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Biomedical subjects

R Sullivan

Publications and source records attributed to R Sullivan.

At least 163 records · Page 9Linked to original sources
PubMed1984

Induction of proliferation of purified human myeloid progenitor cells: a rapid assay for granulocyte colony-stimulating factors.

The proliferation and differentiation of granulocyte and monocyte progenitor cells (CFU-C) in vitro is dependent on the presence of a group of closely related glycoproteins termed colony-stimulating factors (CSF). In order to investigate the interaction of these factors with CFU-C, we purified CFU-C from the peripheral blood of chronic myeloid leukemia patients with an immune rosette technique using specific monoclonal antibodies (mean 74-fold enrichment, 45% cloning efficiency). Colony formation by purified CFU-C demonstrated an absolute dependence on an exogenous source of CSF. Liquid culture of small aliquots of enriched CFU-C with CSF-containing medium resulted in a rapid, time- and concentration-dependent induction of DNA synthesis as measured by 3H-thymidine incorporation. This specific CSF induction of DNA synthesis by enriched CFU-C was used to develop a microassay system for CSF activity. CSF activity could be reproducibly quantitated in 24-48 hr. The proliferating cells in this assay system were shown to be myeloid progenitor cells by examining the morphology of their progeny and by determining the surface antigen phenotype of the responding cells (Ia+, T3-, B1-, Mo1-). This microassay provides a quantitative assessment of CSF activity that may be useful in the purification of human CSF and in the generation of monoclonal antibodies to CFU-C surface structures.

Animals↗
PubMed1984

The production of granulocyte-monocyte colony-stimulating activity by isolated human T lymphocyte subpopulations.

Isolated human T lymphocyte subpopulations were obtained by fluorescence-activated cell sorting using the murine monoclonal antibodies, OKT4 and OKT8. The capabilities of the isolated lymphocytes to produce granulocyte-monocyte colony-stimulating activity (CSA) in response to mitogen challenge were assessed by in vitro assays employing light density nonadherent bone marrow cells. Essentially, no CSA production was noted by any isolated T lymphocyte population [OKT4 positive (+) or OKT8 positive (+)] cultured alone or following the addition of 10(4) autologous monocytes/ml. When phytohemagglutinin (PHA) alone was added, OKT4+ lymphocytes elaborated small amounts of CSA. With the addition of concanavalin A (Con-A) alone, both OKT4+ and OKT8+ cells were able to produce modest amounts of CSA. Significantly enhanced CSA production was observed when either OKT4+ or OKT8+ lymphocytes were coincubated with autologous monocytes in the presence of mitogen. We conclude that highly purified T lymphocyte subpopulations, free of monocytes as assessed by nonspecific esterase staining, can elaborate small amounts of CSA in response to PHA or Con-A challenge. A synergistic augmentation of CSA production was noted with coincubation of sorted lymphocytes and autologous monocytes in the presence of mitogen. Finally, our results suggest that the ability of T lymphocytes to make CSA is not exclusively limited to either the OKT4+ or OKT8+ defined subsets.

Antibodies, Monoclonal↗
PubMed1984

The effects of tumor-promoting phorbol esters on human granulopoiesis in vitro.

In order to determine whether the tumor-promoting phorbol esters are capable of inducing normal human committed granulocytic-monocytic progenitor cells (CFUc) to proliferate and differentiate in the absence of granulocyte-monocyte colony-stimulating activity (CSA), we studied the effects of these compounds on human granulopoiesis in vitro. We found that when light-density human marrow cells or peripheral blood leukocytes were depleted of adherent cells and then incubated in semisolid tissue culture medium under conditions optimal for CFUc growth, phorbol myristate acetate (PMA) and its congeners produced no measurable stimulatory effect on the proliferation of CFUc in the absence of added CSA. Likewise, when light-density marrow cells that had not been depleted of adherent cells were plated in the cultures, no stimulation of CFUc colony growth resulted from the addition of PMA. However, when light-density peripheral blood leukocytes were used as a target source of CFUc without first subjecting them to adherence separation, enhanced proliferation and differentiation of CFUc were noted in cultures that contained PMA. To investigate the possibility that CSA production by monocytes in these cultures in response to activation by PMA might account for the enhanced colony formation that we observed, we incubated isolated peripheral blood monocytes in short-term liquid suspension cultures and found that in the presence of PMA, large quantities of CSA were secreted into the surrounding medium. Finally, we noted that when marrow cell suspensions were suboptimally stimulated by low concentrations of CSA added to the cultures, the effects of PMA on CFUc proliferation were unpredictable, enhancing colony formation in some cases and inhibiting it in others. Our data indicate that although the tumor-promoting phorbol esters do not appear capable of directly stimulating the proliferation or differentiation of human CFUc in the absence of CSA, they may do so indirectly by causing auxiliary cells such as monocytes to secrete CSA.

