Showing papers by "University of Bern published in 1974"

The postnatal growth of the rat lung. I. Morphometry

Abstract: In order to investigate the postnatal growth of the gas exchange apparatus, the lungs of rats aged 1, 4, 7, 10, 13, and 21 days were fixed by intra-tracheal instillation of glutaraldehyde. The analysis and interpretation of the morphological changes observed by light and electron microscopy were based on the results of previous morphometric and autoradiographic studies performed on the same material. The newborn rat has no alveoli, but breathes with smooth walled air channels and saccules, which correspond to the prospective alveolar ducts and alveolar sacs, respectively. The bulk of alveoli are formed between days 4 and 13 by a rapid outgrowth of secondary septa from the primary septa present at birth. The arrangement of elastic fibers during this period suggests that these may play a role in septal outgrowth. Based on ultrastructural observations a model is described for the capillarisation of the secondary septa. Some evidence is given that alveoli may also be formed by outpouchings in the walls of terminal bronchioles. Primary and secondary septa have initially an immature appearance. They both show an apparently double capillary network, whereas the mature interalveolar septum is just wide enough to accommodate a single capillary. Possible mechanisms for this structural transformation which occurs within three weeks after birth are discussed.

The postnatal growth of the rat lung. II. Autoradiography.

Abstract: Combined morphometric and autoradiographic methods were used to analyze the postnatal growth of rat lung from 1–21 days after birth. Each cell population had distinct growth patterns with an increase in the number of fibroblasts and capillary endothelial cells largely determining the increase in interstitial volume and capillary surface, respectively. The height of proliferation activity in mesodermally-derived cells was concurrent with the outgrowth of secondary alveolar septa (between days 4 and 13). Analysis of the location of labeled cells on day 7 showed that the higher labeling index on septal crests could be ascribed to the proliferative activity of fibroblasts and endothelial cells. Within the alveolar epithelium only the type II alveolar cells had a detectable labeling index. Over the first week, the number of type I epithelial cells steadily increased while the number of type II cells remained constant. Subsequently the number of type II cells increased rapidly, reached a peak on day 13 and then decreased, whereas type I cells continued to increase in number. These facts led us to consider that type II epithelial cells may represent the stem cell population of alveolar epithelium. The height of proliferative activity of type II cells on day 7 coincided with the outgrowth of septal crests and was followed by the steepest increase in number of type I and II cells. Between the 10th and 21st day labeling indices rapidly declined, cell production became undetectable after day 13. Increase in alveolar and capillary surface area however continued, resulting in a thinning of the interstitial layer and of the epithelial and endothelial sheets.

Classification and nomenclature of plutonic rocks recommendations of the IUGS subcommission on the systematics of Igneous Rocks

Abstract: The IUGS Subcommission on the Systematics of Igneous Rocks has been formed in order to review classification and nomenclature of igneous rocks and to present proposals to IUGS. Up to the present, the Subcommission has been concerned with plutonic rocks. This paper presents a summary of the recommendations on plutonic rocks to which the Subcommission has agreed at its meeting of Montreal, August 1972. A report that will contain fuller treatment is in preparation.

Heterogeneity of erythrocyte catalase II. Isolation and characterization of normal and variant erythrocyte catalase and their subunits

Abstract: 1 Dissociation of the erythrocyte catalase tetramer into its dimer form proceeds readily in urea: the rate depends on urea concentration, time of inactivation and temperature, but is not influenced by enzyme concentration. This process is accompanied by loss of catalase activity, generation of peroxidase activity and an alteration of antigenic properties. 2 Recombination of dimer subunits to the tetramer molecule can be accomplished by removing urea by dialysis. Under optimal conditions up to 80% of the original catalase activity can be recovered. The reconstituted material is identical with the native catalase regarding enzymatic and antigenic properties, but differs with respect to electrophoretic mobility and heat stability. 3 Normal human erythrocyte catalase and the enzyme species present in blood of individuals heterozygous for Swiss-type acatalasemia differ with regard to electrophoretic mobility and heat stability. Moreover, dissociation of the heterozygote catalase tetramer into dimer subunits occurs at lower urea concentrations when compared to the normal enzyme. Since heterozygote erythrocyte catalase exerts properties intermediate to those of the normal enzyme and of the variant found in homozygotes for Acatalasemia, this enzyme species is considered to represent a molecular hybrid. 4 Hybridization of catalases can be accomplished in vitro by dissociating a mixture of normal and heterozygote catalase preparations in 8 M urea and subsequent dialysis. The resulting enzyme species reveals intermediate electrophoretic mobility and heat stability when compared with its native constituents.

