PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Diffusion Chambers, Culture”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources
PubMed1993

[Production of activity stimulating an increase of clonal granulocytic precursors by normal B lymphocytes under the influence of various mitogens].

The effect of mitogen-stimulated (concanavalin A, Con A; phytohemagglutinin, PHA; pokeweed mitogen, PWM; Staphylococcus aureus Cowan I, SAC I) normal B lymphocytes on the clonal proliferation of granulocytic progenitors from marrow of healthy subjects (CFU-dG) was studied in diffusion chamber culture. PWM-, SAC- and Con A-stimulated B lymphocytes produced an humoral activity that increased the CFU-dG-derived colony formation. The highest growth-stimulating effect was induced by SAC I-preincubated B lymphocytes and to a lesser degree by PWM- or Con A-stimulated B cells. In contrast, PHA-preincubated and unstimulated B lymphocytes revealed no effect on the CFU-dG proliferation.

B-Lymphocytes↗
PubMed1995

Use of a fibroblastic matrix improves the results of mesothelial-cell seeding on vascular prostheses of polytetrafluoroethylene.

Mesothelial cells (MC) obtained from the human omentum are a good alternative to the use of endothelial cells (EC) as a covering for vascular prostheses of polytetrafluoroethylene (PTFE), given the antithrombogenic properties and good behavior in vitro of mesothelial cells. We studied the behaviour of mesothelial cells seeded on PTFE prostheses with an interposed fibroblastic matrix for seeding. The mesothelial cells were extracted from 30-40 g fragments of human omentum by enzymatic digestion with collagenase. The cells extracted were seeded onto small disks of PTFE to which a matrix composed of fibroblastic cells had been fixed with 5% glycerol after the fibroblasts reached convergence. Interposition of a fibroblastic matrix fixed with glycerol notably improved the adherence of the seeded mesothelial cells and the stability and durability of the cell layer formed on the prosthetic surface. The effectiveness of seeding mesothelial cells was confirmed by labelling the cells with 111In-oxine. This showed that once the cell layer had formed (24 h after seeding), the fibroblastic matrix favoured the maintenance of a stable layer of mesothelial cells 4 hours after uptake of the radioactive substance.

Blood Vessel Prosthesis↗
PubMed1995

Transitional differentiation patterns of principal and intercalated cells during renal collecting duct development.

The developing renal collecting duct epithelium of neonatal rabbits exhibits 3 different zones. The ampullary tip epithelium acts as an embryonic inducer and is responsible for the generation of all of the nephron anlagen. It pilots the whole microarchitecture of the kidney. In the ampullary neck epithelium multiple cell divisions cause the elongation of the embryonic collecting duct so that the organ can grow. Finally, the cells in the ampullar shaft transdifferentiate into the functional collecting duct epithelium (CD) consisting of Principal (P) and various kinds of Intercalated (IC) cells. It is unknown by which morphogenic mechanisms the ampullar cells develop into the heterogeneously composed collecting duct epithelium. Using both morphological and immunohistochemical methods, we investigated the transdifferentiation patterns leading from the ampullar epithelium to the P and IC cells in the neonatal kidney. An electron microscope analysis of the cortico-medullary course of the developing collecting duct revealed that conspicuous morphological alterations start in the neck of the ampulla. The lumen of the neck region is narrowed to a slit. While most of the cells in the ampullar tip exhibit few, short microvilli, the neck cells bear numerous, extremely long microvilli at their apical cell poles. All of the neck cells exhibit the same cytoplasmic staining pattern and the same number of mitochondria. Farther down in the shaft, clearly recognizable P and IC cells are found. Thus, differentiation into P and IC cells starts with a transitional precursor cell type in the ampullar neck. Perfusion culture experiments with the embryonic collecting duct epithelium made it possible to generate transitional and differentiated cell types for the first time under in vitro conditions. The cultured epithelial cells showed characteristics common to both P and IC cells. Immunohistochemical findings revealed that morphological differentiation starts before the functional properties of P and IC cells can be detected.

Animals↗
PubMed1977

Hydroxyurea (HU) in experimental hematology. II. Similarities and dissimilarities between HU and 3H-thymidine killing.

The lethal effects of hydroxyurea (HU) and 3H-thymidine (3H-dT) on mouse hematopoietic cells were compared after various experimental procedures. The aim was to explore the relative efficiency of these two methods in analyzing the kinetic properties of progenitor cells. Both methods indicated that 40-50% of progenitor cells assayed with diffusion chamber culture (DCPC) were in S phase 3 days after cyclophosphamide treatment. Effects of HU, but not 3H-dT, were altered by neostigmine triggering of normal DCPC into cell cycle. On the other hand, cooling marrow cells before exposure to HU or 3H-dT largely abrogated the effect of HU, but not of 3H-dT. Blood-borne DCPC were not in cycle according to the HU effect. Separated blood DCPC were apparently in cycle, as judged with 3H-dT, but the Isopaque-Ficoll separation procedure rendered normal marrow DCPC susceptible to 3H-dT killing. When marrow cells were cultured in DC the HU technique appeared to be suitable for evaluation of modulation of progenitor cell (CFU-S or CFU-C) proliferation, whereas our previous experiments have shown that the 3H-dT technique is a convenient method to assess the initial triggering of CFU-S into cycle in DC culture.

Animals↗
PubMed1998

Autocrine hepatocyte growth factor provides a local mechanism for promoting axonal growth.

