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G Tudor

Publications and source records attributed to G Tudor.

At least 19 recordsLinked to original sources
PubMed2006

Transcriptomic response to differentiation induction.

BACKGROUND: Microarrays used for gene expression studies yield large amounts of data. The processing of such data typically leads to lists of differentially-regulated genes. A common terminal data analysis step is to map pathways of potentially interrelated genes. METHODS: We applied a transcriptomics analysis tool to elucidate the underlying pathways of leukocyte maturation at the genomic level in an established cellular model of leukemia by examining time-course data in two subclones of U-937 cells. Leukemias such as Acute Promyelocytic Leukemia (APL) are characterized by a block in the hematopoietic stem cell maturation program at a point when expansion of clones which should be destined to mature into terminally-differentiated effector cells get locked into endless proliferation with few cells reaching maturation. Treatment with retinoic acid, depending on the precise genomic abnormality, often releases the responsible promyelocytes from this blockade but clinically can yield adverse sequellae in terms of potentially lethal side effects, referred to as retinoic acid syndrome. RESULTS: Briefly, the list of genes for temporal patterns of expression was pasted into the ABCC GRID Promoter TFSite Comparison Page website tool and the outputs for each pattern were examined for possible coordinated regulation by shared regelems (regulatory elements). We found it informative to use this novel web tool for identifying, on a genomic scale, genes regulated by drug treatment. CONCLUSION: Improvement is needed in understanding the nature of the mutations responsible for controlling the maturation process and how these genes regulate downstream effects if there is to be better targeting of chemical interventions. Expanded implementation of the techniques and results reported here may better direct future efforts to improve treatment for diseases not restricted to APL.

Cell Differentiation↗
PubMed2000

Efficacy of abciximab readministration in coronary intervention.

Abciximab, an Fab monoclonal antibody fragment that blocks the platelet glycoprotein IIb/IIIa receptor, is increasingly used as an adjunct to coronary intervention. Little is known, however, about the efficacy and safety of readministration of abciximab. This study examined and characterized outcomes of patients receiving abciximab for a second time. From April 1995 to June 1997, 164 consecutive patients were readministered abciximab at our 3 institutions. We retrospectively examined and analyzed in-hospital outcomes in this cohort. The median time to readministration was 95 days. The angiographic success rate of percutaneous intervention was 99.5%. Rates and 95% confidence intervals of in-hospital events were death 2% (0.7% to 6.1%), myocardial infarction 3% (1% to 7%), coronary bypass surgery 0% (0% to 2.2%), and intracranial hemorrhage 2% (0.4% to 5.3%). Severe thrombocytopenia was observed in 4% of patients (1.4% to 7.8%) after readministration. Allergic or anaphylactic reactions were not observed. Major bleeding was associated with excessive concomitant antithrombotic therapy. Patients undergoing readministration of abciximab within 2 weeks of first administration experienced a higher incidence of severe thrombocytopenia (12% vs. 2%, p = 0.046). Thus, abciximab remains clinically efficacious when readministered as an adjunct to percutaneous coronary intervention. However, concomitant heparin administration must be carefully monitored and warfarin therapy should be avoided. Vigilant surveillance for thrombocytopenia should be employed. Reduced dosing may be necessary when abciximab is readministered within days of the initial administration.

Abciximab↗
PubMed2000

Susceptibility to drug-induced apoptosis correlates with differential modulation of Bad, Bcl-2 and Bcl-xL protein levels.

