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Biomedical subjects

R G Holt

Publications and source records attributed to R G Holt.

28 records · Page 2Linked to original sources
PubMed1989

CT and MR of lateral disc herniation: typical appearance and pitfalls of interpretation.

Lateral disc herniation is a relatively uncommon manifestation of intervertebral disc disease, defined as herniation of disc material lateral to or into the vertebral foramen. Failure to recognize this lesion preoperatively may lead to unsuccessful surgical exploration. We describe here the radiologic findings in seven patients with lateral disc herniation. Three were evaluated with magnetic resonance imaging alone, three with computed tomography alone, and one with both modalities. Example of three entities which may mimic lateral disc herniation (pseudodisc protrusion of scoliosis, paravertebral masses, and volume averaging artifacts) are illustrated.

Adult↗
PubMed1985

Sedimentation analysis of ribonucleotide reductase activity in extracts of Pseudomonas stutzeri.

Analysis of ribonucleotide reductase and DNA polymerase activities in extracts of Pseudomonas stutzeri by centrifugation in discontinuous sucrose gradients indicated that these two enzymes are associated with two different high molecular weight cellular components. In addition, 95% of the ribonucleotide reductase activity was pelleted by centrifugation of extracts for 4 hr at 200,000 X G. The reductase activity remained particulate (sedimentable) following sonication whereas some 90% of the DNA polymerase activity was rendered soluble (non-sedimentable) by this technique. This data indicate that the P. stutzeri ribonucleotide reductase is not a cytosolic enzyme, but is associated with a macromolecular component in the cell.

Centrifugation, Density Gradient↗
PubMed1982

Streptococcus mutans genes that code for extracellular proteins in Escherichia coli K-12.

Chromosomal DNA from Streptococcus mutans 6715 (serotype g) was cloned into Escherichia coli K-12 by using the cosmid pJC74 cloning vector and a bacteriophage lambda in vitro packaging system. Rabbit antiserum against S. mutans extracellular proteins was used for immunological screening of the clone bank. Twenty-one clones produced weak to strong precipitin bands around the colonies, but only after the lambda c1857 prophage was induced by being heated to lyse the E. coli cells. None of the clones expressed enzyme activity for several known S. mutans extracellular enzymes. One of these clones contained a 45-kilobase recombinant plasmid designated pYA721. An 8.5-kilobase fragment of S. mutans DNA from pYA721 was isolated and recloned into the BamHI restriction site of the plasmid vector pACYC184 to construct pYA726. pYA726 contained all, or nearly all, of the gene for a surface protein antigen (the spaA protein) of S. mutans 6715. This was deduced from immunological studies in which extracts of cells harboring pYA726 reacted with antisera against both purified 6715 spaA protein (about 210,000 daltons) and the immunologically similar antigen I/II of serotype c strains of S. mutans. In addition, the S. mutans spaA protein was found to possess at least one antigenic determinant not present on the protein specified by pYA726. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of E. coli clone extracts revealed that pYA726 produced a polypeptide with a molecular mass of about 180,000 daltons which was predominantly found in the periplasmic space of E. coli cells. Antisera to the spaA protein of S. mutans reacted with extracellular protein from representative strains of S. mutans serotypes a, c, d, e, f, and g, but not b.

Antigens, Bacterial↗
PubMed1979

Tantalum labelling in vivo of cardiac ventricular chambers in dogs.

Demarcating fixed points in cardiac ventricles in the dog by catheter placement of tantalum coils has been shown to provide an excellent physiologic model. A new method emplying direct ventricular puncture has been developed for implanting these markers. The method has several advantages over an earlier peripheral catheter technique. Apical approach allows easier screw placement near the aortic and pulmonary valves. Peripheral vessels are left intact and pressure monitoring as well as contrast medium injection can be performed through the same catheter.

Animals↗
PubMed1978

Angiographic features of carcinoid heart disease.

Cineangiocardiograms from 2 patients with carcinoid syndrome and cardiac involvement were reviewed. Gross and microscopic pathology specimens were available for 1 case. Both patients exhibited tricuspid valvar stenosis and insufficiency. The area of the pulmonic valve was similar in both with narrowing of the annulus and tapering toward the valve of the proximal pulmonary artery and the subvalvar right ventricular outflow tract, producing an hourglass appearance, which the authors feel is characteristic of this disease.

Angiocardiography↗
PubMed1975

Angiographic features of benign renal adenoma.

Five cases of beign renal adenoma were studied angiographically. The findings are presented along with a review of the literature. There were 4 males and 1 female ranging in age from forty-two to sixty-three years. Each presented with a mass on excretory urography, and 1 contained calcification. The largest two lesions showed circumferentially distributed vascular supply. Two lesions showed a faint homogenous blush on the nephrogram phase of the angiogram, and the firth lesion, which arose in the wall of a cyst, was angiographically silent.

Adenoma↗