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Biomedical subjects

D H Hayes

Publications and source records attributed to D H Hayes.

At least 37 records · Page 2Linked to original sources
PubMed1991

Patterns of utilization of mammography comparison by physician specialties in 6,000 consecutive mammograms.

Mammography is regarded as the most important screening test for breast cancer. The combination of physical examination of the breast by a physician and mammography can result in reduced breast cancer mortality. Evidence is mounting that mammography alone can produce similar results. Despite these facts, mammography is underutilized in the United States. In an attempt to define the utilization of mammography in the Ochsner Medical Institutions, New Orleans, Louisiana, the records of 6,000 consecutive patients who underwent mammography were reviewed with respect to the specialty of the physician ordering the test. The ratio of the number of mammograms ordered by each service to the number of eligible patients (women over age 50) visiting that service provided insight into the patterns of utilization of mammography in the Ochsner Clinic. This information will allow for efficient utilization of time and resources in planning continuing education programs geared toward mammographic screening.

Adult↗
PubMed1990

The perioperative management of neonates with congenital oropharyngeal teratomas.

Oropharyngeal teratomas are rare congenital neoplasms that distort orofacial anatomy and often cause respiratory embarrassment at birth. Immediate management of such lesions should include establishment of a secure upper airway, radiographic exclusion of midline central nervous system anomalies, and early surgical excision to prevent asphyxia or permanent disfigurement. Perioperative assessment and surgical management are reported for three oropharyngeal teratomas.

Female↗
PubMed1989

Crosslinking of ribosomal proteins S4, S5, S7, S8, S11, S12 and S18 to domains 1 and 2 of 16S rRNA in the Escherichia coli 30S particle.

RNA-protein crosslinks were introduced into Escherichia coli 30S ribosomal subunits by treatment with 1-ethyl-3(3-dimethylaminopropyl)carbodiimide (EDC). Complexes of 16S rRNA cross-linked to 30S ribosomal proteins were isolated and hybridized with a series of single-stranded bacteriophage M13-rDNA probes. These probes, each carrying an inserted rDNA fragment, were used to select contiguous 16S rRNA sections covering all of domain 1 and the major part of domain 2 (starting at the 5'-P terminus and ending at nucleotide 869) and the proteins covalently linked to each of these sections were identified by 2-dimensional polyacrylamide gel electrophoresis. This procedure identified proteins S4, S5, S7, S8, S11, S12, and S18 as the species most efficiently crosslinked to domains 1 and 2 of 16S rRNA. These results are discussed in the light of current knowledge of the tertiary structure of 16S rRNA in the E. coli 30S ribosomal subunit.

Cross-Linking Reagents↗
PubMed1989

Acute hepatic failure: the emerging role of orthotopic liver transplantation.

From 1985 through 1987, we diagnosed acute hepatic failure in 13 patients. Spontaneous recovery occurred in three of these patients. Eight patients underwent liver transplantation, five of whom survived and three of whom died. In addition, two patients died before undergoing transplantation. The survival rate of 62% was better than that among our previous series of similar patients. This improvement seems to be related to the use of orthotopic liver transplantation as a therapeutic alternative among these patients. One of the three patients who died after liver transplantation had normal liver function, but respiratory failure caused by Pneumocystis carinii developed 4 months after the transplantation. The surgical procedure was less difficult in patients with acute fulminant hepatitis than in those with chronic liver disease because fewer problems arose from adhesions, venous collaterals, and ascites. The emerging role of orthotopic liver transplantation in patients with acute hepatic failure is demonstrated by the improvement of survival rates observed by various groups, including ours, when this therapeutic modality is available.

Acute Disease↗
PubMed1988

Splenic artery aneurysms in liver transplant patients.

