Biomedical subjects
Publications and source records attributed to R Sharon.
We describe the results of clinical, cytogenetic, and molecular biological studies of a patient who, after two courses of treatment with Busulphan, has remained free of symptoms of Philadelphia chromosome-positive chronic myeloid leukemia for 27 years, except for the persistence of a Ph1 chromosome and the presence of its transcribed chimeric mRNA.
BACKGROUND: During aging of red cells they undergo a multitude of physical and chemical changes. STUDY DESIGN AND METHODS: Age-dependent changes in the expression of ABH major blood group antigens on red cells were studied in a two-variable flow cytometric analysis. The expression of the antigens was measured after staining with fluorescence antibodies (for A and B) or lectin (for H). Cell age was related to size as measured by forward light scattering. Aging senescent cells are smaller and have low forward light scattering properties. RESULTS: The results indicated that, within a given population, the A and/or B and H antigens decreased with the decrease in forward light scattering (i.e., increase in age), but A and B antigen expression decreased to a greater extent than did H. CONCLUSION: During aging, red cells lose the antigens of the major blood groups, but the degree of this loss is related to the fact that these antigens are located on the cell surface.
Physiological concentrations of insulin support the in vitro growth of LB T-cell lymphoma. We could not detect similar insulin dependence in other tumor cell lines. This study reports that insulin also enhances the growth of LB cells in vivo. Mice treated with Streptozotocin (SZ) developed partial resistance to LB lymphoma growth and they survived longer (p < 0.0025) than non-diabetic mice after LB-cell inoculation. A few diabetic mice developed complete tumor resistance, manifested by total regression of the lymphoma. SZ-treated diabetic mice reconstituted with external insulin died as fast as non-diabetic mice when both were inoculated with the same number of LB cells. The SZ-treated diabetic mice did not develop resistance to the growth of BCLI B-cell leukemia, which demonstrated only a marginal proliferative response to insulin in vitro. Mice fed a low-energy diet exhibited low insulin levels and also developed resistance to lymphoma growth (50% survival 21 days vs. 15 days; p < 0.0005), supporting the concept that insulin enhances LB T-cell tumor development in mice.
To test the hypothesis that transfusion of blood donated by individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency may result in a hemolytic reaction, we conducted a prospective longitudinal study in which 10 patients transfused with 1 unit of G6PD-deficient and 1 unit of normal red blood cells (RBC) were compared with 10 patients transfused with 2 units of age-matched normal RBC. We found that 24 h after transfusion serum bilirubin (mumol/l) in the recipients of G6PD-deficient RBC was significantly higher than in the recipients of normal RBC (36 +/- 14 vs. 18 +/- 5, respectively, p > 0.004). A parallel increase was found in the serum lactate dehydrogenase (LDH; IU/l) between the two groups (378 +/- 151 vs. 264 +/- 56, p < 0.001). The difference in serum bilirubin (26 +/- 10 vs. 15 +/- 5, p < 0.03) was still noted 48 h after transfusion, with only a marginal difference (p < 0.08) in LDH. We conclude that an immediate posttransfusional hemolytic reaction can occur in recipients of G6PD-deficient RBC and therefore suggest that the differential diagnosis of posttransfusional hemolysis, particularly in populations where G6PD deficiency is prevalent, includes transfusion of erythrocytes from G6PD-deficient donors.
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A simple method for detecting damage to the blood genital tract barrier (BGTB) is presented. The method is based on the ubiquitous presence of the natural anti-alpha-galactosyl (anti-Gal) IgG antibodies in high titers in the serum of every normal individual, and the interaction between this antibody and alpha-galactosyl residues on rabbit red blood cells (RabRBC). The binding of the anti-Gal antibodies to RabRBC could be demonstrated by the rosetting antiglobulin test. The seminal fluid (SF), normally compartmentalized from the blood, is devoid of anti-Gal reactivity. The SF of a large proportion of infertile males contained significant anti-Gal reactivity, implying transudation of serum IgG molecules probably due to damage in the selective permeability of the BGTB. The diagnostic potential of this assay is discussed.
In this paper we describe a murine experimental model of autoimmune hemolytic anemia induced with multiple injections or oral feeding of levodopa. Strain A mice were intraperitoneally injected or fed with levodopa, at a dose equivalent to the one used in human therapy, and subsequently they developed cycles of IgM, IgG and IgA anti-mouse red blood cells (MRBC) autoantibody responses. Levodopa injection induced serum IgM and IgG anti-MRBC responses and levodopa feeding enhanced the serum anti-MRBC IgA response. The appearance of autoantibodies in the serum was followed by binding of the autoantibodies to mice erythrocytes and three phases of anemia. Red cell bound IgM and IgG autoantibodies were predominant in levodopa-injected mice whereas red cell bound IgA autoantibodies were predominant in levodopa-fed mice. The specificity of the serum IgA autoantibody was not restricted since it interacted with erythrocytes of various species.
