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Biomedical subjects

K McGrath

Publications and source records attributed to K McGrath.

At least 37 records · Page 2Linked to original sources
PubMed1993

Macrophage colony-stimulating factor and granulocyte-macrophage colony-stimulating factor stimulate the synthesis of plasminogen-activator inhibitors by human monocytes.

Macrophage colony-stimulating factor (M-CSF or CSF-1) and granulocyte-macrophage CSF (GM-CSF) have been shown to increase human monocyte urokinase-type plasminogen-activator (u-PA) activity with possible consequences for cell migration and tissue remodeling; because monocyte u-PA activity is likely to be controlled in part also by the PA inhibitors (PAIs) made by the cell, the effect of M-CSF and GM-CSF on human monocyte PAI-2 and PAI-1 synthesis was investigated. To this end, elutriation-purified human monocytes were treated in vitro with purified recombinant human M-CSF and GM-CSF, and PAI-2 and PAI-1 antigen and mRNA levels measured by specific enzyme-linked immunosorbent assays and Northern blot, respectively. Each CSF could enhance the protein and mRNA levels of PAI-2 and PAI-1 at similar concentrations for each product. This similar regulation of monocyte PAI expression in response to the CSFs contrasted with that found for the effects of lipopolysaccharide, transforming growth factor-beta and a glucocorticoid. Therefore, PAIs may be modulating the effects of the CSFs on monocyte u-PA activity at sites of inflammation and tissue remodeling.

Dose-Response Relationship, Drug↗
PubMed1993

Contrasting effects of transforming growth factor-beta and IL-1 on the regulation of plasminogen activator inhibitors in human synovial fibroblasts.

TGF-beta increased in a dose-dependent manner the production of plasminogen activator inhibitor-1 (PAI-1) in cultured human synovial fibroblast-like cells, as measured by ELISA. Significant increases in PAI-1 were first detected in cell supernatants within 4 h after cytokine addition. Increases were also observed in PAI-1 mRNA expression. IL-1 suppressed these increases in PAI-1 Ag and mRNA. In contrast, when PAI-2 levels were measured by ELISA, TGF-beta did not raise them but inhibited slightly the enhancement caused by IL-1 of PAI-2 Ag and mRNA. Therefore TGF-beta selectively stimulates the formation of one PAI; TGF-beta and IL-1 have opposing effects on PAI-1 and PAI-2 synthesis in the synovial cells. These findings are proposed to help define the control of fibrinolysis and tissue remodeling in the rheumatoid synovium.

Cells, Cultured↗
PubMed1993

Thrombin stimulates expression of tissue-type plasminogen activator and plasminogen activator inhibitor type 1 in cultured human vascular smooth muscle cells.

The effect of thrombin on the fibrinolytic potential of human vascular smooth muscle cells (SMC) in culture was studied. SMC of different origin responded to thrombin treatment with a dose and time dependent increase in tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1) levels in both cell lysates and conditioned media with maximum effects achieved at 10-20 IU/ml thrombin. PAI-1 antigen levels also increased in the extracellular matrix of thrombin treated SMC. PAI-2 levels in cell lysates of such SMC were not affected by thrombin. The effect was restricted to active thrombin, since DFP-thrombin and thrombin treated with hirudin showed no increasing effect on t-PA and PAI-1 levels in SMC. Enzymatically active thrombin also caused a four-fold increase in specific PAI-1 mRNA and a three-fold increase in t-PA mRNA. Furthermore we demonstrated the presence of high and low affinity binding sites for thrombin on the surface of SMC with a KD = 4.3 x 10(-10)M and 9.0 x 10(4) sites per cell and a KD = 0.6 x 10(-8) M and 5.8 x 10(5) sites per cell respectively. Thrombin could come in contact with SMC in case of vascular injury or following gap formation between endothelial cells. Our data support the idea that besides its known proliferative effect for SMC, thrombin could also modulate their fibrinolytic system.

Antigens↗
PubMed1993

Interleukin-4 stimulates expression of urokinase-type-plasminogen activator in cultured human foreskin microvascular endothelial cells.

