Larva tick bite of the conjunctiva.
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Adult↗
Biomedical subjects
G Lam
Publications and source records attributed to G Lam.
IFN-gamma and IFN-alpha induce the expression and synthesis of Leu 13 antigen by cultured human endothelial cells.
Leu 13 is a 16 kDa human lymphocyte surface Ag and monoclonal anti-Leu 13 induces T cell aggregation and alters T cell proliferation. In previous studies using anti-Leu 13, Leu 13 Ag has been detected on endothelial cells (EC) of arteries, capillaries, and veins in human tissue sections. In contrast, in this study using the same antibody, Leu 13 Ag could not be detected on unstimulated cultured human umbilical vein endothelial cells (HUVEC) by indirect immunofluorescence, immunoperoxidase staining, or immunoisolation of radiolabeled Ag from labeled endothelial cells. However, when HUVEC were cultured with IFN-gamma, Leu 13 Ag was demonstrable using all three detection techniques. Leu 13 Ag was detectable after 24 h of incubation with IFN-gamma (30 U/ml) and was maximally expressed after 72 h. After removal of IFN-gamma, Leu 13 Ag progressively declined back to basal levels by 4 days. Induction of Leu 13 Ag expression by IFN-gamma was suppressed by cycloheximide. Although Leu 13 Ag expression was also induced by IFN-alpha, PMA, and IL-1 were inactive. When HUVEC were incubated with IFN-gamma, surface-labeled with 125I, and then solubilized, anti-Leu 13 immunoisolated a 16-kDa radioactive band that comigrated with Leu 13 immunoisolated from T cells. Similar results were obtained using HUVEC that were metabolically labeled with 35S-methionine. These results demonstrate that HUVEC stimulated with IFN-gamma and IFN-alpha express Leu 13 Ag on their surface and suggest that exposure of EC to IFN may induce EC to develop new functional properties at sites of inflammatory and immune reactions.
Antibodies, Monoclonal↗
Thrombin and histamine stimulate the phosphorylation of elongation factor 2 in human umbilical vein endothelial cells.
The effects of thrombin and histamine on protein phosphorylation in intact cultured human umbilical vein endothelial cells (HUVEC) prelabeled with 32PO4 were investigated. Incubation of HUVEC with either thrombin or histamine, agonists known to induce rapid transient increases in intracellular calcium levels in HUVEC, caused a rapid reversible increase in the phosphorylation of a protein with a Mr = 100,000 independent of the presence of extracellular calcium. Immunological and biochemical studies demonstrated that this Mr = 100,000 protein is elongation factor 2 (EF-2), a substrate previously shown to be phosphorylated by calcium/calmodulin-dependent protein kinase III (Nairn, A. C., and Palfrey, H. C. (1987) J. Biol. Chem. 262, 17299-17303). EF-2 is crucial for protein synthesis because it catalyzes the translocation of peptidyl-tRNA on the ribosome. Phosphoamino acid analysis of the EF-2 immunoprecipitated from HUVEC revealed that all of the thrombin-stimulated phosphorylation occurred on threonine. EF-2 was also phosphorylated when HUVEC were treated with the calcium ionophore, ionomycin. Phosphorylation of EF-2 was not increased by treatment with D-Phe-Pro-Arg-chloromethyl ketone thrombin, phorbol dibutyrate, forskolin, or 8-bromo-cGMP. The transient nature of the phosphorylation of EF-2 is consistent with it having a role in mediating some of the transient effects of thrombin and histamine on endothelial cell protein synthesis and functional capabilities.
Calcium-Calmodulin-Dependent Protein Kinases↗
Gene mapping by enzymatic amplification from flow-sorted chromosomes.
A new approach to gene mapping which combines enzymatic amplification with high-resolution flow sorting of human chromosomes has been devised. Reliable amplification from as few as 200 chromosomes has been demonstrated. This method, with particular application to mapping the position of chromosomal translocations, has been used to show that the breakpoint for the constitutional translocation t(11;22)(q23;q11) lies proximal to the genes c-ets-1, Thy-1, and T3 delta and distal to the int-2 gene. The mapping was confirmed by Southern analysis to much larger numbers of chromosomes sorted from the same cell line. Control reactions for the bcl-2 gene on chromosome 18 and the C alpha gene of the IGH locus on chromosome 14 demonstrated the discrimination which can be achieved.
Base Sequence↗
Assignment of the gene encoding the beta-subunit of the human fibronectin receptor (beta-FNR) to chromosome 10p11.2.
