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S Lyman

Publications and source records attributed to S Lyman.

34 records · Page 2Linked to original sources
PubMed1991

A deletion in the gene for glycoprotein IIb associated with Glanzmann's thrombasthenia.

The platelet fibrinogen receptor is composed of a complex of glycoproteins (GP) IIb and IIIa on the surface of platelets. Deficient function of this receptor prevents normal platelet aggregation, resulting in Glanzmann's thrombasthenia (GT). In this paper, we describe a black thrombasthenic patient who is either homozygous or hemizygous for a deletion within the GPIIb gene. Initial Western blot analysis of platelet proteins from this patient did not detect any GPIIb, but did detect small amounts of GPIIIa of normal mobility. Quantitation of vitronectin receptor (VNR) demonstrated that this thrombasthenic patient had approximately 1.5-2 times the number of these receptors per platelet compared with controls, a finding that has previously been noted in other thrombasthenic patients with defects in GPIIb. Genomic Southern blot studies demonstrated a deletion in the GPIIb gene of approximately 4.5 kilobasepairs (kb). Analysis of the isolated GPIIb gene demonstrated that the deletion begins between two Alu repeats within intron 1 and ends in intron 9. Polymerase chain reaction (PCR) studies using platelet RNA and oligonucleotides directed to both the 5' and 3' ends of the GPIIb cDNA sequence easily detected GPIIb transcript, suggesting that the genomic deletion of exons 2-9 does not significantly decrease the level of the GPIIb mRNA. Sequence analysis of PCR-generated GPIIb cDNA showed that a cryptic AG splice acceptor sequence was being utilized, resulting in a transcript that contained a portion of introns 1 and 9, as well as having a deletion of exons 2-9. Unlike the GPIIb gene, the GPIIIa gene appears to be intact by Southern blot analysis. PCR studies using platelet RNA and oligonucleotides directed to the GPIIIa cDNA sequence demonstrated the presence of GPIIIa mRNA. In summary, the thrombasthenic state in this patient appears to be due to a GPIIb gene deletion resulting in an abnormal transcript and no detectable platelet GPIIb. Platelet GPIIIa levels were secondarily low presumably due to the known instability of GPIIIa in the absence of GPIIb.

Adolescent↗
PubMed1990

Intracellular DNA strand scission and growth inhibition of Ehrlich ascites tumor cells by bleomycins.

A comparison of the intracellular DNA strand scission activities of the antitumor drug bleomycin, three of its metal complexes, demethyl bleomycin A2, and iron-containing, redox-inactivated bleomycin in Ehrlich ascites tumor cells was performed by means of the alkaline elution technique. This comparison was aided by use of CoCl2 to eliminate or minimize post-cell lysis strand scission by bleomycin in aliquots of treated cultures. No strand scission resulted from treatment of cells with the cobalt complex. The levels of intracellular DNA degradation by copper bleomycin and iron bleomycin were equivalent to those produced by metal-free bleomycin. The findings are correlated with previous measurements of growth inhibition by these three bleomycins as well as by cobalt bleomycin and related to the concentrations of radiolabeled bleomycin bound to DNA after treatment of cells with each form of drug. In comparison, both demethyl bleomycin A2 and iron-containing, redox-inactivated bleomycin showed marked, concentration-dependent reductions in random DNA strand scission, as compared with unmodified bleomycin or iron bleomycin prepared from Fe(III) and bleomycin. However, the fraction of DNA from cells treated with these two bleomycins, which eluted through filters prior to alkaline denaturation, was equivalent to that for unmodified bleomycin and Fe(III)bleomycin. The generation of this class of damaged DNA correlates more closely with concentration-dependent growth inhibition by each of the six forms of bleomycin than the degree of random strand scission.

Animals↗
PubMed1990

Polymorphism of human platelet membrane glycoprotein IIb associated with the Baka/Bakb alloantigen system.

