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Biomedical subjects

B Krempien

Publications and source records attributed to B Krempien.

At least 55 records · Page 3Linked to original sources
PubMed1980

Acquired cystic transformation of the kidneys of haemodialysed patients.

In the present study, the kidneys of patients who had been on maintenance haemodialysis for variable periods of time were examined at autopsy. In 21 of the 22 patients, multiple pinhead-size to pea-size, non-loculated cysts were observed both in the cortex and the medulla. In some of the cysts (4/20 patients), papillary adenomata were observed which were visible by light microscopy in 3 cases and macroscopically in 1 case. Clinical complications resulting from haemorrhage or neoplastic transformation were not observed in any of the patients of this series. Similar cysts, smaller in size and fewer in number, were also observed in kidneys of uraemic patients who had not been dialysed. Thus, the lesion does not appear to be a specific consequence of maintenance haemodialysis. It appears more likely that extensive cystic transformation of the kidneys of patients in terminal renal failure is made possible by prolonged survival on maintenance haemodialysis. The possibility of malignant transformation of the papillomata cannot be refuted, but epidemiological surveys fail to document more frequent occurrence of renal carcinoma in dialysed patients.

Adult↗
PubMed1980

Action of 1,25-dihydroxycholecalciferol on cartilage mineralization and on endosteal lining cells of bone. Experimental in vitro studies.

The aim of our study was to answer the following question: 1) Does 1,25-dihydroxycholecalciferol influence the mineralization process directly? 2) How does 1,25-D3 act on the endosteal cell envelope of bone, which is thought to be engaged in the moment to moment regulation of calcium homeostasis? We studied the endosteal surface of calvaria and the epiphyseal cartilage of rachitic rats in a tissue culture system in order to avoid the secondary effects of endogenous hormones or mineral sources. Investigations were carried out using transmission and scanning electron microscopy. Compared with untreated rachitic control specimens, 1,25-D3 (4 X 10(-8) M) did not enhance the mineralization process. We therefore conclude that the established in vivo effect of 1,25-D3 on the mineralization process must be an indirect one. Within 2 h the flat-shaped surface lining cells of calvaria showed a rapid transformation into globiform cells and a loss of cell adhesion. Within two days a second slower transformation into spindle-shaped fibroblast-like proliferating cells occurred. All changes of cell shape were reversible within several days in the absence of 1,25-D3. Obviously, bone matrix fiber texture influences the spatial movement of proliferating cells. The endosteal cell envelope is considered to act as a functional membrane of bone. Starting from this consideration we conclude that the changes of cellular shape described are the morphological basis for the action of 1,25-D3 in the regulation of calcium homeostasis in bone at the cellular level.

Animals↗
PubMed1980

The effect of 1,25 (OH)2D3 on bone mineralization: ultrastructural studies in patients with renal osteodystrophy.

The acute effects (15-50 days) of 1,25(OH)2D3 (0.5-2 microgram/day) on the histological, fluorescence-microscopical and ultrastructural appearance of mineralizing osteoid in iliac crest spongiosa were studied in 6 uremic patients on maintenance hemodialysis. While there was a marked decrease on endosteal fibrosis and osteoclast counts, volumetric and surface densities of osteoid continued to stay elevated during the observation period. The number of osteoid seams with tetracycline double label increased in 4/6 patients but no such seams appeared in 2 patients who had shown only nonlabeled seams with diffuse staining of osteoid prior to therapy. In studies with transmission electron microscopy, the interface between non-mineralized osteoid and mineralized bone was irregularly outlined and broad. In contrast to normals, coarse mineral deposits were widely scattered in the nonmineralized osteoid. The mineral deposits had two different appearances, presumable depending on the plane of section relative to the direction of collagen fiber bundles: patches of microcristalline deposits encircling perpendicularly cut non-mineralized collagen bundles and needle- or plate-shaped crystals following the striation pattern of collagen fibers. The findings point to close interaction between the pattern of mineral deposition and collagen texture. The latter was highly irregular (woven) in all uremic patients. Mineral deposits were in part normal and in part highly abnormal in texture, the latter particularly in sites with irregular collagen texture. Upon therapy, no consistent change of the ultrastructure of the mineralizing osteoid/bone interface was observed by transmission or scanning and electron microscopy.

Adult↗
PubMed1980

[Morphological evaluation of joint-crossing expanded PTFE prosthesis (author's transl)].