A cDNA corresponding to the beta-subunit of the human fibronectin receptor (beta-FNR) was used as a probe in Southern blot analysis of mouse/human somatic cell hybrid DNAs and in in situ hybridization to metaphase chromosomes. The beta-FNR cDNA detects sequences present on human chromosome 10 as well as recognizing homologous sequences in the genome of the mouse parent of the somatic cell hybrids. In situ hybridization refined the localization of human sequences reacting with the beta-FNR cDNA to 10p11.2. The A-1A5 monoclonal antibody which recognizes the beta-subunit of the fibronectin receptor on the cell surface was used to confirm that the sequences present on chromosome 10 correspond to those required for expression of beta-FNR.
Animals↗
Rearrangement of T-cell receptor and immunoglobulin heavy chain genes in childhood acute mixed lineage leukaemia.
Rearrangement of the beta and gamma chain genes of the TCR gene complex and of the Ig heavy chain genes were examined in three cases of childhood acute mixed lineage leukaemia. Blast cells, classified morphologically as acute lymphoblastic leukaemia (ALL) in one child and acute non-lymphocytic leukaemia (ANLL) in the other two, all co-expressed markers associated with both T (CD7, TdT) and myeloid (CD33) cells. Cytogenetic analysis detected abnormalities associated with myeloid leukaemia. Immunoglobulin heavy chain genes were not rearranged in two patients but a novel rearrangement was seen in the third. No rearrangement of the beta or gamma chains of the T-cell receptor complex were seen. Acute mixed lineage leukaemia may thus arise from a pluripotent precursor cell capable of both lymphoid and myeloid differentiation.
Antigens, Differentiation↗
Cellular and molecular studies on infant null acute lymphoblastic leukemia.
We have studied the cellular and molecular basis of eight cases of infant null acute lymphoblastic leukemia (ALL). All eight patients were under 9 months of age and presented with leukocyte counts in excess of 60 X 10(9)/L, organomegaly, and in two cases CNS infiltration. Although seven cases were morphologically classified as ALL, one patient had both lymphoid and myeloid features. Phenotypic analysis of leukemic blasts from all patients showed a typical null ALL pattern, ie, CD10 (common ALL antigen)-negative, strongly HLA-DR-positive, and CD19 (B4)-positive. The presence of terminal deoxynucleotidyl transferase (TdT) at presentation was positive in six patients' cells and negative in two. Two patients also expressed the myeloid-associated markers CD33 (MY9) and CD15 (TG1), and coexpression of CD19 and CD33 was confirmed in these two by using dual marker flow cytometry (fluorescence-activated cell sorting). Electron microscopic examination of the same two patients' cells showed the presence of monocytoid blasts that labeled with the pan-B cell antibody B4 (CD19). Short-term culture of one of these patients cells in the presence of phorbol ester resulted in the majority of the cells exhibiting myeloid markers, strong nonspecific esterase positivity, and phagocytic properties. Cytogenetic analysis showed the common feature in 7 of 8 cases to be a break in band 11q23. Molecular analysis of DNA from the blast cells of all eight patients showed rearrangement of the immunoglobulin heavy-chain genes in all cases without, however, any evidence of kappa light-chain rearrangement. T cell receptor genes were present in the germline configuration in all cases. Rearrangements of the c-ets 1 oncogene, which maps to band 11q23, were not detected, thus providing no evidence for involvement of this oncogene in the common disease process. Our data indicate that although infant null ALL may present as a heterogeneous disease the similarity of many features between cases suggests a common derivation from a precursor cell sharing phenotypic and genotypic features of both B and myeloid progenitor cells.
Antigens, Neoplasm↗
Electrochemical determination of oxymorphone in rat plasma by ion-pair reversed-phase high-performance liquid chromatography.
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Animals↗
Effect of platelet-derived growth factor on enriched populations of haemopoietic progenitors from patients with chronic myeloid leukaemia.
The effect of pure platelet-derived growth factor and fresh serum on the in-vitro growth of purified haemopoietic progenitors from the peripheral blood of 12 patients with CML was studied. Purified haemopoietic progenitors were prepared using Percoll separation followed by cell sorting with the monoclonal antibody BI.3C5. Both pure PDGF at a concentration of 20 ng/ml and fresh serum significantly increased the numbers of BFU-E (p less than 0.01) and CFU-GEMM (p less than 0.014), but not the CFU-GM. That the PDGF effect was not mediated to any significant extent via prostaglandins, was shown by the lack of inhibitory effect of indomethacin on the growth of purified progenitor cells in the presence of fresh serum. Increased amounts of pure PDGF were required to give maximal stimulation of purified CML peripheral blood progenitors compared to normal bone marrow progenitors. These results show that CML progenitors are capable of responding to PDGF. Whether the quantitative difference in response is due to a reduced proportion of mesenchymal cells in CML peripheral blood compared to normal marrow, or whether CML progenitors are most likely already stimulated by autocrime PDGF or other growth factors remains to be elucidated.