Bone Marrow↗
PubMed1983

Acute chemical meningitis after metrizamide-lumbar myelography.

Severe acute meningitis developed after the use of metrizamide for lumbar myelography; cerebrospinal fluid findings included a white blood cell count of 2300, mostly polymorphonuclear cells, glucose level of 8 mg% and protein level of 253%. This apparent chemical meningitis could not be distinguished, either clinically or by cerebrospinal fluid examination, from acute bacterial meningitis. This case emphasizes that severe acute meningeal reactions, while very rare, can occur after the use of metrizamide for myelography. Such patients must be evaluated promptly to rule out bacterial meningitis and should be followed carefully for possible later sequelae.

Acute Disease↗
PubMed1983

The synthesis and secretion of granulocyte-monocyte colony-stimulating activity (CSA) by isolated human monocytes: kinetics of the response to bacterial endotoxin.

We studied the kinetics of the synthesis and secretion of granulocyte-monocyte colony-stimulating activity (CSA) by human monocytes stimulated by S. typhi endotoxin. We found that these cells initially secrete copious quantities of CSA when exposed to endotoxin but rapidly become refractory to its stimulatory effect. When monocytes were incubated in liquid suspension cultures, large amounts of CSA were generated during the first 24 hr of culture after the addition of as little as 10 ng/ml of endotoxin to previously unstimulated monocytes. After the addition of endotoxin, CSA secretion abruptly took place after an initial 1 to 2 hr lag phase, and occurred primarily within the first 6 to 12 hr of culture. The addition of puromycin or cycloheximide to the cultures significantly inhibited CSA secretion in response to endotoxin, suggesting that CSA production by stimulated monocytes requires de novo protein synthesis and does not solely result from the release of preformed active CSA. After initial exposure to endotoxin, CSA production by monocytes steadily decreased after 24 hr and ceased after 72 hr. Subsequent reexposure to the same concentration of endotoxin resulted in little CSA production, whereas the refractory state could be overcome by increasing the quantity of endotoxin added. Additional studies demonstrated that refractoriness of monocytes to further CSA production after initial response to endotoxin was not due to a loss of cell viability, degradation of endotoxin, or inhibition of CSA synthesis by soluble metabolites generated by stimulated monocytes. Our data suggest that the capacity of human monocytes to synthesize CSA in response to endotoxin rapidly becomes blunted after initial exposure of the cells to the lipopolysaccharide, but that the refractory state of these cells can be overcome by increasing the concentration of endotoxin. Acquired hyporesponsiveness of cells that produce CSA may in part account for the phenomenon of immediate endotoxin tolerance observed in vivo.

Cell Separation↗
PubMed1983

Stimulation of increased capillary endothelial cell motility by chondrosarcoma cell-derived factors.

The ability of chondrosarcoma cell-derived preparations to stimulate an increase in the motility of bovine capillary endothelial (BCE) cells was quantitated using a phagokinetic track assay which measures the area of tracks produced by BCE cells after ingestion of gold particles. Chondrosarcoma preparations stimulated a 2-fold increase in the mean track area produced by BCE cells in an 18-hr incubation period. The motility-stimulating activity of chondrosarcoma was purified about 120-fold. The most highly purified fractions had molecular weights between 16,000 and 20,000 and stimulated a 2-fold increase in BCE cell motility at concentrations of 10 to 20 ng/ml.

Animals↗
PubMed1982

The role of intraoral and gastrointestinal cues in the control of sucking and milk consumption in rat pups.

