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991.
992.
Fragments of cancellous and cortical bone from human maxilla and mandible were cultured by the explant technique. Cells isolated by trypsinization of primary cultures were characterized as osteoblasts on the basis of intracellular alkaline phosphatase activity, the constituents of the extracellular matrix, and response to human parathormone (PTH). In culture, the osteoblasts often gave rise to superposed clumps of large cells whose cytoplasm contained endoplasmic reticulum, numerous mitochondria, vacuoles, and a dense network of intermediate filaments, often at the level of the plasma membrane. In the presence of vitamin C and 1,25-dihydroxyvitamin D3, the osteoblasts produced an extracellular matrix composed of collagen type I and various non-collagenous proteins, including osteocalcin. Biochemical test results were comparable to those reported for osteoblasts of other origins (rat calvaria, human iliac crest), and namely elevated intracellular alkaline phosphatase activity and cAMP accumulation in response to stimulation by human PTH (1–34). Osteoblasts isolated in this manner were cultured in the presence of pure titanium disks to determine the effects of exposure to this metal. Electron microscopy revealed few significant differences in cell growth and specific enzyme activity compared to control osteoblasts grown on plastic dishes, reflecting the excellent biologic and biochemical relationship between the osteoblasts and pure titanium. This experimental system thus appears suitable for biocompatibility studies, and in particular, evaluation of dental implants. 相似文献
993.
Carlos Garbisu Jone M. Gil Michael J. Bazin David O. Hall Juan L. Serra 《Journal of applied phycology》1991,3(3):221-234
Cells of the non-N2-fixing cyanobacteriumPhormidium laminosum were immobilized in polyurethane (PU) foams either by absorption or by entrapment in the PU prepolymer followed by polymerisation
and by adsorption onto polyvinyl (PV) foams. Although entrapment caused toxicity problems which lead to rapid death of the
immobilized cells, they were immobilized successfully by adsorption onto PU or PV foams and maintained their photosynthetic
electron transport activities (PS I, II, I + II) for at least 7 weeks. Changes in the morphology resulting from immobilization,
as revealed by scanning electron microscopy (SEM) and low temperature-SEM, were investigated. Batch cultures and a continuous-flow
packed bed photobioreactor were used to study nitrate removal from water. The effects of light intensity and CO2 concentration on bioreactor performance were studied with respect to the nitrate uptake efficiency of the system. It was
concluded thatP. laminosum immobilized on polymer foams is of potential value for biological nitrate removal in a continuous-flow system.
author for correspondence 相似文献
994.
The effect of implantation of Ehrlich ascites tumor (EAT) cells of creatine distribution was investigated. It was also studied how depletion of creatine by feeding creatine-analogue β-guanidinopropionic acid (β-GPA) affects the growth of EAT cells in mice. Enhanced mobilization of creatine from host tissues to EAT cells against a greater concentration gradient was observed. The creatine (but not creatinine) level in blood plasma was lowered to 22% of the normal value by β-GPA feeding alone and assimilation of 14C-creatine into EAT cells was inhibited. The growth of EAT cells was significantly reduced and the duration of survival of mice after implantation of EAT cells was extended when the creatine concentration was decreased. A decrease in daily food consumption and the degree of muscle atrophy after implantation of EAT cells was less in β-GPA than control groups. In the creatine-depleted mice, the rate of increase in total EAT cell number and the volume of abdominal ascites were approximately half of the control values, and more dead EAT cells were observed. These results suggest that supplementation of β-GPA inhibits creatine transfer to EAT cells and reduces the growth of cancer cells. 相似文献
995.
