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Biomedical subjects

J Boyd

Publications and source records attributed to J Boyd.

At least 217 records · Page 12Linked to original sources
PubMed1985

Identification of glycine spin systems in 1H NMR spectra of proteins using multiple quantum coherences.

Double-quantum filtered COSY and triple-quantum filtered COSY techniques have been compared for the tripeptide Gly-Tyr-Gly and for human lysozyme. The insertion of a triple-quantum filter in the COSY experiment leads to dramatic spectral simplification in the fingerprint region of the spectrum and permits the specific identification of glycine spin systems in the complex 1H NMR spectra of proteins. The assignment of these peaks to glycine H alpha can be confirmed using 2D double-quantum correlated spectroscopy.

Glycine↗
PubMed1985

1H- and 13C-n.m.r. assignments and conformational analysis of some monosaccharide and oligosaccharide substrate-analogues of lysozyme.

The 1H- and 13C-n.m.r. spectra of solutions of GlcNAc, beta-GlcNAc-(1----4)-GlcNAc, and beta-GlcNAc-(1----4)-beta-GlcNAc-(1----4)-GlcNAc in D2O at 50 degrees are interpreted in terms of the conformations, using a combination of 1D- and 2D-n.m.r. spectroscopy and spectra simulation techniques. Two preferred orientations of the hydroxymethyl group were found for each of these saccharides. The conformations have been compared with those found from X-ray crystallographic data and conformational energy calculations.

Animals↗
PubMed1984

Neutron scattering studies of subcomponent C1q of first component C1 of human complement and its association with subunit C1r2C1s2 within C1.

Neutron scattering studies are reported on subcomponent C1q of component C1 of human complement, and on C1, the complex of C1q with subunit C1r2C1s2. For C1q, the molecular weight was determined as 460,000. The radius of gyration at infinite contrast RC is 12.8 nm. The RC values for the proteolytically cleaved forms of C1q, namely the heads and the stalks, are 1.5 to 2 nm and 11 nm, respectively, and thus the axis-to-arm angle of C1q is estimated at 45 degrees. Neutron data for subunit C1r2C1s2 are published elsewhere. The neutron data on C1 lead to an RC value of 12.6 nm for proenzymic C1 and a molecular weight of 820,000. The wide-angle scattering curve of C1q exhibits a minimum at Q = 0.28 nm-1 and a maximum at 0.39 nm-1; on the addition of C1r2C1s2, this minimum disappears. The neutron data on C1 indicate that C1q and C1r2C1s2 have complexed with a large conformational change in one or both parts. No conformational changes can be detected on the activation of C1 by this method.

Complement Activating Enzymes↗
PubMed1984

Subpopulations of colony-forming B lymphocytes exhibit distinct in vitro growth characteristics.

Human peripheral blood cells enriched for B lymphocytes were stimulated to focal proliferation in semisolid cultures with lymphocyte-conditioned media, Protein A (Prot A), lipopolysaccharide (LPS) and 2-mercaptoethanol (2-ME). After 6-8 days of incubation, two morphologically distinct colony types were observed. Type I colonies were diffusely proliferating aggregates within the agar layer, whereas another subset of B-cell-colony-forming cells (CFU-BL) formed round compact type II colonies which appeared to leave the agar layer and continued to proliferate in the liquid overlayer of our culture system. They reached maximum proliferation 2 days earlier than type I colonies. Cells derived from both colony types were positively identified as B lymphocytes by monoclonal antibodies using immunoperoxidase staining. In addition to this distinct growth pattern, both colony types exhibited different proliferative responses which were dependent on the kind of conditioned media used and the mitogen concentration. In secondary cultures both type I and type II colony-derived cells showed recloning capacity. However, after replating, both colony types gave rise to round compact type II colonies. These results demonstrate that there exist at least two subpopulations of colony-forming B lymphocytes, possibly one more primitive than the other, which can be distinguished by in vitro growth characteristics.

B-Lymphocytes↗
PubMed1984

A multinuclear NMR study of 2,3-bisphosphoglycerate metabolism in the human erythrocyte.

