PubMed Health⌕ Search

Biomedical subjects

B Krempien

Publications and source records attributed to B Krempien.

At least 19 recordsLinked to original sources
PubMed1992

24R,25-dihydroxyvitamin D3 prevents aluminum-induced alteration of brain gangliosides in uremic rats by keeping the metal within perivascular astrocytes of the blood-brain barrier.

The administration of aluminum (Al) to uremic rats leads to Al accumulation in different brain regions with subsequent alteration of brain gangliosides. Addition of 24R,25-dihydroxyvitamin D3[24R,25-(OH)2D3] did not influence the brain Al content determined by plasma argon emission spectrometry, but prevented the decrease in brain gangliosides. By using electron microscopy and laser microprobe mass analysis, it was demonstrated that in rats given 24R,25-(OH)2D3 together with Al, the metal was mainly kept within perivascular astrocytes of the blood-brain barrier. On the contrary, in rats given Al only, the metal was evenly distributed throughout the brain areas causing extensive demyelination, chromatolysis of nerve cells in some brain regions (hippocampus) and brain edema. Our results could find application in the prevention of Al-induced encephalopathy in patients on hemodialysis.

24,25-Dihydroxyvitamin D 3↗
PubMed1992

[Sonography in therapy-oriented diagnosis and after-care of primary bone and soft tissue tumors].

Based on the results of 150 patients with primary tumors or the suspicion of malignant lesions of the locomotor system the perspectives and limits of the sonographic diagnosis under the therapeutic aspects of interdisciplinary oncologic cooperation is demonstrated. As the ideal adjunct to conventional roentgenograms, ultrasound is the first-line imaging procedure in the fields of primary diagnosis, follow-up, post-therapeutic care as well as tumor exclusion for methodic, patient-related and economic/logistic reasons. Its consequent application will markedly reduce the number of more invasive and expensive methods.

Adult↗
PubMed1990

[The prognostic significance of tumor cell detection in bone marrow of patients with breast cancer].

In 95% of patients with primary breast cancer, the extent of metastases cannot be proven by conventional methods. Nevertheless, more than 50% of these patients have a relapse within five years. To improve the predictive value for recurrency, we examined bone marrow aspirates of 128 patients with primary breast cancer. Bone marrow aspirates from 2-6 sites of the skeleton (iliac crest and sternum) were taken as well as biopsies for histological examination. The immunohistochemical studies were carried out on interphase smears and stained with cytoceratin antibodies (PKK 1) and antibodies against tumor-specific antigen TAG 12 (12 H 12). All patients were screened for distant metastases (X-ray, ultrasound, bone scan). Tumor cells and micrometastases in bone marrow were detected in 41 patients (32%). Their presence was correlated to other prognostic factors (tumor size, lymph node status, oestrogen/progesterone receptors). The median duration of follow-up was 39.5 months. 14 patients (45%) in the tumor cell positive group relapsed, compared to only 4 out of 36 patients in the tumor cell negative group. In 29% we found bone metastases. The relapse free interval was shorter for patients with micrometastases (8 vs. 15.8 months). The presence of tumor cells in bone marrow aspirates detected at the time of primary surgery, is a useful prognostic factor and a good predictor of metastases and may help in selecting patients for systemic adjuvant treatment.

Antibodies, Monoclonal↗
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↗
PubMed1977

Fetal development in experimental uremia.

Uremic women on hemodialysis with metabolic bone disease (hyperparathyroidism, osteomalacia resulting from defective vitamin D metabolism) and anemia (erythropoietin deficiency) are known to give birth to infants without bone disease or anemia. Therefore, skeletal development (enchondral and desmal bone formation) and hepatic erythropoiesis were evaluated in fetuses of uremic rats. These fetuses failed to show defective mineralisation or evidence of bone disease. Bolus injection of high doses of exogenous PTH into the maternal or fetal organism did not affect fetal bone histology. In addition, no apparent defect of bone mineralisation or bone formation was found in fetuses of ricketic rats. Normal mineralisation in the offspring of uremic rats may be explained by fetal hyperphosphatemia and/or insensitivity of fetal (woven) bone mineralisation to vitamin D. Absence of fetal anemia (normal hematocrits, normal density of hematopoietic cells in the liver) in the presence of maternal anemia is presumably due to the insensitivity of fetal erythropoiesis to erythropoietin.

Animals↗