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Biomedical subjects

I Bleiberg

Publications and source records attributed to I Bleiberg.

At least 37 records · Page 2Linked to original sources
PubMed1987

New bone formation and bone marrow differentiation induced in rats by extracellular bone matrix implantation: effect of local preirradiation on the process.

Subcutaneous implantation of demineralized diaphyseal rat bone matrix in ACI rats initiates a developmental cascade that results in the formation of new endochondral bone and an associated hematopoietic bone marrow differentiation. Irradiation (1500 rad, 60Co) of the implantation site 24 h prior to implantation suppresses the formation of endochondral bone and bone marrow. All phases of the developmental cascade, including chemotaxis, proliferation, and differentiation, are arrested by the irradiation. Simultaneous implantation with the extracellular matrix of bone marrow, bone, pieces of a four-day-old implant or of thoracic muscle--but not of brain, liver, or spleen tissue--results in the development of endochondral bone and bone marrow at the irradiated site. Concurrent implantation with the extracellular matrix of in vitro growing fibroblasts of marrow or ossicle origin does not restore the developmental cascade.

Alkaline Phosphatase↗
PubMed1985

Identification of a PDGF-like mitoattractant produced by NIH/3T3 cells after transformation with SV40.

It has previously been shown that fibroblastic cells transformed by SV40 exhibit a reduced requirement for PDGF for growth. In addition, NIH/3T3 cells lose both their chemotactic response to PDGF and specific cell surface binding of PDGF after transformation with SV40. We have now examined whether the SV40 transformed NIH/3T3 cells are producing a factor which acts similarly to PDGF. Our studies indicate that NIH/3T3 cells transformed with SV 40 produce a factor which shares many biological properties with PDGF. We were unable to detect this activity in conditioned media from nontransformed NIH/3T3 cells. The SV40/NIH/3T3 derived factor appears to possess both chemotactic and mitogenic activity for connective tissue cells but not endothelial or epithelial cells. Furthermore, in preliminary studies, this activity competes with 125I-PDGF for binding to smooth muscle cells. The biochemical properties of the SV40/NIH/3T3 derived factor are different from those of PDGF. The SV40 activity appears to reside in a heat labile acidic protein (pI less than 7.0) of MW less than 30,000 whereas PDGF is a heat stable basic protein (pI9.8) of 30,000 MW. Production of this factor may play a role in the decreased serum requirement for cell replication exhibited by SV40-transformed NIH/3T3 cells by supplying the cells with their own PDGF-like growth factor.

Animals↗
PubMed1985

Colony forming cell-fibroblast development in extracellular matrix-induced bone and bone marrow formation in rat.

The development of murine endochondral bone and bone marrow as a result of demineralized bone matrix implantation is preceded by the accumulation and proliferation of colony forming cell fibroblasts. These cells appear first at 24 hours post-implantation, after which they increase in 2 swells, achieving peak number between days 10-14. The observed differences in developmental kinetics of colony forming cell fibroblasts in culture were not found to be related to qualitative differences in the synthesis of collagens, fibronectin, laminin or proteoglycans. The colony forming cell fibroblasts were shown to be radiosensitive, with the Do = 339 +/- 63.

Animals↗
PubMed1983

Heparin receptors on mouse macrophages.

This study deals with the nature of the attachment between the macrophage cell membrane and heparin molecules. Treatments intended to remove or internalise macrophage receptors (trypsinisation and stimulation of phagocytosis respectively) were shown to considerably modulate the attachment of heparin. An excess of heparin fractions ranging in mean molecular weight from 8100 to 25700 all inhibited attachment of 35S heparin as did a mixed isomer chondroitin sulphate preparation. Our study provides evidence for the presence of receptors for sulphated glycosamino-glycans on the mouse macrophage cell membrane.

Animals↗
PubMed1981

Mode of binding and internalization into mouse macrophages of heparin complexed with polycations.

Heparin uptake by cultured macrophages was investigated from the standpoint of: (1) whether the increased uptake in the presence of polycations is due to charge neutralization, and (2) whether the heparin becomes internalized. Regarding the first point, our results are compatible with the notion that charge neutralization is mainly responsible for the enhanced uptake of heparin in the presence of protamine, histone, poly(DL-lysine) and poly(L-ornithine). As for the second point, chasing experiments at low and high temperatures strongly suggest that while heparin binds onto the cell membrane at both 4 degrees C and 37 degrees C, it undergoes internalization only at 37 degrees C.

Animals↗
PubMed1979

Differential effect of polycations on uptake and desulphation of heparin.

Previous work has established that macrophages in culture release sulphate from heparin. We now report that increased uptake and desulphation of heparin occurred in the presence of polycations (poly-L-ornithine and poly-DL-lysine) and that the increase in heparin uptake was by about 30-fold. The desulphation was less related to uptake than to the nature of the bound polycation. Serum was found to have an inhibitory effect on heparin uptake while polycations inhibited heparin desulphation by macrophage extracts.

Albumins↗
PubMed1979

Effect of estradiol on erythropoiesis and megakaryocytopoiesis in mice.