The effect of interleukin-4 (IL-4) on the fibrinolytic system of human microvascular and macrovascular endothelial cells in culture was studied. Only foreskin microvascular endothelial cells (EC) responded to IL-4 treatment with a dose- and time-dependent increase in urokinase-type plasminogen activator (u-PA) (control: 3.0 +/- 0.8 ng/10(5) cells/24 h; 200 U/mL IL-4: 6.7 +/- 0.8 ng/10(5) cells/24 h), whereas human macrovascular EC remained unaffected. A maximum effect was achieved with 200 U/mL IL-4. Little u-PA activity was detected in the conditioned media of human foreskin microvascular EC (HFMEC) treated without and with IL-4 before plasmin treatment (control: 0.03 +/- 0.003 IU/10(5) cells/20 h; 200 U/mL IL-4: 0.09 +/- 0.007 IU/10(5) cells/20 h). These values increased to 0.18 +/- 0.02 IU/10(5) cells/20 h and 0.53 +/- 0.04 IU/10(5) cells/20 h, respectively, after plasmin treatment, indicating that u-PA is released by HFMEC predominantly in its inactive precursor form single-chain u-PA (scu-PA). u-PA activity increased also in the cell lysates of HFMEC up to 2.5-fold after IL-4 treatment. Plasminogen activator inhibitor type-1 (PAI-1) levels produced by HFMEC remained unaffected by IL-4, whereas tissue-type plasminogen activator (t-PA) levels were slightly decreased when HFMEC were treated with IL-4. These findings were also reflected in the specific mRNA levels as determined by Northern blotting. u-PA-specific mRNA increased significantly in HFMEC in the presence of IL-4, whereas t-PA mRNA and PAI-1-specific mRNA in HFMEC and u-PA specific mRNA in human saphenous vein EC (HSVEC) remained unaffected by IL-4 treatment. Our findings suggest a role for IL-4 in the process of angiogenesis, in addition to its known proliferative effect on human microvascular EC, by increasing the fibrinolytic potential of such EC, thereby facilitating extracellular proteolysis and cell migration.

Blotting, Northern↗
PubMed1993

Cytokine regulation of the synthesis of plasminogen activator inhibitor-2 by human vascular endothelial cells. Comparison with plasminogen activator inhibitor-1 synthesis.

Plasminogen activators are inhibited by plasminogen activator inhibitors-1 (PAI-1) and -2 (PAI-2). We describe the synthesis of PAI-2 by human vascular endothelial cells (EC) cultured from umbilical vein, saphenous vein and foreskin microvasculature in response to interleukin-1 alpha (IL-1 alpha) and tumour necrosis factor alpha (TNF alpha) and compare it with that of PAI-1. Both PAI-2 and PAI-1 were quantitated by ELISAs. PAI-2 was cell-associated while PAI-1 was secreted by EC. IL-1 alpha and TNF alpha increased the synthesis of PAI-2 and PAI-1 by EC in a dose-dependent manner. IL-1 alpha was a stronger stimulus for PAI-2 synthesis than TNF alpha, while both cytokines were equally effective for PAI-1. Northern blot analysis revealed similar changes in mRNA levels to those in antigen levels. PAI-2 synthesis by cytokine-stimulated EC may be important in thrombus formation and inflammation.

Cells, Cultured↗
PubMed1993

Regulation of plasminogen activator inhibitor-1 levels in human monocytes.

The regulation of PAI-1 synthesis by elutriation-purified human monocytes was studied in vitro and compared to that for PAI-2. PAI-1 formation, as measured by ELISA, was upregulated by TGF-beta (> or = 1 ng/ml) and surprisingly down-regulated by LPS (100 ng/ml), particularly in the presence of TGF-beta; LPS elevated PAI-2 levels (ELISA) while TGF-beta reduced its basal levels and those in LPS-treated cultures. Concomitant changes in mRNA expression occurred. The glucocorticoid dexamethasone (10(-7) M) elevated PAI-1 and acted in concert with TGF-beta in this regard at both the antigen and mRNA levels; interleukin-4 (IL-4) (250 pM) failed to mimic the steroid in its regulation of PAI-1 formation. Since monocyte/macrophage PA activity is likely to be important in tissue remodeling and cell migration at sites of inflammation and in fibrinolysis, it is proposed from these studies that PAI-1, as well as the usually considered PAI-2, may be involved in the negative control of PA activity in this cell type. The synthesis of each PAI appears to be independently regulated.

