Search PubMed⌕ Search

Biomedical subjects

C G Green

Publications and source records attributed to C G Green.

33 records · Page 2Linked to original sources
PubMed1988

Water vapour and temperature dynamics in the upper airways of normal and CF subjects.

Water vapour partial pressure (PH2O) and temperature (T) were measured together, continuously, at the airway opening (either lips or nares) and at the oropharynx of human subjects with normal lungs or with cystic fibrosis (CF). No apparent differences in PH2O or T were found between normal and CF groups breathing ambient air (22 +/- 2 degrees C). During inspiration the relative humidity at the pharynx for nose breathing (95%) was higher than for mouth breathing (75%). For hot air breathing (48 +/- 2 degrees C), the PH2O and relative humidity of inspired gas at the pharynx was lower for the CF group than for the normal group. Also, the CF group had a higher airway surface temperature at the airway openings on inspiration. These data suggest that when the rate of evaporation is sufficiently high, the rate-limiting step may be water transport through the mucosal tissue and/or secretions. At least for the upper airways, this rate limitation is more evident for CF patients than for normal subjects.

Adult↗
PubMed1986

Antibody to human lymphocyte actin regulates immunoglobulin secretion by an EBV-transformed human B-cell line.

Antibody against actin isolated from a human EBV-transformed lymphoblastoid B-cell line exerted an inhibitory effect on in vitro IgM secretion by a different lymphoblastoid B-cell line, LA350. This effect was dose dependent showing from 24-40% inhibition at a dilution of 1:100 and 68-80% inhibition at a dilution of 1:50. This effect was noted in the absence of changes in either total cell count or [3H]-thymidine incorporation and was reversed by co-incubation with purified rabbit thymus actin (100 micrograms/ml) but not bovine serum albumin at the same concentration. These data demonstrate regulation of immunoglobulin synthesis by antibodies against human lymphocyte derived actin in a lymphoblastoid B-cell line.

Actins↗
PubMed1985

Anti-rabbit thymus actin antibody inhibits proliferation of Epstein-Barr virus-transformed human B cell line LA350: augmentation by cyclic AMP.

Antibody to actin isolated from the rabbit thymus gland exerted a dose-dependent inhibitory effect upon the proliferation of an Epstein-Barr virus-transformed human B cell line, LA350. Purified rabbit thymus actin specifically reversed the inhibitory effect of antibody by competing with surface actin on LA350. For example, LA350 proliferation at 48 hr was inhibited 90% at a 1:10 antibody dilution (p less than 0.001) but only 48% and 20% in the presence of 190 and 380 micrograms/ml of rabbit thymus actin, respectively (p less than 0.001 for reversal). Cyclic AMP augmented in a dose-related fashion the inhibitory effects of antibody, e.g., a 1:20 dilution of antibody inhibited 10, 19, 41, and 67% at 0.0, 0.5, 1.0, and 2.0 mM cAMP, respectively (p less than 0.001). We conclude that anti-actin antibody recognizes surface actin on a human B cell line and produces a functional inhibition of proliferation by a process that is augmented by cAMP.

Actins↗
PubMed1985

Identification of L-cell growth stimulating antibody as anti-actin.

Anti-L-cell antisera having potent cell growth stimulatory properties were shown by Western blotting to have predominant specificity toward a protein with a molecular weight of 42K which we identified as actin. Extractions of L cells, based upon the known insolubility of cytoskeletal proteins (including actin) in Triton X-100 and the solubility of actin in low ionic strength Ca2+ and ATP-containing buffer, led to actin-enriched preparations that retained immunoreactivity with the anti-L-cell antisera. The 42-kDa antigen binds to deoxyribonuclease I, has a pI = 5.2-5.4, and has an amino acid composition, including the presence of 3-methylhistidine, compatible with compositions determined for actins from other sources. Rabbit antiserum specific for this 42-kDa protein, isolated by SDS-PAGE, reproduced the cell growth stimulation by the anti-L-cell antisera and absorption of the antiserum with purified L-cell actin eliminated this stimulation. Moreover, these antibodies bind to the microfilaments of 3T3 fibroblasts. When purified actins were used as soluble antigen inhibitors of the immune reactivity of antiserum to 42-kDa protein with intact L cells, rabbit thymus actin competed with the surface molecules on L cells and reduced the stimulatory effect of the antiserum by 80% at an actin concentration of 150 micrograms/ml. Chicken muscle actin reduced the antibody stimulation effect by only 24% at the same protein concentration, and mouse muscle actin was ineffective as an inhibitor. The F(ab')2 fraction of anti-42K IgG was effective in stimulating L cells, thus documenting the immune nature of the actin-anti-42K interaction. We conclude that anti-actin antibodies, upon binding to actin-like cell surface determinants on L cells, stimulate cellular metabolism.