In this report, we describe a novel local mechanism necessary for optimal axonal growth that involves hepatocyte growth factor (HGF). Sympathetic neurons of the superior cervical ganglion coexpress bioactive HGF and its receptor, the Met tyrosine kinase, both in vivo and in vitro. Exogenous HGF selectively promotes the growth but not survival of cultured sympathetic neurons; the magnitude of this growth effect is similar to that observed with exogenous NGF. Conversely, HGF antibodies that inhibit endogenous HGF decrease sympathetic neuron growth but have no effect on survival. This autocrine HGF is required locally by sympathetic axons for optimal growth, as demonstrated using compartmented cultures. Thus, autocrine HGF provides a local, intrinsic mechanism for promoting neuronal growth without affecting survival, a role that may be essential during developmental axogenesis or after neuronal injury.

Animals↗
PubMed1998

Control of myelination by specific patterns of neural impulses.

A cell culture preparation equipped with stimulating electrodes was used to investigate whether action potential activity can influence myelination of mouse dorsal root ganglia axons by Schwann cells. Myelination was reduced to one-third of normal by low-frequency impulse activity (0.1 Hz), but higher-frequency stimulation (1 Hz) had no effect. The number of Schwann cells and the ultrastructure of compact myelin were not affected. The frequency of stimulation that inhibited myelination decreased expression of the cell adhesion molecule L1, and stimulation under conditions that prevented the reduction in L1 blocked the effects on myelination. This link between myelination and functional activity in the axon at specific frequencies that change axonal expression of L1 could have important consequences for the structural and functional relationship of myelinating axons.

Action Potentials↗
PubMed1977

Proliferation of diffusion chamber colony-forming units (CFUD) in cultures of normal human bone marrow in diffusion chambers in mice.

Normal human bone marrow contains cells capable of forming colonies of hemopoietic cells in fibrin clots in diffusion chambers implanted intraperitoneally (i.p.) into irradiated mice. The present paper describes the proliferation of such colony-forming units (CFUD) in cultures in vivo. Cells harvested from diffusion chambers after 1-14 days of culture in 450-R irradiated mice contained CFUD, which formed neutrophilic, eosinophilic, or megakaryocytic colonies when tested by secondary culture in fibrin clot chambers. When bone marrow was precultured in irradiated mice at a concentration of 10(6) cells per chamber, an initial fall in the number of neutrophilic CFUD was observed. This decrease was followed by an increase to a maximum at day 2, and then a secondary decrease. The number of neutrophilic CFUD recovered after 2 days of preculture in irradiated mice varied between 60% and 250% of the number present before preculture. Preculture in nonirradiated mice resulted in a significantly lower recovery of neutrophilic CFUD. In vitro treatment of bone marrow cells with hydroxyurea (OHU) after 2 days of preculture in irradiated mice resulted in a 68% +/- 5% reduction in the number of neutrophilic CFUD. In contrast, OHU had no similar effect on precultures from nonirradiated mice. Both the recovery and sensitivity to OHU of eosinophilic CFUD were independent of host irradiation. Similarly, no effect of host irradiation on the recovery or the 3H-thymidine (3HTdR) labeling index of morphologically recognizable granulocytic cells was observed at day 2. The data suggest an effect of humoral host factor(s) on the proliferation of early precursor cells, which are or become committed to differentiate into the neutrophilic pathway in diffusion chambers.

Animals↗
PubMed1978

Inhibition of haemopoietic stem cell proliferation by a diffusible product of bone marrow cells.

In a double diffusion chamber (DC) culture system bone marrow cells elaborated diffusible factor(s) that prevented spleen colony-forming cells (CFU-S), but not PHA stimulated lymphocytes, from entering cell cycle. Mature granulocytes and macrophages did not produce such factors(s). Various number of steady-state or regenerating mouse bone marrow cells were cultured in single diffusion chamber for periods up to 7 d. After the initial cell loss,the net growth of CFU-S was inversely related to both total cell number and CFU-S number in DC. Diffusible factors rather than cell-to-cell contact appeared to be involved in the inhibition, even though we were not able to demonstrate inhibition of net growth of CFU-S with the double chamber approach.

Animals↗
PubMed1992

A novel directly coupled gradostat.

The original bidirectional compound chemostat (gradostat) described by Lovitt and Wimpenny has been simplified by making a more compact apparatus in which chemical gradients are established by diffusion between adjacent culture chambers. The experimental model (diffusion coupled (DC) gradostat) consisted of five chambers whose contents could be agitated by turbines rotating in the horizontal plane on a common shaft. Two biological experiments were designed to reveal the value of the DC gradostat. A methylotroph (Methylophilus methylotrophus) grown in a methanol gradient showed expected changes in cell viability as a function of position in the five vessel array. Cells of two species of photosynthetic bacteria (Rhodobacter capsulata and Rhodopseudomonas marina/agilis) with different salt sensitivities could be mixed and subsequently separated by the DC gradostat operating with a NaCl gradient of 0-3% w/v.

Bacteria↗
PubMed1982

The culture of lymphoma cells in diffusion chambers.

The leukemia blast cells from peripheral blood of 5 patients with acute leukemia were cultured in diffusion chambers implanted into peritoneal cavity of mice. In two patients with AML an increase of the blast counts was observed, whereas in 3 other cases the leukemic leukocytes number decreased more or less rapidly. The number of CLL lymphocytes cultured in diffusion chambers decreased more slowly in comparison with the control lymphocytes. A small increase in the number of leukemic and normal lymphocytes during culture was noted. The CLL lymphocytes with no acid phosphatase content during the culture in diffusion chambers demonstrated an increase of enzyme activity.

Animals↗