Cells, Cultured↗
PubMed1992

Gamma-interferon counteracts interleukin-1 alpha stimulated expression of urokinase-type plasminogen activator in human endothelial cells in vitro.

The effect of gamma-interferon (gamma-IFN) on the interleukin-1 alpha (IL-1 alpha) induced stimulation of urokinase-type plasminogen activator (u-PA) expression in human foreskin microvascular endothelial cells (HFMEC) and in human umbilical vein endothelial cells (HUVEC) was investigated. When gamma-IFN and IL-1 alpha were added to the cells simultaneously, gamma-IFN inhibited the IL-1 alpha induced increase in u-PA antigen production in both HFMEC and HUVEC in a dose dependent fashion, with a maximum inhibitory effect achieved between 2.0 and 20.0 U/ml of gamma-IFN. Pretreatment of HFMEC with gamma-IFN for 1 hour before addition of IL-1 alpha resulted in a significant reduction in u-PA synthesis. However, when HFMEC were pretreated for 8 hours with gamma-IFN before the addition of IL-1 alpha the reduction in u-PA production was even more significant. When gamma-IFN was added to HFMEC 1 hour after IL-1 alpha, a significant inhibition in u-PA synthesis was seen. In contrast only a slight inhibition in IL-1 alpha induced u-PA production was seen when gamma-IFN was added to the cells 8 hours after IL-1 alpha. gamma-IFN also inhibited significantly the IL-1 alpha induced increase in u-PA specific mRNA in HUVEC and HFMEC.

Blotting, Northern↗
PubMed1992

Independent regulation of plasminogen activator inhibitor 2 and plasminogen activator inhibitor 1 in human synovial fibroblasts.

OBJECTIVE: To study the plasminogen activator inhibitor(s) (PAI) produced in vitro by human synovial fibroblast-like cells. METHODS: Human synovial cell explant cultures were established using cells from nonrheumatoid donors. PAI-2 and PAI-1 antigens were measured by enzyme-linked immunosorbent assay, and messenger RNA (mRNA) levels were determined by Northern blot. RESULTS: The synovial fibroblasts produced both PAI-2 and PAI-1. Interleukin-1 (IL-1) increased PAI-2 but decreased PAI-1 formation, both at the protein and the mRNA levels. Using cyclooxygenase inhibitors, evidence was obtained that an endogenous cyclooxygenase product(s) in the IL-1-treated cultures inhibited formation of both PAIs; exogenous prostaglandin E2 (10(-7) M) reversed the effect of cyclooxygenase inhibition. The glucocorticoid dexamethasone (10(-6) to 10(-7) M) inhibited IL-1-stimulated PAI-2 formation but reversed the suppressive effect of IL-1 on PAI-1 production. CONCLUSION: PAI-2 formation and PAI-1 formation can be regulated independently in human synoviocytes, illustrating the complexity of the modulation of the net PA activity expressed by these cells.

Blotting, Northern↗
PubMed1992

Amphotericin B-induced injury in stored human platelets.