Actins↗
PubMed1985

Cyclic AMP and theophylline enhance DNA synthesis in L cells stimulated with anti-actin IgG and [(IgG)2 protein A]2 complex by recruiting cells into S-phase.

Surface binding of anti-actin IgG alone or in a Mr = 716 000 [(IgG)2 Protein A]2 complex results in a stimulation of DNA synthesis and cell growth in L cells. Cyclic-AMP (0.01-1.0 mM) added to such cell cultures augmented DNA synthesis as measured by incorporation of [3H]thymidine into DNA. Theophylline (0.1-1.0 mM), a phosphodiesterase inhibitor which prevents enzymatic breakdown of cAMP, had similar effects, but cGMP (0.01-1.0 microM) reversed the effects of cAMP and theophylline upon DNA synthesis. Analysis of the cell cycle by flow cytometry revealed that antibody produced a shift (7%) of cells from the G1-phase to the S-phase (DNA-synthetic) of the cell cycle at 72 hr of incubation. Addition of cAMP (0.5 mM) to cell cultures, however, produced significant shifts of antibody stimulated cells from G1-phase to S-phase at all time points measured, i.e., 24 (12%), 48 (22%), 72 hr (23%). Thus, antibody recruited cells into S-phase of the cell cycle and cAMP greatly augmented the effect. These observations suggest that the mechanism of activation of L cell growth by antibody to surface antigens involves a recruitment of cells into the DNA-synthetic phase and that the effect may be mediated by cAMP.

Actins↗
PubMed1984

Antibody to immunoselected L-cell antigens mimics stimulating activity of antibody to whole L cells.

A heterogeneous IgG antibody raised in rabbits in response to injections of whole L cells was used to identify and select relevant antigens in a nonionic detergent extract of L cells prelabeled with [35S]methionine by means of immunoprecipitation and immunoaffinity chromatography. When analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the immunoprecipitate and immunoeluate contained far fewer protein bands than the whole cell extract but selectively retained a 42,000-MW protein species. In response to injections of the immunoprecipitate, rabbits produced a new antiserum which reacted predominantly with the 42,000-MW protein when reacted with L-cell proteins separated by sodium dodecyl sulfate-gel electrophoresis and transferred to nitrocellulose paper by the Western blot technique. The new antiserum (raised to the immunoprecipitate) and the original antiserum (raised to whole cells) were equipotent in stimulating calcium transport, phospholipid metabolism, and DNA synthesis in L cells. Binding of the IgG fractions of the two antisera displayed identical high affinity binding to L-cell surface antigens, with the same average association constant of 1.5 X 10(6) M-1. These studies have shown that an antiserum raised to whole L cells has a much narrower reactive spectrum with L-cell membrane antigens than might be imagined and has identified a 42,000-MW membrane protein as an important immunogen which itself elicits a potent immune response resulting in an antibody capable of mimicking the cell stimulatory properties of the original antiserum.

Animals↗
PubMed1984

[(IgG)2 protein A]2 complex stimulates cytosine arabinoside incorporation into DNA and inhibits L cell proliferation.

A Mr = 716 000 complex, [(IgG)2 Protein A]2, formed when Protein A is mixed with a molar excess of IgG anti-L cell antibody, augmented [3H]thymidine incorporation in DNA and growth of a murine transformed L cell line. It was also possible to augment the incorporation of [3H]cytosine arabinoside (2.3-fold) in DNA by the binding of this complex to L cells. A synergistic inhibition of L cell proliferation was produced using the complex and certain concentrations of cytosine arabinoside. By binding the complex to L cells, a 5-fold lower concentration of cytosine arabinoside (0.050 microgram/ml) was as effective in inhibiting cell replication as the higher dose of the drug (0.25 microgram/ml) with cells bound by IgG antibody alone, and a 20-fold lower concentration compared to the effects of the drug itself (1.0 microgram/ml). Addition of 10 microM thymidine to the complex permitted the use of an even lower dose of cytosine arabinoside (0.004 microgram/ml) for inhibition of cell growth. Thymidine caused this effect by producing an even greater incorporation of drug into the DNA of complex-stimulated cells. Thus, by stimulating the cell with the immune [(IgG)2 Protein A]2 complex it was possible to stimulate uptake of a chemotherapeutic nucleoside and selectively inhibit cell replication at non-toxic doses of nucleoside.