A flow cytometry method has been employed to quantitatively compare the expression of A, B and H antigens on various red blood cells (RBC). The H substance was directly labelled by fluorescein-conjugated anti-H lectin and the A and B antigens by indirect staining first with monoclonal anti-A or anti-B antibodies followed by fluorescently, fluorescein (FITC) or phycoerythrin (PE), labelled anti-mouse immunoglobulin (Ig) antibodies. More than a ten-fold difference in cellular fluorescence intensity was found within each sample. Both the percentage and the mean fluorescence of the positive subpopulation for each antigen were determined. Each RBC population was characterized with respect to the expression of A, B or H antigen by a compound mean value that was the calculated product of these two parameters. The results demonstrated a reciprocal relationship between the compound means of A or B and H. The ratio of A/H or B/H was found to be most informative. Homozygotes for A or B had ratios of greater than 200 and greater than 30, respectively, while heterozygotes (AO or BO) had ratios of less than 5. This method could also distinguish between A1 and A2; RBC carrying the A1 phenotype (as determined by agglutination with anti-A1 lectin) showed a higher A/H ratio than those carrying A2. In contrast to the reciprocity in the expression of A (or B) and H found in RBC obtained from different individuals, a direct correlation was found in the expression of these antigens by individual cells within a given population.(ABSTRACT TRUNCATED AT 250 WORDS)
The cochlea is innervated by sympathetic nerves originating or passing the superior cervical ganglion. The termination of one type (the vascular independent) is in the habenular region close to the auditory nerve fibers, and the other, the perivascular type, is associated with blood vessels, particularly in the spiral vessel of the tympanic lip. Suggested functions have so far received partial evidence in the literature. Borg (1982) suggested the protective value of sympathectomy of the ear in noise. Our experiments further elaborate this protective value, as it was seen that bilateral cervical sympathectomy diminished the temporary threshold shift in awake, sound exposed GP.
Diffracting crystals, suitable for X-ray crystallographic analysis, have been obtained from large (50 S) ribosomal subunits from Thermus thermophilus. These crystals, with P4(1)2(1)2 symmetry and a unit cell of 495 A x 495 A x 196 A, reach typically a size of 0.15 mm x 0.25 mm x 0.35 mm. Using synchrotron radiation at cryo-temperature, these crystals diffract X-rays to better than 9 A resolution, and do not show any measurable decay after a few days of irradiation. They complete a series of crystals, grown by us, from ribosomal particles of the same source, including a 30 S subunits, 70 S ribosomes and complexes of the latter with: (1) an oligomer of 35 uridine residues and (2) the same oligonucleotide together with approximately two Phe-tRNA(Phe) molecules. Crystallographic analysis of the various members of this series should provide information for investigating the conformational changes that take place upon the association of ribosomes from their subunits as well as upon binding of non-ribosomal components that participate in protein biosynthesis.
Xeroderma pigmentosum cells, which are deficient in the repair of UV light-induced DNA damage, have been used to clone DNA-damage-inducible transcripts in human cells. The cDNA clone designated pC-5 hybridizes on RNA gel blots to a 1-kilobase transcript, which is moderately abundant in nontreated cells and whose synthesis is enhanced in human cells following UV irradiation or treatment with several other DNA-damaging agents. UV-enhanced transcription of C-5 RNA is transient and occurs at lower fluences and to a greater extent in DNA-repair-deficient than in DNA-repair-proficient cells. Southern blot analysis indicates that the C-5 gene belongs to a multigene family. A cDNA clone containing the complete coding sequence of C-5 was isolated. Sequence analysis revealed that it is homologous to a human cellular sequence encoding the amino-terminal activating sequence of the trk-2h chimeric oncogene [Kozma, S. C., Redmond, S. M. S., Xiao-Chang, F., Saurer, S. M., Groner, B. & Hynes, N. E. (1988) EMBO J. 7, 147-154]. The presence of DNA-damage-responsive sequences at the 5' end of a chimeric oncogene could result in enhanced expression of the oncogene in response to carcinogens.