Antibodies, Monoclonal↗
The response of mouse epidermis to fractionated doses of pi mesons.
An extensive series of preclinical experiments are described in which the relative biological effectiveness (RBE) of pions from TRIUMF has been determined for mouse skin. To measure the RBE at both high and low doses per fraction, a range of fractionation schedules was used, with 1, 2, 4, 10, and 20 fractions. Because the pion dose rate is much lower than the dose rate of X or gamma-rays used in radiotherapy, two sets of reference X ray data were obtained: one at the same dose rate as the pions (15 cGy min-1), and another at the more conventional 150 cGy min-1. This allowed a "biophysical" RBE for equivalent dose rates and a "practical" RBE for preclinical evaluation to be calculated. The pion RBE was significantly higher for 20 small fractions than for fewer large doses. The absolute value of RBE depends upon the dose rate of the reference X ray treatments. The "practical" RBE increased from 1.05 at high doses to 1.45 at the smallest dose per fraction tested. The "biophysical" RBE for equivalent dose rates ranged from 1.20 at high doses to 1.5 for 20 fractions.
Animals↗
Co-ordinate expression of BI.3C5 and HLA-DR antigens on haemopoietic progenitors from chronic myeloid leukaemia.
Haemopoietic cells isolated from the peripheral blood of patients with chronic myeloid leukaemia (CML), have been extensively purified and enriched using either Percoll density gradients or Percoll density gradients combined with elutriation. The quantitative expression of the BI.3C5 associated antigen and the co-expression of BI.3C5 and HLA-DR antigens on these two populations has been studied using either single or simultaneous two colour FACS sorting, following by in-vitro culture for single and multilineage haemopoietic progenitors thus obtained. The data show that the CFU-GEMM are always found in the most strongly BI.3C5 positive fraction, irrespective of the separation procedure and that the bulk of the CFU-GEMM co-express BI.3C5 and HLA-DR. The cell types initiating these CFU-GEMM are morphologically immature blasts. The more mature cells of the myelomonocytic and erythroid lineages forming single lineage colony types show variable BI.3C5 expression, although most are HLA-DR positive. Such enriched populations of malignant progenitors could provide a useful source of material to study both gene expression and the molecular mechanisms underlying malignant transformation.
Antibodies, Monoclonal↗
Pions and pig skin: preclinical evaluation of RBE for early and late damage.
The skin of 50 pigs has been irradiated with negative pi mesons and with X rays in order to determine the RBE for early epidermal and later dermal damage. Late fibrosis was not studied. Four, 7, 9 and 10 fractions were used. An estimate of the RBE was made from the reactions on each pig for both early and late damage so that interanimal variability would be avoided. The data were also averaged to obtain mean dose response curves. There was no tendency for higher RBE's for late than for early skin damage. These pig studies have demonstrated an RBE of about 1.5 for early epidermal reactions and a slightly lower RBE (approximately 1.4) for later dermal damage in the same animals. This indicates that at doses of about 2.0 to 3.5 Gy pions, the medium wave skin damage is unlikely to be more severe than would be predicted from the early skin reactions and the accumulated clinical experience with X rays. However, if the trend to a steeper slope for the RBE versus dose per fraction for late injury is correct, as indicated by other published studies a relative increase in the late injury might be expected if much lower doses per fraction are used. The present clinical studies at Vancouver using 15 X 2.1 Gy pions indicate that an RBE of 1.5 is appropriate for epithelia, brain and colorectum.
Animals↗
Rapid estimation of total body clearance of theophylline in patients receiving intravenous aminophylline infusion.
The method of Chiou to rapidly estimate theophylline total body clearance using two serum concentration data during the early stage of intravenous aminophylline infusion was evaluated in 16 patients with acute exacerbation of asthma or chronic obstructive pulmonary disease. The observed serum concentrations at later times were compared with those predicted. The mean prediction error for serum concentrations was 4.93% with a standard deviation of 20.06%. These results indicate that this simple method of Chiou may offer a reliable rapid estimation of total body clearance for dosage individualization in patients receiving intravenous aminophylline infusion.
