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Biomedical subjects

G Stearns

Publications and source records attributed to G Stearns.

At least 19 recordsLinked to original sources
PubMed2001

Monitoring end-tidal carbon dioxide during weaning from cardiopulmonary bypass in patients without significant lung disease.

End-tidal carbon dioxide tension (PETCO(2)) changes with fluctuations in cardiac output (CO). We compared PETCO(2) to pulmonary artery blood flow (PAQt) during weaning from cardiopulmonary bypass (CPB) in normothermic patients without significant pulmonary disease. Fifteen consecutive adult cardiac surgical patients were prospectively studied during and shortly after weaning from CPB. Before separation from CPB, PETCO(2) and PAQt were measured, the latter by transesophageal Doppler echocardiography. At the time of measurements patients were normothermic, and ventilated at 6 breaths/min with tidal volumes of 10 mL/kg. After separation from CPB, thermodilution cardiac output (TDCO) was measured in addition to PAQt and PETCO(2). Regression and bias analyses were used to compare PETCO(2), PAQt, and TDCO. Seventy measurements were recorded; 31 before separation from CPB and 39 after separation from CPB. A good correlation was seen between PAQt and PETCO(2) (r = 0.88) and between TDCO and PAQt (r = 0.93; mean bias 0.03 L/min; SD 0.52 L/min). The regression analysis of PAQt on PETCO(2) showed greater variability at PETCO(2) levels > 34 mm Hg (n = 22; r = 0.14). Increases in PETCO(2) plateaued at this level, although PAQt continued to increase. When PETCO(2) was more than 30 mm Hg, all PAQt and TDCO values were >4.0 L/min (>2.0 L/min/m(2)). When PETCO(2) exceeded 34 mm Hg, all values of PAQt, and 28/29 values of TDCO were more than 5 L/min (>2.5 L/min/m(2)). One patient had TDCO of 4.69 L/min (2.39 L/min/m(2)). In normothermic patients without significant pulmonary disease, PETCO(2) is a useful index of PAQt during separation from CPB. Under the clinical settings in this study, a PETCO(2) greater than 30 mm Hg was invariably associated with a CO more than 4.0 L/min or a cardiac index >2.0 L/min/m(2).

Aged↗
PubMed1997

Conformational changes in G-CSF/Receptor complex as investigated by isotope-edited FTIR spectroscopy.

Conformations of G-CSF and the extracellular domain of its receptor as well as their complex have been investigated by employing isotope-edited FTIR spectroscopy. To determine unambiguously the protein conformations of G-CSF and the receptor in the complex, we have prepared uniformly 13C/15N isotope labeled G-CSF to resolve its amide I' band from that of the receptor in the IR spectrum of the complex. By comparing the IR spectra of the isotope-labeled G-CSF and the receptor with that of the complex, we have provided spectral evidence that the AB loop region involving the unique 310 helix segment of G-CSF likely undergoes a conformational change to a regular alpha-helix upon binding to the receptor. The IR data also indicate a possible minor increase in alpha-helical conformation for the receptor in the complex. Furthermore, FTIR spectra of G-CSF, the receptor, and their complex demonstrate clearly that protein conformations of both G-CSF and the receptor have been dramatically stabilized by complex formation. Specifically, the melting transition (Tm value) of the alpha-helix in G-CSF is increased by nearly 30 degrees C and that of the beta-strand in the receptor by nearly 15 degrees C in the G-CSF/receptor complex. We estimate from the current FTIR data that the native conformations of approximately 15% of all receptor residues are stabilized by G-CSF binding. On the other hand, the entire alpha-helical content of G-CSF appears to be stabilized in the complex. Together, these results indicate that formation of the ligand/receptor complex results in not only conformational changes in the receptor but also significant structural changes in the ligand. This adds insight to the general consensus that binding of ligand to cytokine receptors induces mostly structural changes in the receptor which lead to receptor oligomerization and signal transduction. The current data also suggest a possible physiological role of the 310 helix present in G-CSF for its receptor binding activity.

Carbon Isotopes↗
PubMed1997

Minimal endoscopic approach to subperiosteal orbital abscess.

OBJECTIVE: To limit endoscopic abscess drainage to the opening of the ethmoid cells involved, adjacent to the subperiosteal orbital abscess. DESIGN: Prospective study. PATIENTS: Twenty children with subperiosteal orbital abscess complicating acute sinusitis. INTERVENTION: Endoscopic opening of the medial wall of the bulla ethmoidalis and of the lamina papyracea. RESULTS: The limited endoscopic approach allowed subperiosteal orbital abscess drainage in all patients with positive clinical outcomes. Extensive ethmoidectomy was not necessary to achieve drainage. CONCLUSIONS: Endoscopic subperiosteal orbital abscess drainage does not require complete ethmoidectomy as was previously performed and can be limited to the opening of the bulla ethmoidalis and the lamina papyracea through the bulla ethmoidalis.

Abscess↗
PubMed1994

Cloning and characterization of the cDNA encoding a novel human pre-B-cell colony-enhancing factor.

A novel gene coding for the pre-B-cell colony-enhancing factor (PBEF) has been isolated from a human peripheral blood lymphocyte cDNA library. The expression of this gene is induced by pokeweed mitogen and superinduced by cycloheximide. It is also induced in the T-lymphoblastoid cell line HUT 78 after phorbol ester (phorbol myristate acetate) treatment. The predominant mRNA for PBEF is approximately 2.4 kb long and codes for a 52-kDa secreted protein. The 3' untranslated region of the mRNA has multiple TATT motifs, usually found in cytokine and oncogene messages. The PBEF gene is mainly transcribed in human bone marrow, liver tissue, and muscle. We have expressed PBEF in COS 7 and PA317 cells and have tested the biological activities of the conditioned medium as well as the antibody-purified protein in different in vitro assays. PBEF itself had no activity but synergized the pre-B-cell colony formation activity of stem cell factor and interleukin 7. In the presence of PBEF, the number of pre-B-cell colonies was increased by at least 70% above the amount stimulated by stem cell factor plus interleukin 7. No effect of PBEF was found with cells of myeloid or erythroid lineages. These data define PBEF as a novel cytokine which acts on early B-lineage precursor cells.

