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Biomedical subjects

D Manor

Publications and source records attributed to D Manor.

At least 91 records · Page 5Linked to original sources
PubMed1985

DNA synthesis by erythroid precursors in a completely defined medium: a rapid, sensitive, and convenient bioassay for erythropoietin.

We detail a novel, sensitive, and reproducible in vitro bioassay for erythropoietin that can be performed conveniently in any laboratory and is well suited for analysis of large numbers of samples. The assay measures DNA synthesis by a cohort of highly erythropoietin-responsive red cell precursors appearing in bone marrow of anemic rabbits after treatment with a single dose of actinomycin D. The assay is conducted in a completely defined culture medium that totally dispenses not only with serum but also with serum-replacing factors. Under well-defined conditions, incorporation of [3H]thymidine by the cells depends specifically on erythropoietin. A stimulation index of up to 40-fold is obtained at 50 mU/ml of the hormone. The assay is linear in the range 0-50 mU/ml and not saturated before 1 U/ml of erythropoietin. Sample volumes of 1-30 microliter suffice for assay. Assay cells can be frozen in aliquots that retain their viability and ability to respond to erythropoietin over extended periods. Using microtiter-plate techniques, cells from one rabbit suffice for over 5000 triplicate erythropoietin determinations. Concentrations of 0.1-0.2 mU/well of erythropoietin can be detected. Erythropoietin values determined in sera from a variety of patients correlate extremely well with values obtained by the colony formation method. The ability to follow erythropoietin-dependent DNA synthesis and multiple cell divisions by a cohort of erythroid precursors in completely defined culture conditions may find application in controlled studies of red cell development.

Anemia↗
PubMed1984

Elimination of graft-versus-host disease by in-vitro depletion of alloreactive lymphocytes with a monoclonal rat anti-human lymphocyte antibody (CAMPATH-1).

A new monoclonal rat anti-human lymphocyte antibody (CAMPATH-1) which lyses cells with autologous human complement was used for depletion of T lymphocytes from human bone-marrow allografts in vitro before transplantation in 11 high-risk patients. HLA-matched siblings were used as marrow donors. T-cell depletion was substantial when measured by E-rosette formation (0-0.18% residual T cells) and immunofluorescence with a monoclonal anti-T-cell antibody (0-0.5%). No anti-graft-versus-host disease prophylaxis was given after transplantation. Rapid engraftment was reported in all patients, and the post-transplantation course was uneventful. No signs of graft-versus-host disease developed in any of the patients, who were observed for a maximum period of 12 months. The method might be suitable for larger-scale studies in high-risk patients. The late graft failure seen in 2 patients may reflect residual host resistance uncompromised by GvHD.

Adolescent↗
PubMed1984

Tailor-made agarose-based reactive beads for hemoperfusion and plasma perfusion.

Composite beads of approximately 1 mm diameter, made of crosslinked agarose and containing Fuller's Earth or zirconium oxide powders, were prepared and used in extracorporeal systems for blood detoxification. The former was used for the removal of Paraquat, while the latter was used to remove inorganic phosphate from hyperphosphatemic animals with or without acute renal failure. The high surface area of the powder, combined with the low resistance to diffusion in the crosslinked agarose matrix, are highly advantageous. The crosslinking provides high mechanical strength, heat stability, prolonged shelf life, good blood flow characteristics, and prevents the release of fine particles into the blood. Crosslinked agarose beads of 1 mm diameter, containing chemically-bound heparin were also prepared, and used as a model for direct contact removal of LDL-cholesterol from the blood of familial hypercholesterolemic patients by hemoperfusion. The high capacity of these beads (over 5 mg LDL/mL beads) indicates that this clinical modality can replace the highly expensive plasmapheresis procedure presently used.

Animals↗
PubMed1983

Cytotoxicity of arabinofuranosyladenine and erythro-9-(2-hydroxy-3-nonyl) adenine to Epstein-Barr virus producer and nonproducer lymphoma cells in culture.

Adenine arabinoside (ara-A) at a concentration of 5-10 micrograms/ml inhibited the multiplication of two Epstein-Barr virus (EBV) producer lymphoblastoid cell lines B . 95-8 and P3HR-1. The nonproducer EBV genome carrier cell line, Raji, and the EBV negative cell line, Ramos, were not significantly affected. The cytotoxicity of ara-A to Ramos, Raji and P3HR-1 cells increased in the presence of 1 . 10(-5)M erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), an inhibitor of adenosine deaminase. EHNA alone was noncytotoxic and even had a mild stimulatory effect on cell multiplication. The level of adenosine deaminase in Raji and Ramos cells was similar to that observed in human cord blood lymphocytes, as determined by starch gel electrophoresis. A low level of adenosine deaminase was detected in P3HR-1 cells and the enzyme was absent from B . 95-8 cells. These findings indicate that in the absence of adenosine deaminase, ara-A cytotoxicity increased. Ara-A (5 micrograms/ml) and EHNA (1 . 10(-5)M) had no effect on human cord blood lymphocytes stimulated by phytohemagglutinin as measured by (3H) thymidine uptake, but had some effect on protein A-stimulated lymphocytes. Ara-A, however, inhibited the transformation of human cord blood lymphocytes by EBV, which EHNA did not inhibit. The synthesis of EBV capsid antigen in B . 95-8 cells was also inhibited by ara-A and slightly stimulated by EHNA.