STEREOLOGICAL ANALYSIS OF THE GUINEA PIG PANCREAS I. Analytical Model and Quantitative Description of Nonstimulated Pancreatic Exocrine Cells

Abstract: A stereological model which provides detailed quantitative information on the structure of the fasted, nonstimulated gland has been developed for the guinea pig pancreas. The model consists of morphologically defined space and membrane compartments which were used to describe the general composition of the tissue and the specific components of exocrine cells. The results are presented, where appropriate, relative to a cubic centimeter of pancreas, a cubic centimeter of exocrine cell cytoplasm, and to the volume of an average exocrine cell. The exocrine cells, accounting for 82% of the pancreas volume, consisted of 54% cytoplasmic matrix, 22% rough-surfaced endoplasmic reticulum (RER), 8.3% nuclei, 8.1% mitochondria, 6.4% zymogen granules, and 0.7% condensing vacuoles. Their total membrane surface area was distributed as follows: 60% RER, 21% mitochondria, 9.9% Golgi apparatus, 4.8% plasma membranes, 2.6% zymogen granules, 1.8% plasma membrane vesicles, and 0.4% condensing vacuoles. The application of this model to the study of membrane movements associated with the secretory process is discussed within the framework of an analytical approach.

Effect of hydration upon the thermal stability of tropocollagen and its dependence on the presence of neutral salts

Abstract: The endotherm enthalpy changes ΔHD and temperatures TD of thermal denaturation of tropocollagen fibers were measured by DSC calorimetry as functions of water content. The denaturation temperatures decrease with increasing water content. The enthalpy change values increase sharply in the range 0–28% of water content, where a maximum of 14.3 cal g−1 is reached. The effect of water uptake on the enthalpy term is explained by water bridge formation within the collagen triple helix. Evidence is given for the existence of approximately three intercatenary water bridges per triplet at the enthalpy maximum, their H-bond energy amounting to approximately 4000 kcal/mol of protein. In the 30–60% range of water content, ΔHD decreases by 2 cal−1 probably due to interactions between secondary water structures and the stabilizing intrahelical water bonds. The influence of two neutral potassium salts, with a structure-stabilizing and a structure-breaking anion (F− and I−), on the hydration dependence of ΔHD and TD was also studied. It was shown that the primary hydration is not influenced by these ions, but that TD and ΔHD are altered in an ion specific way in the presence of interface and bulk water. Hydrophobic interactions do not explain the experimental results. A reaction mechanism of the effects of ions upon the structural stability of collagen is proposed and discussed in terms of interactions of the medium water molecules with the intrahelical water bonds, and in terms of proton-donor/proton-acceptor equilibria between peptide groups, hydrated ions, and intrahelical water molecules.

Energy dissipation by calcium recycling and the efficiency of calcium transport in rat-liver mitochondria.

Abstract: The recycling of endogenous calcium across the inner membrane of incubated mitochondria consists of a passive efflux of calcium from the matrix which is compensated by an active re-uptake of this ion from the medium. Upon addition of ruthenium red which inhibits only the re-uptake, mitochondrial calcium accumulated in the medium at a rate of 3.5 nmol × min−1× mg protein−1. The ATP balance of this experiment, measured with the help of [2-14C]pyruvate as a substrate, revealed that ruthenium red inhibited about 20% of the energy dissipation of the mitochondria. It is concluded that the calcium recycling is one of the processes related to state 4 respiration of the mitochondria. Ca/O ratios for the calcium recycling were calculated from the rates of calcium release into the medium and the concomitant decrease in the respiratory rates observed after addition of ruthenium red. When the calcium transport system was progressively inhibited with increasing concentrations of ruthenium red, the intramitochondrial ATP/ADP ratios and the rates of calcium release gradually increased up to a maximal value, whereas the Ca/O ratios concomitantly decreased. Moreover, in the presence of barely uncoupling concentrations of dinitrophenol the Ca/O ratios were larger than in the control, whereas in the presence of oligomycin they were smaller. These results indicate that the efficiency of mitochondrial calcium transport decreases when the mitochondria approach a state of a maximal energy charge.