The human Baka/Bakb alloantigen system has been implicated in the pathogenesis of post-transfusion purpura and neonatal alloimmune thrombocytopenic purpura. Human alloantisera specific for either the Baka or Bakb allele have been shown to react exclusively with the heavy chain of membrane glycoprotein (GP) IIb. To investigate the structure of the Bak epitopes, we used the polymerase chain reaction (PCR) to amplify GPIIb cDNA synthesized from platelet RNA samples prepared from individuals of known serologic phenotype. Subsequent DNA sequence analysis of amplified GPIIb cDNAs derived from one Baka homozygous individual and one Bakb homozygous individual revealed a single nucleotide base difference near the 3' end of the mRNA encoding the GPIIb heavy chain. Short 13 base allele-specific oligonucleotides (ASO) containing the putative phenotype-specific base in the middle were then synthesized, end-labeled with digoxigenin-11-dUTP using terminal transferase, and used as probes in subsequent dot-blot hybridization experiments. Platelet RNA was prepared from a panel made up of four Baka/a, three Bakb/b, and two Baka/b individuals, and the mRNA encoding GPIIb was amplified using PCR and spotted onto nylon membranes. ASO hybridization showed that the nucleotide base difference identified above segregated with Bak phenotype in all nine individuals examined (P = .002). The base pair substitution results in an amino acid polymorphism at residue 843 of the mature heavy chain. The Baka form of GPIIb encodes an isoleucine at this position, whereas the Bakb allele contains a serine. Identification of the polymorphism associated with this clinically important alloantigen system should permit new therapeutic and diagnostic approaches for treating and managing patients with alloimmune thrombocytopenic disorders.

Amino Acid Sequence↗
PubMed1990

PECAM-1 (CD31) cloning and relation to adhesion molecules of the immunoglobulin gene superfamily.

An antibody to a platelet integral membrane glycoprotein was found to cross-react with the previously identified CD31 myelomonocytic differentiation antigen and with hec7, an endothelial cell protein that is enriched at intercellular junctions. This antibody identified a complementary DNA clone from an endothelial cell library. The 130-kilodalton translated sequence contained six extracellular immunoglobulin (Ig)-like domains and was most similar to the cell adhesion molecule (CAM) subgroup of the Ig superfamily. This is the only known member of the CAM family on platelets. Its cell surface distribution suggests participation in cellular recognition events.

Amino Acid Sequence↗
PubMed1990

Radiographic examination of edentulous mouths.

Many dentists routinely make radiographs of edentulous patients who request replacement dentures. In the American Dental Associations' Guide to Dental Health, the public is informed that "an x-ray examination is performed only when necessary, not as a routine procedure, and only when the dentist believes such an examination will benefit your health." In light of the changing patterns of the incidence of disease and the cumulative effects of radiation exposure, a study was made of 300 edentulous ridges of dental patients. The study was confined to patients who were treated elsewhere with maxillary and mandibular dentures and who requested new dentures. Patients who had some clinically apparent finding that required radiographic investigation were excluded from the study. Only one impacted tooth that required extraction was found. The diagnosis of edentulous patients seeking treatment with replacement dentures should include a thorough patient history and clinical examination. When radiographs are indicated, they should be made but their routine use in such patients should be discouraged.

Aged↗
PubMed1990

Enhancement of cytotoxicity of bleomycin by dithiocarbamates: formation of bis(dithiocarbamato) cu(II).

Properties of the reactions of dithiocarbamates and their Cu(II) or Fe(III) complexes with Ehrlich cells were determined and related to their effects on the inhibition of cell proliferation caused by bleomycin and Cu bleomycin. In complete culture medium containing Eagle's minimal essential medium plus Earles salts and 2.5% fetal calf serum, dimethyl- and diethyldithiocarbamates and their copper complexes inhibit cell proliferation and cause cell death. The copper complexes are more effective agents. Ferric tris-diethyldithiocarbamate is also a cytotoxic species. In contrast, when cells are exposed to dimethyldithiocarbamate or its copper complex in Ringer's buffer under metal-restricted condition, washed, and then placed in complete medium, the copper complex is much more active in inhibiting cell growth. The difference is magnified when dihydroxyethyldithiocarbamate and N-methylglucamine dithiocarbamate and their copper complexes are compared in complete media. Incubation of bleomycin or copper bleomycin with Ehrlich cells in Ringer's buffer with or without dimethyldithiocarbamate or bis-dimethyldithiocarbamato Cu(II) leads to no enhancement of cytotoxicity from combinations of agents, except when the two copper complexes are present. Diethyl- or dimethyldithiocarbamate readily extracts copper from Cu(II)bleomycin and iron from Fe(III)bleomycin when ethylacetate is present to remove the tris-dithiocarbamato Fe(III) complex from aqueous solution. When bis-dimethyldithiocarbamato Cu(II) is incubated with Ehrlich cells, copper is released from the complex and bound to high molecular weight and metallothionein fractions. A reductive mode of dissociation of the copper complexes in cells is supported by ESR experiments. Reactions of diethyl- and dimethyldithiocarbamato Cu(II) with thiol compounds demonstrates one possible mechanism of reduction of these complexes.

