Biomedical subjects

M W Buser

Publications and source records attributed to M W Buser.

7 recordsLinked to original sources

PubMed1992

Morphological, immunohistochemical, stereological and nuclear shape characteristics of proliferative Leydig cell alterations in rats.

Proliferative Leydig cell (LC) alterations (hyperplasia, adenoma) of laboratory rats often pose diagnostic problems because the progression from normal to hyperplasia to neoplasia is continuous. The LC compartments of 130 Wistar rats (kfm: WIST strain) of approximately 2 years of age were examined. Ten typical cases conventionally classified as being normal or as showing diffuse or focal hyperplasia or small or large adenomata were investigated in more detail. In large adenomata, areas with large and small LC nuclei were identified. Immunohistochemical characterization, EM examination, as well as stereologic and planimetric investigations were performed. Hyperplastic and neoplastic LC essentially retained their normal appearance and immunohistochemical characteristics, but were found to contain more lipid droplets, fibroblast-like cells and patches of collagen than normal LC at the EM level. LC proliferation was accompanied by significant LC hypertrophy. LC nuclei of hyperplastic LC compartments were slightly larger while those of LC adenoma were markedly larger than nuclei of normal LC. The values for circle-related and ellipticity factors indicated that the nuclei of normal and hyperplastic LC were more markedly oval than nuclei of neoplastic LC. Concavity factor and bending energy measurements revealed that the small and oval nuclei of normal and hyperplastic LC had significantly more and deeper indentations than the larger and somewhat rounder nuclei of neoplastic LC. It is concluded that LC proliferations conventionally diagnosed as hyperplasia or adenoma on the basis of their size were composed of cytologically different LC populations.

Adenoma↗

PubMed1991

Smoking and hypertension: risk factors for carotid stenosis.

The prevalence of smoking, hypertension and diabetes mellitus was assessed in 221 patients suffering from internal carotid stenosis and compared with the prevalences in two sex- and age-matched control groups composed of subjects having normal Doppler findings and from non-neurological outpatients. Of the subjects with carotid stenosis 27.6% were hypertensive smokers in comparison with 9.5% and 17.2% in the two control groups. The difference of the stenosis cohort from the two control groups was significant (P less than 0.01 and P = 0.016 respectively). There was no statistically significant differences between the occurrence of diabetes and hypertension in non-smokers and patients who smoked. In 394 investigated patients suffering from carotid stenosis or occlusion an obstruction index, based on the Doppler shift frequency, was calculated. This index was lowest in the normotensive smokers [corrected]. It was only insignificantly higher in the hypertensive non-smokers but significantly so in the normotensive smokers. The index was highest in the hypertensive smokers [corrected]. It was concluded that cigarette smoking, especially if associated with hypertension, is a determinant risk factor for carotid stenosis and occlusion.

Adult↗

PubMed1990

Internal jugular venous flow measurement by means of a duplex scanner.

Using a special probe holder, cross-sectional area and time-averaged mean spatial velocity of the internal jugular vein were measured by means of a duplex scanner and multiplied to calculate volume flow. In a cohort of 100 subjects ages 21 to 70 years, average right plus left flow was 740 +/- 209 mL/min. Flow was 8.7% lower in females than in males. Normalization of flow to 100 g brain tissue by dividing it through the mean sex specific brain weight resulted in no significant sex difference. Within the age range investigated, there was no decrease of flow with age.

Adult↗

PubMed1990

[Determination of human brain weight in vivo by skull measurements].

The length, width as well as the axial, sagittal and transversal circumferences of the skull were measured before autopsy in 112 cadavers. The brain was weighed immediately after removal. A residual analysis of the correlations between skull measurements and the true brain weight was carried out, resulting in the formula: brain weight, g = (21.8 x axial circumference, cm) + (13.9 x transversal circumference, cm) + (2.105 x length x width, cm) - 890. The mean brain weight as calculated by this formula was within 1.5% of the true weight in the male and within 0.08% in the female cadavers examined.

Brain↗

PubMed1987

Morphometry and immunocytochemistry.

The use of morphometry (and stereology), especially in conjunction with immunocytochemistry, in surgical and experimental pathology is reviewed. The combined use of morphometry and immunocytochemistry permits the study of secretory products and the distinction between cells that produce them, e.g., as in the pancreas. Several examples to illustrate the application of immunocytochemical techniques in morphometry are presented. For example, using this approach on the pancreas, it was shown that not only B cells, but also A and D cells, seem to undergo pathologic changes in a prediabetic organism. Since morphologic alterations may be distributional as well as quantitative, a model for the assessment and statistical evaluation of the distribution of objects within an area is discussed. Similar procedures were used to analyze the distribution of cytochrome P-450 molecules along intracellular membranes; however, special labeling techniques were necessary for this quantification in the electron microscope. Immunoenzyme cytochemically stained secretions can also be studied morphometrically, and microdensitometry and microfluorometry can also be used to quantify immunocytochemical reactions, as is shown in the analysis of the intralobular distribution of NADPH-cytochrome P-450 reductase in the rat liver. Finally, the BIVAS semiautomatic system for morphometric measurements, developed at the Department of Pathology of the University of Basel, is briefly described.

Animals↗

PubMed1987

Analysis of object clustering.

Objects of a given type lie on a plane or in a thin layer. In the analysis of the arrangement of such objects, the question may arise as to whether these objects form clusters or whether they are randomly distributed. This question can be answered by the calculation of the coefficient of dispersion (CD) of the objects. Some statistical properties of this coefficient, i.e., its sensitivity and its chi-square approximation, are analyzed in this paper. The proposed approach for calculating sensitivity is a mathematical simulation that is not generally applicable but is valid in various biologic applications. Assuming that the objects are much smaller than the expected clusters and that no knowledge exists about interactions among the objects or between the objects and their surroundings, the objects can be assumed to be distributed randomly on the plane. Such situations may occur in various fields, i.e., biology, sociology, archaeology and ecology. The authors have applied this approach successfully in investigating the densities of T-cell lymphocytes in renal transplants treated with Cyclosporin A or conventional immunosuppressive therapy.

Computer Simulation↗

PubMed1986

The value of testicular biopsy in patients with varicocele.

With the use of semi-thin sections of 88 testicular biopsies from 44 patients, we were able to separate a relatively uniform group of patients with idiopathic left varicocele and infertility into 4 groups with different pathophysiological conditions. Group 1 patients had atrophy of the Leydig cells, decreased Leydig cell ratio, low plasma testosterone, and normal luteinizing and follicle-stimulating hormone levels. Surgery resulted in a significant improvement in sperm count. Group 2 patients had undergone attempted repair of Leydig cells, and had a normal Leydig cell ratio, and normal testosterone, luteinizing hormone and follicle-stimulating hormone plasma values. Group 3 patients demonstrated hyperplasia and an increased Leydig cell ratio, high luteinizing and follicle-stimulating hormone values, and relatively high testosterone values. Group 4 patients had an increased Leydig cell ratio but severe atrophy of the Leydig cells and tubuli, indicating burned out testes with high luteinizing and follicle-stimulating hormone but low testosterone levels. A successful operation failed to increase the sperm count in the latter groups. The technique used should allow better patient selection for medical treatment, as well as lead to a better understanding of the etiopathogenesis of infertility in varicocele patients. Therefore, the histological technique has an important role in the evaluation of patients suffering from infertility in general.

Adolescent↗