To define the responses of apoptotic regulatory proteins to different chemotherapeutic agents, we investigated the expression of Bcl-2 family gene products, the release of cytochrome c, and the activation of pro-caspase-3 during apoptosis induced by Taxol and Thiotepa, in the MCF-7 breast carcinoma and the HL-60 leukemia cell lines. The earliest event induced by drug exposure was increase in Bad protein levels, followed by Bcl-2 down-regulation, cytochrome c release, and Bcl-xL and Bax up-regulation. Bak accumulation was a late event. Activation of pro-caspase-3 and cleavage of Bcl-2 protein occurred in the HL-60 cells only, and followed the cytochrome c release. The overall responses were qualitatively similar in both cell types, but MCF-7 cells treated with Taxol showed a significant delay in apoptosis, correlating with early up-regulation of Bcl-2 and delayed release of cytochrome c. We conclude that Bad up-regulation is an early indicator of a cellular response that will lead to cell death, but may be modulated by survival mechanisms, which cumulatively govern the ultimate susceptibility to apoptosis.

14-3-3 Proteins↗
PubMed2000

Outcome analysis of chest pain patients discharged from the ED--a pilot study.

The objective of this pilot study was to determine clinical predictors of adverse outcome, defined as myocardial infarction, angioplasy or stent placement, coronary artery bypass graft, or death, within 60 days for patients discharged from the emergency department with a presenting complaint of chest pain. All patients presenting to the emergency department with a chief complaint of chest pain were eligible for the study. A chest pain risk analysis sheet was completed as part of the patient evaluation. Patients discharged from the emergency department, in whom a risk analysis sheet was completed, were contacted to determine their clinical course within 60 days of their discharge from the emergency department. During the 6-month study period, 129 eligible patients were enrolled. Of these 129 patients, four had an adverse outcome within 60 days of their discharge. All four patients had either a balloon angioplasty procedure, coronary artery bypass graft, or both. None of the study patients had a myocardial infarction or died. Statistically significant predictors of adverse outcome in our study population were an abnormal electrocardiogram (ECG), a history of myocardial infarction, and a history of hypertension. In conclusion, patients discharged from the emergency department with a presenting complaint of chest pain were at a low risk for having a myocardial infarction or dying within 60 days of their discharge. Several patients, however, did have significant coronary artery disease requiring angioplasty or bypass. These patients were more likely to have an abnormal ECG, a history of myocardial infarction, or have a history of hypertension. A prospective study with larger numbers of patients is needed to validate these findings.

Adult↗
PubMed2000

Heart transplant center practice patterns affect access to donors and survival of patients classified as status 1 by the United Network of Organ Sharing.

OBJECTIVE: To determine the effect of adult cardiac transplant center practice patterns within a single organ procurement organization on access to donors and survival for patients listed as United Network of Organ Sharing (UNOS) status 1. METHODS: A total of 662 patients listed (January 1, 1992, through December 31, 1995) as UNOS status 1 for heart transplantation by the 4 adult cardiac transplant centers in an organ procurement organization were analyzed in a retrospective cohort study to determine differences in clinical outcomes. RESULTS: The specific center at which an individual was listed as UNOS status 1 was a significant independent predictor of receiving a transplant (odds ratios for 3 centers vs center with highest likelihood = 0.73, 0.64, 0.35, respectively; P <. 01). Only 1 center had a significantly increased mortality rate compared with the other centers (odds ratio 2.03, P <.01). CONCLUSION: Within a single regional organ procurement organization, cardiac transplant centers demonstrate significant variability in the likelihood of transplantation and survival for patients listed as UNOS status 1.

Adult↗
PubMed2000

Expression and prognostic significance of IAP-family genes in human cancers and myeloid leukemias.

