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Biomedical subjects

S M Sullivan

Publications and source records attributed to S M Sullivan.

At least 37 records · Page 2Linked to original sources
PubMed1999

Heat generation by superpulsed CO2 lasers on plasma-sprayed titanium implants: an in vitro study.

OBJECTIVE: The purpose of this study was to record the generation of heat in selected titanium implants while exposing them to a superpulsed CO(2) laser mode. These results can be compared with previous studies in which continuous and pulsed CO(2) laser modes were used. STUDY DESIGN: Titanium implants with cover screws were used in this study. The length of exposure time ranged from 2 to 15 seconds, and the wattage ranged from 3 to 15 W. A thermocoupler with a module recorder was used to record temperature changes at the implant-cover screw interface with the implant in a 37 degrees C water bath. Temperature changes were documented during the exposure phase, as well as after termination of the exposure. Statistical analysis consisted of analysis of variance (P <.05) for statistically significant differences among the exposure time-wattage pairs. RESULTS: Temperature increases were directly related to wattage and exposure time. All temperatures returned to baseline within 1 minute. CONCLUSION: Superpulsed CO(2) lasers generate significantly less heat with the 15-second, 15-W trial as compared with continuous and pulsed laser modes. Peak temperature increases with similar exposure and wattage times are comparable to those of the pulsed-laser mode.

Carbon Dioxide↗
PubMed1999

A retroperitoneal bronchogenic cyst with malignant change.

A unique case of adenocarcinoma arising in a retroperitoneal bronchogenic cyst is presented. A 55-year-old woman presented with lower abdominal discomfort. Computed tomography revealed a retroperitoneal cystic mass attached to the ascending colon. The resected cyst was unilocular and filled with milky white mucus and hemorrhagic debris. Histologically, most of the cyst wall was of well-differentiated papillary adenocarcinoma with no cyst wall invasion. Other small areas of the cyst were lined with variably atypical dysplastic/metaplastic cuboidal to pseudostratified columnar epithelium. The cyst wall was mostly hyalinized, but there was apparent thickened subepithelial basement membrane, elastosis, and a single layer of smooth muscle that suggested bronchial wall structures. A mucin staining study with O-acylated sialic acid, which is used for the demonstration of gastrointestinal, cholecystic and uterine cervical mucins, was negative for the mucin-producing epithelial cells of the cyst. Thus, to our knowledge, this is the first reported case of adenocarcinoma arising in a retroperitoneal bronchogenic cyst.

Adenocarcinoma↗
PubMed1998

Mutational analysis of a transcriptional activation region of the VP16 protein of herpes simplex virus.

The VP16 protein of herpes simplex virus is a potent transcriptional activator of the viral immediate early genes. The transcriptional activation region of VP16 can be divided into two functional subregions, here designated VP16N (comprising amino acids 413-456) and VP16C (amino acids 450-490). Assays of VP16C mutants resulting from both random and alanine-scanning mutagenesis indicated that the sidechains of three phenylalanines (at positions 473, 475 and 479) and one acidic residue (glutamate 476) are important for transcriptional activation. Aromatic and bulky hydrophobic amino acids were effective substitutes for each of the three Phe residues, whereas replacement with smaller or polar amino acids resulted in loss of transcriptional function. In contrast, many changes were tolerated for Glu476, including bulky hydrophobic and basic amino acids, indicating that the negative charge at this position contributes little to the function of this subregion. Similar relative activities for most of the mutants were observed in yeast and in mammalian cells, indicating that the structural requirements for this activation region are comparable in these two species. These results reinforce the hypothesis that bulky hydrophobic residues, not acidic residues, are most critical for the activity of this 'acidic' transcriptional activation region.

Amino Acid Sequence↗
PubMed1998

The development and use of a computerized database for the evaluation of facial fractures incorporating aspects of the AAOMS Parameters of Care.