Ten expanded polytetrafluoroethylene (PTFE) vascular grafts were implanted in dogs crossing the joint, performed as iliofemoral bypass. After 1, 3, 6, and 9 months the grafts were studied by light microscopy, scanning, and transmission electron microscopy. There was a good patency of all straight prostheses. The pre- and postkink areas showed thrombosis leading to stenosis. After 9 months endothelium was spread over all other parts of the luminal surface, including the kink area. Intramurally there was a focal ingrowth of fibroblastic cells with the characteristics of myocytes.

Animals↗
PubMed1979

Bone modelling processes at the endosteal surface of human femora. Scanning electron microscopical studies in normal bone and in renal osteodystrophy.

In femoral bone of 10 adult patients without bone disease and of 15 patients with secondary hyperparathyroidism, thy after nonmineralised organic material had been removed from the endosteal surface by sodium hypochlorite. This technique permits one to analyse the effects of past osteoblastic and osteoclastic activities. Im normal bone, the endosteal envelope shows a highly ordered texture: The main part of the inner surface is represented by fully mineralised smooth surfaces without evidence of apposition or resorption (so called neutral surfaces). In apposition areas, collagen fibers are still incompletely mineralised. Ordered mineral deposits are observed, consisting of spindleshaped calcospherites of uniform size. The resorption areas are sharply delimited. The resorption layer shows a small difference of level with respect to the surrounding neutral surface. Resorption areas consist of numerous lacunae with a smooth bottom. Individual lacunae are encircled by shallow ridges which run almost perpendicularly to the main direction of collagen fibers that have been exposed by resorption. These findings suggest that in normal bone osteoclasts act as a corrdinated group of cells. The direction of advance of the resorption area is to some extent influenced by the collagen pattern of bone. In patients with secondary hyperparathyroidism, domain formation of the endosteal surface can no longer be recognized. The size and shape of caleospherites are extremely heterogeneous, a finding interpreted as evidence of formation of woven bone. Resorption areas are irregularly determined and often resemble worm-eaten wood. The planes of resorption vary in direction and depth and in general resorption cavities penetrate deeper than in normal bone. These findings point to loss of coordinated cell action under the influence of hyperparathyroidism. The observations suggest that in hyperparathyroidism endosteal cells do not respond to local factors which influence endosteal cell activities in modelling processes of normal bone. Such local factors consist of the pattern of collagen andlamellar organisation on one hand and mechanical forces presumably via pizo-electrical potentials, on the other. In hyperparathyroidism the interdependence between bone matrix texture and spatial orientation of bone surface lining cell activities is lost.

Adult↗
PubMed1979

Surfactant substitution.

A mixture of synthetic phospholipids containing 90% Dipalmitoylphosphatidylcholine and 10% Dipalmitoylphosphatidylglycerol was tested for its suitability as surfactant substitute. Different methods of preparation were employed. The substance was studied by chromatography, Wilhelmy balance, and in rabbits after tracheal instillation during mechanical ventilation. When prepared as suspension of multilamellar liposomes in NaCl, the phospholipid samples displayed the essential surfactant features of adsorption from the subphase, spreading to a monolayer and lowering the surface tension to 3.7 dyn/cm at compression. For a dose of 2.55 microgram/cm2, the stability index was 1.83 +/- 0.29. Samples prepared with ultrasound were not surface-active. Sonication also destroyed the surface-tension-lowering ability of previously active samples. No signs of local toxicity were found in the treated animals. When radioactive DPPC/DPPG was instillated into the trachea of the ventilated rabbit, autohistoradiography demonstrated radioactive material in the alveoli covering the alveolar wall with a thin layer. Provided that proper techniques of preparation and administration are employed, the phospholipids tested are a promising surfactant substitute worthy of clinical study.

Adsorption↗
PubMed1978

Effect of PTH on osteocyte ultrastructure.

Osteocyte ultrastructure was studied in the cortical bone of the tibia of rats after acute or chronic administration of supraphysiological doses of PTH. Confirming previous reports, an increase in the width of the cytoplasm with the appearance of numerous thin cytoplasmic processes, an increase in rough ergastoplasmic reticulum and Golgi apparatus, an increase in lacunar width and lysis of the lacunar wall ("brush border" after Bonucci) were observed. Particularly striking was the appearance of numerous microfilaments and microtubules in the cytoplasm of activated osteocytes. The appearance of microfilaments, often densely packed in cytoplasmic processes or running parallel to the plasma membrane, points to a role of the cytoskeleton in mediating the effects of PTH on conformational changes of the plasma membrane (and possible on cell motility); microtubules were particularly prominent in the Golgi field and are presumably involved in the exocytosis of lysosomes. Another striking feature was the non-random distribution of periosteocytic osteolysis along the lacunar perimeter. Osteolysis was particularly pronounced at the cell pole opposite to the cell nucleus. After chronic administration of PTH, autolysis of osteocytes, associated with signs of excessive periosteocytic osteolysis, was frequently encountered.