Expression of several inhibitor of apoptosis proteins (IAPs) was investigated in the National Cancer Institute panel of 60 human tumor cell lines, and the expression and prognostic significance of one of these, XIAP, was evaluated in 78 previously untreated patients with acute myelogenous leukemia (AML). XIAP and cIAP1 were expressed in most cancer lines analyzed, with substantial variability in their relative levels. In contrast, NAIP mRNA was not detectable, and cIAP2 was found at the mRNA and protein levels in only 34 (56%) and 5 (8%) of the 60 tumor cell lines analyzed, respectively. Interestingly, XIAP, cIAP1, and cIAP2 mRNA levels did not correlate with protein levels in the tumor lines, indicating posttranscriptional regulation of expression. High levels of XIAP protein in tumor cell lines were unexpectedly correlated with sensitivity to some anticancer drugs, particularly cytarabine and other nucleosides, whereas higher levels of cIAP1 protein levels were associated with resistance to several anticancer drugs. The relevance of XIAP to in vivo responses to cytarabine was explored in AML, making correlations with patient outcome (n = 78). Patients with lower levels of XIAP protein had significantly longer survival (median, 133 versus 52.5 weeks; P = 0.05) and a tendency toward longer remission duration (median, 87 versus 52.5 weeks; P = 0.13) than those with higher levels of XIAP. Altogether, these findings show that IAPs are widely but differentially expressed in human cancers and leukemias and suggest that higher XIAP protein levels may have adverse prognostic significance for patients with AML.

Gene Expression Regulation, Neoplastic↗
PubMed1998

Expression and location of Hsp70/Hsc-binding anti-apoptotic protein BAG-1 and its variants in normal tissues and tumor cell lines.

BAG-1 is a multifunctional protein that blocks apoptosis and interacts with several types of proteins, including Bcl-2 family proteins, the kinase Raf-1, certain tyrosine kinase growth factor receptors, and steroid hormone receptors, possibly by virtue of its ability to regulate the Hsp70/Hsc70 family of molecular chaperones. Two major forms of the human and mouse BAG-1 proteins were detected by immunoblotting. The longer human and mouse BAG-1 proteins (BAG-1L) appear to arise through translation initiation at noncanonical CTG codons located upstream of and in-frame with the usual ATG codon used for production of the originally described BAG-1 protein. Immunoblotting experiments using normal tissues revealed that BAG-1L is far more restricted in its expression and is present at lower levels than the more prevalent BAG-1 protein. Human but not mouse tissues also produce small amounts of an additional isoform of BAG-1 of intermediate size (BAG-1M) that probably arises through translation initiation at yet another site involving an ATG codon. All three isoforms of human BAG-1 (BAG-1, BAG-1M, and BAG-1L) retained the ability to bind Hsc70. Subcellular fractionation and immunofluorescence confocal microscopy studies indicated that BAG-1L often resides in the nucleus, consistent with the presence of a nuclear localization sequence in the NH2-terminal unique domain of this protein. In immunohistochemical assays, BAG-1 immunoreactivity was detected in a wide variety of types of cells in normal adult tissues and was localized to either cytosol, nucleus, or both, depending on the particular type of cell. In some cases, cytosolic BAG-1 immunostaining was clearly associated with organelles resembling mitochondria, consistent with the reported interaction of BAG-1 with Bcl-2 and related proteins. Furthermore, experiments using a green fluorescence protein (GFP)-BAG-1 fusion protein demonstrated that overexpression of Bcl-2 in cultured cells can cause intracellular redistribution of GFP-BAG-1, producing a membranous pattern typical of Bcl-2 family proteins. The BAG-1 protein was found at high levels in several types of human tumor cell lines among the 67 tested, particularly leukemias, breast, prostate, and colon cancers. In contrast to normal tissues, which only rarely expressed BAG-1L, tumor cell lines commonly contained BAG-1L protein, including most prostate, breast, and leukemia cell lines, suggesting that a change in BAG-1 mRNA translation frequently accompanies malignant transformation.

Amino Acid Sequence↗
PubMed1998

Flavopiridol induces apoptosis of normal lymphoid cells, causes immunosuppression, and has potent antitumor activity In vivo against human leukemia and lymphoma xenografts.