Animals↗
PubMed1984

Heat acclimation in cystic fibrosis.

Cystic fibrosis (CF) patients may be at risk for heat illness because of their high sweat chloride and sodium concentrations ([Cl-], [Na+]), but it is not known if they can heat acclimate. We studied 10 CF patients and 10 normal controls on 8 consecutive days of cycle exercise in the heat (37 degrees C dry bulb, 24-29 degrees C wet bulb). Both groups acclimated. CF peak rectal temperature (Tre) was 38.2 +/- 0.3 degrees C on day 1 and 37.8 +/- 0.4 degrees C on day 8 (P less than .005), and peak heart rates (HR) were 151 +/- 24 beats/min on day 1 and 136 +/- 22 beats/min on day 8 (P less than 0.025). Control temperature (T) and HR were similar. Controls decreased sweat [Cl-] from 37.2 +/- 14.6 meq/l on day 1 and to 24.9 +/- 10.6 meq/l on day 8 (P less than 0.005). CF sweat [Cl-] was significantly higher and did not change with acclimation (day 1, 71.1 +/- 20.9 meq/l; day 8, 72.6 +/- 21.6 meq/l, NS). Before and after acclimation, exercise-heat sessions resulted in significant decreases in serum [Cl-] in CF patients (104.5 +/- 4.6 to 101.3 +/- 4.4 meq/l on day 1, P less than 0.05; 103.5 +/- 5.1 to 99.7 +/- 4.2 meq/l on day 8, P less than 0.025) but not in controls. Serum [Cl-] was significantly lower in CF than control subjects at every measurement. Both groups had significant renal Na+ conservation after exercise on both days.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1984

IgG-protein A complexes modulate thymidine incorporation into DNA of antibody and complement-stimulated cells.

Incubation of protein A (PA) and molar excess of whole rabbit immune IgG in solution favored the formation of high m.w. complexes with the molecular formula of [(IgG)2(PA)]2, which enhanced the incorporation of [3H]thymidine ([3H]dThd) into DNA of L cells, especially in the presence of rabbit or human complement (C). In contrast, complexes with the molecular formula (IgG)(PA), formed by incubation of IgG with molar excess of PA, failed to enhance, or inhibited, the incorporation of [3H]dThd into cells treated with immune IgG alone or with C present, respectively. Concanavalin A (Con A), which is known to bind to critical exposed oligosaccharide structures present in the Fc region of IgG in the [(IgG)2(PA)]2 complexes, reversed the enhancement of [3H]dThd incorporation, and alpha-methyl mannoside, but not D-galactose, inhibited the Con A reversal. The [(IgG)2(PA)]2 complexes efficiently activated the C cascade, caused significantly higher levels of aggregation of cells, and increased the binding of immune IgG to the cells when compared to the (IgG)(PA) complexes. Both types of complexes, isolated by sucrose density ultracentrifugation, were precipitable in a radioimmunoassay with chicken anti-PA antibodies and were capable of binding to intact L cells.

Agglutination↗
PubMed1983

Modulation of metabolism of cytosine arabinoside in L cells by antibody and complement.

