloid test-lattice on micrographs of ultrathin sections cut roughly longitudinal to the tubular axis. The unbiased estimate of the surface area of basolateral membranes per tubule length in the thick ascending limb was 1.45 x 10(6) microns 2/mm. The results are compared with previous surface area measurements in this segment of the tubule and discussed with respect to the contributions from all sampling levels to the real biological variation. An optimized sampling scheme with a roughly fourfold reduction in workload is suggested.

Animals↗

PubMed1991

The absolute number of nerve cells in substantia nigra in normal subjects and in patients with Parkinson's disease estimated with an unbiased stereological method.

Using an unbiased stereological technique, the total numbers of pigmented and non-pigmented neurons were estimated in the substantia nigra of seven patients with Parkinson's disease and seven control patients. Compared with the controls, in which the average total number of pigmented neurons was 550,000, the number of neurons was reduced by 66% in the patients. The average total number of non-pigmented neurons was 260,000 in controls and reduced by 24% in the patients. A significant correlation (r = 0.81) existed between the total numbers of pigmented and non-pigmented neurons in the controls, whereas a similar correlation (r = 0.72) in the patients fell just short of statistical significance. The stereological estimates made in this study are unbiased, in that they are independent of nerve cell size, section thickness and of dimensional changes in brain tissue induced by histological procedures. The stereological method is considerably more efficient than previous conventional methods.

Aged↗

PubMed1990

Unbiased stereological estimation of the number of neurons in the human hippocampus.

The total numbers of neurons in five subdivisions of human hippocampi were estimated using unbiased stereological principles and systematic sampling techniques. The method addresses the problems associated with the results and conclusions of previous quantitative studies, virtually all of which have been based on biased estimates of neuron densities. For each subdivision, the total number of neurons was calculated as the product of the estimate of the volume of the neuron-containing layers and the estimate of the numerical density of neurons in the layers. Each hippocampus was cut into 3-mm-thick slabs, transverse to the rostrocaudal axis. One 70-micron-thick section from each slab was used in the analysis. The volumes of the layers containing neurons in five major subdivisions of the hippocampus (granule cell layer, hilus, CA3-2, CA1, and subiculum) were estimated with point-counting techniques after delineation of the layers on each section. The numerical densities of neurons in each subdivision were estimated on the same sections with optical disectors. The sampling used in both estimates was performed systematically in all three dimensions. In an example of five hippocampi, the mean numbers of neurons (CV = SD/mean) in the different subdivisions were as follows: granule cells 15 X 10(6) (0.28), hilus 2.0 X 10(6) (0.16), CA3-2 2.7 X 10(6) (0.22), CA1 16 X 10(6) (0.32), subiculum 4.5 X 10(6) (0.19). The stereological measurements contributed approximately 25% of the observed variance. Among the five subjects there was a significant inverse relationship between age (which ranged from 47 to 85 years) and the total number of neurons in CA1 (which ranged from 24 to 11 X 10(6)). An optimized sampling scheme for studies of the number of neurons in the human hippocampus has been designed on the basis of an analysis of variance of the estimates at different levels of the sampling scheme. Counting neurons in the five subdivisions of the human hippocampus with the optimized sampling scheme takes less than 4 hours.

Aged↗

PubMed1990

An efficient method for estimating the total number of neurons in rat brain cortex.

An efficient method for the unbiased estimation of the total number of neurons in rat brain cortex is presented. The method is reasonable fast, the counting procedure takes 2-3 h per rat, and gives an estimate of the total neuron number in cortex cerebri with an CE of 0.10. The rat cerebral cortex is found to have a mean volume of 253 mm3 and to contain a mean of 21 million neurons. The method has been used in a neurotoxicologic study, in which rats were given toluene perorally in doses of 200, 400 and 800 mg/kg/day, respectively, for 12 weeks, followed by an exposure-free period of 4 weeks. The total number of neurons in rat brain cortex cerebri showed no significant difference between exposed and non-exposed animals. The applicability of the method is discussed.

Animals↗

PubMed1990

Estimation of structural anisotropy based on volume orientation. A new concept.

The quantification of anisotropy--its main direction and the degree of dispersion around it--is desirable in numerous research fields dealing with physical structures. Conventional methods are based on the orientation of interface elements. The results of these methods do not always agree with perceived anisotropy, and anisotropic structures do not necessarily turn out to be 'anisotropic' using these methods. In the present paper, we propose an alternative to curve and surface orientation, namely volume orientation. Using trabecular bone as an example of a two-phase anisotropic structure, the new concept is studied in some detail. In particular, a parametric method of estimating volume orientation from sections is presented and discussed.

Adult↗

PubMed1990

The total number of neurons in the human neocortex unbiasedly estimated using optical disectors.

An efficient method is presented for obtaining, in under 4 h, an unbiased estimate of the total number of neurons in the human neocortex, with a coefficient of error on the estimate of approximately 5%. The novel sampling scheme used in this study is unbiased and was designed so that only a small amount of neocortical grey matter had to be removed. Hence, the majority of the cerebral grey matter and all the internal grey matter was left intact for further resampling and analysis. Each cerebral hemisphere was subdivided into the four major neocortical regions, sliced coronally at 7-mm intervals and the volume of the neocortex determined using Cavalieri's principle. Uniform sampling of neocortex was performed in the hemisphere followed by regional subsampling with a varying sampling fraction being taken from each region. Neuronal density estimates were made in thick plastic sections using optical disectors. Shrinkage estimates were made in parallel with the number estimates and found to be negligible. The total number of neocortical neurons in the right hemisphere of five normal 80-year-old men was found to be 13.7 x 10(9) with an inter-individual coefficient of variation of 12%.

Aged↗

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↗