Nutritive deprivation, suckling deprivation, gastronintestinal fill, and milk availability contribute to the control of sucking (as measured by jaw-muscle electromyograph) and ingestion of milk (provided via a tongue cannula) in 11-13-day-old rat pups. Depriving pups of the opportunity to suckle reliably increases subsequent sucking and milk intake. Intraoral delivery of milk also increases sucking, regardless of whether or not pups are suckling-deprived. Gastrointestinal preloads have no effect on sucking if pups are not receiving milk, but reliably block the increase in sucking which accompanies milk delivery. Finally, milk delivered to the pup's mouth prior to a suckling opportunity can either enhance or attenuate subsequent sucking depending on whether pups are allowed to consume milk while suckling. In all cases, a particular mode of sucking ("rhythmic" sucking) is most affected by experimental manipulation, and appears to be an important component of the pup's ingestive behavior.

Animals↗
PubMed1982

Short- and long-term effects of various milk-delivery contingencies on sucking and nipple attachment in rat pups.

Varied milk delivery contingencies differentially affect sucking in rat pups as measured by jaw-muscle electromyographic activity. In Experiment I we found that 11-13-day-old pups sucked more frequently when receiving tiny intermittent pulses of milk than when receiving no milk, and continued to suck at a high rate for at least 30 min after cessation of milk delivery. In subsequent experiments we found that pups 13-18 days of age engaged in more frequent sucking if receiving milk continuously rather than intermittently, and that this increased rate of sucking persisted for at least 24 hr after cessation of milk delivery. Pups given experience with continuous milk delivery from 14 to 18 days of age also spent significantly more time attached to the nipple at 19 days of age than did pups in control groups. It was concluded that experience with different milk delivery schedules can affect subsequent sucking and nipple attachment behavior.

Animals↗
PubMed1980

The role of colony stimulating activity in modulating murine diffusion chamber granulopoiesis.

We studied the effects of high circulating Colony Stimulating Activity (CSA) levels and irradiation induced marrow hypoplasia in CF1 and C57B1/6J host mice upon granulopoiesis in intraperitoneal diffusion chamber (DC) cultures. Serial endotoxin injections resulted in marked elevation of circulating CSA for the first half of an 8 d culture period, and CSA was shown to diffuse into the chamber environment; yet this manipulation alone did not significantly accelerate DC cell growth. Pre-irradiation of the host mice produced no elevation of circulating CSA during the early phase of culture, but resulted in significant stimulation of DC granolopoiesis. Fluctuations in circulating inhibitors of in vitro granulopoiesis did not correlate well with DC cellularity. We conclude that endogenous CSA elevation does not providean effective stimulus per se for granulocyte-monocyte proliferation within DC culture and cannot be solely responsible for mediating the exuberant DC granulopoietic response seen in the pre-irradiated host.

Animals↗
PubMed1980

Aplastic anemia: lack of inhibitory effect of bone marrow lymphocytes on in vitro granulopoiesis.

Prompted by previous reports that in certain patients with aplastic anemia, cell-mediated autoimmune suppression of myeloid stem cell proliferation may be demonstrable in vitro, we studied the effects of bone marrow lymphocytes from 18 patients with myeloid aplasia on the proliferation of committed granulocytic-monocytic progenitor cells (CFU-C). When assayed in soft agar cultures, marrow suspensions from 10 patients with aplastic anemia contained significantly fewer viable CFU-C than similar cell preparations from control subjects. To deplete marrow cell suspensions of lymphocytes, we employed rabbit anti-human thymocyte serum (ATS), which after multiple adsorptions exhibited marked cytotoxicity for human B and T lymphocytes but had negligible effect on normal CFU-C proliferation. Preincubation of marrow samples from 12 patients with ATS and complement resulted in no inhibition or enhancement of CFU-C growth. In further experiments, marrow cells from 8 patients were incubated with marrow from control subjects prior to CFU-C culture. No suppression of donor CFU-C proliferation was observed in any of these studies, and in 4 cocultures, mixture of the 2 marrow suspensions resulted in stimulation of CFU-C growth. Using these assays, we detected no evidence of cell-mediated inhibition of CFU-C proliferation in any of the 18 patients that we evaluated. Our data support the conclusion that in the majority of patients with aplastic anemia, an absolute deficiency of hemopoietic stem cells is present within the marrow that does not appear to be effected or sustained by suppressor lymphocytes. Whether the reduction of viable stem cells is the cause or the consequence of the process that leads to marrow failure remains unknown.