Lipopolysaccharide (LPS) induced a time-dependent synthesis of nitric oxide (NO) in EMT6 adenocarcinoma cells, assayed by accumulation of NO-derived nitrite in the medium. The induction NO synthesis was inhibited in a concentration-dependent manner by the glucocorticoids dexamethasone (IC50 = 5 nM) and hydrocortisone (IC50 = 20 nM) and this effect was partially antagonized by progesterone and cortexolone. If addition of dexamethasone was delayed 6 h or more, inhibition of nitrite accumulation over 24 h was substantially reduced, indicating a lack of direct effect of glucocorticoids on the NO synthase. Nitrite accumulation was accompanied by cell damage, which was increased by L-arginine and inhibited by (L-NMMA) and dexamethasone. These data show that NO is a primary cytotoxic mediator and that suppression of its formation by glucocorticoids explains some of their anti-inflammatory and cytoprotective effects. 相似文献
996.
Breast Carcinoma With Osteoclast-Like Giant Cells 总被引:1,自引:0,他引:1
The cytological and histological findings of a case of breast carcinoma with osteoclast-like giant cells are presented. A fine needle aspiration specimen demonstrated the characteristic combination of malignant epithelium and reactive multinucleated cells and enabled identification of this rare variant of breast cancer. Immunocytochemical studies using the monoclonal antibody KP1[CD68] support a histiocytic origin for the osteoclast-like cells. 相似文献
997.
Yanan Zhang Dilbir S. Bindra Marie-Bernadette Barrau George S. Wilson 《Biosensors & bioelectronics》1991,6(8):653-661
Cell culture toxicity testing methods were modified and applied to the development of implantable glucose microsensors, and positive and negative control materials suitable for the microsensor assessment were established. The location, source and degree of the toxic effect in a multi-component biosensor was spatially visualized with cell monolayers. A freshly prepared sensor showed moderate toxicity, mainly as a result of the presence of glutaraldehyde and the residual solvents in the polymer layers. However, it was possible to reduce the toxicity by removing the leachable toxic substances through extraction in phosphate, buffer, and a non-toxic sensor was readily obtained. 相似文献
998.
Masamitsu Honma Eiko Kataoka Kiyokata Ohnishi Tadao Ohno Masao Takeuchi Nobuo Nomura Hiroshi Mizusawa 《In vitro cellular & developmental biology. Animal》1992,28(1):24-28
Summary Using the polymorphic DNA probes, ChdTC-15, ChdTC-114, pYNH24, and λTM-18, a DNA profiling system was developed that verified
identities of individual cultured cell lines collected in the Japanese cell banks, JCRB, RCB, and IFO. These highly polymorphic
DNA probes include both VNTR (Variable Number of Tandem Repeats) sequences and substantial lengths of unique regions. In the
mixed probe system, several distinct bands from four to eight can be used for cell line identification. These bands were widely
spread in a range of molecular sizes, and were stable and reproducible under stringent conditions of Southern blot hybridization.
Because the DNA profile was specific for each individual human cell line, it is useful not only to authenticate many existing
cultured cell lines but also to monitor their identity during propagation in a laboratory, and to confirm newly established
lines as unique. 相似文献
999.
Jan-Kan Chen Ying-Tung Lau Jackson Chu 《In vitro cellular & developmental biology. Animal》1992,28(2):143-145
Summary Rat aortic endothelial cells were found to exhibit clonal variations in response to EGF stimulation in cell growth and prostacyclin
synthesis. EGF-induced growth and prostacyclin synthesis appeared to be regulated in a coordinated manner in that a clone
with a higher response to EGF growth stimulation also exhibited a higher response to EGF-stimulated prostacyclin synthesis.
This observation implys a possible involvement of prostacyclin synthesis in some of the biological effects of EGF on vascular
endothelial cells. 相似文献
1000.
Jan E. M. Souren Chris Schneijdenberg Arie J. Verkleij Roeland van Wijk 《In vitro cellular & developmental biology. Animal》1992,28(3):199-204
Summary A floating collagen matrix culture of neonatal rat heart myocardial cells shows rhythmic contractions which are dependent
on localization of cells, cell density, and collagen concentration. The rhythmic contractions of the collagen matrix can be
registered by a device scanning the optical density at the edge of the gel and have been observed over a temperature range
from 9° to 40° C. The results of the present study underline the usefulness of myocardial cell populated collagen matrixes
for studies on coherent contractions of heart cell cultures. 相似文献