Animals↗
PubMed1978

Skeletal X-ray findings and bone histology in patients on hemodialysis.

X-ray films of the hand skeleton (mammography technique), serum chemistry, and quantitative bone histology (micromorphometry of undecalcified sections, iliac crest spongiosa) were compared in 25 patients on maintenance hemodialysis. The X-ray findings correlated better with serum PTH levels than with bone histology. Of all radiological signs of renal osteodystrophy, pronounced subperiosteal resorption (radial aspect, second finger, middle phalanx) and periosteal new bone formation (middle phalanx) correlated best with histological indicators of osteitis fibrosa. These signs were never seen in control patients. Acroosteolysis (endphalanx) and intracortical or endosteal resorption (middle phalanx) were less specific (i.e., seen even in the absence of metabolic bone disease) and correlated less with bone histology. Osteosclerosis in iliac cancellous bone was paralleled by abnormal texture of spongy bone in the proximal metaphysis of the middle phalanx (second finger).

Adult↗
PubMed1978

Effect of vitamin D on growth in experimental uremia.

Acceleration of growth of uremic children after administration of vitamin D has been demonstrated by various authors. This has been attributed to healing of skeletal lesions. Clinical observations suggest that vitamin D has also an effect on food intake perhaps associated with improvement of vitality. This could be confirmed in an experimental study in which uremic rats (subtotal nephrectomy) with and without vitamin D supplementation were compared with sham-operated pair-fed control rats with and without vitamin D supplementation. In uremic animals supplemented with vitamin D, weight gain and growth were significantly greater than in uremic animals on the control diet. Both with and without vitamin D supplements, weight gain and growth rate were greater in sham-operated pair-fed control than in the corresponding uremic animals. Histological abnormalities in the growth zone of uremic rats were markedly reduced by vitamin D. Since food intake was greater in vitamin D-treated uremic animals than in nonvitamin D-treated uremic animals, the increase in growth rate under vitamin D cannot be attributed exclusively to the skeletal effects of vitamin D. This study demonstrates important extraskeletal actions of vitamin D which may be associated with or causally related to the improvement of growth.

Animals↗
PubMed1978

[The effect of the shape of aluminum oxide-ceramic implants on its staying power in the dog mandible].

Investigations were carried out on implants of Al2O3 ceramic as secondary single toothe replacement in the lower jaw of young Beagle test dogs. Two basically different forms with altogether 7 variations were tested: the first three types of implants had conical roots and a further 4 had cylindrical roots. Common to all 7 types was an implantation shoulder which was tested for its ability to conduct the masticatory force via the cortical substance to the mandibular bone. All implants are at least under indirect masticatory strain; type 80-40-027-00 was directly under strain: part of the implant, shaped like a premolar protrudes through the gum directly into the oral cavity. Preliminary results show that cylindrical root shapes stood the test well. Their length was of no great importance. Conical root shapes without special provision of retention are not suitable. Firm positioning of the implant during introduction is of prime importance. A cortically placed implantation shoulder is not suitable for the conduction of the masticatory pressure into the mandibular bone in dogs.

Aluminum Oxide↗
PubMed1978

[Light and scanning electronmicroscopic studies of border surfaces of aluminum oxide-ceramic implants in the dog mandible].

The mandibular bone of beagles as well as foxhounds and the border surfaces in the area of implants of dense Al2O3 ceramic were examined by scan electron microscope and optically in undecalcified preparations 4 and 6 months after the start of the experiment. All implants healed without foreign body or inflammatory reaction and exhibited a firm contact with the newly-formed surrounding osseous tissue. The border surface was always formed by osseous tissue and bone marrow and not by connective tissue. The bony border surface presented a casting of the structure proper of the ceramics as well as orderly remodelling. The tooth implants which had in part been under strain for a long time were surrounded by newly formed osteoid bone and supported by bone trabeculi. In the immediate proximity of the surface of the ceramic vital osteophites were found. The gum which was placed in a groove of the step implants showed firm epithelial covering and orderly fibrous texture.

Aluminum Oxide↗