Amino Acid Sequence↗
PubMed1992

Cysteine to serine substitutions in basic fibroblast growth factor: effect on inclusion body formation and proteolytic susceptibility during in vitro refolding.

We have investigated the effect of cysteine to serine substitutions in human basic fibroblast growth factor (bFGF) on the formation of inclusion bodies in Escherichia coli. Using a temperature-sensitive expression, system, about 30% of human bFGF, which contains four cysteines at positions 26, 70, 88, and 93, is deposited into inclusion bodies. A single mutation at position 88 and a double mutation at positions 70 and 88 do not greatly alter the partition of bFGF into soluble and insoluble cell fractions. However, a single substitution of cysteine 70 by serine decreases the fraction of soluble bFGF significantly. When cysteines 26 and 93 (conserved among related growth factors) are replaced by serines, no soluble bFGF is formed in E. coli. Cysteine to serine substitutions also affect proteolytic susceptibility of bFGF during in vitro refolding from crude inclusion bodies. About 60% of human bFGF is lost to proteolytic degradation during in vitro refolding. Replacement of cysteines by serines increases the total recovery of bFGF, although more aggregates are formed during refolding. Ser-88-bFGF was expressed at the highest level, gave the highest soluble fraction in vivo, and exhibited the greatest fractional recovery and was recovered with the largest insoluble fraction after in vitro refolding. Thermal stability experiments at 42 degrees C and 70 degrees C revealed that cysteine to serine substitutions did not cause aggregation of the folded protein in vitro.

Base Sequence↗
PubMed1991

Instituting a concurrent process for monitoring the clinical risk of physicians' practice.

By implementing a more concurrent program for identifying and responding to situations that put patients at risk, such as the approach described in this article, hospital quality assurance and risk management professionals, as well as the medical staff and administration, may finally achieve the complementary goals of increasing the quality of clinical care while simultaneously reducing claims and suits against the hospital and its physicians.

Concurrent Review↗
PubMed1990

Identification of interleukin 6 as a synergistic factor for the differentiation-inducing effect of TNF on leukemic ML-1 cells.

Recombinant TNF was capable of inducing differentiation of human leukemic ML-1 cells in the monocytic pathway. Recombinant interleukin 6 did not have the activity but it could significantly increase the activity of recombinant TNF. Both of these molecules were found to play a similar role in PWM-induced conditioned medium from human lymphocytes (LCM). The differentiation inducing effect of LCM could be partially neutralized by antibody to interleukin 6. Fractionation of LCM also identified interleukin 6 as the factor that synergizes with TNF.

Acid Phosphatase↗
PubMed1986

Acute restraint device for rhesus monkeys.

A practical and inexpensive alternative to the standard primate chair is described. The apparatus is designed to allow easy removal of rhesus monkeys from their home cages and to allow restraint without anesthesia. A portable Plexiglas cage, which can be adjusted to accommodate rhesus monkeys of varying sizes, is placed against an animal's home cage. The animal is then trained to avoid the squeeze mechanism of the home cage by going into the Plexiglas cage. The animal's head can then be secured by means of poles hooked to a light weight collar worn permanently. This device and procedure allows an investigator to work with a restrained animal without resorting to drugs, unnecessary force or chronic restraint. Animals can be transferred daily with this technique with minimal conditioning and cooperation.

Animals↗
PubMed1984

Partial characterization of a 230,000-dalton reticulocyte protein and peptides derived from it that affect the activity of a protein phosphatase.

Monoclonal antibodies were raised that recognize a series of highly antigenic, protease-sensitive peptides that modulate protein phosphatase activity in reticulocyte extracts. Purified antigen peptides cause a 3-fold increase in the enzymatic activity of a homogeneous Mr congruent to 56,000 protein phosphatase. The monoclonal antibodies inhibit protein phosphatase activity in crude extracts but do not recognize the protein phosphatase itself. The antigen peptides are associated with the phosphatase throughout its purification from the postribosomal supernatant of rabbit reticulocytes but are separated from it during size exclusion high performance liquid chromatography (see accompanying article: Wollny, E., Watkins, K., Kramer, G., and Hardesty, B. (1984) J. Biol. Chem. 259, 2484-2492). The series of antigenic peptides appears to be derived by proteolysis from a 230,000-Da precursor, which is relatively abundant in undegraded form in the membrane fraction of rabbit reticulocytes and is present in erythrocyte ghosts. Antigen peptides are extracted with spectrin from both sources. The Mr congruent to 230,000 peptide is not the alpha or beta subunit of spectrin or ankyrin and appears not to have been recognized previously. The name "regulin" is proposed.

Animals↗
PubMed1977

Nitrogen balance studies with normal children.

A total of 1148 nitrogen balance studies were conducted in 100 boys and 23 girls 1 to 11 years old. Mixed, customary diets supplied between 8.9 and 21.4% of calories from protein. Duration of balance studies ranged from 72 hr in the youngest subjects to 120 hr in older children. Regressions and 95% confidence intervals of nitrogen retention on nitrogen intake are presented. The slope of the regression was significantly greater for children 12 to 18 months old than for children of other age groups. Correlation coefficients between various parameters of nitrogen balance and energy intake are presented. Although variability in results of nitrogen balances within subjects appears to be rather large, a significant difference between subjects was observed.

Absorption↗