Adenine↗
PubMed1982

Organophosphorous compounds as inhibitors of EBV infection and transformation.

Phosphonoformic acid trisodium salt (PF), ethyl diethyl-phosphonoformate (Et-PF), phosphonoacetic acid (PAA), ethyl diethyl phosphonoacetate (Et PAA), ethyl diethyl-2-phosphonopropionate (Et-2-PPA) and ethyl diethyl-3-phosphonopropionate (Et-3-PPA) were tested as inhibitors of EBV virus capsid antigen (VCA) synthesis in B.95-8 cells by immunofluorescence. The most effective inhibitors were: PF, inhibition of 96.74 percent of VCA synthesis at a concentration of 500 microM and PAA, inhibition of 82.05 percent of VCA synthesis at a concentration of 250 microM. Much higher concentrations of the other compounds were needed for inhibition with lower efficiency. Synthesis of EBV nuclear antigen (EBNA) was not inhibited by PF or PAA. However, only PF and PAA inhibited the transformation of human cord blood lymphocytes (CBL) by EBV, as measured by 3H-thymidine uptake, even when added 24 hours after infection. The degree of inhibition of transformation correlated with the concentration. Complete inhibition of CBL transformation by EBV was achieved by 1,000 microM PF and 500 microM PAA, which were noncytotoxic. Removal of PAA from B.95-8 cells cultivated in the presence of high concentrations of PAA for 15 weeks restored VCA synthesis without full concomitant production of transforming EBV.

Antigens, Viral↗
PubMed1982

In vitro bioassay of erythropoietin using synchronized rabbit erythroid precursors.

Synchronized erythroid precursors obtained from the bone marrow of rabbits and plated in methyl-cellulose were used as a bioassay for the measurement of erythropoietin (Ep). Rabbits were given five daily injections of phenylhydrazine followed by a single dose of actinomycin-D. This treatment resulted in a rapid repopulation of bone marrow by synchronized erythroid precursors which can be stored at -180 degrees C for long periods. Grown in vitro for 2 days in the presence of added Ep these cells divided to form colonies (CFUE). The erythroid nature of these colonies was confirmed by 59Fe incorporation into heme. Preliminary studies indicate that this system is suitable for the measurement of Ep in human sera. It is simple, inexpensive, reproducible, and permits measurements at the physiologic range of Ep concentrations.

Animals↗
PubMed1980

On the continuous culturing of B.95-8 cells in the presence of phosphonoacetic acid.

Lymphoblastoid B.95-8 cells were cultured for four months and three weeks in the presence of increasing concentrations (50--200 microgram/ml) of phosphonoacetic acid (PAA). Several weeks after removal of the PAA, the cultures, in parallel with untreated B.95-8 cells, were tested for the presence of: 1) Epstein-Barr virus (EBV) viral capsid antigen (VCA), and b) transformation of human cord blood lymphocytes. There was no difference in the percentage of cells exhibiting VCA in the B.95-8 PAA treated and untreated cells. However, transformation assays indicated 10 times less transforming virus in culture supernatant harvested from B.95-8 cultures treated with PAA, as compared with the control cultures. Electron microscopic studies indicated the presence of virus particles in B.95-8 control cells and their almost complete absence in the PAA-treated cells.

Antigens, Viral↗
PubMed1980

Esters of phosphonopropionic and phosphonoacetic acids: effect on synthesis of Epstein-Barr virus (EBV) antigens and on transformation of cord blood lymphocytes by EBV.

