PubMed Health⌕ Search

Biomedical subjects

L S Johnson

Publications and source records attributed to L S Johnson.

At least 37 records · Page 2Linked to original sources
PubMed1989

Comparison of variable region primary structures within an anti-fluorescein idiotype family.

Previous reports described the properties of a high affinity (Ka = 1.7 X 10(10) M-1) prototype anti-fluorescein monoclonal antibody 4-4-20, an intermediate affinity (Ka = 3.7 X 10(7) M-1) prototype 9-40, and Ig members of the 9-40 idiotype family (comprised of 3-24, 5-14, 5-27, 10-25 and 12-40). Although the seven monoclonal anti-fluorescein antibodies expressed similar active site structural determinants (idiotypes) as determined serologically, each was characterized by different affinities for fluorescein and fine specificity binding patterns. Partial heavy (H)- and light (L)-chain N-terminal amino acid sequence analyses revealed all antibodies (except 5-27) were composed of highly homologous VHIII(C) and V kappa II subgroup genes, respectively. Antibody 5-27 utilized a VHIII(B) and a V kappa V subgroup genes and shared low V-region sequence homology with 4-4-20, 9-40 and the remaining 9-40 idiotype family. In addition, complete 4-4-20, VH- and VL-region primary structures were determined to better understand antibody-antigen interactions. Antibody 4-4-20 utilized a VHIII(C) subgroup VH-gene, a truncated Sp2 D gene segment, JH4, a V kappa II subgroup VL-gene, and J kappa 1. Antibody 4-4-20 VH and VL complementarity-determining regions contained many basic and aromatic amino acid residues capable of interaction with fluorescein. Results are discussed in terms of idiotypic and fluorescein-binding characteristics as well as antibody structural and functional diversity in the immune response.

Amino Acid Sequence↗
PubMed1984

Outpatient arteriography: its safety and cost effectiveness.

An 11-year experience with 2,029 outpatient arteriograms in a 500-bed community hospital with active vascular and cardiovascular services is reported. During this period 3,864 inpatient arteriograms were also obtained. The major complication rate has been lower for the outpatient procedures than for the inpatient procedures, and no malpractice claims have been made as a result of outpatient arteriography. There were considerable cost savings with the outpatient arteriography. Since conventional arteriography can be done safely and economically on an outpatient basis, and provides images of superior quality, it is considered highly competitive with digital subtraction angiography.

Angiography↗
PubMed1981

The uses of hypnotherapy with learning disabled children.

Explored the impact of group hypnotic and self-hypnotic training on the academic performance and self-esteem of learning disabled (LD) children. Three hypnotic training sessions and instructions for 6 weeks of daily self-hypnotic practice that contained suggestions for imagery related to improvement in these areas were given to 15 children (12 males and 3 females, ages from 7 to 13), their reading teacher, and both their parents, and their responses were compared to a similar but untreated control group of 18. No overall differences were observed between groups. A multiple regression analysis revealed important predictors of self-esteem improvement for the experimental group. The child's hypnotic susceptibility score and self-hypnotic practice by children and parents were the most relevant. These LD children were at least as hypnotically susceptible as a normative sample. Hypnotherapy is seen as feasible in group administration by persons only moderately trained in hypnosis and of potential benefit to self-esteem improvement in LD children, depending on individual difference factors.

Adolescent↗
PubMed1978

'Downhill' esophageal varices. A rare cause of upper gastrointestinal bleeding.

The submucosal venous network of the esophagus is part of the collateral system that develops following superior vena caval obstruction from any cause. The direction of flow in these thin-walled, valveless veins is "downhill," towards the azygous vein or to the inferior vena cava. Bleeding from upper esophageal varices is extremely rare. This case report describes a patient with massive bleeding from upper esophageal varices secondary to superior vena caval obstruction by a malignant thyroid tumor. Total thyroidectomy relieved the obstruction, with cessation of hemorrhage and subsequent disappearance of the varices.

Aged↗
PubMed1975

Incorporation of L-azetidine-2-carboxylic acid into hemoglobin in rabbit reticulocytes in vitro.

L-Azetidine-2-carboxylic acid is the naturally occurring lower homologue of L-proline. Reticulocytes from anemic rabbits incubated with DL-[14-C]azetidine-2-carboxylic acid synthesized radiolabeled hemoglobin, which when isolated from cell lysates co-chromatographed with unlabeled hemoglobin on Sephadex G-100 columns. Amino acid analysis of hemoglobin from reticulocytes incubated with DL-[14-C]-azetidine-2-carboxylic acid suggested that the homologue was incorporated into hemoglobin intact and unaltered. Alternatively, another amino acid analogue, 1-aminocyclopentane-[1-14-C]carboxylic acid, which is purported to be a valine antagonist, was not incorporated into hemoglobin under these conditions. Incubation of reticulocytes with 1, 5, and 10 mM L-azetidine-2-carboxylic acid reduced L-[U-14-C]proline (0.10 mM) incorporation into hemoglobin by 25, 58, and 72%, respectively. Conversely, 1.45 and 145 muM L-proline reduced radiolabeled azetidine-2-carboxylic acid (0.8 mM) in corporation into hemoglobin by 45 and 92%, respectively. Incorporation of L-[U-14-C]leucine and L-[U-14-C]lysine (0.1 mM each) into hemoglobin was unaffected at these concentrations of L-azetidine-2-carboxylic acid. These results suggest that L-azetidine-2-carboxylic acid is incorporated into hemoglobin without reducing the rate of globin synthesis in rabbit reticulocytes in vitro. The alpha and beta chains of hemoglobin into which [14-C]azetidine-2-carboxylic acid had been incorporated in rabbit reticulocytes in vitro were resolved electrophoretically on sodium dodecyl sulfate-polyacrylamide gels. The ratio of total radioactivity in the alpha and beta chains separately extracted from gels was in good agreement with the known 7:4 ratio of prolyl residues in the respective chains. Autoradiograms of two-dimensional tryptic peptide maps of rabbit globin into which either [14-C]azetidine-2-carboxylic acid or [14-C]proline had been incorporated showed nearly identical patterns of radioactivity. These results suggest that azetidine-2-carboxylic acid substitutes specifically for prolyl residues during in vitro hemoglobin synthesis in rabbit reticulocytes.

Amino Acids↗
PubMedDate not supplied

Calculation of beta dosimetry in radiation synovectomy using Monte Carlo simulation (EGS4).

Using the EGS4 Monte Carlo code, absorbed dose rate factors were estimated for four radionuclides of interest in radiation synovectomy, an intra-articular radiation therapy to treat rheumatoid arthritis. The treatment consists of the injection of a beta-emitting radionuclide into the joint capsule in order to eliminate diseased synovium through irradiation. The radionuclides investigated are 32P, 90Y, 165Dy, and 198Au. Calculations reveal the absorbed dose factor (cGy cm2/MBq s) as a function of distance (mm) in an EGS4 model of the rheumatic joint. The model incorporates bone, articular cartilage, joint capsule, and tissue (synovium) components found in all synovial joints, with dimensions in the model corresponding to dimensions typically found in larger joints, e.g., the knee, shoulder, or hip. Results are compared with previous, analytical approaches to beta dosimetry in radiation synovectomy. In addition, radiation backscatter due to the presence of bone is investigated and determined to have a negligible enhancement effect on absorbed dose to synovium.

Arthritis, Rheumatoid↗