PURPOSE: This article discusses the development and use of a computerized database to evaluate facial fracture patients. Examples of epidemiologic and treatment outcome analyses that can be performed are also discussed. MATERIALS AND METHODS: FileMaker Pro 2.1 and 3.0 (Claris Corporation, Santa Clara, CA) for the Macintosh (Apple Computer, Inc, Cupertino, CA) was used for the development of the database. The database contained information on the facial fracture patients treated at The University of Oklahoma Health Sciences Center by the Oral and Maxillofacial Surgery service between January 1, 1994 and December 31, 1996. Eight evaluation forms were used: general information, and mandibular, maxillary, zygomatic, nasal, naso-orbital-ethmoid, orbital, and frontal sinus fractures. Indications for therapy and postoperative complications from the AAOMS Parameters of Care, Section on Trauma Surgery, were also included. RESULTS: This database allowed collection of a vast amount of data on 265 patients. Some of the analyses done on patients with mandibular fractures are described. CONCLUSION: This computerized database provides a quick and systematic method of obtaining and retrieving information on facial fracture patients. Numerous epidemiologic and treatment outcome analyses can be performed. Overall complication rates based on the AAOMS Parameters of Care are higher than previously published rates because of the longer list of complications being evaluated.

Adolescent↗
PubMed1998

Mechanisms of viral activators.

Adenovirus large E1A, Epstein-Barr virus Zebra, and herpes simplex virus VP16 were studied as models of animal cell transcriptional activators. Large E1A can activate transcription from a TATA box, a result that leads us to suggest that it interacts with a general transcription factor. Initial studies showed that large E1A binds directly to the TBP subunit of TFIID. However, analysis of multiple E1A and TBP mutants failed to support the significance of this in vitro interaction for the mechanism of activation. Recent studies to be reported elsewhere indicate that conserved region 3 of large E1A, which is required for its activation function, binds to one subunit of a multisubunit protein that stimulates in vitro transcription in response to large E1A and other activators. A method was developed for the rapid purification of TFIID approximately 25,000-fold to near homogeneity from a cell line engineered to express an epitope-tagged form of TBP. Purified TFIID contains 11 major TAFs ranging in mass from approximately 250 to 20 kD. Zta and VP16, but not large E1A, greatly stimulate the rate and extent of assembly of a TFIID-TFIIA complex on promoter DNA (DA complex). For VP16, this is a function of the carboxy-terminal activation subdomain. An excellent correlation was found between the ability of VP16C mutants to stimulate DA complex assembly and their ability to activate transcription in vivo. Consequently, for a subset of activation domains, DA complex assembly activity is an important component of the overall mechanism of activation.

Adenovirus E1A Proteins↗
PubMed1998

DA-complex assembly activity required for VP16C transcriptional activation.

One class of transcriptional activation domains stimulates the concerted binding of TFIIA and TFIID to promoter DNA. To test whether this DA-complex assembly activity contributes significantly to the overall mechanism of activation in vivo, we analyzed mutants of the 38-amino-acid residue VP16C activation subdomain from herpes simplex virus. An excellent correlation was observed between the in vivo activation function of these mutants and their in vitro DA-complex assembly activity. Mutants severely defective for in vivo activation also showed reduced in vitro binding to native TFIIA. No significant correlation between in vivo activation function and in vitro binding to human TATA binding protein, human TFIIB, or Drosophila melanogaster TAFII40 was observed for this set of VP16C mutants. These results argue that the ability of VP16C to increase the rate and extent of DA-complex assembly makes a significant contribution to the overall mechanism of transcriptional activation in vivo.

Animals↗
PubMed1997

The use of fibrin adhesive in sinus lift procedures.

Sinus lift bone grafting has expanded the use of dental implants in reconstructions of the atrophic maxilla. Potential problems include sinus membrane tear, which can lead to graft infection and early failure. Attempts at managing sinus membrane perforations are often limited by difficulty of access, as well as by the friability of the soft tissue lining the sinus. Various techniques have been proposed for managing such membrane tears. The use of fibrin adhesive, however, may present a potential solution in such situations. This article reports our experience with the use of fibrin adhesive in sinus lift procedures, as well as on its autologous preparation.

Bone Transplantation↗
PubMed1997

In vivo gene transfer by intravenous administration of stable cationic lipid/DNA complex.