We found splenic artery aneurysms in 6 of 71 consecutive patients who underwent orthotopic liver transplantation at the Mayo Clinic. The incidence of splenic artery aneurysms in cirrhotic patients with portal hypertension was 10%. Five of the aneurysms were found in patients suffering from chronic active hepatitis, whereas no aneurysms were encountered in patients with primary sclerosing cholangitis or primary biliary cirrhosis. One patient ruptured a splenic artery aneurysm shortly after liver transplantation, and 1 patient developed an aneurysm 3 months after transplantation. We recommend coeliac angiography to be performed prior to liver transplantation, and if splenic artery aneurysms are found, ligation of the splenic artery should be performed at the time of transplantation to prevent possible rupture.

Adolescent↗
PubMed1987

Comparison of active and inactive forms of the E. coli 30S ribosomal subunits.

Dissociation of E. Coli 70S ribosomes in the presence of 0.1 mM Mg++ yields partially inactivated 30S and 50S subunits. This inactivation can be avoided by dissociating the 70S ribosome in a medium containing 10 mM Mg++. 400 mM Na+. Comparison of the active and inactive forms of the 30S and 50S subunits has led to the following conclusions: 1) The two forms possess identical (50S subunits) or very similar (30S subunits) hydrodynamic properties. No differences in their morphologies is detectable by electron microscopy. 2) They possess the same protein compositions except for the presence of a larger amount of protein S1 in the inactive than in the active form of the 30S subunit. 3) They differ significantly in functional properties: more efficient association of the active than of the inactive forms with the complementary subunit; extensive dimerization of inactive 30S subunits in the presence of 10 mM Mg++; no dimerization of active 30S subunits under the same conditions; six-fold higher peptidyl transferase activity of active as compared to inactive 50S subunits.

Bacterial Proteins↗
PubMed1987

Carcinoma of the ampulla of Vater.

Thirty-five consecutive cases of adenocarcinoma of the ampulla of Vater seen over the past 36 years were reviewed. The introduction of new diagnostic techniques over the course of this study improved the accuracy of preoperative diagnosis but did not lead to earlier diagnosis. The surgical resectability rate was 88%, and 53% of postoperative survivors were free of disease at 5 years. Of the 14 patients with metastases to regional lymph nodes, 27% survived disease-free for 5 years. Surgical mortality was 25% for the entire series but has been reduced to 6.6% over the past decade. Surgical mortality was primarily due to leakage of the pancreaticojejunostomy; the risk of pancreaticojejunostomy leak correlated inversely with the degree of chronic pancreatitis in the pancreatic remnant. In 35% of resected cases, a benign adenomatous component was contained within the cancer of the ampulla of Vater. Cure rates are good for this lesion. The most important factor in maximizing cure rate is careful attention to the technical details of pancreaticojejunostomy in order to minimize surgical mortality. Benign adenomas appear to be a frequent precursor of carcinoma of the ampulla of Vater.

Adenocarcinoma↗
PubMed1986

Multiple crosslinks of proteins S7 and S9 to domains 3 and 4 of 16S ribosomal RNA in the Escherichia coli 30S particle.

RNA-protein cross-links were introduced into Escherichia coli 30S subunits by treatment with 1-ethyl-3(3-dimethylaminopropyl)carbodiimide. 16S rRNA, cross-linked to 30S ribosomal proteins, was isolated and hybridized with seven single-stranded bacteriophage M13-DNA probes. These probes, each carrying an inserted rDNA fragment, were used to select contiguous RNA sections covering domains 3 and 4 (starting at nucleotide 868 and ending at the 3'OH terminus) of the 16S rRNA. The proteins covalently linked to each selected RNA section were identified by two-dimensional polyacrylamide gel electrophoresis. Proteins S7 and S9 were shown to be efficiently cross-linked to multiple sites belonging to both domains.

Bacterial Proteins↗
PubMed1985

Structure of the Escherichia coli 16 S ribosomal RNA. Psoralen crosslinks and N-acetyl-N'-(p-glyoxylylbenzoyl)cystamine crosslinks detected by electron microscopy.

