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T A Sullivan

Publications and source records attributed to T A Sullivan.

13 recordsLinked to original sources
PubMed2001

Cloning and characterization of a bean UDP-glucosyltransferase cDNA expressed during plant-bacterial interactions.

A cDNA clone, which corresponds to an RNA transcript that accumulates in bean during the hypersensitive reaction, was isolated and designated Hra25 (for hypersensitive reaction associated). Hra25 is predicted to encode a UDP-glucosyltransferase. Northern analysis was used to study Hra25 transcript accumulation in bean in response to incompatible and compatible strains of Pseudomonas syringae, an Hrp- mutant, and wounding. Our data suggest that the Hra25 transcript is activated in response to specific avr-derived signals as well as non-avr, general signals.

Cloning, Molecular↗
PubMed2001

Thirty-day mortality after total knee arthroplasty.

BACKGROUND: There have been sporadic reports on perioperative mortality associated with total knee arthroplasty. The purpose of this study was to determine risk factors for such mortality. METHODS: A computer-assisted review of the records of 22,540 consecutive patients who had undergone total knee arthroplasty between 1969 and 1997 was performed to identify all patients who had died within thirty days after the procedure. A detailed analysis of the medical, surgical, anesthetic, and pathological records of the patients was performed, and the mortality was determined according to age, gender, diagnosis, and fixation method. RESULTS: The rate of mortality within thirty days after the operation was 0.21% (forty-seven of 22,540). All deaths occurred in the group of 18,810 patients who had received a cemented implant, and no deaths occurred among the 3730 patients who had received an uncemented implant (p < 0.0001). The mortality rate was 0.24% (forty-three of 18,165) after primary arthroplasty and 0.09% (four of 4375) after revision arthroplasty (p < 0.0003). Three patients (0.01%) died during the operation. Forty-three of the forty-seven patients who died had a history of preexisting cardiovascular and/or pulmonary disease. Simultaneous bilateral total knee arthroplasty was associated with a significantly higher rate of perioperative mortality (p < 0.002). CONCLUSIONS: Factors that were associated with a significantly increased mortality after total knee arthroplasty included an age of more than seventy years, primary (as compared with revision) knee surgery, use of a cemented prosthesis, preexisting cardiopulmonary disease, and simultaneous bilateral arthroplasty.

Aged↗
PubMed1997

Rapid chondrocyte maturation by serum-free culture with BMP-2 and ascorbic acid.

In serum-containing medium, ascorbic acid induces maturation of prehypertrophic chick embryo sternal chondrocytes. Recently, cultured chondrocytes have also been reported to undergo maturation in the presence of bone morphogenetic proteins or in serum-free medium supplemented with thyroxine. In the present study, we have examined the combined effect of ascorbic acid, BMP-2, and serum-free conditions on the induction of alkaline phosphatase and type X collagen in chick sternal chondrocytes. Addition of either ascorbate or rhBMP-2 to nonconfluent cephalic sternal chondrocytes produced elevated alkaline phosphatase levels within 24-72 h, and simultaneous exposure to both ascorbate and BMP yielded enzyme levels at least threefold those of either inducer alone. The effects of ascorbate and BMP were markedly potentiated by culture in serum-free medium, and alkaline phosphatase levels of preconfluent serum-free cultures treated for 48 h with BMP+ascorbate were equivalent to those reached in serum-containing medium only after confluence. While ascorbate addition was required for maximal alkaline phosphatase activity, it did not induce a rapid increase in type X collagen mRNA. In contrast, BMP added to serum-free medium induced a three- to fourfold increase in type X collagen mRNA within 24 h even in the presence of cyclohexamide, indicating that new protein synthesis was not required. Addition of thyroid hormone to serum-free medium was required for maximal ascorbate effects but not for BMP stimulation. Neither ascorbate nor BMP induced alkaline phosphatase activity in caudal sternal chondrocytes, which do not undergo hypertrophy during embryonic development. These results indicate that ascorbate+BMP in serum-free culture induces rapid chondrocyte maturation of prehypertrophic chondrocytes. The mechanisms for ascorbate and BMP action appear to be distinct, while BMP and thyroid hormone may share a similar mechanism for induction.