PURPOSE: A stable cationic lipid/DNA complex has been developed for in vivo gene transfer. The formulation capitalizes on a previously described procedure to obtain stable lipid/DNA complexes for in vitro gene transfer (1). METHODS: Conditions for DNA/lipid complex formation were modified to yield a DNA concentration of 1 mg/ml. Heat stable alkaline phosphatase (AP) under a CMV promoter was used as a reporter gene. RESULTS: The resulting complex was completely insensitive to serum inactivation. Tail vein injection of a 80 micrograms DNA into Balb C mice yielded significant levels of reporter enzyme activity in the lung, heart, spleen, muscle, and liver. Less AP activity was observed in the kidney. No AP activity was observed in blood, bone marrow or brain. A titration of the lipid (DOSPA) to DNA-nucleotide ratio showed the optimal molar ratio for in vivo gene transfer to be 1/1. Using this ratio in a dose response study showed approximately 80 micrograms of DNA/mouse yielded the highest level of gene expression. Using this dose at a 1/1 lipid to DNA nucleotide ratio, the time course for alkaline phosphatase activity was determined. Maximal AP activity was observed 24 hours after injection for all tissues. By day 5, the activity dropped approximately 10 fold for all tissues. By day 7, residual activity was detected in the lung, heart, and muscle. Histology of the lung showed both interstitial and endothelial cells to be transfected. In all other tissues, however, endothelial cells were the only transfected cell type. CONCLUSIONS: These results demonstrate that reformulation of an existing cationic lipid can result in the formation of a stable lipid/DNA complex, which is able to reproducibly transfect lung, heart, spleen, and liver upon intravenous administration.

3T3 Cells↗
PubMed1996

Formation of stable cationic lipid/DNA complexes for gene transfer.

Stable cationic lipid/DNA complexes were formed by solubilizing cationic liposomes with 1% octylglucoside and complexing a DNA plasmid with the lipid in the presence of detergent. Removal of the detergent by dialysis yielded a lipid/DNA suspension that was able to transfect tissue culture cells up to 90 days after formation with no loss in activity. Similar levels of gene transfer were obtained by mixing the cationic lipid in a liposome form with DNA just prior to cell addition. However, expression was completely lost 24 hr after mixing. The transfection efficiency of the stable complex in 15% fetal calf serum was 30% of that obtained in the absence of serum, whereas the transient complex was completely inactivated with 2% fetal calf serum. A 90-day stability study comparing various storage conditions showed that the stable complex could be stored frozen or as a suspension at 4 degrees C with no loss in transfection efficiency. Centrifugation of the stable complex produced a pellet that contained approximately 90% of the DNA and 10% of the lipid. Transfection of cells with the resuspended pellet and the supernatant showed that the majority of the transfection activity was in the pellet and all the toxicity was in the supernatant. Formation of a stable cationic lipid/DNA complex has produced a transfection vehicle that can be stored indefinitely, can be concentrated with no loss in transfection efficiency, and the toxicity levels can be greatly reduced when the active complex is isolated from the uncomplexed lipid.

3T3 Cells↗
PubMed1995

Magnetic resonance imaging assessment of acute soft tissue injuries to the temporomandibular joint.

PURPOSE: This study involves the use of magnetic resonance imaging (MRI) to document acute soft tissue injuries involving the temporomandibular joint (TMJ) after condylar fractures. MATERIALS AND METHODS: Patients with condylar fractures whose clinical and radiographic examinations, as well as the mechanism of their injury, suggested specific damage to the temporomandibular soft tissues underwent MRI scanning. Thirteen patients who met selected criteria were included in this study. RESULTS: Ten patients demonstrated disc avulsion, usually in the anterior or medial direction. Two patients had disruption of the lateral capsule, and one patient showed no MRI evidence of acute injury. Joint effusions were frequently demonstrated. CONCLUSIONS: MRI of condylar fractures in those patients with displacement, or in whom the mechanism of injury would predispose them to posttraumatic internal derangement, may assist the clinician in determining whether primary or delayed treatment is indicated. Furthermore, MRI may be a useful resource for enhancing the level of understanding regarding soft tissue changes that occur in the TMJ after acute condylar trauma.

Cartilage, Articular↗
PubMed1994

Development of ribozymes for gene therapy.

Ribozymes are a class of RNA molecules that can perform catalytically in the absence of protein. Specifically, they can hybridize to and cleave target RNA molecules independent of cellular proteins. The cleaved target RNA can not be translated thereby preventing synthesis of a specific protein. The therapeutic application is to target the ribozyme to the mRNA of a key protein or proteins involved in maintaining a disease state resulting in a cure. The ribozymes can be chemically synthesized and delivered to cells or they can be expressed from an expression vector following either permanent or transient transfection. Therapeutic applications of ribozymes have been in the areas of AIDS and cancer. The following article describes the ribozymes in more detail with respect to optimizing the design to obtain the maximal cleavage rate, identifying cleavage sites within the target RNA and delivering the ribozymes to cells of interest both in vitro and in vivo.

Base Sequence↗