The effect of four 1.0-mg estradiol benzoate injections on hemopoiesis in the spleen and bone marrow in mice was studied. The number, concentration and mitotic activity of megakaryocytes (MKC) and number of MKC colonies in the spleen were found to be increased one and two weeks after cessation of the estradiol injections. MKC concentration in the bone marrow rose during the experimental period. The MKC increased in number during the first week after estradiol, but dropped to normal after the second week. The number and mitotic activity of erythroid precursors increased in the bone marrow and spleen three days after the cessation of estradiol injections. These findings suggest that estrogen enhances megakaryocytopoiesis and erythropoiesis in the bone marrow and spleen in mice.

Animals↗
PubMed1978

Increased uptake and desulphation of heparin by mouse macrophages in the presence of polycations.

Heparin uptake and desulphation by cultured macrophages were investigated. Histones, polyamino-acids, protamine and eosinophil-basic protein stimulated both heparin uptake and desulphation, processes found to be non-related. Poly-L-ornithine and poly-DL-lysine increased the heparin uptake by about 33-fold, and histone produced up to 7.5-fold increase in the desulphation. The same polycations inhibited heparin desulphation by macrophage extracts.

Animals↗
PubMed1978

Histological study of homografts showing delayed rejection following levan administration.

The delaying effect of continued administration of levan on mouse skin homograft rejection was found to be due mainly to inhibition of thrombotic occlusion of the nutrient blood vessels. Levan administration did not appear to affect epidermal regeneration, but it seemed to inhibit degranulation of mast cells, resorption of plasma extravasated during the operation and growth of granulation tissue. The delayed rejection caused by levan treatment was apparently caused by infiltration of the graft by activated mononuclear cells from the blood stream. The phenomenon is believed to represent a late stage of the graft rejection process, its apperance depending on the survival of the graft beyond the stage of vascular occlusion.

Animals↗
PubMed1977

Histological criteria for immunological rejection of mouse skin homografts.

The sequence of events in homograft rejection of skin in mice was studied by light microscopy in comparison to the reactions to isografts. Male C3H mice were used as donors and Balb/c mice were the recipients. In non-infected grafts no invasion of graft tissue by inflammatory cells occurred except for the marginal areas bordering on the graft bed. The most constant feature of immunological rejection was occlusion of blood vessels at the graft-host border with ischaemia of the graft. This indicated that skin homograft rejection is mainly a vascular phenomenon which can be best diagnosed by the presence of empty venules and capillaries. Leukocytic infiltration was prominent in presumably infected grafts. Destruction and inflammatory infiltration of the epidermis was not found to be a criterion for immunological rejection. In the graft bed adjoining the graft the granulation tissue contained basophilic and small lymphocytes, and macrophages. These cell tended to concentrate nearest to the graft and were surrounded on the outside by the lymphoid cells. It is probable that the macrophages were active in digestion of breakdown products.

Animals↗
PubMed1976

Desulphation of heparin by mice and guinea pig leukocytes.

Leukocytes from mice and guinea pigs were tested for their sulphate-splitting activity on heparin. Mouse macrophages showed the highest degrading activity while mouse neutrophils and lymphocytes showed only a week degrading activity. Mouse macrophages maintained in tissue culture were also found to degrade heparin, the amount of sulphate released increasing with time up to 96 h. Spleen extracts were found to neutralize the anticoagulatory activity of heparin.

Animals↗
PubMed1975

The effect of heat treatment on the damage and recovery of the protein synthesis mechanism of human kidney cell line.

The effect of supraoptimal temperature on the suppression and recovery of protein synthesis activity in cultures of human kidney cell line was studied. It was shown that 44 degrees C is a critical temperature to these cells, and after exposure to this temperature for 3 hours no recovery of protein synthesis activity could be detected. The cloning efficiency of cells exposed to 44 degrees C for 2 hours was irreversibly reduced to zero. Protein synthesis at 43 degrees C was much less affected, showing considerable recovery after eight hours exposure. Differences in heat susceptibility of individual cells in the culture were observed, but the reason for this heterogeneity is not yet known.

Autoradiography↗
PubMed1975

Effect of native levan on homograft rejection in mice.

The effect of high-molecular-weight levan on skin graft rejection was studied. Daily ip administration of 15-30 mg levan was shown to delay rejection in Balb/c and C57BL recipient mice. An increase in MST value by 3.6 days was obtained in Balb/c mice and of 5.6 days for C57BL.

Animals↗
PubMed1975

Sex hormones and the regulation of erythroid spleen colonies development of fetal liver origin.

The development of erythroid colonies of fetal liver hemopoietic cell origin in adult irradiated polycythemic mice was studied. It was found that orchidectomy sharply reduced the number of erythroid colonies developed in the spleen of these polycythemic male recipients. Estrogen injection to the orchidectomized polycythemic recipient did not further decrease the number of erythroid colonies developed. It is concluded that the development of erythroid colonies of fetal liver origin in polycythemic male recipients is maintained mainly by testicular testosterone. The complete suppression of these colonies in female recipients does not seem to be a result of inhibition by estrogen.

Animals↗
PubMed1975

Stimulation of murine amyloidosis by a dializable product from pretreated donors.

Amyloid was obtained in recipient mice by implantation into their peritoneal cavity of a dialysis bag containing spleen cells obtained from donor mice which were treated with casein for 6 days and while no amyloid was found in their implanted spleens. The transplantations were performed with 2 cell systems, one containing whole spleen suspension and the other washed cells. Amyloid was obtained in the recipient mice within 6 days after the implantation and in a more massive quantity than in mice treated by casein for a similar period.

Amyloid↗