Cell cytotoxicity, inhibition of synthesis of Epstein-Barr virus (EBV) viral capsid antigen (VCA), nuclear antigen (EBNA) and transformation of human cord blood lymphocytes (CBL) by EBV, were studied using the disodium salt of phosphonoacetic acid (PAA), ethyl diethyl-phosphonoacetate (Et-PAA) and two derivatives of phosphonopropionic acid: ethyl diethyl-2-phosphonopropionate (Et-2-PPA) and ethyl diethyl-3-phosphonopropionate (Et-3-PPA). These substances were tested on EBV producing cell lines, B.95-8 and P3HR1. VCA and EBNA synthesis were determined by immunofluorescence and transformation of CBL by 3H-thymidine uptake. Up to 100 micrograms/ml of PAA were not toxic to 2.10(5) cells. Et-PAA, Et-2-PPA and Et-3-PPA were nontoxic at concentrations up to 2000 micrograms/ml. PAA inhibited 82.05% of EBV VCA synthesis at a concentration of 50 micrograms/ml. Et-PAA inhibited 47.01% of VCA at a concentration of 100 micrograms/ml and 78.09% at a concentration of 2000 micrograms/ml. Et-2-PPA inhibited 41.04% of VCA at 100 micrograms/ml and 80.87% when used at 2000 micrograms/ml. Et-3-PPA inhibited 35.06% of VCA at 100 micrograms/ml and 69.92% at 2000 micrograms/ml. Removal of the substances restored VCA synthesis. EBNA synthesis was not affected by these substances. PAA completely inhibited the transformation of human CBL by EBV at a concentration of 100 micrograms/ml. Et-PAA at a concentration of 2000 micrograms/ml completely inhibited 3H-thymidine uptake. ET-2-PPA was less effective whereas Et-3-PPA had almost no effects at the same concentration.

Animals↗
PubMed1979

Phosphonoacetic acid: inhibition of transformation of human cord blood lymphocytes by Epstein-Barr virus.

Phosphonoacetic acid disodium salt (PAA) inhibited the transformation of human cord blood lymphocytes by Epstein-Barr virus (EBV) at concentrations of 50-100 microgram/ml. At these concentrations, PAA had no effect on the multiplication of EBV transformed human lymphoblastoid cells or on the survival of human cord blood lymphocytes. The transformation of human cord blood lymphocytes by the B95-8 strain of EBV was measured by 3H-thymidine uptake, 5 days or more after infection. The degree of inhibition of transformation was correlated with the relation between the input of EBV and the concentration of PAA in the experiment. PAA inhibited the transformation even when added 24 h after EBV infection, but had no effect when added 48 h after EBV infection. The inhibitory effect of PAA could be overcome by its removal and normal 3H-thymidine uptake was restored even after 6 days of inhibition. The specificity of the inhibitory effect on EBV induced transformation of human cord blood lymphocytes is discussed.

Animals↗
PubMedDate not supplied

Coronary flow patterns in normal and ischemic hearts: transmyocardial and artery to vein distribution.

The dynamics of the transmyocardial coronary flow patterns during normal and ischemic conditions are complex and relatively inaccessible to measurements. Therefore, theoretical analyses are needed to help in understanding these phenomena. The proposed model employs compartmental division to three layers, each with four vessel-size compartments which are characterized by resistance and compliance. These compartments are subjected to the extravascular compressive pressure (ECP) generated by cardiac contraction, which by modifying the transmural pressure causes changes in cross-sectional area of the vessels in each compartment continuously determining the resistance and capacitance values. Autoregulation and collaterals are also included in order to simulate the flow patterns during regional ischemia. Using these features, the model predicts the typical out of phase arterial and venous flow patterns. Systolic collapse of the large intramyocardial veins during the normal cycle, as well as systolic arteriolar collapse during ischemia are predicted. The transmural flow during ischemia is characterized by alternating flows between the layers. The ECP is considered here is two ways: (a) as a function of left ventricle (LV) pressure, decreasing linearly from endocardium to epicardium and (b) as the interstitial fluid pressure, employing a multilayer muscle-collagen model of the LV. While both of these approaches can describe the dynamics of coronary flow under normal conditions, only the second approach predicts the large compressive effects due to high ECP obtained at very low cavity pressure, resulting from significant muscle shortening and radial collagen stretch. This approach, combining a detailed description of transmural coronary circulation interacting with the contracting myocardium agrees with many observations on the dynamics of coronary flow and suggests that the type of LV mechanical model is important for that interaction.

Animals↗
PubMedDate not supplied

An ultrasonic system for diameter pulse tracking in arteries: problems and pitfalls.

Non-invasive ultrasonic techniques for measuring the mechanical behaviour of large arteries have a potential clinical application for physiological studies of the circulation and early detection of degenerative arterial disorders. A newly developed system for such purposes, comprising two double-echo trackers with zero-crossing phase-locked circuits and interfacing a B-mode real-time scanner, has been introduced for on-line recording of the diameter in a selected aortic segment. The aim of this report is to draw attention to the limitations of the technique in order to avoid misinterpretation of results. The various problems associated with the use of phase-locked echo followers for tracking sonic echoes of vessel pulse waves are summarized. The high spatial resolution of the measuring system is essential for estimating the elastic properties of the vessel, because the fractional changes of the diameter waveform during a heart cycle are small compared with the swings of intravascular pressure. Measuring errors may originate from either human or technical sources. From several viewpoints correct alignment of the ultrasonic beam vis-à-vis the vessel segment under consideration is crucial for obtaining valid measures. A thorough knowledge of the physics involved is essential for an adequate use of the instrument. With correct use, easily reproducible and reliable estimations are obtained of the mechanical properties of large vessel walls.

Aorta, Abdominal↗