Alkaline Phosphatase↗
PubMed1996

Immigration and the ethics of choice.

"This paper begins by developing a language for ethical discourse on immigration and then examining the extent to which choices may be made at the micro-level and at the macro-level. States and individuals are examined as actors who are variously described as making choices or being choiceless. The concepts of cultural distance, reciprocity, the role of the individual and of the state and their interrelationships are evaluated in the perspective of choice. Whether an ethics of immigration can be successfully developed hinges on the degree of choice that individuals and state have or perceive themselves to have."

Behavior↗
PubMed1995

Distribution of insulin-like growth factor receptors in rat intestinal epithelium.

In summary, we present data from affinity cross-linking and Scatchard plot analysis that demonstrates the presence of both IGF-I receptors and IGF-II receptors on the brush border membranes of rat intestinal mucosa. The brush border location of the IGF receptors suggests that IGFs available in the intestinal lumen may initiate signal transduction events by binding to receptors displayed on the mucosal lining. Our findings provide further support for the notion that at least some of the mitogenic stimulus for rapid proliferation of intestinal epithelium arises from lumenal IGFs, which may be supplied by apical secretions from the mucosa, or in saliva, colostrum, milk, chyme, or bile.

Animals↗
PubMed1994

Ascorbate modulation of chondrocyte gene expression is independent of its role in collagen secretion.

During development and fracture repair, endochondral bone formation is preceded by an orderly process of chondrocyte hypertrophy and cartilage matrix calcification. Analysis of calcifying versus noncalcifying cartilage has identified several differences in matrix proteins; among these are appearance of a novel collagen, type X, and decreased synthesis of type II collagen, the major component of cartilage matrix. In addition, there is a marked increase in alkaline phosphatase, an enzyme expressed at high levels in all mineralizing tissues. Cultured chondrocytes can be induced to undergo these changes in gene expression and to produce calcified matrix by exposure to ascorbic acid. The mechanism by which ascorbate produces these changes has been examined by analyzing the effect of the vitamin on prehypertrophic chick embryo sternal chondrocytes. Nuclear run-on assays demonstrated that ascorbate alters mRNA levels in chondrocytes by changing the transcription rates. The fact that marked changes in mRNA levels require 1-2 days of ascorbate exposure suggested that the effect of this vitamin on gene transcription may be secondary to other, earlier ascorbate-induced effects. Since cells cultured with ascorbate produce a collagen-enriched matrix, we examined the hypothesis that transcriptional changes were secondary to altered cell-matrix interactions. Chondrocytes were cultured after attachment to tissue culture plastic, in suspension, or on plates coated with collagen type I. Comparison of alkaline phosphatase activity with and without ascorbate addition demonstrated that under all of these conditions, induction of enzyme was dependent on the presence of ascorbate. When plates containing ascorbate-conditioned chondrocyte matrix were used as substrate for naive chondrocytes, the cells continued to require ascorbate for induction of high levels of alkaline phosphatase and type X collagen mRNA. Addition of the hydroxylation inhibitor, 3,4-dehydroproline, caused marked inhibition of collagen secretion as well as accumulation of underhydroxylated collagens within the cells. However, even in the presence of this inhibitor ascorbate was effective in inducing elevated alkaline phosphatase and type X collagen. These results indicate that the ability of ascorbate to induce chondrocyte hypertrophy does not depend on production of a collagen-rich matrix.

Alkaline Phosphatase↗
PubMed1994

Induction of rapid osteoblast differentiation in rat bone marrow stromal cell cultures by dexamethasone and BMP-2.