Resonances from 13C, 31P and 1H have been detected simultaneously in suspensions of human erythrocytes using a modified NMR spectrometer equipped with a probe tuned to four different frequencies. The utility of multinuclear NMR in the study of cellular metabolism is demonstrated with an investigation of 13C label flux through the 2,3-bisphosphoglycerate bypass in human erythrocytes. In a single experiment, the respective contributions of this bypass and the pentose-phosphate shunt were found to be 27 and 10% of the total glycolytic rate.

2,3-Diphosphoglycerate↗
PubMed1984

[Proliferation of megakaryocytic precursor cells (CFU-M) in a micro-agar culture system].

The recently described micro-agar culture system for cloning erythropoietic progenitor cells was used to study the optimum conditions for the growth of CFU-M. In this system human mononuclear cells from normal human bone marrow were suspended in agar and incubated for 12 days. Various concentrations of phytohaemagglutinin lymphocyte conditioned medium (PHA-LCM) and prostaglandin E (PGE) were added to the liquid overlayer in the presence of 2-mercaptoethanol (2-ME) for the stimulation of CFU-M. Human AB serum was used instead of fetal calf serum (FCS) in all experiments. A sigmoidal dose-response curve, with a plateau at a concentration of 5 to 10%, was obtained by the addition of different concentrations of PHA-LCM in the presence of 10(-6)PG-E. Under optimal conditions (5% PHA-LCM, PGE 10(-6)M) a linear relation was obtained between the number of seeded cells and the megakaryocytic colonies formed. For routine morphological analysis the whole agar layer was stained using the Pappenheim method. For further characterization of CFU-M, an immunofluorescence test with rabbit antihuman factor VIII related antigen was performed on the whole agar layer.

Agar↗
PubMed1984

Amphetamine disrupts both working and reference memories of rats trained in a radial maze.

To assess the effects of amphetamine on working and reference memory rats were trained on a 12-arm radial maze with six arms baited and six arms unbaited until stable performance was achieved. Administration of 2.0 mg/kg d-amphetamine sulfate increased both working and reference memory errors, but only if a 5-min delay was imposed after three successful choices. With no delay this dose had no reliable effect on either working or reference memory. Lower doses (0.5 or 1.0 mg/kg) were ineffective even when a delay was imposed during the test. We suggest that amphetamine heightens arousal, which disrupts accurate retention when the rat's attention to the relevant cues is interrupted, as during a brief delay. Alternative explanations are discussed.

Animals↗
PubMed1984

Fractionation of hemagglutinating and bacterial binding adhesins of Bacteroides gingivalis.

An outer membrane complex containing hemagglutinating and bacterial aggregating activity has been isolated from Bacteroides gingivalis. Examination of the membrane material by biochemical analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunological means revealed that the crude outer membrane preparation contained three major proteins and a lipopolysaccharide population that displayed size heterogeneity. At least two membrane proteins as well as the lipopolysaccharide were found to be antigenically active by immunoblot analysis. With gel chromatography and a lipopolysaccharide disaggregating buffer the membrane material was separated into two fractions. An accompanying separation of the two adherence activities was observed. The first membrane fraction, containing mostly protein and carbohydrate material, was found to contain the bacterial aggregating activity. This fraction also contained a high-molecular-weight lipopolysaccharide population. The second membrane fraction, consisting of low-molecular-weight lipopolysaccharide, protein, and loosely bound lipid was found to contain the hemagglutinating activity.

Adhesiveness↗
PubMed1984

A miniaturized agar culture system for cloning human erythropoietic progenitor cells.