The fact that levodopa, a drug used for the treatment of Parkinson's disease induces a direct Coombs-positive reaction in about 15% of treated patients, indicating the presence of auto-antibodies against the patient's red blood cells (RBCs), is well known. Another known fact is that only 1% of those patients do actually develop auto-immune haemolytic anaemia. In this paper, we describe our findings utilizing the direct ELISA, a method for measuring the presence of IgM and IgG auto-antibodies on the patients' red blood cells (RBCs), as well as an indirect ELISA, testing the presence of antibodies in their serum. The tests were performed on 8 patients, 7 of whom had been receiving the drug for long periods of time. Our results show that the serum antibodies precede the bound antibodies in a significant fashion and that the severity of the anaemia is directly related to the amount of auto-antibodies. Since auto-antibodies do not seem to be directed against the drug itself, some modification of the RBC must occur. For this reason, we attempted to determine whether patients receiving the drug show any morphological changes of their RBCs which could be determined by scanning electron microscopy (SEM) and whether these changes could be related to direct and indirect ELISA. In most levodopa-treated patients, a small number of echinocytes could be observed by SEM, while in 1 patient who suffered a severe anaemic phase, a very high percentage of the RBCs were echinocytes and spherocytes.(ABSTRACT TRUNCATED AT 250 WORDS)
Erythropoietin-dependent regulation of erythropoiesis in myelodysplastic syndromes (MDS) was evaluated by measuring the in vitro response of primitive (BFU-E) and relatively mature (CFU-E) erythroid progenitors from 12 patients and from eight healthy donors to recombinant human erythropoietin (rhEPO), and by quantifying relationships between circulating EPO levels and progenitor cell frequencies in MDS marrow. Half-maximal growth of MDS CFU-E and BFU-E was detected at a 4-fold higher rhEPO concentration than required by control erythroid progenitors. Nine of the patients evaluated exhibited maximal growth of erythroid colonies at 5- to 20-fold higher than control saturating rhEPO concentrations. Circulating EPO levels in MDS patients were elevated, with a mean value approximately 35-fold higher than that of controls. The frequency of MDS marrow CFU-E and BFU-E was 57 +/- 42% and 18 +/- 9% of the mean control values, respectively. Correlation analysis of the relationships between MDS EPO levels and erythroid progenitors indicated that the anemia in MDS is not attributable to an abnormality in the capacity of EPO to induce the generation of CFU-E, but may be influenced by the BFU-E population, whose severe deficiency results in insufficient influx of EPO-responsive cells. Our findings therefore suggest that treatment of MDS patients with rhEPO may be of limited benefit, since the generation of BFU-E from more primitive ancestors and the initial growth requirements of these cells are not under the regulatory influence of this hormone.
HLA typing of amniotic cells for clinical purposes using the conventional cytotoxicity assay is a laborious and complicated procedure. In the present study we demonstrate that HLA class I typing of the fetus can be determined using the enzyme linked immunosorbent assay (ELISA) either on amniotic cells or soluble free antigens shed by the cells into the culture medium. Our results indicate that the ELISA technique is a sensitive and reliable assay that can be used as an alternative method of HLA class I typing of amniotic cells.
This paper describes an experimental model of autoimmune hemolytic anemia induced with multiple injections of levodopa. The serum antibodies were detected by indirect enzyme-linked immunosorbent assay (ELISA) and autoantibodies bound to syngeneic erythrocytes were detected by direct ELISA. A strain of mice injected with levodopa, at doses which are approximately equivalent to those used in human therapy, developed early and late cycles of IgM and IgG anti-mouse red blood cell (MRBC) autoantibody responses. These responses were followed by binding of IgM and IgG autoantibodies to the syngeneic erythrocytes and by two phases of anemia. Different strains of mice exhibited different sensitivities to Levodopa treatment, suggesting that genetic factors affect the anti-MRBC autoantibody response to levodopa. Indirect ELISA revealed that mice subjected to both X-irradiation (250 rad) and levodopa treatment had higher levels of IgG anti-MRBC autoantibodies than mice subjected to levodopa treatment alone, suggesting that a radiosensitive suppressor mechanism controls the autoantibody response. The autoantibodies induced with levodopa exhibited an unrestricted specificity and retained significant activity after absorption of MRBC. Serum autoantibodies were also detected by indirect ELISA in the sera of normal mice. This "natural" autoimmunity was mouse strain dependent and was possibly further influenced by environmental factors. The various implications of this model of autoimmune hemolytic anemia are discussed.
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Simulation of the molecular dynamics of a small protein, bovine pancreatic trypsin inhibitor, was found to be more realistic when water molecules were included than when in vacuo: the time-averaged structure was much more like that observed in high-resolution x-ray studies, the amplitudes of atomic vibration in solution were smaller, and fewer incorrect hydrogen bonds were formed. Our approach, which provides a sound basis for reliable simulation of diverse properties of biological macromolecules in solution, uses atom-centered forces and classical mechanics.
Structural modelling techniques using energy minimization and molecular dynamics have been employed to generate kinked models for the solution structure of two DNA tridecamer sequences containing inserted adenosines: d(CGCAGAATTCGCG)2 and d(CGCAGAGCTCGCG)2. These models are consistent with NMR studies of these sequences in solution. The overall shapes of the two models are similar, consisting of three B-DNA sections: two outer segments on the same side of the central portion, with the additional adenosines acting as wedges to kink the structure. An alternative scheme for the hydrogen bond pairing at the kink site is suggested as a way for the additional adenosines to be stabilized in the duplex.