Administration of intravenous amphotericin B is a major factor in the reduction of the recovery of transfused platelet concentrates (PCs). For the study of possible drug-induced platelet lesions, fresh platelets and stored PCs were incubated with therapeutic concentrations of amphotericin B (10-50 micrograms/mL) and examined for membrane changes by scanning electron microscopy. Stored platelets demonstrated the formation of "pits" on the surface membrane, which were maximal immediately after preparation and gradually decreased with storage. The number of pits was significantly higher after exposure to amphotericin B. No increase was detected in fresh platelets following exposure to amphotericin B. The maximal effect of the drug was seen after 5 days of storage as PCs. Amphotericin B did not affect platelet shape or the number of pseudopodia. There was no correlation between pit formation and the pH, pO2, or pCO2 of the concentrates. Amphotericin B did not release 51Cr from prelabeled stored platelets after 2 hours' incubation at 37 degrees C. Thus, amphotericin B appears to exacerbate a membrane lesion induced by the preparation and storage of PCs.

Amphotericin B↗
PubMed1992

Marrow proliferation and the appearance of giant neutrophils in response to recombinant human granulocyte colony stimulating factor (rhG-CSF).

During a study of recombinant human granulocyte colony stimulating factor (rhG-CSF) administration, 15 patients received twice daily i.v. infusions and nine patients received daily s.c. infusions of rhG-CSF for 5 d prior to cytotoxic therapy, and then a second course subsequent to melphalan administration. There was a striking dose-related neutrophilia and the appearance in the blood of early myeloid cells that express the intercellular adhesion molecule CD54. In addition, giant neutrophils or macropolycytes were observed in the peripheral blood of all patients. These cells were evident on the display of the Technicon H*1 as a population of large peroxidase positive cells, and using Feulgen staining these cells were shown to be tetraploid. Bone marrow kinetics studies performed on Day 4 or 5 indicated an increase in the proportion of bone marrow cells in S phase, G2 and mitosis, reflecting a proliferative response of the marrow. Large myeloid precursors and occasional binucleate promyelocytes were seen in the bone marrows done on Days 14 and 18 but not on Day 5. These findings indicate that administered G-CSF has both quantitative and qualitative effects on myeloid cells in vivo.

Bone Marrow↗
PubMed1992

The definition of refractoriness to platelet transfusions.

The relationship between the 1 and 20 h post-transfusion platelet count and three parameters used to define refractory transfusions, namely the corrected increment (CI), platelet increment (PI), and percentage platelet recovery (%REC), was studied in 437 non-HLA matched platelet transfusions given to 102 patients with bone marrow failure. The percentage agreement between common definitions of refractoriness was calculated based on these parameters. As the maintenance of platelet counts above 20 x 10(9)/l is a relevant clinical goal for platelet support, the values of the CI, PI and %REC, which best corresponded to 1- and 20-h post-transfusion counts of 20 x 10(9)/l, were identified. A 1-h post-transfusion CI < 3 (PI < 7 x 10(9)/l or % REC < 8%) corresponded to clinically unsuccessful transfusions with a 1-h platelet count < 20 x 10(9)/l. A 1-h CI > or = 5.5 (PI > or = 12 x 10(9)/l or %REC > or = 14%) corresponded to clinically successful transfusions with a 20-h post-transfusion count of > or = 20 x 10/l. These data tie together the end points reported in the literature for defining refractory transfusions.

Blood Platelets↗
PubMed1992

SCL gene in human tumors.

The SCL gene encodes a member of the helix-loop-helix (HLH) family of transcription factors and is reportedly involved in up to 25% of T-cell acute lymphoblastic leukemia (T-ALL). We have surveyed over 120 primary human tumors including melanomas, myeloid, and lymphoid leukemias, and other solid tumors without evidence of rearrangements involving SCL. These results are further supported by low level expression of SCL in these tumors (as assessed by a polymerase chain-reaction-based method). We conclude that rearrangement/translocation with subsequent activation of SCL occurs infrequently in myeloid leukemias and melanomas.

Base Sequence↗
PubMed1991

Factors influencing 20-hour increments after platelet transfusion.