K-Ar and Rb-Sr Dating of Blue Amphiboles, Micas, and Associated Minerals from the Western Alps

Abstract: The results of 63 new radiometric K-Ar and Rb-Sr measurements on metamorphic minerals from the internal units of the Western Alps show Hercynian, Permian, as well as three Alpine age groups. The first of the Alpine ages cover the period between 78 and 100 m.y. and refer to high pressure parageneses. The second group comprises K-Ar 39 to 50 m.y. ages; these values are affected by some inherited argon, as indicated by Rb-Sr measurements which point to 35–36±4–5 m.y., i.e. similar to the culmination of the Lepontine crystallization. The final group includes 15 to 30 m.y. ages. It is not yet clear which geologic processes have led to this isotope re-equilibration. Large amounts of inherited argon have been found in Alpine metamorphic minerals of the basement rocks.

Studies on the pathogenetic mechanism of I-cell disease in cultured fibroblasts.

Abstract: Extract: A marked intracellular reduction of six lysosomal enzymes could be demonstrated in fibroblasts from four different patients with mucolipidosis type II or I-cell disease. In contrast to that finding, conditioned media from the same cells contained a 2—10-fold increase of the activities of five lysosomal enzymes over control values. In obligate heterozygotes elevated lysosomal enzyme activities in the conditioned media were also found, but normal enzyme activities were measured intracellularly. A functional impairment of the lysosomal degradation of (35SO4) mucopolysaccharide (MPS) and of (35S)-sulfatide could be shown in the I-cell fibroblasts, as a consequence of decreased enzyme activities. Substitution of the enzyme-deficient cells with normal urinary arylsulfatase A and with mucopolysaccharide degrading factors from normal conditioned media was possible, but failed when urine from patients or conditioned media factors from the I-cell fibroblasts were used. Speculation: Genetic disorders of lysosomal functions can be caused not only by lack of synthesis or by a structural defect of a lysosomal enzyme, but also by a genetically determined loss of enzyme into the extracellular fluid. These lysosomal enzymes are functionally abnormal only insofar as they cannot be retained within the cells, and, furthermore, once they are outside of the cells, they can not re-enter the cells by pinocytosis as can normal enzymes.

Three remarks on axisymmetric stationary horizons

Abstract: In the first remark the catalogue of axisymmetric stationary horizons is completed by a subset of uncharged translation-symmetric horizons, which was ignored in the previous paper [5]. The subset consists of two one-parameter families: extreme Kerr horizon (a=m) and a more symmetric family. In the second remark the surface area, net angular momentum and net charges of a black hole are computed. It turns out that the four invariant functionsA, B, C, D used in [5] to classify the horizons describe, at least formally and up to a constant factor:A the profile of the black hole surface,B the surface density of angular momentum andC cosD, C sinD the surface density of electric and magnetic charge. In the third remark a simplified model of a black hole surrounded by a charged matter shell is found to satisfy a sort of generalized “no-hair-conjecture”. An example of a non-Kerr-Newman field around a horizon is provided; the magnetic field in it is hoped to have some astrophysical importance.

Selection of the best method in stereology.

Abstract: SUMMARY A brief historical survey of the origin of stereological methods is followed by a synoptic characterization of their nature. They fall into two main classes depending on the structural models at their origin. Those methods which aim at a size analysis of the particle population provide more information, but are more subject to limitations, than those which estimate bulk parameters of the structure as a whole. The choice between the different methods must be guided by a clear definition of the most informative parameters and of the geometric properties of the structure.

Cell-to-cell diffusion of procion yellow in sheep and calf Purkinje fibers.

Abstract: Sheep and calf Purkinje fibers (false tendons) were cut near one end and exposed to a solution containing no calcium and the dye Procion Yellow (M4RS, molecular weight near 700). Fifteen minutes later the damaged end was sealed by applying calcium ions (Tyrode solution). Traces of Procion Yellow were detected within the intracellular compartment at a distance of 2.4 mm from the site of damage when the preparations had been washed in dye-free solution for 4 hr. This indicates that the dye had diffused through about 20 cells in succession. There was no detectable uptake of Procion Yellow through intact surface membranes. Visual curve fitting to quantitative data on concentrationvs. distance gives an apparent diffusion coefficient (cell junctions and myoplasm in series) of 3×10−8 cm2 sec−1, as against 1×10−6 cm2 sec−1 in an agar gel. It is concluded that specialized contact areas between neighboring cardiac cells represent a considerable yet not an absolute hindrance to the movement of this particle.

Enzymic studies of sulphatases in tissues of the normal human and in metachromatic leukodystrophy with multiple sulphatase deficiencies: arylsulphatases A, B and C, cerebroside sulphatase, psychosine sulphatase and steroid sulphatases.