Flavopiridol is a novel semisynthetic flavone derivative of the alkaloid rohitukine. Flavopiridol is known to inhibit potently the activity of multiple cyclin-dependent kinases. We have assessed its effects on normal and malignant cells in preclinical animal models of localized and disseminated human hematopoietic neoplasms. Flavopiridol, when administered as daily bolus intravenous (IV) injections, produced selective apoptosis of cells in the thymus, spleen, and lymph nodes, resulting in atrophy of these organs. With the exception of the intestinal crypts, apoptosis or tissue damage was absent in all other organs investigated (kidneys, liver, lungs, bone/bone marrow, muscle, and heart). Flavopiridol had a marked apoptotic effect documented by DNA nick-end labeling, or DNA agarose gels in xenografts of human hematopoietic tumors HL-60, SUDHL-4, and Nalm/6. After treatment with 7.5 mg/kg flavopiridol bolus IV or intraperitoneal on each of 5 consecutive days, 11 out of 12 advanced stage subcutaneous (s.c.) human HL-60 xenografts underwent complete regressions, and animals remained disease-free several months after one course of flavopiridol treatment. SUDHL-4 s.c. lymphomas treated with flavopiridol at 7.5 mg/kg bolus IV for 5 days underwent either major (two out of eight mice) or complete (four out of eight mice) regression, with two animals remaining disease-free for more than 60 days. The overall growth delay was 73.2%. The acquired immunodeficiency syndrome-associated lymphoma AS283 showed no significant response when flavopiridol was used in advanced s.c. tumors, but when treatment was initiated in early stages, there was a complete regression of the early tumors, and a significant overall growth delay (>84%). When flavopiridol was used in severe combined immunodeficient mice bearing disseminated human acute lymphoblastic leukemia Nalm/6 cells, there was 15-day prolongation in survival (P = .0089). We conclude that flavopiridol greatly influences apoptosis in both normal and malignant hematopoietic tissues. This activity was manifested in our study as a potent antileukemia or antilymphoma effect in human tumor xenografts, which was dose and schedule dependent. These findings provide compelling evidence for the use of flavopiridol in human hematologic malignancies.

Animals↗
PubMed1998

Expression and location of pro-apoptotic Bcl-2 family protein BAD in normal human tissues and tumor cell lines.

The BAD protein is a pro-apoptotic member of the Bcl-2 family whose ability to heterodimerize with survival proteins such as Bcl-X(L) and to promote cell death is inhibited by phosphorylation. Monoclonal antibodies were generated against the human BAD protein and used to evaluate its expression by immunoblotting and immunohistochemistry in normal human tissues and by immunoblot analysis of the National Cancer Institute anti-cancer drug screening panel of 60 human tumor cell lines. BAD protein was detectable by immunoblotting in many normal tissues, with testis, breast, colon, and spleen being among those with the highest steady-state levels. Immunostaining of tissues revealed many examples of cell-type-specific expression of BAD, suggesting dynamic regulation of BAD protein levels in vivo. In many types of normal cells, BAD immunoreactivity was associated with cytosolic organelles resembling mitochondria, suggesting that BAD is often heterodimerized with other Bcl-2 family proteins in vivo. The relative levels of BAD protein varied widely among established human tumor cell lines, with colon, lung, and melanomas generally having the highest expression. As a group, hematopoietic and lymphoid lines contained the least BAD protein. The BAD protein derived from 11 of 41 tumor lines that expressed this pro-apoptotic protein migrated in gels as a clear doublet, consistent with the presence of hyperphosphorylated BAD protein. Taken together, these findings define for the first time the normal cell-type-specific patterns of expression and intracellular locations of the BAD protein in vivo and provide insights into the regulation of this pro-apoptotic Bcl-2 family protein in human tumors.

Antibodies, Monoclonal↗
PubMed1997

Structure and origin of HIV type 1 DNA in persistently infected B lymphoblastoid cell lines.