Adult↗
The human leucocyte-common antigen: differential expression of framework and restricted antigenic determinants on early haemopoietic progenitors.
Monoclonal antibodies have been raised against human LC determinants. One, F10.89.4, recognizes a 'framework' epitope on all LC molecules; the other, F8.11.13, recognizes a 'restricted' epitope present on only a subset of these molecules which are found mainly on B and a subpopulation of T cells. A previous study of leukaemias showed that some early lymphoid and myeloid leukaemic cells totally lack LC (35% of ALLs and AMLs are F10.89.4-, F8.11.13-). In contrast, a proportion of myeloid leukaemias carried both 'framework' and 'restricted' epitopes (30% AMLs and AMMLs are F10.89.4+, F8.11.13+). To determine whether comparable heterogeneity exists in normal bone marrow we have analysed LC expression during haemopoiesis, using FACS separated populations and in vitro progenitor assays. Our data show that the great majority of haemopoietic progenitors express the LC 'framework' epitope. These can be separated by size into myeloid (large) and lymphoid (small) progenitor populations. However, very few myeloid progenitors (11% CFU-GM, 6% CFU-GEMM) express the additional 'restricted' LC F8.11.13 epitope. Most F8.11.13+ progenitors are CFU-lymphoid; these generate both T and B lymphocytes, but show a preference for the B lineage. Thus there is some molecular heterogeneity of LC during normal haemopoiesis, but this is far less extensive than that found in leukaemias.
Adult↗
Determination of tissue to blood partition coefficients in physiologically-based pharmacokinetic studies.
The partition coefficient between tissue and blood used in physiologically-based pharmacokinetic modeling analysis was investigated using the concept of clearance. New equations were derived and compared with previously reported equations in constant intravenous infusion and bolus injection methods. The importance of differentiating arterial from venous blood is discussed.
Infusions, Parenteral↗
Arterial and venous blood sampling in pharmacokinetic studies: griseofulvin.
The pharmacokinetics of griseofulvin were evaluated simultaneously using both arterial and venous plasma in three dogs and one rabbit after a rapid bolus intravenous dosing. Initial arterial-venous ratios 20 sec after injection were the highest and ranged from 15- to 752-fold for dogs; the ratio was 3240-fold for the rabbit. Both curves decayed paralleling each other at the terminal phase with the venous levels higher than arterial levels by 14-43 and 8.4% for the dogs and the rabbit, respectively. The use of the instantaneous input principle was found to overestimate the total area under the plasma level-time curve by as much as 166%. An exponential term with a negative coefficient was used to account for the short and steep rising phase of plasma levels after injection. Detailed analyses showed significant differences in various calculated pharmacokinetic parameters based on arterial or venous data. The present study exemplifies the need for careful assessment and interpretation of classical pharmacokinetic parameters. It appeared that short intravenous infusion rather than the instantaneous or rapid bolus intravenous injection should be preferred for routine pharmacokinetic studies.
Animals↗
Determination of the steady-state volume of distribution using arterial and venous plasma data from constant infusion studies with procainamide.
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Animals↗
Changes in cell surface antigen expression during hemopoietic differentiation.
Human bone marrow cells were separated on a fluorescence activated cell sorter (FACS) according to their binding of a series of monoclonal antibodies; the positive and negative fractions were cloned for erythroid burst and colony-forming units (BFU-E and CFU-E) and myeloid colony-forming units (CFU-GM), and cytocentrifuge slides were prepared for microscopy of maturing precursors. The pattern of antigen expression on hemopoietic progenitor and precursor populations has been established using antibodies defining blood group (A, I/i), HLA-associated (*A, B, C, DR, DC1), lineage specific, and transferrin receptor antigens. Like monomorphic HLA-DR, the antigen defined by monoclonal antibody OKT10 is expressed on the earliest progenitors and lost during differentiation, suggesting a role in interactions regulating the differentiation of these cells. The HLA-linked DC1 determinant, in contrast to HLA-DR, is not expressed at a detectable level on progenitor cells. Although a lineage-specific early antigen has not been identified, the transferrin receptor is expressed on the majority of erythroid progenitors, but only weakly on myeloid progenitors, and may provide an approach to isolating erythroid progenitors. These and earlier studies with monoclonal antibodies against HLA-DR and glycophorin now provide a detailed "map" of antigen expression during hemopoietic differentiation.
ABO Blood-Group System↗