The micro-agar-culture technique for cloning early and late erythropoietic progenitor cells (BFU-E and CFU-E) was further modified and miniaturized in order to study the optimal growth conditions with a minimal consumption of erythropoietin (EP). Using microtiter plates, the total incubation volume was lowered from 0.5 to 0.1 ml and thus reduced the necessary amount of EP and cells by a factor of 5. The method consists of a 50 microliter agar layer, in which the mononuclear cells are suspended, and a 50 microliter liquid overlayer containing bovine serum albumin (BSA), transferrin (TF), and EP. After a seven- or 14-day incubation, the whole agar layers were fixed, transferred to microscopic slides, dried, stained using the Pappenheim method, and permanently preserved. The influences of FCS, BSA, and TF in the presence of EP were studied on the proliferation of human bone marrow CFU-E and BFU-E. The variation of FCS concentration showed an optimum at 10%. The addition of BSA in the presence of optimal concentrations of EP markedly increased the number of BFU-E, but not CFU-E. Furthermore, the threshold concentration of EP required for the initial burst formation could be reduced by half in the presence of BSA. By the addition of TF, a further increase in the number of BFU-E was obtained.

Agar↗
PubMed1983

[In vitro studies of clonable human B lymphocytes].

A recently developed micro agar culture system has been optimized for the in vitro growth of human B-lymphocytes. Enriched B-lymphocytes from the peripheral blood of normal individuals were suspended in an agar layer, above which a liquid overlayer containing 20% PHA-LCM, 2-ME and Prot A or LPS as stimulants was added. Two morphologically distinguishable colony types were observed using this culture technique: diffusely proliferating colonies (Type I) were found within the agar layer, and round, compact colonies (Type II) appeared to leave the agar layer and continue growth in the liquid overlayer. For both colony types a linear relationship was demonstrated between the number of seeded cells and the number of formed colonies. The appearance of the two colony types in vitro was not concurrent, and they exhibited differing sensitivity to mitogen concentration and to the type of serum used as additive to the culture medium. The implications of clonal in vitro cultivation of lymphocytes, both normal and pathological, are discussed.

Adult↗
PubMed1983

Clonal growth of human megakaryocytic progenitor cells in a micro-agar culture system: simultaneous proliferation of megakaryocytic, granulocytic, and erythroid progenitor cells (CFU-M, CFU-C, BFU-E) and T-lymphocytic colonies (CFU-TL).

A simple and reproducible micro-agar culture technique for cloning human CFU-M is described. Human bone marrow mononuclear cells were suspended in agar and incubated for 12 days. Stimulation was provided by the direct addition of phytohemagglutinin-P (PHA-P), erythropoietin (Epo) and 2-mercaptoethanol (2-ME) to the liquid overlayer. A shift from BFU-E and CFU-C proliferation to CFU-M and CFU-TL was observed with increasing PHA concentrations. Under optimal conditions (PHA 50 micrograms, Epo 1.2 IU, 2-ME 2 x 10(-4) M, 1% purified BSA, 0.04% human transferrin, saturated with Fe C13) a linear relationship between colonies formed and plated cell number were observed. For the routine morphological analysis, the whole agar layers were stained using the Pappenheim method. For further characterization of CFU-M, cytochemical stainings and immunofluorescence tests with rabbit-antihuman factor VIII-related antigen were performed on the whole agar layers.

Clone Cells↗
PubMed1983

Myelopoiesis of human bone marrow cells in a micro-agar culture system: comparison of two sources of colony stimulating activity (CSA).

Human bone marrow cells were grown in a micro-agar culture system in the presence of human placenta (HPCM) and giant cell tumor conditioned media (GCT). The effects of HPCM and GCT conditioned media on linearity, growth dynamics, and morphological composition of colonies were studied after 7 and 14 days of incubation. Under the described conditions the dose-response curves for HPCM and GCT were different: on day 7 maximal stimulation was obtained with 2.5% HPCM and 20% GCT; on day 14 a maximal response was reached with 1.25% HPCM and 5% GCT. Both stimuli produced maximal growth after 7 days of incubation, followed by a rapid decrease in the number of formed colonies up to day 14. The morphological study of aggregates showed that after 7 days of incubation 80% pure granulocyte and 20% mixed granulocyte-macrophage colonies were found in the presence of both stimuli. However, on day 14 the incidence of granulocyte-macrophage colonies increased to 60%, whereas the percentage of pure granulocyte colonies decreased to 20%. The frequency of eosinophil colonies was relatively low (median 15%) with both stimuli. The described system can be applied successfully for studies of myelopoiesis in vitro. Both sources of colony stimulating activitites (CSA) employed had no significant difference in their ability to stimulate myelopoiesis.