The Epstein-Barr virus (EBV) and human immunodeficiency virus type 1 (HIV-1) can coinfect resting B cells, leading to EBV-carrying lymphoblastoid cell lines (LCLs) persistently infected with HIV-1. LCLs established from coinfected peripheral blood lymphocytes (PBLs) differed from LCLs derived from HIV-1-infected cell lines, in that the majority if not all of the cells expressed gp120 and a high percentage produced infectious HIV-1 after continuous passage for 6-9 months. Restriction analysis of the putative HIV-1 provirus revealed that persistently infected LCLs carried variable copies of primarily unintegrated circular and/or linear forms of HIV-1 DNA. This extrachromosomal location is strikingly different from that of the one to three copies of integrated proviral DNA deleted in persistently infected T cell and monocytic cell lines. Anti-gp120 monoclonal antibody and 3'-azido-3'-deoxythymidine (AZT) inhibited HIV-1 expression and reduced HIV-1 DNA copy number in persistently infected LCLs, supporting the hypothesis that unintegrated HIV-1 DNA accumulates primarily as a result of superinfection. We propose that the extrachromosomal location of the HIV-1 DNA contributes to the semipermissive nature of B cell infection by HIV-1.

Acyclovir↗
PubMed1997

A stereoselective cobalt-containing nitrile hydratase.

Nitrile hydratase from Pseudomonas putida NRRL-18668 has been purified and characterized. The purified enzyme catalyzes the hydration of 2(S)-(4'-chlorophenyl)-3-methylbutyronitrile at least fifty times faster than that of 2(R)-(4'-chlorophenyl)-3-methylbutyronitrile. This enzyme is a member of the class of nitrile hydratase that contains cobalt. Visible absorption and CD spectra suggest the cobalt exists as a non-corrin low-spin Co3+ ion in a tetragonally-distorted octahedral ligand field. Chemical reduction of the native enzyme results in a species with the EPR signature of a low-spin Co2+ complex. Like the other cobalt-containing nitrile hydratases, this enzyme is relatively stable, maintaining its activity below 35 degrees C, and it shows a broad activity optimum between pH 7.2 and 7.8. The structural genes for this enzyme have been cloned and sequenced. The deduced amino acid sequences for the alpha and beta subunits show 48-63% and 35-41% homology, respectively, to other sequenced nitrile hydratases. In particular, the cysteine residues in the alpha subunit that have been suggested to coordinate the metal ion in the iron-containing nitrile hydratases [Brennan, B. A., Cummings, J. G., Chase, D. B., Turner, I. M., Jr., & Nelson, M. J. (1996) Biochemistry 35, 10068-10077] are conserved in this enzyme, suggesting that this nitrile hydratase, like the enzyme from Rhodococcus rhodochrous J1, is a member of a newly described class of metalloenzymes with Co3+-thiolate ligation [Brennan, B. A., Alms, G., Nelson, M. J., Durney, L. T., & Scarrow, R. C. (1996) J. Am. Chem. Soc. 118, 9194-9195].

Amino Acid Sequence↗
PubMed1994

Review of nonparametric methods for the analysis of crossover studies.

This paper reviews nonparametric methods for the analysis of crossover studies. Primary attention is given to crossover studies to compare two treatments for a response variable that has a metric measurement level. For this situation, one can often test hypotheses or obtain confidence intervals for parameters of interest by applying well known univariate nonparametric rank methods (e.g., the Wilcoxon rank sum test, or the Wilcoxon signed rank test) to appropriately specified functions of the data. Related extensions are also available, to some degree, for crossover studies to compare more than two treatments or those for which the measurement level of the response variable is ordinal or has a censored time-to-event nature. Methods for several specific situations along these lines are discussed in terms of principles with potentially broader applicability. Several examples are provided to illustrate the performance of some of the methods.

Confidence Intervals↗
PubMed1992

Inactivation of the human immunodeficiency virus type 1 (HIV-1) by ultraviolet and X irradiation.