Escherichia coli 16 S ribosomal RNA in reconstitution buffer has been photochemically crosslinked with aminomethyltrimethylpsoralen and chemically crosslinked with N-acetyl-N'-(p-glyoxylylbenzoyl)cystamine. The positions of crosslinking have been detected by viewing the molecules in the electron microscope. DNA restriction fragments that contain psoralen mono-adducts were hybridized and crosslinked to the samples so that the orientations of the crosslinked molecules were seen directly. A two-dimensional histogram method has been used to classify the different types of looped crosslinked molecules. These methods allow the identification of 13 distinct types of loops in the photochemically crosslinked molecules and 31 distinct types of loops in the chemically crosslinked molecules. The psoralen experiments are a reinvestigation of some of our earlier results. Some of the crosslinks were previously reported in the incorrect orientation; with the corrected orientation, seven of the psoralen crosslinks can now be correlated with complementarities in the proposed secondary-structure models. However, there are still six other psoralen crosslinks that indicate additional contacts not found in the current models. The chemical crosslinks indicate pairs of single-stranded regions that must be close in the folded molecule. Many of these crosslinks occur between regions that are distant in the secondary structure; these crosslinks indicate part of the three-dimensional form of the folded molecule.

Cross-Linking Reagents↗
PubMed1985

The specific phosphorylation of a 40S ribosomal protein in growth-arrested tetrahymena is induced by sodium.

In the past few years, in vivo phosphorylation of ribosomal proteins has been the subject of extensive studies and the results have shown that reversible phosphorylation of small subunit ribosomal protein S6, ubiquitous in eukaryotic cells, is apparently related to regulation of protein synthesis initiation. Thus the level of protein synthesis under various conditions is correlated with the level of S6 phosphorylation. In exponentially growing Tetrahymena, however, such phosphorylation does not occur, but when these cells are transferred to starvation buffers, the rate of protein synthesis is drastically reduced and a 40S ribosomal protein analogous to S6 of higher eukaryotic cells is fully and rapidly phosphorylated in all the ribosomes. We have studied the conditions which lead to this phosphorylation in growth-arrested Tetrahymena, in order to understand the physiological significance of this process. Our results show that there is no obvious correlation between this phosphorylation and starvation. Moreover, it is not a developmentally regulated process related to the conjugation cycle, but a modification induced by the presence of sodium ions or high concentration of Tris in the starvation buffer. The physiological significance of this process is discussed in terms of accumulation of negative charge density probably required for initiation of protein synthesis in the growth-arrested cells starving in Na+-containing buffers.

Animals↗
PubMed1979

Reconstitution of active 30-S ribosomal subunits in vitro using heat-denatured 16-S rRNA.

30-S ribosomal subunits which have been reconstituted using heat-denatured 16-S rRNA can participate in the synthesis of lysosyme in vitro. Therefore all the information contributed by 16-S rRNA to the reconstitution process is carried in the primary sequence of this RNA. The specific protein-synthesizing activity of 30-S subunits reconstituted from 30-S subunit proteins and heat-denatured 16-S rRNA is about one third of that observed if unheated 16-S rRNA is used and is comparable to the activity of 30-S particles isolated after dissociation of 70-S ribosomes in the presence of 0.1 mM Mg2+.

Base Sequence↗
PubMed1979

Translation in vitro of Tetrahymena pyriformis polyadenylated mRNA. Identification of tubulin amongst the translated products and demonstration of its heterogeneity.

The capacity of poly(A)-containing RNA of the protozoan ciliate Tetrahymena pyriformis to direct the synthesis of proteins in vitro has been tested using two cell-free systems: a wheat germ extract and a rabbit reticulocyte lysate. The results obtained with these two systems are compared and the identification of alpha and beta tubulins among the products of protein synthesis in vitro, after separation by one-dimensional and two-dimensional electrophoresis, is described. By isoelectric focusing in polyacrylamide gels, each species of tubulin is resolved into several bands, suggesting that the main subunits are more heterogeneous than has been generally described. Poly(A)-containing RNA has also been fractionated on a 70% formamide/sucrose gradient and it is shown that alpha and beta tubulins are coded by separate mRNAs.

Animals↗