Animals↗
PubMed1990

Iron deficiency in growing male rats: a cause of development of cardiomyopathy.

Weanling male rats were fed a purified iron-adequate, a purified iron-deficient or a commercial diet for 12 weeks. At that time the rats were sacrificed, their hearts and livers were excised, and blood samples were taken. Heart and liver weights were recorded; organ tissue and serum samples were analyzed for Zn, Cu and Fe. Hemoglobin and hematocrit values were also obtained. The iron-deficient rats grew much more slowly than controls on the iron-adequate or commercial diets. The iron-deficient rats were severely anemic and had enlarged hearts (cardiomegaly). A histopathologic examination of the hearts of all animals showed that each heart of the iron-deficient rats had lesions characteristic of cardiomyopathy by dilatation, whereas none of the hearts of the iron-adequate group or the chow controls showed any lesions at all. The iron-deficient animals had only about 25% of the hepatic iron found in the iron-adequate animals but about 5 times the hepatic copper of the latter group or the chow controls. Heart iron of the iron-deficient group was 27% of the concentration found in hearts of the iron-adequate rats; heart copper was similar in all groups. Animals on the commercial stock diet accumulated significantly more iron in their hearts than did those on the purified iron-adequate diet but not in the livers. There was also a direct correlation of heart iron or heart zinc with log concentrations of dietary iron and consequently a direct correlation between heart iron and zinc concentrations.

Animals↗
PubMed1989

Activity of bleomycin in iron- and copper-deficient cells.

Three models were used to examine the requirement of bleomycin (Blm) for iron (Fe) to carry out its antitumor or cytotoxic activity. Mice were made iron deficient by dietary means. Animals with depressed iron stores in liver and low plasma and ascites fluid iron supported Ehrlich tumor growth as well as mice maintained on a control diet. Bleomycin was equally effective against this tumor in iron-deficient mice as it was against the tumor in iron-sufficient controls. Likewise, nutrient copper deficiency did not change the efficacy of the drug. Ehrlich cells in culture were treated with a non-growth inhibiting concentration of the chelating agent, 1,10-phenanthroline before or during their exposure to bleomycin. Again, the treated cells were as sensitive to drug as controls, despite the fact that this ligand reduces cellular iron and zinc and can extract iron from Fe(II)Blm. Lastly, it was demonstrated that iron-depleted Euglena gracilis cells growing at reduced rates were as sensitive to growth inhibition by bleomycin as control cells.

Animals↗
PubMed1986

Properties of the initial reaction of bleomycin and several of its metal complexes with Ehrlich cells.

Characteristics of the reaction of bleomycin-A2 (BLM) and several of its metal complexes with Ehrlich cells in culture are described. Short incubation of BLM and Fe(III)-, Cu-, Zn-, and CdBLM with Ehrlich cells effectively inhibits cell proliferation. There is a sharp break at 30 min in the dependence of cytotoxicity upon time of exposure of cells to these forms of the drug. Qualitatively, the same curve can be generated by sequential additions of CoCl2 to cells during their first hour of incubation with BLM or Fe(III)BLM. The cobalt salt has less effect on CuBLM. The kinetics of initiation of the effect are directly correlated with the rapid kinetics of uptake of [3H]BLM by cells. Measurements of the initial rate of association of drug with cells as a function of extracellular BLM concentration suggest that a binding step is involved, for the rate of association approaches a maximal velocity at large concentrations of BLM. Uptake leads to both specific and nonspecific binding of tritium label; however, very little BLM gets into these cells. The internal concentration is estimated to be less than that in the external medium. BLM and its Fe(III) and copper complexes are taken up by Ehrlich cells to the same general extent after 60 min incubation; the cellular uptake of CoBLM is 25-50 times higher. Even the distributions of Fe(III)-, Cu-, and metal-free BLM within cytosol are comparable. A fraction binds to macromolecules; the rest appears unbound in low molecular weight fractions. The binding of [3H]BLM to cells cannot be reversed by incubation of labeled cells in drug-free medium or in media containing large concentrations of cold BLM.