Here we report the kinetics of inactivation of HIV-1 by ultraviolet (UV) or X irradiation. Inactivation of HIV-1 by UV irradiation followed quasi first-order, i.e., single-hit, kinetics. The LD37 for inactivation of syncytia formation in SupT1 cells by limiting dilutions was approximately 780 J/m2. The LD37 for inactivation of HIV-1-induced syncytia by UV irradiation was nearly identical when measured in UV repair-proficient and -deficient lymphoblastoid cell lines (LCLs), demonstrating that immediate host cell reactivation (repair) of UV damage in the HIV-1 genome does not occur. The ability of HIV-1 to induce the accumulation of reverse transcriptase activity showed similar dose-dependent inhibition by UV irradiation (LD37, 845 J/m2). Inactivation of HIV-1-induced syncytia formation by X rays also approached first-order kinetics. The LD37 for syncytia formation as measured by limiting dilutions was approximately 3 x 10(3) Gy. HIV-1-induced accumulation of reverse transcriptase activity was slightly more resistant to inactivation by X rays, with an LD37 of approximately 4.5 x 10(3) Gy. Syncytia-forming ability was still present in HIV-1 preparations X-irradiated with 1.6 x 10(4) Gy. For the first time, we utilized the polymerase chain reaction (PCR) to measure the effects of radiation on virus replication. A decrease in the presence of the HIV-1 DNA could be detected by PCR in PBL cultures infected with UV- and X-irradiated virus. It required 12.96 J/m2 to eliminate the signal specific for HIV-1 DNA completely. The ability of HIV-1 to establish long-term infection in LCLs was also resistant to UV and X irradiation. Only linear and circular forms of HIV-1 DNA could be detected in LCLs established from PBL cultures infected with UV-irradiated virus. The significance of the relative resistance of HIV-1 to inactivation by UV and X irradiation is discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1982

Effect of 2-mercaptoethanol on pH gradients in isoelectric focusing.

When hydrophobic samples, or membrane proteins, are disaggregated in buffers containing detergents (e.g. Nonidet P-40), urea and 2-mercaptoethanol, and applied at the cathodic end of a gel cylinder or slab for isoelectric separation, as routinely performed for two-dimensional techniques, a severe disturbance of the alkaline region of the pH gradient ensues. This phenomenon has been attributed to high protein loads, which supposedly overcome the buffering power of isoelectric carrier ampholytes. On the contrary, in the present study it has been found that this suppression of the alkaline end of the pH gradient is due to 2-mercaptoethanol, which is a buffer with pK 9.5. This compound ionizes at the basic gel end and is driven electrophoretically along the pH gradient, sweeping away, along its path, the focused carrier ampholytes.

Amino Acids↗
PubMed1982

The effect of 2,6-bis(diethanolamino)-4-piperidinopyrimido [5,4-d]-pyrimidine (RA233) on growth, metastases and lung colony formation of B16 melanoma.

The dissemination of malignant cells from a primary tumor to distant host sites appears to be influenced by blood platelets of the hemostatic system. Under conditions that did not inhibit primary tumor growth, RA233 decreased both the incidence and frequency of spontaneous lung metastases by 66% and 69%, respectively. Although RA 233 effectively inhibited the formation of spontaneous metastases, oral administration of RA233 prior to and after the intravenous inoculation of 1 X 10(5) B16F10 murine melanoma cells failed to inhibit subsequent lung colony formation. These findings indicate that RA233 has antimetasttic activity, and that inhibition of platelet aggregation is not the sole determinant of this action.

Animals↗
PubMed1975

Investigations on the presence of antibodies to several flaviviruses in humans and some domestic animals in a biotope with a high frequency of migratory birds.

Data are reported on the presence of HAI antibodies to several flaviviruses (tick-borne encephalitis, West Nile, and Ntaya viruses) in humans and some domestic animals in a biotope with a high frequency of migratory birds. The results obtained prove the presence in humans of specific antibodies in a proportion of 11.8% to tick-borne encephalitis and of 25.5% to West Nile and Ntaya antigens. Among domestic animals it was only possible to detect antibodies to West Nile (4.9% in sheep, 4.1% in cattle, and 12% in goats) and to Ntaya antigens (1.9% in sheep, 1.6% in cattle, 8% in goats, and 13.9% in swine).

Animals↗