Complement modulated the metabolic conversion of cytosine arabinoside into its nucleotide and nucleic acid derivatives in L cells by augmenting the biphasic effect (inhibitory/stimulatory) of anti-L cell antibody. Antibody in the absence of complement affected both the total cellular pool of cytosine arabinoside (containing the nucleotide and nucleic (DNA) acid derivatives) and the acid-insoluble pool (containing the DNA derivative). Addition of complement in high concentrations inhibited and, in low concentrations, stimulated the incorporation of cytosine arabinoside into DNA of antibody stimulated L cells. At the point of maximum stimulation of cytosine arabinoside incorporation into DNA, there was a pronounced decrease in the size of the total cellular pool with the result that 75% of the total pool of cytosine arabinoside was due to its incorporation into DNA. Simultaneous measurements upon cytosine arabinoside and thymidine or deoxycytidine metabolism were made; the effects of antibody and complement appeared to be quite similar with all three nucleosides, with the exception that all thymidine and deoxycytidine taken up into the cells was incorporated into DNA. Addition of exogenous thymidine (up to 100 microM produced the same enhanced incorporation of [3H]Ara-C and [14H]dCyd into control cells that was observed in antibody and complement stimulated cells. Measurement of deoxycytidine kinase activity in cell-free extracts of cell cultures stimulated by antibody, however, did not reveal enhanced enzymatic activity due to stimulated enzyme synthesis, but, rather indicated that antibody and complement altered the intracellular concentrations of nucleotides which affected the interaction of cytosine arabinoside with deoxycytidine kinase in intact cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

BOLD-fMRI of PTZ-induced seizures in rats.

PURPOSE: To develop a non-invasive method for exploring seizure initiation and propagation in the brain of intact experimental animals. METHODS: We have developed and applied a model-independent statistical method--Hierarchical Cluster Analysis (HCA)--for analyzing BOLD-fMRI data following administration of pentylenetetrazol (PTZ) to intact rats. HCA clusters voxels into groups that share similar time courses and magnitudes of signal change, without any assumptions about when and/or where the seizure begins. RESULTS: Epileptiform spiking activity was monitored by EEG (outside the magnet) following intravenous PTZ (IV-PTZ; n=4) or intraperitoneal PTZ administration (IP-PTZ; n=5). Onset of cortical spiking first occurred at 29+/-16 s (IV-PTZ) and 147+/-29 s (IP-PTZ) following drug delivery. HCA of fMRI data following IV-PTZ (n=4) demonstrated a single dominant cluster, involving the majority of the brain and first activating at 27+/-23s. In contrast, IP-PTZ produced multiple, relatively small, clusters with heterogeneous time courses that varied markedly across animals (n=5); activation of the first cluster (involving cortex) occurred at 130+/-59 s. With both routes of PTZ administration, the timing of the fMRI signal increase correlated with onset of EEG spiking. CONCLUSIONS: These experiments demonstrate that fMRI activity associated with seizure activity can be analyzed with a model-independent statistical method. HCA indicated that seizure initiation in the IV- and IP-PTZ models involves multiple regions of sensitivity that vary with route of drug administration and that show significant variability across animal subjects. Even given this heterogeneity, fMRI shows clear differences that are not apparent with typical EEG monitoring procedures, in the activation patterns between IV and IP-PTZ models. These results suggest that fMRI can be used to assess different models and patterns of seizure activation.

Animals↗
PubMedDate not supplied

The stages of change for dietary fat and fruit and vegetable intake of patients at the outset of a cardiac rehabilitation program.

PURPOSE: To determine the stages of change for dietary fat and fruit and vegetable intake of cardiac patients entering a rehabilitation program. DESIGN: A cross-sectional study using a convenience sample of newly admitted cardiac rehabilitation patients. SETTING: Department of Pulmonary and Cardiac Rehabilitation, Moses H. Cone Memorial Hospital, Greensboro, North Carolina. SUBJECTS: Subjects (n = 226) were predominantly men, Caucasian, married, smokers with 9 to 12 years of education, and with primary diagnoses of coronary artery bypass graft. MEASURES: Stages of change and food frequency questionnaires were completed by subjects upon admission to cardiac rehabilitation. RESULTS: Subjects in action and maintenance stages for dietary fat reduction comprised 78.7% of the population. Subjects' percentage of energy from fat decreased linearly from the precontemplation stage (38.8%) to the maintenance stage (30.9%). Eighty-one percent of subjects were in precontemplation/contemplation for increasing fruit and vegetable intake. Daily servings of fruits and vegetables ranged from 2.6 for precontemplation to 5.1 for maintenance subjects. Age, body mass index (BMI), education, and family history for coronary disease were unrelated to stage of change for the dependent variables. CONCLUSIONS: Patients were in different stages of change for two nutritional behaviors linked to the same disease. Results support the need to assess patients for food behaviors and apply different educational interventions for each food behavior.

Behavior Therapy↗