Animals↗
PubMed1985

Terminal transferase surveillance of remission bone marrows in childhood acute lymphoblastic leukemia: improved sensitivity with countercurrent centrifugal elutriation.

In an attempt to better define hematologic remission and relapse in children with TdT positive acute lymphoblastic leukemia (ALL), 101 bone marrow (BM) aspirates were obtained from 74 pediatric patients. The mononuclear cell population of these specimens was isolated using countercurrent centrifugal elutriation (CCE) and characterized by an immunofluorescent terminal deoxynucleotidyl transferase (IF-TdT) assay. Twenty-two children with non-leukemic disorders had a median of 8% (range 0-34%) TdT positive mononuclear bone marrow cells. This was similar to values obtained for 25 children with ALL off therapy and in remission (median 10%, range 1-22%) and 16 children with ALL on continuous anti-leukemic therapy and in remission (median 7%, range 1-26%). Twenty-three BM samples were obtained from 11 children in early or high risk to relapse because of increased immature cells on a routine marrow examination or previous relapse(s). Samples from the early and high risk to relapse groups contained a median of 56% (range 25-80%) and 39% (range 25-72%) TdT positive cells. In contrast, the median percent marrow lymphoblasts identified using standard morphologic criteria for these 2 groups was 12.5% (range 9-23%) and 3% (range 0-5%), respectively. All high risk patients relapsed in their BM 1-4 1/2 months after these TdT determinations. Longitudinal studies in 4 patients at increased risk to relapse consistently demonstrated elevated percentages of TdT positive cells while morphologic surveillance was inadequate in establishing a clinical diagnosis of leukemic relapse. CCE in combination with an IF-TdT assay may enhance detection of recurrent and/or residual leukemia in BM samples from children with TdT positive ALL.

Bone Marrow↗
PubMed1984

Soldering index for minimal coverage retainers.

The soldering index serves to record the precise alignment of the separate parts of a fixed partial prosthesis as positioned on the abutments. The use of an all-acrylic resin index is not as accurate as a plaster index. When impression plaster is used alone, it is difficult to place minimal coverage retainers such as inlays back into the index. This article describes a simple method that may overcome the difficulty without sacrificing the dimensional accuracy inherent in a plaster index.

Acrylic Resins↗
PubMed1981

Immunoregulatory abnormalities in chronic lymphocytic leukemia. I. Correlations of immunoregulatory subpopulations with stage of disease.

Previous studies have demonstrated multiple immunologic abnormalities in Chronic Lymphocytic Leukemia (CLL). We, therefore, investigated the relationship of immunoregulatory mononuclear cell subpopulations and disease activity in inactive and active CLL. The absolute number of T cells is increased in both groups compared to controls and a significant increase (p less than 0.001) in the number of monocytes was found in active patients. When the number of Fc gamma bearing T cells was compared to the number of B cells, active patients revealed a 993% decrease and inactive patients a 93% decrease compared to controls. Inactive patients also revealed increased proliferation when stimulated (PHA) after 48 hours in media alone compared to fresh cells. The active group revealed no increase in preincubated (PHA) stimulated cultures. As this suggested the possibility of immunoregulatory differences, suppressor cells were studied. Con A induced suppressor cells decreased proliferation of PHA stimulated cultures in inactive and control groups but had no effect in active patients. Isolated fresh autochthonous T cells (1:1) decreased PHA-induced proliferation 86% in the inactive group, 50% in the control group but had no effect in active patients. Pre-incubation (48 hr) followed by T cell separation revealed decreased Fc gamma T cells and abrogation of this suppressive effect in both inactive and control groups. Finally, isolated adherent cells decreased PHA stimulation by 86% in active patients but had insignificant effects on preincubated PHA stimulated cultures in the other groups. These data suggest that inactive CLL is characterized by a population of T suppressor cells that are more active than similar numbers of this population in control cultures. This population is short-lived and correlated with the Fc gamma bearing T cell population. This population appears inactive or non-functional in active CLL where adherent suppressor cells are increased.

B-Lymphocytes↗