The 20-hour posttransfusion platelet count determines transfusion policy for patients requiring platelet support, and yet factors influencing the 20-hour count have been poorly defined. The clinical factors influencing both the 1- and 20-hour corrected count increment (CCI), were studied in 623 human leukocyte antigen (HLA)-unmatched platelet transfusions in 108 patients. The 1- and 20-hour CCIs were highly correlated (r = 0.67, p less than 0.001). On average, the 20-hour CCI was 64 percent of the 1-hour CCI. Multiple linear regression analyses identified splenectomy, bone marrow transplantation, disseminated intravascular coagulation, administration of amphotericin B, palpable spleen, and HLA antibody grade as the major factors influencing the 20-hour posttransfusion CCI. Platelet-specific antibodies, number of concurrent antibiotics, clinical bleeding, and temperature did not significantly influence the 20-hour posttransfusion CCI. The 1-hour CCI was the only significant factor influencing the 20-hour CCI in a regression model containing the 1-hour CCI and the above factors. Thus, the same clinical factors exert a major influence on the CCI at both 1 and 20 hours after platelet transfusion, with no evidence that any factor has more influence at 20 hours after transfusion than at 1 hour.

Blood Platelets↗
PubMed1990

Phase I study of intravenously administered bacterially synthesized granulocyte-macrophage colony-stimulating factor and comparison with subcutaneous administration.

A Phase I study of bacterially synthesized recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) was undertaken in 21 patients with advanced malignancy or neutropenia. rhGM-CSF was administered once daily by i.v. bolus injection (0.3 to 3 micrograms/kg/day) or 2-h i.v. infusion (3 to 20 micrograms/kg day) for 10 days. rhGM-CSF at all i.v. doses caused an immediate transient decrease in circulating neutrophils, eosinophils, and monocytes. By 6 h after rhGM-CSF, circulating leukocyte levels were restored. Daily i.v. bolus dosing (0.3 to 3 micrograms/kg/day) did not elevate leukocyte levels except in one neutropenic patient. Daily 2-h i.v. infusions (10 to 20 micrograms/kg/day) caused a dose-dependent leukocytosis with increased levels of neutrophils (up to 4.3-fold), eosinophils (up to 18-fold), and monocytes (up to 3.5-fold). Marrow aspirates showed increased proportions of promyelocytes and myelocytes during rhGM-CSF administration. Retreatment after 10 days without rhGM-CSF resulted in a more marked leukocytosis at doses greater than or equal to 10 micrograms/kg/day. Platelet levels decreased for the first 3 days and then increased during the first course of rhGM-CSF administration. Two patients with chronic lymphocytic leukemia had a transient reduction in lymphocytosis. Serum cholesterol and albumin levels decreased, and vitamin B12 levels increased during rhGM-CSF treatment. At doses of up to 15 micrograms/kg/day, rhGM-CSF was relatively well tolerated by the patients, but adverse effects included bone pain, lethargy, fever, rash, and weight gain. A first dose reaction characterized by hypoxia and hypotension was identified at dose levels greater than or equal to 1 microgram/kg. Dosing i.v. was less potent at inducing a leukocytosis than previously observed for equivalent s.c. doses and was associated with a higher incidence of generalized rash and first dose reactions. The maximal tolerated dose of i.v. rhGM-CSF was 15 micrograms/kg/day. Phase II studies in which the derived effect is to raise leukocyte levels should be undertaken at rhGM-CSF doses of 3 to 15 micrograms/kg/day.

Adult↗
PubMed1989

Platelet anti-Bakb antibody associated with neonatal alloimmune thrombocytopenia.

A platelet alloantibody of IgG class but unknown specificity was detected in the serum from the mother of an infant with neonatal alloimmune thrombocytopenia. The antibody reacted by indirect immunofluorescence with 33/65 random donors, 10/11 Baka-negative donors and 23/54 Baka-positive donors. The mother's platelet phenotype was PLA1, Koa, Kob, Baka and the father's was PLA1, Koa, Kob, Baka. Immunoblotting and immunoprecipitation of maternal serum with paternal platelets produced a band at molecular weight 140 kilodaltons identical to the band obtained with Baka antiserum. Family studies confirmed the allelic distribution of Baka and the unknown antigen. The platelet-specific antibody in this patient meets the criteria for an antibody to the new platelet antigen, Bakb.

Adult↗