Abstract: — Several sulphatases (arylsulphatases A, B and C, cholesterol sulphatase, dehydroepiandroster-one sulphatase, cerebroside sulphatase and psychosine sulphatase) were deficient in various tissues from two patients with a variant form of metachromatic leukodystrophy. Deficient activities of cerebroside sulphatase and psychosine sulphatase, using physiological substrates, in tissues from metachromatic leukodystrophy with multiple sulphatase deficiencies provided another example that these enzymes may be identical to arylsulphatase A. β-Galactosidase activity was reduced to about 30-50 per cent of normal in brain and liver. Other lysosomal enzyme activities were found to be normal or elevated five to eight times. Arylsulphatase B isolated from the liver of one patient was abnormal, with respect to pi (70) and enzyme kinetics. In mixing experiments with normal enzymes the reduced activities of arylsulphatases A. B and C, cerebroside sulphatase and steroid sulphatases were shown not to be due to the presence of endogenous inhibitors. No arylsulphatase A or B activity in the brain specimen from the patient with multiple sulphatase deficiencies could be detected on isoelectric focussing. In normal brain tissue arylsulphatase A had a pi of 4-6-4-8 while arylsulphatase B had a pi of 7-8 and 8-1. When 4-methylumbelliferyl sulphate was used as a substrate the elution patterns of normal brain and liver arylsulphatase B were more heterogeneous and showed more variation than that when p-nitrocatechol sulphate was used. Arylsulphatase C and steroid sulphatases (cholesterol sulphatase, dehydroepiandrosterone sulphatase and oes-trone sulphatase I were solubilized by the addition of lysolecithin and Triton X-100 and subjected to isoelectric focussing. The pi of cholesterol sulphatase, oestrone sulphatase and arylsulphatase C was 6-8, and the elution patterns of the activities of these enzymes were similar. The pattern of dehydroepiandrosterone sulphatase was more heterogeneous and two major peaks were observed at pi 6 5 and 70. Residual enzyme activities of arylsulphatase C and steroid sulphatases from the brain of the patient with multiple sulphatase activities were not detectable by isoelectric focussing. Simultaneous deficiencies of arylsulphatase C and steroid sulphatases plus isoelectric focussing findings in tissues suggest that these enzymes are closely related in regard to their function. The nature of the genetic defect in metachromatic leukodystrophy with multiple sulphatase deficiencies is discussed.

A formalism for the investigation of algebraically special metrics. II

Abstract: A new formalism is proposed for the investigation of algebraically special metrics. Among its advantages are that the essential calculations are co-ordinate free and the equations are gauge invariant. The derived equations are simple in form hence easy to work with and the approach is rich in possibilities not explored by previous techniques.

Structural Studies of Human‐Liver Alcohol‐Dehydrogenase Isoenzymes

Abstract: 1 Alcohol dehydrogenase isoenzymes BE were isolated from human livers of both “normal” and “atypical” phenotypes [1]. Their pH-rate profiles, their behaviour on CM-cellulose and the number of hybrids formed with horse subunit A show that the “atypical” isoenzymes contain subunits B1 and B2 the “normal” one only subunit B1. These results indicate that most “atypical” individuals genetically represent heterozygotes. 2 A high degree of homology between horse subunit A and human subunits B is found. However, the human isoenzymes have a molecular weight of 87000 and contain about 410 amino acid residues, 6 tyrosines and 3 tryptophans per subunit. 3 The sequence of one tryptic peptide from subunit B1 is Phe-Ala-Lys and is altered to Phe-Pro-Lys in the subunit B2. This substituted residue is located in a region which corresponds to the coenzyme-binding site of the horse enzyme.

The innervation of the trapezius muscle. An electrophysiological study.

Abstract: In 10 healthy subjects stimulation of the accessory nerve in the posterior triangle of the neck always elicited action potentials in all 3 parts of the trapezius muscle. Of 8 patients with a lesion of the accessory nerve 3 had no evoked potentials, while 5 showed evoked potentials in the 3 parts of the muscle. 7 of these patients had voluntary activity in the lower part of the trapezius muscle. 7 patients with lesions of the accessory nerve showed, by electromyographic investigation, no constant pattern of the neurogenic involvement in the 3 different parts of the muscle. Direct stimulation of the accessory nerve during neck dissection in 3 patients gave evoked potentials in the ascending and the horizontal part in all 3 cases and in the descending part in 2 cases.