Adult vertebrates require a continuous supply of osteoblasts for both bone remodeling and regeneration during fracture repair. This implies the existence of a reservoir of cells in the body capable of osteogenesis. One source of these osteoprogenitors is the stem cells within the fibroblastic component of bone marrow stroma. Mature osteoblasts are characterized by high alkaline phosphatase and osteopontin levels, combined with expression of the bone-specific matrix proteins osteocalcin and bone sialoprotein and the capacity for matrix mineralization. We have used these markers to define the conditions permitting rapid osteoblast differentiation from cultured bone marrow stromal cells. Osteoblastic differentiation was induced by continuous culture with 10(-8) M dexamethasone (dex) which stimulated alkaline phosphatase (AP) activity and mRNA levels as well as osteopontin, bone sialoprotein, and osteocalcin mRNA by Day 8 of culture; coaddition of 10(-8) M 1,25-dihydroxyvitamin D3 (vitamin D) with dex was essential for high osteocalcin mRNA expression. Recombinant bone morphogenetic protein-2 (BMP-2) exerted similar effects to dex and acted in synergy with dex to yield greatly elevated AP activity as well as increased levels of osteoblastic mRNAs. Using in situ hybridization to detect the presence of mRNAs in individual cells, it was shown that appearance of osteopontin mRNA preceded AP mRNA, and was expressed in dex-treated cell colonies as early as Day 4. Quantitation of cell surface AP protein by flow cytometry indicated that culture with dex or BMP-2 produced a mixed population of cells with low AP (dim cells) and cells with high AP levels, while the combination of dex + BMP-2 yielded very few dim cells and a population of cells containing higher AP levels than with either inducer alone. When the dim population from dex-treated cells was sorted and recultured with inducers, these cultures developed high AP levels and were able to deposit a mineralized matrix. Thus, treatment of marrow stromal cells with inducer results in a population of mature osteoblasts as well as a population of undifferentiated cells which retains the capacity for osteoblastic differentiation with further exposure to inducers. These data demonstrate that stem cells within the stromal compartment of bone marrow are capable of rapidly acquiring osteoblast features and suggest a potential role for glucocorticoids in combination with BMP-2 and vitamin D in stages of osteogenic development.

Alkaline Phosphatase↗
PubMed1992

Flow cytometric analysis of pulmonary fluids and cells for the detection of malignancies.

Cells from a pulmonary or bronchial origin were analyzed with flow cytometry to assess the sensitivity and specificity of this method in diagnosing malignancy. In all instances, cells submitted for flow cytometry analysis were excess cells from specimens submitted for routine cytology. Less than 3% of all samples were rejected for insufficient material. Overall sensitivity from all sources was 86%, specificity 96%. Although cytology results were the standard for determining accuracy of flow cytometry, in a few patients cytology appeared normal and initial evidence for malignancy was obtained from flow cytometry. For this reason, flow cytometry may be a valuable adjunctive technology in the diagnosis of malignancy.

DNA↗
PubMed1986

Irreversible inhibition of calmodulin-sensitive cyclic nucleotide phosphodiesterase.

Photolysis of solutions containing 4-azido-7-phenylpyrazolo-[1,5a]-1,3,5-triazine (APPT) and calmodulin-sensitive cyclic nucleotide phosphodiesterase resulted in reduction of both cyclic GMP and cyclic AMP hydrolytic activity. The inactivation was dependent upon both time of exposure to ultraviolet irradiation and the initial concentration of APPT. The photo-induced inactivation could be attenuated by the presence of cyclic GMP, 1-methyl-3-isobutylxanthine, and papaverine. alpha-Chymotrypsin treatment caused the enzyme to be fully active in the absence of calmodulin but this treatment did not alter the ability of APPT to inactivate the enzyme. Thus, inhibition of calmodulin-binding did not contribute to the photo-induced inactivation. These data indicate that APPT acts as a photoaffinity agent to covalently modify the APPT-binding site of calmodulin-sensitive phosphodiesterase.

1-Methyl-3-isobutylxanthine↗