Anemia, Aplastic↗
PubMed1980

Fractionation of human bone marrow cell suspensions in nylon fiber columns: an efficient method for the removal of cells that produce colony stimulating factor (CSF).

In this report, we describe an efficient technique for the extraction of CSF-producing cells from human marrow suspensions. Prior to plating in agar cultures, we incubated buoyant human marrow cells for 45 min in columns packed with nylon fiber or subjected the cells to two one-hour incubations in glass petri dishes. Recoveries of total cells, differential marrow elements, and committed granulocyte-monocyte progenitor cells (CFUc) were similar after each separative procedure. However, spontaneous CFUc proliferation was more effectively eliminated when cells were fractionated in nylon fiber columns. After the removal of cells which were adherent to glass, spontaneous CFUc proliferation in cultures containing no exogenous CSF accounted for 2.1% of total CFUc at a plating concentration of 10(5) cells/ml and 7.8% at a concentration of 3 X 10(5) cells/ml. After the fractionation of marrow cell suspensions in nylon fiber columns, spontaneous CFUc growth was completely obliterated at a plating concentration of 10(5) cells/ml, and at a concentration of 3 X 10(5) cells/ml accounted for only 0.09% of total CFUc. Further experiments were undertaken which demonstrated that buoyant marrow cells after incubation in nylon fiber columns may be employed to assay CSF in extremely dilute concentrations. Because of the simplicity and efficiency of this procedure, nylon fiber chromatography appears to be a highly useful technique for the rapid semi-purification of marrow suspensions for use in the assay of human CSF.

Bone Marrow↗
PubMed1979

Stem cell migration induced by erythropoietin or haemolytic anaemia: the effects of actinomycin and endotoxin contamination of erythropoietin preparations.

The injection of erythropoietin or the induction of anaemia with phenylhydrazine leads to changes in murine pluripotent and granulocyte-macrophage stem cells indicating migration from marrow to spleen. In order to evaluate the interrelationship between erythroid differentiation and stem cell migration we have selectively suppressed erythroid differentiation with actinomycin D. Anaemia or EP injection resulted in stem cell changes consistent with migration; actinomycin blocked these changes in anaemic but not EP injected mice while blocking erythropoiesis in both groups. The erythropoietin contained from 0.01 to 1000 microgram/ml of endotoxin as defined by the limulus test; it decreased marrow erythropoiesis and stimulated marrow granulopoiesis. Adsorption of the erythropoietin preparation with limulus lysate removed endotoxin without decreasing erythropoietin activity. Adsorbed erythropoietin stimulated erythropoiesis and not granulopoiesis, and stem cell changes induced by its administration were largely blocked by actinomycin, suggesting that endotoxin in the non-adsorbed erythropoietin caused the actinomycin resistant stem cell changes. The observation that actinomycin blocks both erythroid differentiation and stem cell migration suggests that these two physiologic events are closely linked. The effects of injected erythropoietin on murine haemopoietic stem cells may, to a significant extent, be secondary to the presence of endotoxin in the erythropoietin preparations.

Anemia, Hemolytic↗
PubMed1979

The use of stem cell assays to monitor the proliferative potential of bone marrow cells.

A number of assays exist for hematopoietic stem cells in both humans and mice, but the appropriate stem cell assay for the repopulating potential of human marrow is not clear. Two murine models suggest that these assays may not always predict marrow proliferative potential. In vivo diffusion chamber culture growth of CD1 marrow depleted of pluripotent stem cells (CFU-S) by exposure to mouse-brain antisera plus complement was equivalent to or greater than that of normal serum treated control marrow. Furthermore, CF1 mice repeatedly injected with endotoxin had markedly stimulated granulopoiesis with increases in the number of marrow CFU-S and the % in S phase but no changes in the number or proliferative status of marrow CFU-C. However, inbred BDF1 mice chronically injected with endotoxin although also showing striking increases in granulopoiesis had no significant alteration in their marrow CFU-S or CFU-C number or cell cycle status relative to saline injected controls. Both models present examples where conventional stem cell assays do not provide insight into marrow cell production and suggest that in vitro clonal assays of human marrow cells may not always predict for the potential of marrow to repopulate a human transplant recipient.

Animals↗