Cells, Cultured↗
PubMed1983

Neutron scattering studies of the isolated C1r2C1s2 subunit of first component of human complement in solution.

The subunit complex C1r2C1s2 of the first component of complement was investigated by small-angle neutron scattering in both the activated and unactivated forms. From these experiments, a molecular weight of 390,000 for C1r2C1s2 was found. The matchpoint was determined to be 43% 2H2O. Both results are consistent with composition data. The partial specific volume is 0.751 ml/mg. The radius of gyration at infinite contrast was found to be 17 nm for C1r2C1s2 and 1.1 nm for the cross section. Models for C1r2C1s2 were computed by the method of hard spheres, in which C1r2C1s2 was represented by spheres 0.87 nm diameter arranged in a straight rod of length 59 nm and a circular cross section of 3.2 nm. This rod can be bent at one or two places by up to 60 degrees without significant effect on the calculated radii of gyration. The model is in agreement with published ultracentrifugation and electron microscopy data.

Amino Acids↗
PubMed1983

Effects on the peripheral nervous system of workers' exposure to carbon disulfide.

An evaluation of the effects of occupational exposure to carbon disulfide was performed in a sample of 156 male viscose rayon workers. A composite group of 233 workers drawn from two other artificial fiber plants located on the same premises as the rayon plant was used for comparison. Effects of CS2 on the peripheral nervous system (PNS) were evaluated in ulnar and peroneal nerves using measurements of maximum motor nerve conduction velocity (MCV) and distal latency; and sensory conduction velocity (SCV) in the sural nerve. Self-reported symptoms related to PNS disorders were also obtained from each study participant. Industrial hygiene records showed the rayon workers to have had CS2 exposures that generally had not exceeded 20 ppm. The overall mean number of years of CS2 exposure was 12.1 years (+/- 6.9 S.D.). The viscose rayon workers were divided prior to the study into three groups according to historical mean CS2 levels calculated for job titles, and area and personal CS2 samples were obtained during the conduct of the study to characterize each job. For these three groups the median CS2 levels were measured to be 1.0, 4.1 and 7.6 ppm. The comparison group's median CS2 level approximated 0.2 ppm. Results showed CS2-exposed workers to have small but statistically significant (p less than .05) reductions in sural SCV and peroneal MCV. Other neurophysiological measures consisting of distal latency, residual latency, and muscle or nerve action potential amplitudes showed no significant differences between study groups. A reduction in the ratio of amplitudes of muscle action potentials obtained from peroneal nerve stimulation was significant (p less than .05). Reductions in the peroneal nerve MCV were found to be related, in a dose response sense, to workers' cumulative exposure to CS2. No increase attributable to CS2 was found in the prevalence of symptoms related to PNS disorders. The results from this study generally agree with similar findings from Finland, Sweden and Italy, but at CS2 exposure levels lower than those previously reported for occupational exposure.

Action Potentials↗
PubMed1982

Interference of danazol with the radioimmunoassay of steroid hormones.

The crossreactivity of Danazol, a synthetic steroidal drug with antigonadotropic and impeded androgenic properties, with 12 different antisera against 8 different steroids was studied either by conventional competitive inhibition assay or by competitive saturation assay, the latter of which was found to be more sensitive. It was shown that Danazol strongly reacted with an antiserum against 5 alpha-dihydrotestosterone and also, albeit to a much lesser extent, with antisera against testosterone, cortisol and progesterone in decreasing order. It did not interfere with RIA-systems for 11-desoxycortisol, 17 alpha-hydroxyprogesterone, estradiol-17 beta and estriol. However, out of four antisera against estradiol-17 beta two were found to considerably crossreact with Danazol which might explain apparent increases in plasma levels of this hormone during Danazol treatment as recently reported.

Androgens↗